Bone harvesting device for bone implantation

Abstract

Provided herein are medical devices and methods for treating bone fractures. The medical device includes a body, a stent within the body, and means for concentrating bone growth throughout the body. The device is designed to minimize shear stresses on the distal tip and to distribute micromotion to promote bone ingrowth. The stent may include a three-periodic minimal curved surface (TPMS) having a cubic repeating pattern defining walls within the stent, and the TPMS may be helically wound about a central axis of the device. The device may also contain a biological agent and contain an autologous product. In some embodiments, the medical device is a bone screw or pedicle screw designed to reduce common problems such as screw loosening, screw disengagement, and shaft breakage. The method of treatment involves implanting the medical device into a bone of a patient to aid in fracture healing.

Description

[0001] This application claims the benefit of priority of U.S. Provisional Patent Application Serial No. 63 / 422,640, filed on November 4, 2023, the entire disclosure of which is incorporated herein by reference for all purposes.

[0002] This Publication relates to a scaffold material similar to natural bone, a medical device made from such scaffold material, and related methods for bone implantation.

[0003] Spinal fusion is a common procedure used to manage fractures, instability, and common degenerative conditions, including low back pain. Fusion techniques use bone grafts and hardware, such as pedicle screws, to promote the growth of two vertebral bodies together. Previous lumbar implant designs were smooth-threaded pedicle screws that were fixed in the vertebrae with rods to maintain the corrected height and angle until fusion was achieved.

[0004] It is estimated that 60% to 80% of the global population suffers from low back pain. Between 1998 and 2008, the number of lumbar fusion surgeries performed annually in the United States increased from 77,682 to 210,407. Unfortunately, the overall failure rate of lumbar surgery is high, at approximately 10% to 46%.

[0005] When reviewing spinal fusion surgeries in the PubMed database, 11,692 patients were extracted. A total of 3,646 complications occurred, with an average age of 53.3 years (range: 25 to 77 years) at the time of surgery and an average follow-up time of 3.49 years (range: 6 weeks to 9.7 years). The average incidence of perioperative major complications was 18.5%. The average incidence of perioperative minor complications was 15.7%. The average incidence of long-term complications was 20.5%.

[0006] Despite the continuous progress of technology and surgical techniques, these incidence rates have not changed substantially over the years. For example, lumbar interbody fusion (LIF) techniques have advanced due to computer navigation, augmented reality, minimally invasive surgery (MIS) methods, disc arthroplasty, bone-stimulating pedicle screws, and bone void filler options. However, due to the increasing number of patients and high failure rates, the number of patients developing failed back surgery syndrome (FBSS) is increasing. (FBSS refers to the situation where the outcome of lumbar surgery does not meet the preoperative expectations of the patient and the surgeon.)

[0007] The gold standard for lumbar interbody fusion involves inserting smooth threaded screws into each pedicle (two per vertebral level) and placing rods into the tulip-shaped heads of the pedicle screws to stabilize the construct until fusion is achieved. However, since 1975, little technological progress has been made in spinal stabilization systems, and these constructs do not address key long-term stability issues related to bone mineral density and the quality of patient health. The hardware used in lumbar fusion procedures is subjected to significant forces that result in hardware failure and loosening (the so-called "wiper effect"). Estimates of the frequency of screw loosening during spinal fusion procedures vary significantly, but a recent report estimates that the loosening rate exceeds 40%, with nearly 10% being partial pullout. This loosening due to lack of fusion can place nerves or blood vessels at risk and often requires removal of the hardware and repeat surgery.

[0008] Unfortunately, the success rate of spinal revision surgery is also low. The success rate for secondary revision cases is 30%, for the third surgery it is 15%, and for the fourth surgical intervention it is 5%. In addition, adult spinal deformity patients who have previously undergone two or more revisions exhibit more coronal and sagittal plane imbalance and a worse functional status. Other potential complications of LIF are dural tear, nerve injury, pseudarthrosis, infection, and wound healing problems.

[0009] Another complication of lumbar fusion is infection. Surgical site infection (SSI) is a major healthcare challenge, causing approximately 8,000 deaths annually. It is estimated that the direct and indirect costs associated with SSI total between $1 billion and $10 billion annually. The risk of SSI is greater in spinal instrumentation surgeries compared to other orthopedic surgeries, resulting in higher infection rates. The incidence of SSI caused by spinal surgery is estimated to be between 0.2% and 16.7%. A recent meta-analysis showed that the incidence of SSI in instrumented spinal surgery is 4.4%. Deep incisional and organ space SSIs account for 80% of these infections and are associated with increased morbidity, longer hospital stays, and increased healthcare costs.

[0010] In addition, regardless of the material used, bone mineral density decreases after implantation of a medical device. This loss results in common medical device failures, including screw loosening, screw pullout, and rod fracture. Although many devices facilitate fusion in the intervertebral cage, no device has been developed to support and increase bone mineral density within the vertebral body with a scaffold. Moreover, the structure of cortical bone within the vertebra is different from bone in other parts of the body.

[0011] These challenges related to long-term stability, such as bone quality and the ability to heal functionally, have not been met. None of the prior arts have addressed the first two reasons for revision surgeries due to implant failure: pedicle screw pullout and rod breakage before the patient achieves fusion. Smooth-threaded pedicle screws and rods do not address the issues of bone mineral density and the quality of the patient's health. Summary of the Invention

[0012] The present disclosure provides a medical device that includes a body, a stent located within the body, and a device for concentrating bone growth disposed on the body. The device is designed to minimize shear stress at the distal tip and spread micromotion across the entire medical device, thereby promoting bone ingrowth.

[0013] The present disclosure also provides a method for treating a fracture in a patient in need thereof, the method including implanting the medical device into the patient's bone. