Biocompatible device and methods of making and using the same

Abstract

A device that may be used as a bone implant to help with the treatment of osteonecrosis. The device may include a scaffold, a cap attached to one end of the scaffold, and a base attached to the opposite end of the scaffold. The scaffold may have a cylindrical shape. The scaffold may include a first lattice structure that forms an outer surface of the scaffold and is cylindrical in shape to define an interior space.

Description

BIOCOMPATIBLE DEVICE AND METHODS OF MAKING AND USING THE SAMECROSS REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 574,235, which was filed Apnl 3, 2024, is titled BIOCOMPATIBLE DEVICE AND METHODS OF MAKING AND USING THE SAME, and is incorporated herein by reference in its entirety.FIELD

[0002] The present disclosure generally relates to an implant and a method of using the implant for treatment of osteonecrosis.BACKGROUND

[0003] Osteonecrosis of the femoral head (ONFH) is a painful, debilitating, progressive disease that affects younger individuals in their prime working years. ONFH results from interruption of the blood supply to the femoral head, which leads to the death of mesenchymal and hematopoietic lineage cells, collapse of the femoral head, and secondary degenerative arthritis. If diagnosed early in the disease when the femoral head is still round, the patient’s own femoral head can potentially be retained and not replaced by total hip replacement. One method of treatment is core decompression, which involves drilling one or more paths into the proximal femur (which may include the femoral intertrochanteric area, neck, and head) to encourage new bone formation and ingrow th of blood vessels. Implants may be inserted into the drill holes to provide structural support and guide tissue ingrowth. How ever, implant with sufficient osteogenic properties and load bearing capacity are not known.SUMMARY OF EMBODIMENTS

[0004] A device that may be used as a bone implant to help with the treatment of osteonecrosis. The device may include a scaffold, a cap attached to one end of the scaffold, and a base attached to the opposite end of the scaffold. The scaffold may have a cylindrical shape. The scaffold may include a first lattice structure that forms an outer surface of the scaffold and is cylindrical in shape to define an interior space. The scaffold may include a second lattice structure located within the interior space defined by the first lattice structure. The scaffold may comprise, or be formed from, a biodegradable material, such as zinc or a zinc alloy. The scaffold may have an axial stiffness of from about 0.5 GPa to about 5.0 GPa.

[0005] In some embodiments, the disclosure relates to a device comprising: a scaffold comprising a first end. a second end, and a longitudinal axis, the scaffold comprising: a first lattice structure formed from a first plurality of intersecting struts and defining a first cylindrical or substantially cylindrical shape, the first lattice structure having an outer surface that forms an exterior surface of the scaffold and an inner surface that defines an interior space; and at least one second lattice structure formed from a second plurality of intersecting struts that is located within the interior space defined by the first lattice structure; and wherein the scaffold comprises zinc or a zinc alloy. In some embodiments, the disclosure relates to a device comprising: a scaffold formed from zinc or a zinc alloy, the scaffold being cylindrical or substantially cylindrical, the scaffold being elongated along a longitudinal axis from a first end of the scaffold to a second end of the scaffold, the scaffold comprising: a first lattice structure comprising a plurality of axial sections, each of the plurality of axial sections comprising a plurality of first unit cells arranged circumferentially about the longitudinal axis, each of the first unit cells being a body-centered cubic unit cell, wherein the first lattice structure comprises an outer surface that forms an exterior surface of the scaffold and an inner surface that defines an interior space; and at least one second lattice structure located within the interior space defined by the first lattice structure; and a first cap coupled to the first end of the scaffold.

[0006] In some embodiments, the disclosure relates to a device comprising: a scaffold comprising zinc or a zinc alloy, the scaffold being cylindrical or substantially cylindrical in shape, and the scaffold being elongated along a longitudinal axis from a first end of the scaffold to a second end of the scaffold, the scaffold comprising: a first lattice structure comprising an outer surface that forms an exterior surface of the scaffold and an inner surface that defines an interior space, the first lattice structure comprising a plurality of first nodes and a plurality of first openings; and at least one second lattice structure located within the interior space defined by the first lattice structure, the second lattice structure comprising a plurality of second nodes and a plurality of second openings; wherein the each of the first nodes of the first lattice structure is radially aligned with one of the second nodes of the second lattice structure, and wherein each of the first openings of the first lattice structure is aligned with one of the second openings of the second lattice structure.

[0007] In some embodiments, the disclosure relates to a device comprising a scaffold comprising a first end, a second end, and a longitudinal axis, the scaffold comprising a first lattice structure formed from a first plurality of intersecting struts and defining a first cylindrical or substantially cylindrical shape, the first lattice structure having an outer surface that forms an exterior surface of the scaffold and an inner surface that defines an interior space;wherein the scaffold comprises zinc or a zinc alloy and wherein the axial stiffness of the device is from about 0.5 GPa to about 5.0 GPa.

[0008] In some embodiments, the disclosure relates to a method of making any of the devices mentioned in the preceding paragraphs. In some embodiments, the disclosure relates to a method of treating bone w eakness or osteonecrosis or a method of promoting osteogenesis using any of the devices mentioned in the preceding paragraphs.

[0009] Further areas of applicability of the embodiments become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the invention.BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:

[0011] FIG. 1 is a top perspective view of a device in accordance with an embodiment of the present invention;

[0012] FIG. 2 is a bottom perspective view of the device of FIG. 1;

[0013] FIG. 3 is a front view of the device of FIG. 1;

[0014] FIG. 4 is a close-up view of area IV of FIG. 2;

[0015] FIG. 5 is a cross-sectional view taken along line V-V of FIG. 3;

[0016] FIG. 6 is a cross-sectional view taken along line VI-VI of FIG. 3;

[0017] FIG. 7 is a view of a unit cell of the device of FIG. 1;

[0018] FIG. 8 is a front view of a device in accordance with another embodiment of the present invention;

[0019] FIG. 9 is a cross-sectional view taken along line IX-IX of FIG. 8

[0020] FIG. 10 is a front view of a device in accordance with a first alternative embodiment of the present invention;

[0021] FIG. 11 is a cross-sectional view taken along line XI-XI of FIG. 10;

[0022] FIG. 12 is a front view of a device in accordance with a second alternative embodiment of the present invention;

[0023] FIG. 13 is a front view of a device in accordance with a third alternative embodiment of the present invention;

[0024] FIG. 14 is a front view of a device in accordance with a fourth alternative embodiment of the present invention;

[0025] FIG. 15 is a front view of a human skeleton;

[0026] FIG. 16A is a close-up view of area XVI of FIG. 15 illustrating a hole being drilled into the femoral head. The grey shading in the joint is meant to depict a region of bone comprising osteonecrosis;

[0027] FIG. 16B is the close-up view of area XVI of FIG. 15 illustrating the device of FIG.1 being implanted into the hole drilled in FIG. 16A;

[0028] FIG. 16C is a schematic cross-sectional view illustrating the device of FIG. I implanted into the hole in the femoral head;

[0029] FIG. 17Ais a close-up view of area XVII of FIG. 15 illustrating a hole being drilled into the humeral head; and

[0030] FIG. 17B is the close-up view of area XVII of FIG. 15 illustrating the device of FIG. 1 being implanted into the hole drilled in FIG. 17 A. The area of grey shading in the bone is meant to depict a region of the bone comprising osteonecrosis.

[0031] FIG. 18 is a graph reporting on non-toxicity of zinc materials after surface treatment.DETAILED DESCRIPTION OF EMBODIMENTS

[0032] The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.

[0033] As used throughout, ranges are used as shorthand for describing each and every value that is within the range. Any value within the range can be selected as the terminus of the range. In addition, all references cited herein are hereby incorporated by reference in their entireties. In the event of a conflict in a definition in the present disclosure and that of a cited reference, the present disclosure controls.

[0034] Unless otherwise specified, all percentages and amounts expressed herein and elsewhere in the specification should be understood to refer to percentages by weight. The amounts given are based on the active weight of the material.

[0035]

[0036] Definitions

[0037] Unless otherwise defined herein, scientific and technical terms used in connection with the present disclosure shall have meanings that are commonly understood by those of ordinary skill in the art. The meaning and scope of the terms should be clear, however, in the event of any latent ambiguity, definitions provided herein take precedent over any dictionaryor extrinsic definition. Further, unless otherwise required by context, singular terms shall include pluralities and plural terms shall include the singular.

[0038] The description of illustrative embodiments according to principles of the present invention is intended to be read in connection with the accompanying drawings, which are to be considered part of the entire written description. In the description of embodiments of the invention disclosed herein, any reference to direction or orientation is merely intended for convenience of description and is not intended in any way to limit the scope of the present invention. Relative terms such as "lower." “upper,” “horizontal,” “vertical,” “above,” “below ” “up,” “down,” “top,” and “bottom” as well as derivatives thereof (e.g., “horizontally,” “downwardly,” “upwardly,” etc.) should be construed to refer to the orientation as then described or as shown in the drawing under discussion. These relative terms are for convenience of description only and do not require that the apparatus be constructed or operated in a particular orientation unless explicitly indicated as such.

[0039] Terms such as “attached,” “affixed,” “connected,” “coupled,” “interconnected,” and similar refer to a relationship wherein structures are secured or attached to one another either directly or indirectly through intervening structures, as well as both movable or rigid attachments or relationships, unless expressly described otherwise. Moreover, the features and benefits of the invention are illustrated by reference to the exemplified embodiments. Accordingly, the invention expressly should not be limited to such exemplary- embodiments illustrating some possible non-limiting combination of features that may exist alone or in other combinations of features; the scope of the invention being defined by the claims appended hereto.

[0040] The indefinite articles “a” and “an,” as used herein in the specification and in the claims, unless clearly indicated to the contrary, should be understood to mean “at least one.” The phrase “and / or,” as used herein in the specification and in the claims, should be understood to mean “either or both” of the elements so conjoined, i.e., elements that are conjunctively present in some cases and disjunctively present in other cases. Other elements may optionally be present other than the elements specifically identified by the “and / or” clause, whether related or unrelated to those elements specifically identified unless clearly indicated to the contrary. Thus, as a non-limiting example, a reference to “A and / or B,” when used in conjunction with open-ended language such as “comprising” can refer, in one embodiment, to A without B (optionally including elements other than B); in another embodiment, to B without A (optionally including elements other than A); in yet another embodiment, to both A and B (optionally including other elements); etc.

[0041] As used herein in the specification and in the claims, “or” should be understood to have the same meaning as “and / or’ as defined above. For example, when separating items in a list, “or” or “and / or” shall be interpreted as being inclusive, i.e., the inclusion of at least one, but also including more than one, of a number or list of elements, and, optionally, additional unlisted items. Only terms clearly indicated to the contrary, such as “only one of’ or “exactly one of,” or. when used in the claims, “consisting of.” will refer to the inclusion of exactly one element of a number or list of elements. In general, the term “or” as used herein shall only be interpreted as indicating exclusive alternatives (i.e. “one or the other but not both”) when preceded by terms of exclusivity, “either,” “one of,” “only one of,” or “exactly one of.” “Consisting essentially of,” when used in the claims, shall have its ordinary meaning as used in the field of patent law.

[0042] The term “about” is used herein to mean within the ty pical ranges of tolerances in the art. For example, “about” can be understood as about 2 standard deviations from the mean. According to certain embodiments, when referring to a measurable value such as an amount and the like, “about” is meant to encompass variations of ±20%, ±10%, ±5%, ±1%, ±0.9%, ±0.8%. ±0.7%. ±0.6%, ±0.5%, ±0.4%, ±0.3%. ±0.2% or ±0.1% from the specified value as such variations are appropriate to perform the disclosed methods. When “about” is present before a series of numbers or a range, it is understood that “about” can modify each of the numbers in the series or range.

[0043] The term “at least” prior to a number or series of numbers (e.g. “at least two”) is understood to include the number adjacent to the term “at least,” and all subsequent numbers or integers that could logically be included, as clear from context. When “at least” is present before a series of numbers or a range, it is understood that “at least” can modify each of the numbers in the series or range. Ranges provided herein are understood to include all individual integer values and all subranges within the ranges.

[0044] As used herein, the term “animal” includes, but is not limited to, humans and nonhuman vertebrates such as wild animals, rodents, such as rats, ferrets, and domesticated animals, and farm animals, such as dogs, cats, horses, pigs, cows, sheep, and goats. In some embodiments, the animal is a mammal. In some embodiments, the animal is a human. In some embodiments, the animal is a non-human mammal.

[0045] As used herein, the terms “comprising” (and any form of comprising, such as “comprise,” “comprises,” and “comprised”), “having” (and any form of having, such as “have” and “has”), “including” (and any form of including, such as “includes” and “include”), or“containing” (and any form of containing, such as “contains” and “contain”), are inclusive or open-ended and do not exclude additional, unrecited elements or method steps.

[0046] As used herein, the phrase “in need thereof’ means that the animal or mammal has been identified or suspected as having a need for the particular method or treatment. In some embodiments, the identification can be by any means of diagnosis or observation. In any of the methods and treatments described herein, the animal or mammal can be in need thereof. In some embodiments, the subject in need thereof is a human seeking prevention or treatment of osteonecrosis. In some embodiments, the subject in need thereof is a human diagnosed with a bone disorder. In some embodiments, the subject in need thereof is a human seeking treatment for osteonecrosis. In some embodiments, the subject in need thereof is a human undergoing treatment for osteonecrosis.

[0047] As used herein, the term “mammal” means any animal in the class Mammalia such as rodent (i.e., mouse, rat, or guinea pig), monkey, cat, dog, cow, horse, pig, or human. In some embodiments, the mammal is a human. In some embodiments, the mammal refers to any nonhuman mammal. The present disclosure relates to any of the methods or compositions of matter wherein the sample is taken from a mammal or non-human mammal. The present disclosure relates to any of the methods or compositions of matter wherein the sample is taken from a human or non-human primate.

[0048] As used herein, the term “subject,” “individual” or “patient,” used interchangeably, means any animal, including mammals, such as mice, rats, other rodents, rabbits, dogs, cats, swine, cattle, sheep, horses, or primates, such as humans. In some embodiments, the subject is a human seeking treatment for a bone disease. In some embodiments, the subject is a human diagnosed with osteonecrosis. In some embodiments, the subject is a human suspected of having an bone-related disorder. In some embodiments, the subject is a healthy human being. For treatment of those conditions which are specific for a type of subject, such as a human being, the term "patient" may be interchangeably used. In some instances, in the description of the present invention, the term "patient" will refer to human patients suffering from a particular disease or disorder. In some embodiments, the subject may be a human suspected of having or being identified as at risk to develop a type of a bon disorder. In some embodiments, the subject may be diagnosed as having at resistance to one or a plurality of treatments to treat a disease or disorder afflicting the subject.

[0049] As used herein, the terms “treat,” “treated,” or “treating” can refer to therapeutic treatment and / or prophylactic or preventative measures wherein the object is to prevent or slow down (lessen) an undesired physiological condition, disorder or disease, or obtain beneficial ordesired clinical results. For purposes of the embodiments described herein, beneficial or desired clinical results include, but are not limited to. alleviation of symptoms; diminishment of extent of condition, disorder or disease: stabilized (i.e., not worsening) state of condition, disorder or disease; delay in onset or slowing of condition, disorder or disease progression; amelioration of the condition, disorder or disease state or remission (whether partial or total), whether detectable or undetectable; an amelioration of at least one measurable physical parameter, not necessarily discernible by the patient; or enhancement or improvement of condition, disorder or disease. Treatment can also include eliciting a clinically significant response without excessive levels of side effects. Treatment also includes prolonging survival as compared to expected survival if not receiving treatment.

[0050] As used herein, the term "therapeutic" means an agent utilized to treat, combat, ameliorate or improve an unwanted condition or disease of a patient.

[0051] A “therapeutically effective amount” or “effective amount” of a composition is a predetermined amount calculated to achieve the desired effect, i.e., to treat, combat, ameliorate, prevent or improve one or more symptoms of osteonecrosis. The activity contemplated by the present methods includes both medical therapeutic and. as appropriate. The specific dose of a compound administered according to the present disclosure to obtain therapeutic and / or prophylactic effects will, of course, be determined by the particular circumstances surrounding the case, including, for example, the device implanted, the placement of the device, and the condition being treated. It will be understood that the effective amount of a compound or biologic administered will be determined by the physician in the light of the relevant circumstances including the condition to be treated, the choice of compound to be administered, and the chosen route of administration, and therefore the above dosage ranges are not intended to limit the scope of the present disclosure in any way. A therapeutically effective amount of compounds of embodiments of the present disclosure is typically an amount such that when it is administered in a physiologically tolerable excipient composition, it is sufficient to achieve an effective systemic concentration or local concentration in the tissue.

[0052] As used herein, the term “kit” refers to a set of components provided in the context of a device disclosed herein with an associated delivery system for a treatment of a subject with a bone disorder. Such deliver}' systems may include, for example, systems that allow for implanting the device into a subject, activation of the device, and / or various reagents (e.g., oligonucleotides, probes, extracellular matrix components etc. in appropriate containers) supporting materials (e.g.. buffers, media, cells, written instructions for performing the assay etc.) from one location to another. For example, in some embodiments, kits include one ormore enclosures (e.g., boxes) containing relevant reaction reagents and / or supporting materials. As used herein, the term “fragmented kit " refers to an implantation kit comprising two or more separate containers that each contain a subportion of total kit components. Containers may be used during a surgical procedure with an intended recipient together or separately. For example, a first container may contain a polysty rene guide or titanium guide, while a second container may contain the disclosed device. In some embodiments, the kit comprises a third container comprising a disinfectant solution and / or an element for application of the disinfection solution. As another example, the kit may comprise a first container comprising a device disclosed herein or a plurality of devices disclosed herein and a second container comprising any one or plurality' of reagents necessary for the detection and / or quantification of biomarkers (or probes) in a sample. In some embodiments, the probes are specific for osteogenic proteins. The term “fragmented kit” is intended to encompass kits containing Analyte Specific Reagents (ASR’s) regulated under section 520(e) of the Federal Food, Drug, and Cosmetic Act, but are not limited thereto. Indeed, any delivery system comprising two or more separate containers that each contain a sub-portion of total kit components are included in the term “fragmented kit.” In contrast, a “combined kit” refers to a delivery system containing all components in a single container (e g., in a single box housing each of the desired components). The term “kit” includes both fragmented and combined kits. Functions, operations, components and / or features described herein with reference to one or more embodiments, may be combined with, or may be utilized in combination with, one or more other functions, operations, components and / or features described herein with reference to one or more other embodiments, or vice versa.

[0053] Although the disclosure has been described with reference to exemplary embodiments, it is not limited thereto. Those skilled in the art will appreciate that numerous changes and modifications may be made to the preferred embodiments of the disclosure and that such changes and modifications may be made yvithout departing from the true spirit of the disclosure. It is therefore intended that the appended claims be construed to cover all such equivalent variations as fall within the true spirit and scope of the disclosure.

[0054] All referenced journal articles, patents, and other publications are incorporated by reference herein in their entireties.

[0055] Devices

[0056] Referring to FIGS. 1 through 6. a device 10 is illustrated in accordance with an embodiment of the present invention. The device 10 may be a bone implant that is configured to be positioned within a hole or cavity in a bone. The device 10 may be used for the treatmentof osteonecrosis. The device 10 may be configured to be positioned within a hole that is drilled into a bone to encourage new bone formation and guide tissue ingrowth and the ingrowth of blood vessels. The device 10 may be formed from laser powder bed fusion. The device 10 may comprise, or be formed from, biodegradable and biocompatible materials, and more specifically biodegradable metals such as including without limitation zinc, magnesium, copper, and iron and various combinations and alloys thereof. The device 10 may comprise, or be formed from, zinc or zinc alloys. The device 10 may comprise, or be formed from an alloy comprising zinc and magnesium. The device 10 may comprise no less than about 90%, or about 92%, or about 94%, or about 96%, or about 98% zinc as a w eight percent of a total weight of the device. In one embodiment, the device 10 may comprise no less than about 99% zinc and magnesium as a w eight percent of a total weight of the device. In some embodiments, the device 10 comprises about 90% zinc, about, 91% zinc, about 92% zinc, about, 94% zinc, about 95 % zinc, about 96% zinc, about 97% zinc, about 98% zinc, about 99% zinc, or about 100% zinc. In some embodiments, the device 10 comprises about 90% zinc to about, 91% zinc, about 92% zinc, about, 94% zinc, about 95 % zinc, about 96% zinc, about 97% zinc, about 98% zinc, about 99% zinc, or about 100% zinc. In some embodiments, a zinc alloy comprising about 90% zinc to about, 91% zinc, about 92% zinc, about, 94% zinc, about 95 % zinc, about 96% zinc, about 97% zinc, about 98% zinc, or about 99% zinc further comprises magnesium. In some embodiments, the percent magnesium is about 10%, about 9%, about 8%, about 7%, about 6%, about 5%. about 4%, about 3%. about 2$. about 1%, about 0.9%. about 0.8%, about 0.7%, about 0.6%, about 0.5%, about 0.4%, about 0.3%, about 0.2%, about 0.1 %. Additional alloys possible for the device may be found in Yang, H. et al. “Alloying design of biodegradable zinc as promising bone implants for load-bearing applications'’ (2020) Nature Communications 11, 401, which is incorporated herein by reference in its entirety’. In some embodiments, the device is biodegradable over a period of time. In some embodiments, the period is about 8 months to about 1 year, about 2 years, about 3 years, about 4 years, about 5 years, about 6 years, about 7 years, about 8 years, about 9 years, about 10 years, about 11 years, or about 12 years. In some embodiments, the period is established by degradation of the device in situ. In some embodiments, the degradation is about 0.14 mm / year. In some embodiments, the degradation is about 0.1 to about 0.11 , about 0.12, about 0.13, about 0.14, about 0.15, about 0.16, about 0.17, about 0.18 mm / year.

[0057] The device 10 may comprise a scafibld 100 having a first end 101 and a second end 102, a first cap 190 that is coupled to the first end 101 of the scaffold 100. and a second cap (or base) 191 that is coupled to the second end 102 of the scaffold 100. Each of the first and secondcaps 190. 191 may be solid and non-hollow. The first cap 190 and the second cap 191 may be free of any openings or apertures therein or therealong. The first cap 190 may form the insertion side of the device 10, meaning that the first cap 190 may be the first part of the device 10 to be inserted into a hole drilled into a bone during implantation. The second cap 191 may form a base of the device 10 such that the second cap 191 may be the last portion of the device 10 that is inserted into a hole during implantation.

[0058] The first cap 190 may be hemispherical shaped. The first cap 190 may comprise a lower surface 192 that is coupled to the first end 101 of the scaffold 100 and an upper surface193. The lower surface 192 may be flat or planar, and the upper surface 193 may be curved into a dome shape. Thus, the upper surface 193 may be a convex surface. In alternative embodiment, the first cap 190 may have other shapes, including having a flat / planar upper surface. The first cap 190 may be cylindrical rather than hemispherical in shape. Variations to the specific shape of the first cap 190 are possible within the scope of the invention described herein. For example, the shape of the first cap 190 may be designed to conform to bone it is in contact with after implantation such that it is supported. The first cap 190 may be solid. The outer surface of the first cap 190 may extend radially beyond the outer surface of the scaffold 110. Alternatively, the outer surface of the first cap 190 may be flush with at least a portion of the outer surface of the scaffold 110.

[0059] The second cap 191 may be in the shape of a truncated cone. The second cap 191 may have a lower surface 194, an upper surface 195. and a side surface 196. The lower surface 194 may be coupled to the second end 102 of the scaffold. The upper surface 195 may form a bottom-most surface of the device 10. The lower and upper surfaces 194, 195 may be flat and planar surfaces. The device 10 may be self-supporting with the upper surface 195 resting on a horizontal support structure (such as a table or desk or the like). The upper surface 195 may have an area that is less than an area of the lower surface 194. The side surfaces 196 may be angled so as to diverge moving in a direction from the upper surface 195 to the lower surface194. Thus, the second cap 191 may taper moving from the lower surface 195 to the upper surface 195. Alternative shapes for the second cap 191 may be used in accordance with alternative embodiments. For example, in one embodiment the second cap 191 may have the same shape as the first cap 190 (i.e., hemispherical shape). The first and second caps 190, 191 do not include a lattice structure, but are instead solid and non-hollow portions that form the opposing proximal and distal ends of the device 10.

[0060] The scaffold 100 may extend from the first end 101 to the second end 102 along a longitudinal axis A-A. The scaffold 100 (and also the device 10 generally) may be elongatedin a direction between the first and second ends 100. The scaffold 100 may have a length L measured from the first end 101 to the second end 102. In some embodiments, the length may be from about 50 millimeters (mm) to about 200 mm, more specifically from about 60 mm to about 160 mm, and still more specifically from about 70 mm to about 150mm. In some embodiments, the length may be from about 120 mm to about 160 mm, with the term “about” allowing for a tolerance of plus / minus 5%. Furthermore, the scalfold 100 may have a diameter D. The diameter D may be from about 2mm to about 10mm. or more specifically from about 3mm to about 9mm. Thus, the length L of the scaffold 100 is greater than the diameter D of the scaffold 100. The length L of the scaffold 100 may be at least seven or at least eight or at least nine or at least ten times greater than the diameter D of the scaffold 100. In some embodiments, the length L of the scaffold 100 may be at least fifteen or at least twenty times greater than the diameter D of the scaffold 100. In some embodiments, a ratio of the length to the width may be from about 6: 1 to about 60: 1 , or from about 10: 1 to about 50: 1 , or from about 15: 1 to about 40:1.

[0061] The scaffold 100 may form a generally cylindrical body. That is. the scaffold 100 may have a cylindrical, or substantially cylindrical, shape. The scaffold 100 may have a circular or substantially circular transverse cross-sectional shape along the entire length of the scaffold 100. Specifically, the scaffold 100 may have a generally circular transverse cross- sectional shape, although the circle may be wavy as shown in FIG. 6 and 9 rather than perfectly round. Stated another way, the scaffold 100 may comprise a circular cross-sectional area with a scalloped edge. The shape of the scaffold 100 may be consistent along the full length of the scaffold 100. The scaffold 100 may fit tightly within a hole that is pre-drilled into a bone as described herein so that the device 10 is supported against the wall of the orifice / hole within which it is inserted. Thus, the scalfold 100 may fit within a reference cylinder, such as the reference cylinder R1 shown in dashed lines in FIGS. 5 and 6. At least a portion of the exterior surface of the scaffold 100 may contact the reference cylinder Rl. Thus, if the reference cylinder Rl is representative of a wall surrounding a hole formed into a bone, a portion of the exterior surface of the scaffold 100 will be in contact with the wall surrounding the bone, thereby forming a tight fit between the device 10 and the bone.

[0062] The scaffold 100 may comprise a first lattice structure 110 and a second lattice structure 150. The first lattice structure 110 may comprise an outer surface 111 that defines the exterior surface of the scaffold 100 and an inner surface 112 that defines an interior space 113. The second lattice structure 150 may be located within the interior space 113 of the first lattice structure 110. In an embodiment, the first and second lattice structures 110, 150 may both becoupled to the first cap 190 and to the second cap 191. The first and second lattice structures 110, 150 may also be coupled to one another at discrete points. In other embodiments, the first and second lattice structures 110, 150 may both be coupled to the first and second caps 190, 191 but not to each other. In an alternative embodiment, one of the first and second lattice structures 110, 150 may be coupled to the first and second caps 190, 191, and the other of the first and second lattice structures 110. 150 may be coupled to the one of the first and second lattice structures 110, 150 without also being coupled to the first and second caps 190, 191.

[0063] The first lattice structure 110 may define a generally cylindrical body. That is, the outer surface 111 of the first lattice structure 110 may be generally curved into a round shape and the first lattice structure 110 may be elongated between the first and second ends 101, 102 of the scaffold 100. However, the outer surface 111 of the first lattice structure 110 may not define a perfectly circular shape in all embodiments. For example, as best seen in FIG. 6, the outer surface 111 of the first lattice structure 110 may have valleys and ridges in an undulating pattern. Thus, while not perfectly circular, this may still be considered to be a generally cylindrical body. As noted above, the first lattice structure 110 may fit tightly within the reference cylinder R1 so that at least some portions of the outer surface 111 of the first lattice structure 110 contact an inner surface of the reference cylinder R1. This ensures that the device 10 will fit tightly within a cylindrical hole that is bored into a bone, as described herein.

[0064] The first lattice structure 110 may comprise a first exterior lattice portion 125 and a first interior lattice portion 126. The first exterior lattice portion 125 of the first lattice structure 11 may comprise a first plurality of intersecting struts 115. The first plurality of intersecting struts 115 may form the outer surface 111 of the first lattice structure 110, which forms the exterior of the scaffold 100. The first plurality of intersecting structs 115 may collectively define the cylindrical or substantially cylindrical shape of the first lattice structure 110. The first plurality of intersecting structs 115 may comprise a plurality of first struts 116 and a plurality of second struts 117. The first and second struts 11 , 117 of the first plurality of intersecting struts 115 may be oriented at an angle from about 10° to about 75° relative to the longitudinal axis A- A. The angle may be modified to adjust various characteristics of the first lattice structure 110. The plurality of first struts 116 may be parallel to one another and may extend in a first helical direction from the second end 102 of the scaffold 100 to the first end 101 of the scaffold 100. The plurality of second struts 117 may be parallel to one another and may extend in a second helical direction from the second end 102 of the scaffold 100 to the first end 101 of the scaffold 100. For example, the first helical direction may be counterclockwise and the second helical direction may be clockwise. The plurality of secondstruts 117 may intersect the plurality' of first struts 116 at outer nodes 118 of the first lattice structure 110. The plurality of first and second struts 116. 117 may form a plurality of "X " shapes along the outermost band of the scaffold 100.

[0065] The outer nodes 118 of the first lattice structure 110 may be arranged in offset circumferential rows. Specifically, the first lattice structure 110 may comprise a plurality' of first rows 119 of the outer nodes 118 and a plurality of second rows 120 of the outer nodes 118 that alternate along a length of the scaffold 100 (with the length of the scaffold 100 being measured between the first and second ends 101, 102 of the scaffold 100). The outer nodes 118 in the first rows 119 may be circumferentially aligned with one another and the outer nodes 118 in the second rows 120 may be circumferentially aligned with one another. Furthermore, the outer nodes 118 in each of the first rows 119 may be axially aligned with one another and the outer nodes 118 in each of the second rows 120 may be axially aligned with one another. As such, a first axis parallel to the longitudinal axis A-A may intersect one of the outer nodes 118 in each of the first rows 119 and a second axis parallel to the longitudinal axis A-A may intersect one of the outer nodes 118 in each of the second rows 120. The outer nodes 118 of the first rows 119 may be circumferentially offset from the outer nodes 118 of the second rows 120. As such, the first axis will not intersect the outer nodes 118 of any of the second rows 120 and the second axis will not intersect the outer nodes 118 of any of the first rows 119.

[0066] Moreover, in the exemplified embodiment, the outer nodes 118 of the first rows 119 may be radially offset relative to the outer nodes 118 of the second rows 120. The outer nodes 1 18 of the first rows 119 may be located radially outward relative to the outer nodes 118 of the second rows 120 (i.e., the outer nodes 118 of the first rows 119 may be located further from the longitudinal axis A-A than the outer nodes 118 of the second row s 120). This is because, in the exemplified embodiment, each of the first struts 116 comprises a first linear portion 121 extending downwardly from the outer node 118 of the second rows 120 towards the second cap 191 and a second linear portion 122 extending upwardly from the outer node 118 of the second row s 120 tow ards the first cap 190. Each of the first and second linear portions 121, 122 of the first struts 116 may extend radially outward as it extends from the outer node 118 of the second row 120. Furthermore, each of the second struts 117 may comprise a first linear portion 123 extending downwardly from the outer node 118 of the second row 120 towards the second cap 191 and a second linear portion 124 extending upwardly form the outer node 118 of the second row' 120 towards the first cap 190. Each of the first and second linear portions 123, 124 of the second struts 117 may extend radially outward as it extends from the outer node 118 of the second row' 120. The first and second linear portions 121, 122, 123, 124 of the first and secondstruts 116, 117 may form a zig-zag pattern along the outer surface 111 so that the outer surface 111 has valleys at each of the second rows 120 of the outer nodes 118 and ridges at each of the first rows 119 of the outer nodes 118.

[0067] The first interior lattice portion 126 of the first lattice structure 110 may comprise a third plurality of intersecting struts 127. The third plurality of intersecting stmts 127 may comprise a plurality of first struts 128 that extend helically in the first direction and a plurality of second struts 129 that extend helically in the second direction. Each of the first and second struts 128, 129 of the third plurality of intersecting struts 127 may intersect with the first and second struts 116, 117 of the first plurality of intersecting stmts 115 at the outer nodes 118 of the second rows 120.

[0068] In the exemplified embodiment, the first lattice structure 110 comprises a plurality of first unit cells 130 that are arranged in a repeating fashion to form the first lattice structure 110. A representation of one of the first unit cells 130 is illustrated in FIG. 7 (along with a second unit cell that forms part of the second lattice structure 150, described in more detail below). The representation of the first unit cell 130 in FIG. 7 may include an exaggerated illustration of the nodes.

[0069] The first unit cell 130 may be a body-centered cubic unit cell. Thus, the first unit cell 130 may comprise eight arm members 131-138 that intersect at one of the nodes 118. More specifically, the eight arm members 131-138 of each unit cell 130 may intersect at one of the nodes 118 of the second row of nodes 120. The eight arm member 131-138 may extend at an angle from the node 1 18 so that if the first unit cell 130 were placed within a cube with the node 118 placed at the center of the cube, the distal ends of each of the arm members 131-138 would terminate at one of the interior comers of the cube. The nodes 118 of the first row of nodes 119 may be formed by the vertical stacking of the first unit cells 130. Specifically, the nodes 118 of the first row of nodes 119 may be formed by the intersection of the arm members 131-138 of one of the first unit cells 130 with one or more of the arm members 131-138 of one or more other ones of the first unit cells 130.

[0070] The arm members 131-138 of the unit cells 130 may correspond to the struts 116, 117, 128. 129 described above. That is, the arm members 132 and 133 form portions of the first struts 116, the arm members 131 and 134 form portions of the second struts 117, the arm members 135 and 138 form portions of the first struts 128, and the arm members 136 and 137 form portions of the second struts 129. Thus, the unit cells 130 may form both the first exterior lattice portion 125 and the first interior lattice portion 126 ofthe first lattice structure 110. Each of the first unit cells 130 may have a convex hull that fits snuggly into a cylinder.

[0071] The first lattice structure 110 may comprise a plurality of axial sections 140, with a height of each of the axial sections 140 being equal to a height of the first unit cells 130. Two of the axial sections 140 are identified in FIG. 3, it being appreciated that each single-high circumferential arrangement of the unit cells 130 forms one of the axial sections 140. A plurality7of the first unit cells 130 may be arranged in a side-by-side (or circumferentially adjacent) manner to form each of the axial sections 140, with each axial section 140 being cylindrical or substantially cylindrical in shape. For example, in the exemplified embodiment there are eight of the first unit cells 130 positioned side-by-side in a cylindrical arrangement to form each of the axial sections 140. Greater or fewer than eight of the first unit cells 130 may be used to form each axial section 140, depending on the diameter of the scaffold 100 and the size of each of the first unit cells 130. In the exemplified embodiment, there are ten of the axial sections 140, such that the first unit cells 130 are stacked ten high in the axial direction.

[0072] Thus, in the exemplified embodiment, each of the axial sections 140 comprises eight of the first unit cells 130 connected together to define a cylindrical or substantially cylindrical shape, and the scaffold 100 comprises ten of the axial sections 140. Variations to the number of first unit cells 130 in each axial section 140 and to the number of axial sections 140 are possible within the scope of the invention defined herein depending on the size of each of the first unit cells 130, the overall length of the scaffold 10, and other factors. For example, the height of each unit cell 130 may be increased, which will result in fewer axial sections to achieve the same overall length for the scaffold 100. Alternatively, the height of each unit cell 130 may be decreased, which will result in a greater number of axial sections to achieve the same overall length for the scaffold 100. Furthermore, the number of unit cells 130 that it takes to form each axial section may be adjusted by changing the angle of the various arm members of the unit cell 130, some examples of which are shown in FIGS. 8-14 and described briefly below.

[0073] The first lattice structure 110 may comprise a plurality of openings (or pores) 145. The openings 145 may be diamond-shaped. The openings 145 may have a length measured in the direction of the longitudinal axis A-A and a width measured in a direction transverse to the longitudinal axis A-A. At least one of the length and the width of each of the openings 145 should be at least 100pm. In some embodiments, the length and the width of each of the openings 145 should be at least 100pm. In some embodiments, at least one (or both) of the length and the width of each of the openings 145 may be in a range of 100pm to 300pm.

[0074] As noted above, the scaffold 100 may comprise the second lattice structure 150 in addition to the first lattice structure 110 described above. The second lattice structure 150 maybe located within the interior space 113 defined by the inner surface 112 of the first lattice structure 110. Thus, the second lattice structure 150 may be located radially inward of the first lattice structure 110. The second lattice structure 150 may extend axially from the first end 101 of the scaffold 100 to the second end 102 of the scaffold 100. In that regard, the second lattice structure 150 may be coupled directly to the first and second caps 190, 191.

[0075] The second lattice structure 150 may comprise an outer surface 151 that faces the first lattice structure 110 and an inner surface 152 opposite the outer surface 151. The inner surface 152 may define a central void 153 that extends axially along the entire length of the scaffold 100 from the first cap 190 to the second cap 191. The central void 153 may be cylindrical or substantially cylindrical in shape. The central void 153 may be cylindrical in shape with the outer surface of the cylinder being wavy or scalloped. The cross-sectional shape of the central void 153 may be generally circular or square or rectangular with a scalloped / wavy exterior. The central void 153 may define a central interior region of the scaffold 100 that is free of any lattice structure. The central void 153 may form a hollow interior region of the scaffold 100.

[0076] The second lattice structure 150 may define a second cylindrical or substantially cylindrical shape that is located within the interior space 113 defined by the first lattice structure 110. The second lattice structure 150 may comprise a second plurality of intersecting struts 155 comprising a plurality of third struts 156 and a plurality of fourth struts 157 that intersect the plurality of third stmts 156. Specifically, the plurality of third struts 156 may be parallel to one another and may extend in the first helical direction (counterclockwise) from the first end 101 of the scaffold 100 to the second end 102 of the scaffold 100. The plurality of fourth struts 157 may be parallel to one another and may extend in the second helical direction (clockwise) from the first end 101 of the scaffold 100 to the second end 102 of the scaffold 100. The plurality of fourth stmts 157 may intersect the plurality of first struts 156 at inner nodes 158 of the second lattice structure 150. Each of the inner nodes 158 may be radially aligned with one of the outer nodes 118 of the first lattice structure 110.

[0077] The second lattice structure 150 may be formed by a plurality of second unit cells 160. Each of the second unit cells 160 may be a body-centered cubic unit cell. Thus, the second unit cells 160 may comprise eight arm members 1 1-168 that intersect at one of the inner nodes 158. The eight arm member 161-168 may extend at an angle from the node 158 so that if the second unit cell 160 were placed within a cube with the node 158 placed at the center of the cube, the distal ends of each of the arm members 161-168 would terminate at one of the interior comers of the cube. The inner nodes 158 of the second lattice stmcture 150 maybe spaced radially from the outer nodes 118 of the first lattice structure 110. Thus, the structural makeup of the second lattice structure 150 may be the same as the first lattice structure 110. As such, certain details about the first lattice structure 110 may be applicable to the second lattice structure 150 even if such details are not provided specifically herein with reference to the second lattice structure 150 in the interest of brevity.

[0078] As best shown in FIG. 7, the first and second lattice structures 110. 150 may be coupled together. Specifically, the distal end of the arm member 137 of the first unit cell 130 may be coupled to the distal end of the arm member 163 of the second unit cell 160, the distal end of the arm member 138 of the first unit cell 130 may be coupled to the distal end of the arm member 164 of the second unit cell 160, the distal end of the arm member 135 of the first unit cell 130 may be coupled to the distal end of the arm member 161 of the unit cell 161, and the distal end of the arm member 136 of the first unit cell 130 may be coupled to the distal end of the arm member 162 of the second unit cell 160. This coupling ensures that the first and second lattice structures 110, 150 are coupled together while maintaining the outer and inner nodes 118, 158 in radial alignment and radially spaced apart from one another. In an alternative embodiment, the first and second lattice structures 110, 150 may not be coupled directly together, but instead may each be coupled to the first and second caps 190, 191 to form the integral scaffold 100.

[0079] Each of the axial sections 140 of the scaffold 100 may comprise a plurality of the first unit cells 130 that are in a generally cylindrical arrangement and a plurality of the second unit cells 160 that are in a generally cylindrical arrangement. The plurality of second unit cells 160 may be coupled to the plurality of first unit cells 130 in the manner described herein.

[0080] The first plurality of intersecting struts 115 that form the first lattice structure 110 may have a first thickness. The second plurality of intersecting struts 155 that form the second lattice structure 150 may have a second thickness. In some embodiments the first thickness may be greater than the second thickness so that the thickness of the struts 115, 155 decreases moving radially inward from the outer surface of the scaffold 100 to the inner surface of the scaffold 100. In some embodiments, the thickness of the scaffold 100 may be a gradient whereby the thickness decreases moving from the exterior surface of the scaffold 100 (formed by the outer surface 111 of the first lattice structure 110) to the inner surface of the scaffold 100 (formed by the inner surface 152 of the second lattice structure 150). Thus, for example, the arm members 131-134 of the first unit cell 130 may have a first thickness, the arm members 135-138 of the first unit cell 130 may have a second thickness that is less than the first thickness, the arm members 161-164 of the second unit cell 160 may have a third thicknessthat is less than the second thickness, and the arm members 165-168 of the second unit cell 160 may have a fourth thickness that is less than the third thickness. In some embodiments, the first thickness may be about 0.2mm and the fourth thickness may be 0.1mm. Thus, in some embodiments the struts 115, 155 that form the first and second lattice structures 110 may have a thickness gradient that decreases moving from the outer surface 111 of the first lattice structure 110 to the inner surface 152 of the second lattice structure 150 within a range of 0.1mm and 2.0mm, or 0.1mm and 1.0mm. or 0.1mm and 0.5mm. or 0.1mm and 0.4mm, or 0. 1mm and 0.3mm, or 0. 1mm and 0.2mm.

[0081] In some embodiments, a thickness of a particular strut may decrease along its length to achieve the thickness gradient. That is, the thicknesses of the various arm members 131- 138, 161-168 may not be constant, such that the thickness of the arm member 131-138. 161- 168 may decrease moving radially inward to create a thickness gradient for the scalfold 100. In still other embodiments, the intersecting struts 115, 155 may have a constant thickness. In some embodiments, the thickness of the struts 115, 155 may be the same such that there is no reduction in thickness or thickness gradient moving radially inward along the scaffold 100.

[0082] The second lattice structure 150 may compnse a plurality of openings 146. The openings 146 may be diamond-shaped. The openings 146 may have a length measured in the direction of the longitudinal axis A-A and a width measured in a direction transverse to the longitudinal axis A-A. At least one of the length and the width of each of the openings 146 should be at least 100pm. In some embodiments, the length and the width of each of the openings 146 should be at least 100pm. In some embodiments, at least one (or both) of the length and the width of each of the openings 146 may be in a range of 100pm to 300pm. Each of the openings 146 of the second lattice structure 150 may be at least partially radially aligned with one of the openings 145 of the first lattice structure 110. In some embodiments, each of the openings 146 of the second latice structure 150 may be fully radially aligned with one of the openings 145 of the first latice structure 110. In some embodiments, the openings 146 of the second latice structure 150 may be smaller than the openings 145 of the first latice structure 150 in at least one dimension. For example, the widths of the openings 146 may be smaller than the widths of the openings 145 while the lengths of the openings 145, 146 remain the same. Alternatively, the lengths of the openings 146 may be smaller than the lengths of the openings 145 while the widths of the openings 145, 146 remain the same. In other embodiments, the length and width of the openings 146 may be smaller than the length and width of the openings 145, respectively. In other embodiments the lengths and widths of the openings 145, 146 may be the same.

[0083] As best seen in FIG. 6, the scaffold 100 may be radially symmetric. As described herein, the device 10 including the scaffold 100 may be formed from a biodegradable material, such as zinc, magnesium, copper, iron, and alloys thereof. In some embodiments, the device 10 including the scaffold 100 may be formed from zinc or a zinc alloy. In some embodiments the zinc alloy is a zinc-magnesium alloy. In some embodiments, the scaffold 110 may be free of tantalum, cobalt-chromium (CoCr). stainless steel, titanium, metallic silicon, nickel, and / or alloys thereof. By forming the device 10 from a biodegradable material, the device 10 will degrade over time, making room for new bone grow th to allow more complete bone growth as bone fdls in the regions of degraded material from the device 10. The device 10 may be formed with tailored degradation rates, by, for example without limitation, altering the microstructure (grain size, grain boundaries, etc.), of the device 10 and / or altering the geometry of the structure (thickness of the struts and their connectivity). The structure may be tuned to meet specific criteria related to degradation rates. This may be accomplished by designing the device 10 to provide both the necessary mechanical and biological functionality. Furthermore, because the device 10 may be formed from Laser Powder Bed Fusion techniques, the device 10 may be readily customized to tune and optimize the device 10 for implantation to, among other things, treat ONFH. The density and gradient density of the scaffold 100 may allow" for tunability of desired biodegradation and load bearing capacity.

[0084] The scaffold 110 may have an axial stiffness of from about 0.2 GPa to about 5.0 GPa, or more specifically from about 0.5 GPa to about 5.0 GPa (with the term “about” including a tolerance of plus / minus 5%). This axial stiffness is comparable to that of the surrounding cancellous bone tissue when the device 10 is implanted in a bone as described herein. In some embodiments, the exterior surface and / or the interior surface of the scaffold 100 may comprise one or more layers or regions of carboxymethyl dextran or a salt thereof. In some embodiments, stiffness approximates the surrounding subchondral cancellous bone, which has a stiffness betw een from about 800 MPa to about 2.5 GPa. In some embodiments, the device comprises a max deflection estimated to remain in the elastic deformation mode (z.e., with no permanent deformation) of from about 300 to about 500 pm. In some embodiments, the max deflection estimated to remain in the elastic deformation mode is less if the devices are constrained tightly by the cavity" in the bone. In some embodiments, the max deflection is about from about 250 to about 450 pm, from about 200 to about 400 pm, from about 150 to about 350 pm, from about 100 to about 300 pm, or from about 50 to about 250 pm.

[0085] In some embodiments, the device 10 may be formed by performing laser powder bed fusion to three-dimensionally print one or a plurality of the devices 10 described herein. The device 10 may be heated to a temperature from about 80°C to about 500°C. Such a heat treatment may be used to remove and fix any plastic deformation in the device 10. After the heat treatment, the device 10 may be cooled to an ambient temperature. The device 10 may also be polished to a roughness of from about 0.5 micron to about 5.0 micron. In some embodiments, a polymer layer may be deposited on at least a portion of the exterior surface of the scaffold 100.

[0086] Referring to FIGS. 8 and 9, a device 20 is illustrated in accordance with an embodiment of the present invention. The device 20 is ven,' similar to the device 10. and thus much of the description above with regard to structure, material, characteristics, and properties is applicable to the device 20 and will not be repeated here in the interest of brevity, it being understood that the description above is applicable. The device 20 generally comprises a scaffold 200 having a first end 201 and a second end 202, a first cap 290 coupled to the first end 201, and a second cap 291 coupled to the second end 202. The scaffold 200 may be elongated between the first and second ends 201, 202 along a longitudinal axis B-B.

[0087] The scaffold 200 may comprise a first lattice structure 210 and a second lattice structure 250. The first lattice structure 210 may comprise an outer surface 211 and an inner surface 212, with the inner surface 212 defining and surrounding an interior space 213. The outer surface 211 may form an exposed exterior surface of the scaffold 200. The first lattice structure 210 may define a first cylindrical or substantially cylindrical shape. The second lattice structure 250 may be located within the interior space 213. Thus, the second lattice structure 250 may be circumferentially surrounded by the first lattice structure 210. The second lattice structure 250 may define a second cylindrical or substantially cylindrical shape. In an embodiment, the first and second lattice structures 210, 250 are both coupled to the first cap 290 and to the second cap 291. In some embodiments, the first and second lattice structures 210, 250 may be coupled together.

[0088] The first lattice structure 210 may be formed from a plurality of first unit cells 230 and the second lattice structure 250 may be formed from a plurality of second unit cells 260. The first and second unit cells 230, 260 may have a similar structure and geometric configuration to the first and second unit cells 130, 1 0 described with reference to the previous embodiment. The scaffold 210 may comprise a plurality of axial sections 240, each of the axial sections 240 being defined by the height of the first and second unit cells 230. 260. In the exemplified embodiment the scaffold 100 comprises ten of the axial sections. However, greateror fewer than ten of the axial sections 240 may be used in other embodiments. Furthermore, each of the axial sections 240 may comprise a plurality of the first unit cells 230 positioned in a circumferential arrangement to form an outer cylindrical portion of the scaffold 100 and a plurality of the second unit cells 260 positioned in a circumferential arrangement to form an inner cylindrical portion of the scaffold 100. In this embodiment, each axial section 240 may comprise four of the first unit cells 230 and four of the second unit cells 260, as best shown in FIG. 9. Thus, this embodiment differs from the device 10 and the scaffold 100 of the previous embodiment in that each axial section 240 comprises four of the unit cells 230, 260 whereas in the previous embodiment each axial section 140 included eight of the unit cells 130, 160.

[0089] Furthermore, in this embodiment the various arm members of the first and second unit cells 230, 260 of the first and second lattice structures 230. 260 may be curved or arcuate, whereas in the device 10 the arm members are more linear. Thus, in this embodiment the outer surfaces of the arm members of the first and second unit cells 230, 260 may be convex and the inner surfaces of the arm members of the first and second unit cells 230, 260 may be concave. This may further enhance the cylindrical shape of the scaffold 200, as shown in FIG. 9.

[0090] The scaffold 200 may have a diameter which is similar to the diameter of the scaffold 100, despite fewer of the unit cells 230, 260 being used to form the cylindrical shape. To that end, the orientation / angle of the arm members of the unit cells 230, 260 may be different in the scaffold 200 as compared to the scaffold 100. In particular, the arm members of the unit cells 230, 260 are oriented at an angle relative to the longitudinal axis B-B which is greater than the angle at which the arm members of the unit cells 130, 160 of the previous embodiment are oriented relative to the longitudinal axis A- A.

[0091] Referring to FIGS. 10 and 11, yet another embodiment of a device 30 is illustrated in accordance with an embodiment of the present invention. The device 30 is similar to the devices 10, 20 except for the differences described herein. Thus, much of the description of the devices 10, 20 including with regard to the structure, material, and the like is applicable to the device 30.

[0092] The device 30 generally comprises a scaffold 300 that is elongated along a longitudinal axis C-C from a first end 301 to a second end 302, a first cap 390 coupled to the first end 301, and a second cap 391 coupled to the second end 302. The scaffold 300 may comprise a first lattice structure 310 and a second lattice structure 350. The first and second lattice structures 310, 350 may each be coupled to the first cap 390 and to the second cap 391. The first and second lattice structures 310, 350 may be coupled to one another, as has been described above with reference to the previously described embodiments.

[0093] The first lattice structure 310 may define a first cylindrical or substantially cylindrical shape. The first lattice structure 310 may comprise an outer surface 311 and an inner surface 312 that defines an interior space 313. The second lattice structure 350 may be located within the interior space 313 defined by the first lattice structure 310. The second lattice structure 350 may be circumferentially surrounded by the first lattice structure 310. The first lattice structure 310 may define a cylindrical or substantially cylindrical shape.

[0094] The first lattice structure 310 may be formed from a plurality of first unit cells 330 and the second lattice structure 350 may be formed from a plurality of second unit cells 360. The scaffold 300 may comprise a plurality of axial sections 340, with each axial section 340 being defined by a height of the first and second unit cells 330. 360. In the exemplified embodiment, the scaffold 300 comprises ten of the axial sections 340, although greater or fewer than ten axial sections 340 may be used in other embodiments. Each of the axial sections 340 may comprise a plurality of the first unit cells 330 that collectively define a cylindrical or substantially cylindrical shape and a plurality of the second unit cells 360 that are surrounded by the plurality of the first unit cells 330.

[0095] In this embodiment, there are six of the first unit cells 330 and six of the second unit cells 360 in each of the axial sections 340. Thus, while the structure of the scaffold 300 is similar to the scaffolds 200, 100 previously described, the scaffold 300 differs from the scaffolds 200, 100 in that each axial section comprises six of the unit cells 330, 360 whereas in the prior embodiment the scaffold 200 comprises four of the unit cells 230, 260 and the scaffold 100 comprises eight of the unit cells 130, 160.

[0096] FIG. 12 illustrates a device 40 comprising a scaffold 400, a first cap 490, and a second cap 491. FIG. 13 illustrates a device 50 comprising a scaffold 500, a first cap 590, and a second cap 591. FIG. 14 illustrates a device 60 comprising a scaffold 600, a first cap 690, and a second cap 691. The discussion of the first and second caps 190, 191 is applicable to the caps 490, 491, 590, 591, 690, 691 in these embodiments. These embodiments merely illustrate additional alternative embodiments for the scaffolds 400, 500, 600 whereby different numbers of the unit cells are present within each axial section and whereby the scaffolds 400, 500, 600 include different numbers of the axial sections. The general concepts related to the structure and material of the scaffolds 100, 200, 300 provided above is applicable to the scaffolds 400, 500, 600, with the only difference being the size and dimensions of the unit cells used to form the scaffolds 400, 500, 600.

[0097] The scaffolds 500, 600 may comprise lattice structures that are formed from interleaved helixes rather than body-centered cubic unit cells. The scaffold 500 may comprisea first lattice structure 510 having a cylindrical or substantially cylindrical shape that defines an interior space. The scaffold 500 may not include any second lattice structure located within the interior space. The first lattice structure 10 may be formed by interleaved helical struts. Specifically, the first lattice structure 510 may comprise a plurality of first helical struts 511 that extend in a first helical direction (counterclockwise) and a plurality of second helical struts 512 that extend in a second helical direction that is opposite the first helical direction (clockwise). The first and second helical struts 511, 512 may intersect one another at nodes 513. The first and second helical struts 511, 512 may define openings 514. The openings 514 may be diamond shaped, although other shapes may be used in other embodiments.

[0098] The scaffold 600 may comprise a first lattice structure 610 having a cylindrical or substantially cylindrical shape that defines an interior space. The scaffold 600 may comprise a second lattice structure 610 located within the interior space defined by the first lattice structure 610. The second lattice structure 650 may have a cylindrical or substantially cylindrical shape. Thus, the first lattice structure 610 may circumferentially surround the second lattice structure 650. The first and second lattice structures 610, 650 may both extend between and be connected to the first and second caps 690, 691. In some embodiments, the first and second lattice structures 610, 650 may not be directly coupled to one another. In other embodiments, the first and second lattice structures 610, 650 may be directly coupled to one another.

[0099] The first and second lattice structures 610, 650 may be formed by interleaved helical struts. The first lattice structure 610 may comprise a plurality of first helical struts 611 that extend in a first helical direction (counterclockwise) and a plurality of second helical struts 612 that extend in a second helical direction that is opposite the first helical direction (clockwise). The first and second helical struts 611, 612 may intersect one another at nodes 613. The first and second helical struts 611, 612 may define openings 614. The openings 614 may be diamond shaped, although other shapes may be used in other embodiments. The second lattice structure 650 may comprise a plurality of first helical struts 651 that extend in the first helical direction and a plurality of second helical struts 652 that extend in the second helical direction. The first and second helical struts 651, 652 may intersect one another at nodes. The first and second helical struts 651, 652 may define openings 654 which may be diamond shaped although other shapes may be used.

[0100] In an alternative embodiment, a device may be formed that includes a scaffold having a first (or outer) lattice structure and a second (or inner) lattice structure that is surrounded by the first lattice structure. The first lattice structure may have a cylindrical orsubstantially cylindrical shape, and the second lattice structure may be located within an interior space defined by and surrounded by the first lattice structure. One of the first and second lattice structures may be formed from helical struts as described above with reference to FIGS. 13 and 14, and the other one of the first and second lattice structures may be formed from body-centered cubic unit cells as described above with reference to FIGS. 1-7. Thus, various combinations of the different lattice structures described herein may be used in accordance with embodiments of the invention.

[0101] FIG. 15 illustrates a human skeleton, with close-up illustrations of portions thereof provided in FIGS. 16A-17B. Specifically, FIGS. 16A and 16B are close-up illustrations of the hip joint and FIGS. 17A and 17B are close-up illustrations of the shoulder joint. In some embodiments the subject who may benefit from having one of the devices 10, 20, 30, 40, 50, 60 described herein implanted into his / her bone may be between 20 and 50 years of age. However, the devices and techniques described herein may also be used for people outside of this age range.

[0102] Referring now to FIGS. 16A and 16B, the use and / or implantation of the device 10 (or any of the other devices 20, 30, 40, 50, 60) described above into the proximal femur will be described. In some embodiments, the device 10 is configured to be implanted adjacent to regions of osteonecrosis in the femoral head of a subject. The first step in the process may be to drill a hole 901 into the proximal femur 902, as shown in FIG. 16 A. An orthopedic drill 900 may be used to drill the hole 901 into the proximal femur 902. The hole 901 may be drilled into the femoral head. The process of drilling the hole 901 into the proximal femur 902 may remove tissue from the proximal femur 902 to create a cavity (i.e., the hole 901) into which the device 10 may be implanted. The cavity or the hole 901 may be cylindrical or substantially cylindrical in shape.

[0103] Next, the device 10 may be inserted into the pre-drilled hole 901. Upon the device 10 being fully seated within the hole 901, the device 10 is implanted within the bone (i.e., the femur) of the subject. Because the device 10 is formed from a biodegradable material, the device 10 will degrade over time as new bone growth takes place. In some embodiments, the device 10 may be configured to degrade over a time penod sufficient to allow enhanced vascularization proximate to the exterior surface of the scaffold 100 of the device 10. In some embodiments, the period of time may be from about 6 months to about 10 months after the device 10 is exposed to the bone of the subject. In some embodiments, a steroid or a salt may be administered to the subject before, during, or after implantation of the device 10 as described herein.

[0104] As above, hole 901 may be drilled into the femoral head and the device 10 implanted through the hole 901 and into a volume created by the drill, also interchangeably identified as a drill bed. In some embodiments, the drill bed comprises a substantially cylindrical volume in a subject’s bone, such that the cap head of one end of the device 10 (exemplified in a nonlimiting fashion by 290, 390, 490, or 590) is proximate to or seated immediately adjacent to the internal surface of the volume most distal from the hole 901. In some embodiments, the cap in this position is cap 190. 290, 390, or 490. In some embodiments, the end of the volume is within the femoral head. In some embodiments, the end of the volume is within healthy tissue. In some embodiments, the volume comprises at least one region of osteonecrotic tissue. In some embodiments, the end of the volume or drill bed proximate to the joint by about 1, 2, 3, 4, 5, 6. 7, 8, 9. 10. 11. or 12 millimeters (mm) from the outer surface of the femur head and proximate to the joint of the subject. In some embodiments, the volume or drill bed is at position within of from about 1 mm to about 20 mm, from about 1 mm to about 15 mm, from about 1 mm to about 12 mm, from about 1 mm to about 11 mm, from about 1 mm to about 10 mm, from about 1 mm to about 9 mm, from about 1 mm to about 8 mm, from about 1 mm to about 7 mm, from about 1 mm to about 6 mm. from about 1 mm to about 5 mm, from about 2 mm to about 20 mm, from about 2 mm to about 15 mm, from about 2 mm to about 10 mm, from about2 mm to about 9 mm, from about 2 mm to about 8 mm, from about 2 mm to about 7 mm, from about 2 mm to about 6 mm, from about 2 mm to about 5 mm, from about 2 mm to about 4 mm, from about 2 mm to about 3 mm, from about 3 mm to about 20 mm. from about 3 mm to about 15 mm, from about 3 mm to about 10 mm, from about 3 mm to about 9 mm, from about 3 mm to about 8 mm, from about 3 mm to about 7 mm, from about 3 mm to about 6 mm, from about3 mm to about 5 mm, from about 3 mm to about 4 mm, from about 4 mm to about 20 mm, from about 4 mm to about 20 mm, from about 4 mm to about 20 mm, from about 4 to about, from about 4 mm to about 12 mm, from about 4 mm to about 10 mm, or from about 4 mm to about 9 mm from the most proximate position of the volume or drill bed to the outer surface of the femur head proximate to the joint of a subject. In some embodiments, the of the hole 901 is about 1, 2, 3, 4. 5, 6, 7, 8. 9, 10, 11. or 12 mm from the edge of the bone. In some embodiments, a method of placing or implanting the device comprises: (a) drilling a hole into the femoral or humoral end of a subject, the end proximate to the hip joint or shoulder joint, respectively. In some embodiments, the method further comprises: (b) placing the device through the hole 901 and at a position from about 1 to about 12 mm from the end of the femoral or humoral head proximate to the joint and within a region of bone comprising osteonecrotic tissue. In some embodiments, the method comprises (b) placing the device through the hole 901 and at aposition from about 1 to about 20 mm from the end of the bone proximate to the joint. In some embodiments, the method comprises (b) placing the device through the hole 901 and at a position from about 1 to about 15 mm from the end of the bone proximate to the joint. In some embodiments, the method comprises (b) placing the device through the hole 901 and at a position from about 1 to about 10 mm from the end of the bone proximate to the joint. In some embodiments, the method comprises (b) placing the device through the hole 901 and at a position from about 1 to about 5 mm from the end of the bone proximate to the joint. In some embodiments, the method comprises (b) placing the device through the hole 901 and at a position about 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 mm from the end of the bone proximate to the joint.

[0105] FIGS. 16A and 16B illustrate the hole 901 at a particular angle, and thus the device 10 may be implanted at a particular angle relative to a longitudinal axis of the bone coinciding with its longest dimension lengthwise. The angle at which the hole is drilled relative to the longitudinal axis, and thus where the device 10 is implanted, may be considered in reference to the longitudinal axis of the shaft of the femur or humerus. In some embodiments the angle is from about 10° to about 80° from the longitudinal axis. In some embodiments, the angle is from about 20° to about 60° from the longitudinal axis. In some embodiments the angle is one within (endpoints inclusive) about 10 to about 80°, 20 to about 80°, 30 to about 80°, 40 to about 80°, 45 t about 80°, 50 to about 80°, 55 to about 80°, 60 to about 80°, 65 to about 80°, 70 to about 80°, or from about 75 to about 80° from the longitudinal axis with the longest dimension. In some embodiments the angle is one within (endpoints inclusive) about 10 to about 70°. from about 20 to about 70°, from about 30 to about 70°, from about 40 to about 70°, from about 45 to about 70°, from about 50 to about 70°, from about 55 to about 70°, from about 60 to about 70°, or from about 65 to about 70° from a longitudinal axis within longest dimension of the shaft. In some embodiments the angle is one within (endpoints inclusive) about 10 to about 60°, 20 to about 60°, 30 to about 60°, 40 to about 60°, 45 to about 60°, 50 about 60°, or 55 to about 60°. In some embodiments the angle is one within (endpoints inclusive) about 10 to about 50°, 20 to about 50°, 30 to about 50°, 40 to about 50°, or from about 45 to about 50° from the longitudinal axis. In some embodiments the angle is one within (endpoints inclusive) about 10- 40°, 20-40°, or 30-40° from the longitudinal axis. In some embodiments the angle is one within (endpoints inclusive) about 10-30° or 20-40° from the longitudinal axis. In some embodiments the angle is one within about 10-20° from the longitudinal axis.

[0106] FIGS. 16A and 16B illustrate the cap at the end of hole 901 with a hemispherical shape. Similarly, caps 190, 290. 390, and 490 in FIGS. 1-5. 8, 10, and 12-14 are illustrated with a hemispherical shape. A cap at this position of an implant herein may, however, have analternate shape. In some embodiments, a cap at this position of an implant herein has a shape adopting either a smaller or larger portion of a sphere than a hemisphere. In some embodiments, a cap at this position of an implant herein has a shape selected from conical, frustoconical, rhombohedral, or triangular. In some embodiments, a cap at this position of an implant herein is solid in that the material of the cap occupies the entire geometrical shape of the cap. In some embodiment, a cap at this position of an implant herein is a shell in that the material of the cap occupies the outer surface of the geometrical shape of the cap but a portion of the interior of the geometric shape is empty or occupied by a different material. In some embodiments, the cap includes openings such that a material may penetrate into the cap. In some embodiments, the cap includes openings such that a material may penetrate through the cap. The openings may represent 0.5, 1. 2, 3, 4, 5, 6, 7, 8. 9, 10, 15, 20. 25. 30. 40, or 50 percent of the volume of the cap. The openings may represent a percent of the volume of the cap between any two of 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 40, and 50. In some embodiments, the material of a cap at this position of an implant herein has a density similar to that of bone. In some embodiments, the material of a cap at this position of an implant herein has a density greater than that of bone. In some embodiments, the material of a cap at this position of an implant herein has a density of materials used in implants. The density, in some embodiments, is the density of zinc, magnesium, copper, and iron and various combinations and alloys thereof. The density, in some embodiments, is the density of zinc or zinc alloys. The density, in some embodiments, is the density of an alloy comprising zinc and magnesium. The density, in some embodiments, is the density of an alloy comprising about 90%, or about 92%, or about 94%, or about 96%, about 98% or about 99% zinc as a weight percent of a total weight of the device. The alloy may comprise zinc with magnesium making the remainder of the weight percent of the alloy.

[0107] FIG. 16C is a cross-sectional view illustrating the device 10 implanted within the hole 901 in the proximal femur (i.e., the femoral head) 902. The hole 901 is defined by an inner wall 903 of the femur. The device 10 is implanted so that portions of the outer surface 111 of the first lattice structure 110 (which forms the exterior of the scaffold 100) are in contact with the inner wall 903 of the hole 901. The device 10 may therefore be supported against the inner w all 903 of the hole / orifice 901 w here it is inserted / implanted. Thus, there is a snug or tight fit achieved betw een the device 10 and the hole 901.

[0108] FIGS. 17A-17B illustrate the device 10 being implanted into a proximal humerus 910 of a subject. Specifically, in FIG. 17A an orthopedic drill 911 is used to form a hole 912 into the proximal humerus 910, such as the humeral head. Next, as shown in FIG. 17B, thedevice 10 may be inserted into the hole 912. This illustrates that the device 10 (and any of the other devices described herein) may be used not only in the femur, but in any bone location where a patient may have osteonecrosis.

[0109] Next, the device 10 may be inserted into the pre-drilled hole 912. Upon the device 10 being fully seated within the hole 912, the device 10 may is implanted within the bone (i.e., the humerus) of the subject. Because the device 10 is formed from a biodegradable material, the device 10 will degrade over time as new bone growth takes place. In some embodiments, the device 10 may be configured to degrade over a time period sufficient to allow enhanced vascularization proximate to the exterior surface of the scaffold 100 of the device 10. In some embodiments, the period of time may be between 6 months and 10 months after the device 10 is exposed to the bone of the subject. In some embodiments, a steroid or a salt may be administered to the subject before, during, or after implantation of the device 10 as described herein.

[0110] As above, hole 912 may be drilled into the humeral head and the device 10 implanted through the hole 912 and into a volume created by the drill, also interchangeably identified as a drill bed. In some embodiments, the drill bed compnses a substantially cylindrical volume in a subject’s bone, such that the cap head of one end of the device 10 (exemplified in a non-limiting fashion by 290, 390, 490, or 590) is proximate to or seated immediately adjacent to the internal surface of the volume most distal from the opening of the hole 912. In some embodiments, the cap in this position is cap 190. 290, 390, or 490. In some embodiments, the end of the volume is within the femoral head. In some embodiments, the end of the volume is within healthy tissue. In some embodiments, the volume comprises at least one region of osteonecrotic tissue. In some embodiments, the end of the volume is proximate to the joint by about 1, 2, 3, 4, 5, 6, 7. 8, 9, 10, 11, or 12 millimeters (mm) from the outer surface of the humeral head and proximate to the joint of the subject. In some embodiments, the end of the volume is at position from about 1 mm to about 20 mm, from about 1 mm to about 15 mm, from about 1 mm to about 12 mm, from about 1 mm to about 11 mm, from about1 mm to about 10 mm, from about 1 mm to about 9 mm, from about 1 mm to about 8 mm, from about 1 mm to about 7 mm, from about 1 mm to about 6 mm, from about 1 mm to about 5 mm. from about 1 mm to about 4 mm, from about 1 mm to about 3 mm, from about 1 mm to about2 mm from about 2 mm to about 20 mm, from about 2 mm to about 15 mm, from about 2 mm to about 10 mm, from about 2 mm to about 9 mm, from about 2 mm to about 8 mm, from about 2 mm to about 7 mm, from about 2 mm to about 6 mm, from about 2 mm to about 5 mm. from about 2 mm to about 4 mm, from about 2 mm to about 3 mm, from about 3 mm to about 20mm, from about 3 mm to about 15 mm, from about 3 mm to about 10 mm, from about 3 mm to about 9 mm. from about 3 mm to about 8 mm, from about 3 mm to about 7 mm, from about 3 mm to about 6 mm, from about 3 mm to about 5 mm, from about 3 mm to about 4 mm, from about 4 mm to about 20 mm, from about 4 mm to about 20 mm, from about 4 mm to about 15 mm, from about 4 mm to about 12 mm, from about 4 mm to about 11 mm, from about 4 mm to about 10 mm, or from about 4 mm to about 9 mm from the most proximate position of the volume or drill bed to the outer surface of the humeral head proximate to the joint of a subject. In some embodiments, the of the hole 912 is about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12 mm into osteonecrotic tissue. In some embodiments, a method of placing or implanting the device comprises: (a) drilling a hole into the femoral or humoral end of a subject, the end proximate to the hip joint or shoulder joint, respectively. In some embodiments, the method further comprises: (b) placing the device through the hole 912 and at a position from about 1 to about 12 mm from the end of the femoral or humoral head proximate to the joint and within a region of bone comprising osteonecrotic tissue. In some embodiments, the method comprises (b) placing the device through the hole 912 and at a position from about 1 to about 20 mm from the end of the bone proximate to the joint. In some embodiments, the method comprises (b) placing the device through the hole 912 and at a position from about 1 to about 15 mm from the end of the bone proximate to the joint. In some embodiments, the method comprises (b) placing the device through the hole 912 and at a position from about 1 to about 10 mm from the end of the bone proximate to the joint. In some embodiments, the method comprises (b) placing the device through the hole 912 and at a position from about 1 to about 5 mm from the end of the bone proximate to the joint. In some embodiments, the method comprises (b) placing the device through the hole 901 and at a position about 1, 2, 3, 4, 5, 6, 7. 8, 9 or 10 mm from the end of the bone proximate to the joint.

[0111] While the figures illustrate the device 10 being used in the hip and shoulder joints, other uses for the device 10 may include treatment of osteonecrosis within other large joints such as the knee, elbow, wrist, and ankle.

[0112] FIGS. 16A. 16B, 17A, and 17B illustrate the cap at the end of hole 910 (FIGS. 16A and 16B) or 912 (FIGS. 17A or 17B) with a hemispherical shape. Similarly, caps 190. 290. 390, and 490 in FIGS. 1-5, 8, 10, and 12-14 are illustrated with a hemispherical shape. A cap at this position of an implant herein may, however, have an alternate shape. In some embodiments, a cap at this position of an implant herein has a shape adopting either a smaller or larger portion of a sphere than a hemisphere. In some embodiments, a cap at this position of an implant herein has a shape selected from conical, frustoconical, rhombohedral, or triangular.In some embodiments, a cap at this position of an implant herein is solid in that the material of the cap occupies the entire geometrical shape of the cap. In some embodiment, a cap at this position of an implant herein is a shell in that the material of the cap occupies the outer surface of the geometrical shape of the cap but a portion of the interior of the geometric shape is empty or occupied by a different material. In some embodiments, the cap includes openings such that a material may penetrate into the cap from the surface thereof. In some embodiments, the cap includes openings such that a material may penetrate through the cap. The openings may represent about 0.5, about 1, about 2, about 3, about 4, about 5, about 6, about 7, about 8, about9, about 10, about 15, about 20, about 25, about 30, about 40, or about 50 percent of the volume of the cap. The openings may represent a percent of the volume of the cap between any two of about 0.5, about 1, about 2, about 3, about 4, about 5, about 6, about 7, about 8, about 9, about10, about 15, about 20, about 25, about 30, about 40, and about 50. In some embodiments, the material of a cap at this position of an implant herein has a density similar to that of bone. In some embodiments, the material of a cap at this position of an implant herein has a density- greater than that of bone. In some embodiments, the material of a cap at this position of an implant herein has a density of materials used in implants. The density, in some embodiments, is the density of zinc, magnesium, copper, and iron and various combinations and alloys thereof. The density, in some embodiments, is the density7of zinc or zinc alloys. The density7, in some embodiments, is the density of an alloy comprising zinc and magnesium. The density, in some embodiments, is the density of an alloy comprising about 90%, or about 92%, or about 94%, or about 96%, about 98% or about 99% zinc as a weight percent of a total weight of the device. In some embodiments, the device comprises zinc and magnesium making the remainder of the weight percent of the alloy.

[0113] In some embodiments, the cap comprises a flat end at one or both ends, and, in such cases, a healthcare provider can utilize the end to push the cap, optionally assisted by a tool, into the hole and position the device in a place comprising osteonecrotic tissue. In some embodiments the cap comprises threads or a screw top that allows adjustable movement along the lengthwise axis of the device or removal from the end of the device. In such embodiments, the mostly cylindrical shape of the device comprises a screw or screw-compatible thread upon which one or both ends operably linked to the cap or caps.Methods

[0114] The disclosure relates to methods of treating or preventing osteonecrosis in a subject in need thereof comprising exposing the disclosed devices herein to bone cells or bone tissue. In some embodiments, the step of exposing comprises exposing one or more devices of thedisclosure into a bone cell or plurality of bone cells in vitro. In some embodiments, the method further comprises exposing the device or devices to one or a plurality of cell culture media. In some embodiments, the method further comprises exposing the device or devices to one or a plurality of reagents to induce bone cell growth or tissue structure at, proximate to or around the device. In some embodiments, the method further comprises exposing the device or devices to one or a plurality of cell culture media for a time period sufficient to induce bone cell growth or tissue structure at, proximate to or around the device. In some embodiments, the step of exposing comprises exposing one or more devices of the disclosure into a bone cell or plurality of bone cells in vivo by implanting one or more devices into the bone tissue of a subject.

[0115] The disclosure relates to the methods of treating osteonecrosis in a subject in need thereof comprising implanting the disclosed devices herein into the subject. In some embodiments, the methods further comprise exposing a femur of a subject, drilling a hole in the femur of a subject and placing one or more devices into the bone of the subject. In some embodiments, the methods further comprise allowing the device or devices to remain in the body of the subject for 1, 2, 3. 4, 5, 6. 7, 8, 9. 10 or more months. In some embodiments, the methods further comprise allowing the device or devices to remain in the body of the subject for 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or more years after implantation.

[0116] The disclosure relates to the methods of preventing osteonecrosis or preventing progression of osteonecrosis in a subject in need thereof comprising implanting the disclosed devices herein into the subject. In some embodiments, the methods further comprise exposing a femur of a subject, drilling a hole in the femur of a subject and placing one or more devices into the bone of the subject. In some embodiments, prior to drilling a hole in the bone of s subject, the bone is imaged for identifying where within the bone osteonecrotic regions exist. In some embodiments, the method comprises drilling or creating hole in the bone at a region comprising osteonecrotic regions. In some embodiments, the region comprising the osteonecrotic region is within about 150 mm from the edge of the bone proximate to the shoulder or hip joint. In some embodiments, the method comprises positioning a device disclosed herein into the hole at or proximate to or adjacent to a joint. In some embodiments, the methods further comprises allowing the device or devices to remain in the body of the subject for 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or more months. In some embodiments, the methods further comprise allowing the device or devices to remain in the body of the subject for 1, 2, 3, 4, 5, 6, 7. 8, 9, 10 or more years after implantation.

[0117] Methods of the disclosure include methods of implanting one of the disclosed devices into a mammal diagnosed with or suspected of having osteonecrosis. Implanting thedevices generally involves the insertion of the rod-shaped device into the head or epiphysus through a point located at the end of the bone. An osteotomy is made to create an entry site and, in some embodiments, after a suitable hole has been prepared, the device is inserted through the entry site and into the m edull ary canal. However, the size and shape of the device can make its insertion through the hole difficult. As the device may be smooth and may have a narrow diameter, the surgeon may not be able to achieve a tight grip on the rod in surgery. Furthermore, a large amount of force may be needed to push the rod into the hole and the rod may also need to be rotated along its axis or otherwise maneuvered to assist in insertion, which can all make insertion difficult. In addition, the location of the individual holes of the rod must be identified in order to place cross-members through the rod while it is in place within the hole.

[0118] A variety of insertion systems have been developed in order to facilitate orthopedic implant placement in performing surgery. The use of such insertion systems have assisted orthopedic surgeons in aligning and implanting the devices to insure the proper healing of the bon with the implant. For example, implant insertion handles are commonly used to align and hold rod-shaped implants as it is inserted into the marrow canal of a fractured bone, and to connect to the other implant insertion instruments, such as an aiming arm comprising a handle. The handle member is a curved body which may have a bore located at a first end of the handle for coupling to a fixation implant and may have a plurality of bores located at a second end of the handle.

[0119] In some embodiments, the disclosure relates to the use of a device herein to treat osteonecrosis in a subject in need thereof. In some embodiments, the subject is a mammal. In some embodiments, the subject is a human. In some embodiments, the osteonecrosis is in the femur or the humerus. In some embodiments the device is comprised of zinc or a zinc alloy. The zinc alloy may be a zinc-magnesium alloy. In some embodiments, the use comprises exposing the device to a prepared hole in a bone in the subject for a period of about 8 months to about 12 years. In some embodiments, the period is about 8 months to about 1 year, about 2 years, about 3 years, about 4 years, about 5 years, about 6 years, about 7 years, about 8 years, about 9 years, about 10 years, about 11 years, or about 12 years. In some embodiments, the period is established by degradation of the device in situ. In some embodiments, the degradation is about 0. 14 mm / year. In some embodiments, the degradation is about 0.1 to about 0.11 , about 0.12, about 0.13, about 0.14, about 0.15, about 0.16, about 0.17, about 0.18 mm / year.

[0120] In some embodiments, a device herein is subjected to cleaning and surfaceenhancement prior to being implanted or employed in a method of treating or preventing osteonecrosis or a method of implanting herein.

[0121] Exemplary cleaning and surface-enhancement procedure for biodegradable Zn- based implants comprise complementary etching methods, each drawing on principles analogous to ASTM F86-13 for metallic surgical implants. ASTM F86-13 is incorporated herein by reference in its entirety. In some embodiments, a method of cleaning and surfaceenhancement comprises immersing the implant in an acid-ethanol mixture to dissolve surface contaminants, an etching step, and then rinsing the implant with water. The water may be deionized (DI) water. The method may further comprise ultrasonically cleaning the implant in a mixture of ethanol and water. The method may also comprise drying the implant. The method may also comprise preparing the acid-ethanol mixture. The acid-ethanol mixture may comprise hydrochloric acid, nitric acid, and ethanol. The acid-ethanol mixture may comprise about 5 vol% hydrochloric acid (HC1), about 5 vol% nitric acid (HNO3), and about 90 vol% ethanol (C2H5OH). As an example, a solution containing 5 vol% hydrochloric acid (HC1), 5 vol% nitric acid (HNO3), and 90 vol% ethanol (C2H5OH) is prepared. The implant is immersed in this acid- ethanol mixture for 60 seconds to dissolve surface oxides and contaminants. Immediately after immersion, the device may be rinsed thoroughly with DI water and may be ultrasonically cleaned in a 1: 1 mixture of DI water and ethanol to remove residual particulates. The sample is then dried under ambient or controlled conditions. In some embodiments, a method of cleaning and surface-enhancement, the method comprises the same immersing the device in the same initial acid-ethanol solution but with a shorter immersion time; for example, an immersion time of about 30 seconds. The method may then comprise rinsing in water, exposing the device to a second etching solution comprising phosphoric acid (H3PO4) and ethanol and electrochemically etching the device in the second etching solution. The device may serve as the anode while a metallic foil serves as the cathode. The device may then be rinsed with w ater and, optionally, to ultrasonication, and then dried. As an example, after exposure to the first etching solution and rinsing with DI water, the sample is transferred to a second etching solution composed of 50 vol% phosphoric acid (H3PO4) and 50 vol% ethanol. A DC power supply is set to 16 V, allowing the current to float freely, with the Zn implant serving as the anode and a thin metallic foil (e.g., steel, nickel, or platinum) serving as the cathode. This electrochemical etching is conducted under continuous stirring for up to 10 minutes for thicker implants (>500 pm) or under 5 minutes for thinner implants (<500 pm). Upon completion, the sample is again rinsed with DI w ater and optionally ultrasonicated in a 1 : 1 mixture of DI waterand ethanol prior to drying. This electrolyte can be reused multiple times, although it will discolor and warm with repeated use; placing the vessel in a water bath helps dissipate heat. The latter method including electrochemical etching has been shown to yield unexpected in vitro results, providing a more uniform, corrosion-optimized surface critical for the performance of biodegradable Zn implants.

[0122] The disclosure relates to a method of making a device disclosed herein comprising:(i) 3D printing the device according to the range of dimensions set forth in this disclosure; and(ii) treating the surface of the device with the aforementioned electrochemical etching process of this disclosure.

[0123] The disclosure also relates to disclosed devices for use in a method of treating the human or animal body by therapy. In some embodiments, the therapy is implantation of the device into bone of a human or animal subject in need thereof. In some embodiments, the human or animal subject has been diagnosed with osteonecrosis. The disclosure also relates to disclosed devices for use in a method of treating osteonecrosis in a subject in need thereof. In some embodiments, the device is a device for use in a method of exposing the bone of a subject to the device for no more than about 6. 7, 8, 9, 10, 12 months or from about 6 to about 12 years.

[0124] While the foregoing description and drawings represent exemplary embodiments of the present disclosure, it will be understood that various additions, modifications and substitutions may be made therein without departing from the spirit and scope and range of equivalents of the accompanying claims. In particular, it will be clear to those skilled in the art that the present invention may be embodied in other forms, structures, arrangements, proportions, sizes, and with other elements, materials, and components, without departing from the spirit or essential characteristics thereof. In addition, numerous variations in the methods / processes described herein may be made within the scope of the present disclosure.

[0125] One skilled in the art will further appreciate that the embodiments may be used with many modifications of structure, arrangement, proportions, sizes, materials, and components and otherwise, used in the practice of the disclosure, which are particularly adapted to specific environments and operative requirements without departing from the principles described herein. The presently disclosed embodiments are therefore to be considered in all respects as illustrative and not restrictive. The appended claims should be construed broadly, to include other variants and embodiments of the disclosure, which may be made by those skilled in the art without departing from the scope and range of equivalents.

[0126] EXAMPLE

[0127] The goal of this example was to evaluate the cytocompatibilty of pure zinc disks after surface treatment. This is important because these disks are to be used as an implant to treat osteonecrosis of the femoral or humoral head, so it’s important that they are at conducive cell proliferation.

[0128] W20-17 cells were used for proof of concept as there are an osteogenic cell line.For counting cells, the Beckman-coulter cell counter was used to quickly quantify proliferation.

[0129] FIG. 18 shows the results of the proliferation assay quantified with the cell counter. Cells were seeded at a density of 10,000 cells / well. The cells showed rapid proliferation between days 0 and 3, and stayed consistent for the next 7 days. The results show that the zinc disks after surface treatment are non-cytotoxic, and suitable for implantation.

Claims

CLAIMS1. A device comprising: a scaffold comprising a first end, a second end, and a longitudinal axis, the scaffold comprising: a first lattice structure formed from a first plurality of intersecting struts and defining a first cylindrical or substantially cylindrical shape, the first lattice structure having an outer surface that forms an exterior surface of the scaffold and an inner surface that defines an interior space; and at least one second lattice structure formed from a second plurality of intersecting struts that is located within the interior space defined by the first lattice structure; and wherein the scaffold comprises zinc or a zinc alloy.

2. The device according to claim 1, wherein: the first plurality of intersecting struts comprise a plurality of first struts that are parallel and that extend in a first helical direction from the first end of the scaffold to the second end of the scaffold and a plurality of second struts that are parallel and that extend in a second helical direction from the first end of the scaffold to the second end of the scaffold, the plurality of second struts intersecting the plurality of first struts at outer nodes of the first lattice structure; and the second plurality of intersecting structs comprising a plurality of third struts that are parallel and that extend in the first helical direction from the first end of the scaffold to the second end of the scaffold and a plurality of fourth struts that are parallel and that extend in the second helical direction from the first end of the scaffold to the second end of the scaffold, the plurality of fourth struts intersecting the plurality of second struts at inner nodes of the at least one second lattice structure.

3. The device according to claim 2 wherein each of the inner nodes of the at least one second lattice structure is radially aligned with one of the outer nodes of the first lattice structure.

4. The device of claim 1 through 3, wherein the second lattice structure defines a second cylindrical or substantially cylindrical shape in the interior.

5. The device according to any one of claims 1 through 4 wherein the first lattice structure comprises a plurality of first unit cells, and wherein the at least one second lattice structure comprises a plurality of second unit cells, each of the first and second unit cells being a bodycentered cubic unit cell.

6. The device according to claim 5. wherein each of the first unit cells comprises eight arm members that intersect at an outer node and wherein each of the second unit cells comprises eight arm members that intersect at an inner node, and wherein the inner nodes are radially spaced apart from the outer nodes.

7. The device according to any one of claims 1 through 6, wherein the first plurality of intersecting struts intersect at outer nodes of the first lattice structure, wherein the outer nodes comprise a plurality of first rows of first outer nodes and a plurality of second rows of second outer nodes, the first and second rows arranged in an alternating manner moving in an axial direction, wherein the first outer nodes of the first rows are circumferentially aligned with one another, wherein the second outer nodes of the second rows are circumferentially aligned with one another, and wherein the first outer nodes of the first rows are circumferentially offset from the second outer nodes of the second rows.

8. The device according to claim 7, wherein the first outer nodes are located radially outward relative to the second outer nodes.

9. The device according to any one of claims 1 through 8, further comprising: the first lattice structure comprising a plurality of first unit cells that define a plurality of outer nodes; each of the first unit cells comprising an X-shaped portion that comprises one of the outer nodes, a portion of one of the plurality of first struts, and a portion of one of the plurality of second struts, and wherein for each of the plurality of first unit cells, the plurality of first and second struts extend radially inward from the outer node.

10. The device according to any one of claims 1 through 9, wherein each of the first lattice structure and the at least one second lattice structure comprise diamond-shaped openings, and wherein the diamond-shaped openings of the first lattice structure are radially aligned with the diamond-shaped openings of the at least one second lattice structure.

11. The device according to claim 10, wherein the diamond-shaped openings of the first lattice structure have a diameter of at least 100 pm in an axial direction.

12. The device according to any one of claims 1 through 11, wherein the at least one second lattice structure comprises an inner surface that defines a central void that extends axially from the first end of the scaffold to the second end of the scaffold.

13. The device according to claim 12, wherein the central void is cylindrical or substantially cylindrical.

14. The device according to any one of claims 1 through 13, wherein the first plurality of intersecting struts have a first thickness and the second plurality of intersecting struts have a second thickness, the first thickness being greater than the second thickness.

15. The device according to any one of claims 1 through 14, further comprising: wherein the first lattice structure comprises a plurality of first unit cells, each of the first unit cells comprising a node and a portion of the first plurality of intersecting struts, and wherein the first lattice structure comprises a plurality of axial sections, each of the plurality of axial sections comprising X number of the plurality of first unit cells arranged along a circumference of the scaffold; and wherein the plurality of axial sections are vertically stacked so that each of the nodes of the first unit cells in each of the axial sections is axially aligned with one of the nodes of one of the first unit cells in each other axial section.

16. The device according to any one of claims 1 through 15, further comprising: wherein the first lattice structure comprises a plurality of first unit cells, each of the first unit cells comprising a first node and a plurality of first arm members extending from the first node: and wherein the at least one second lattice structure comprises a plurality of second unit cells, each of the second unit cells comprising a second node and a plurality of second arm members extending from the second node; and wherein the first nodes of the first lattice structure are not attached to the at least one second lattice structure and wherein the second nodes of the at least one second lattice structure are not attached to the first lattice structure.

17. The device according to claim 16 wherein one or more of the plurality of first arm members of each of the plurality of first unit cells of the first lattice structure are connected to a respective one of the plurality of second arm members of one of the plurality of second unit cells of the at least one second lattice structure.

18. The device according to any one of claims 1 through 17. wherein the first plurality of intersecting struts are oriented at an angle from about 10° and to about 75° relative to the longitudinal axis.

19. The device according to any one of claims 1 through 18 further comprising: a first cap coupled to the first end of the scaffold; and a second cap coupled to the second end of the scaffold.

20. The device according to claim 19 wherein the first cap is a solid, non-hollow structure having a hemisphere shape, the first cap having an outer surface, and wherein the second cap has an outer surface that protrudes radially beyond the exterior surface of the scaffold and the outer surface of the first cap.

21. The device according to any one of claims 1 through 20. wherein the scaffold comprises no less than about 90% zinc as a weight percent of a total weight of the device.

22. The device according to any one of claims 1 through 21, wherein the scaffold comprises no less than about 99% zinc and magnesium as a weight percent of a total weight of the device.

23. The device according to any of claims 1 through 22, wherein each of the first and second lattice structures define openings having a minimum dimension that is from about 100 pm to about 300 pm.

24. The device according to any one of claims 1 through 23, wherein the scaffold has a length measured from the first end to the second end, from about 60 mm to about 160 mm.

25. The device of according to any one of claims 1 through 24, wherein the scaffold comprises a maximum diameter of from about 2 mm to about 10 mm.

26. The device according to any one of claims 1 through 25, wherein the scaffold comprises an axial stiffness of from about 0.5 GPa to about 5 GPa.

27. The device according to any one of claims 1 through 26, wherein the first plurality of intersecting struts have a first thickness and the second plurality of intersecting struts have a second thickness, the first and second thicknesses are from about 0.1 mm to about 1.0 mm.

28. The device according to any one of claims 1 through 27, wherein the scaffold is free of tantalum, CoCr, stainless steel, titanium, metallic silicon, nickel and alloys thereof.

29. The device according to any one of claims 1 through 28. wherein the scaffold comprises radial symmetry.

30. The device according to any one of claims 1 through 29, wherein the exterior surface and / or an interior surface of the scaffold comprises one or more layers or regions of carboxymethyl dextran or a salt thereof.

31. A method of making a device or implant comprising: performing laser powder bed fusion to three-dimensionally print one or a plurality of devices according to any one of claims 1 through 30.

32. The method according to claim 31 further comprising: heating the device to a temperature from about 80 to about 500 degrees Celsius.

33. The method according to claim 32 further comprising: cooling the device to ambient temperature after performance of the heating.

34. The method according to any one of claims 31 through 33 further comprising: polishing the device to a roughness of from about 0.5 micron to about 5.0 microns.

35. The method according to any one of claims 31 through 34 further comprising: depositing a polymer layer on at least a portion of the exterior surface of the scaffold.

36. A method of treating bone weakness or osteonecrosis in a subject in need thereof comprising exposing the device of any of claims 1 through 30 to a bone of the subject.

37. The method according to claim 36, wherein the step of exposing the device to the bone of the subject comprises implanting the device into an interior portion of the bone of the subject.

38. The method according to any one of claims 36 through 37. wherein the subject is from about 20 to about 50 years of age.

39. The method according to any one of claims 36 through 38 wherein the osteonecrosis is osteonecrosis of the femoral head.

40. The method according to any one of claims 36 through 39, wherein the device comprises a length dimension from the first end to the second end of from about 120 mm to about 160 mm.

41. The method according to any one of claims 36 through 40 further comprising removing tissue from the bone to create a cavity into which the device is implanted.

42. The method according to any one of claims 36 through 41 further comprising allowing the device to degrade over a time period sufficient to allow enhanced vascularization proximate to the exterior surface of the scaffold.

43. The method according to claim 42 wherein the time period is from about 6 months to about 10 months after the device is exposed to the bone of the subject.

44. The method according to any one of claims 36 through 43 further comprising administering a steroid or salt thereof to the subject.

45. A method of promoting osteogenesis in a subject in need thereof comprising implanting the device according to any one of claims 1 through 30 into a bone of a subject.

46. The method according to claim 45, wherein the subject is from about 20 to about 50 years of age.

47. The method according to claim 45 or claim 46, wherein the subject is diagnosed with or suspected of having osteonecrosis.

48. The method according to any one of claims 45 through 47 wherein the device comprises a total length dimension of from about 120 mm to about 160 mm.

49. The method according to any one of claims 45 through 48 further comprising removing tissue from the bone to create a cavity into which the device is implanted.

50. The method according to any one of claims 45 through 49 further comprising allowing the device to degrade over a time period sufficient to allow enhanced vascularization proximate to the exterior surface of the scaffold.

51. The method according to claim 50, wherein the time period is from about 6 months to about 10 months from a day that the device is implanted into the bone of the subject.

52. The method according to any one of claims 45 through 51 further comprising administering a steroid or salt thereof to the subject.

53. The method according to any one of claims 48 through 52, wherein the step of implanting comprises implanting the device in a cavity within the proximal femur of the subject.

54. The method of claim 53, wherein the cavity is cylindrical or substantially cylindrical in shape.

55. A device comprising: a scaffold formed from a biodegradable metal, the scaffold being cylindrical or substantially cylindrical, the scaffold being elongated along a longitudinal axis from a first end of the scaffold to a second end of the scaffold, the scaffold comprising: a first lattice structure comprising a plurality of axial sections, each of the plurality of axial sections comprising a plurality of first unit cells arranged circumferentially about the longitudinal axis, each of the first unit cells being a body-centered cubic unit cell, wherein the first lattice structure comprises an outer surface that forms an exterior surface of the scaffold and an inner surface that defines an interior space; andat least one second lattice structure located within the interior space defined by the first lattice structure; and a first cap coupled to the first end of the scaffold.

56. The device according to claim 55, wherein the first cap has a hemispherical shape.

57. The device according to claim 55 or claim 56 further comprising a second cap coupled to the second end of the scaffold.

58. The device according to claim 55 or claim 56 wherein the scaffold comprises a length measured between the first and second ends and a diameter, the length being greater than the diameter.

59. The device according to claim 58 wherein the length is from about 70 mm to about 150 mm, and wherein the diameter is from about 3 mm to about 9 mm.

60. The device according to any one of claims 55 through 59, wherein the scaffold has an axial stiffness between 0.2 GPa and 5 GPa.

61. The device according to any one of claims 55 through 60, wherein the scaffold comprises radial symmetry.

62. The device according to any one of claims 55 through 61, wherein the first lattice structure comprises a plurality' of first struts having a first thickness and the second lattice structure comprises a plurality of second struts having a second thickness that is less than the first thickness.

63. The device of claim 62, wherein the first lattice structure comprises a plurality of first struts and the second lattice structure comprises a plurality’ of second struts, and yvherein a thickness of the first and second struts gradually decreases moving in a direction from the outer surface of the exterior surface of the scaffold towards the longitudinal axis.

64. A device comprising:a scaffold comprising zinc or a zinc alloy, the scaffold being cylindrical or substantially cylindrical in shape, and the scaffold being elongated along a longitudinal axis from a first end of the scaffold to a second end of the scaffold, the scaffold comprising: a first lattice structure comprising an outer surface that forms an exterior surface of the scaffold and an inner surface that defines an interior space, the first lattice structure comprising a plurality of first nodes and a plurality of first openings; and at least one second lattice structure located within the interior space defined by the first lattice structure, the second lattice structure comprising a plurality' of second nodes and a plurality of second openings; wherein the each of the first nodes of the first lattice structure is radially aligned with one of the second nodes of the second lattice structure, and wherein each of the first openings of the first lattice structure is aligned with one of the second openings of the second lattice structure.

65. The device according to claim 64 wherein the first lattice structure comprises a plurality of first unit cells and the second lattice structure comprises a plurality of second unit cells, each of the first and second unit cells being a body-centered cubic unit cell.

66. The device according to claim 64 or claim 65 wherein the first lattice structure defines a first cylindrical or substantially cylindrical shape and wherein the second lattice structure defines a second cylindrical or substantially cylindrical shape.

67. The device according to any one of claims 64 to 66 wherein the first and second lattice structures are attached.

68. A device comprising: a scaffold comprising: a first end, a second end, and a longitudinal axis; a first lattice structure formed from a first plurality of intersecting struts and defining a first cylindrical or substantially cylindrical shape, the first lattice structure having an outer surface that forms an exterior surface of the scaffold and an inner surface that defines an interior space; andwherein the scaffold is formed from a biodegradable metal, and wherein the scaffold has an axial stiffness from about 0.5 GPa to about 5.0 GPa.69 The device according to claim 68 wherein the scaffold further comprises a second lattice structure located within the interior space defined by the first lattice structure, wherein the second lattice structure is coupled to the first lattice structure.

70. The device according to claim 69 wherein each of the first and second lattice structures is elongated in a direction of the longitudinal axis.

71. The device according to any one of claims 68 through 70 further comprising: a first cap coupled to the first end of the scaffold; and a second cap coupled to the second end of the scaffold.

72. The device according to any one of claims 68 through 71 further comprising: the first lattice structure comprising a plurality of axial sections, each of the axial sections having a cylindrical or substantially cylindrical shape defined by a plurality of unit cells that are integrally connected.

73. The device according to claim 72 wherein each of the unit cells is a body -centered cubic unit cell.

74. The device according to any one of claims 68 through 73 wherein the biodegradable metal is zinc or a zinc alloy.

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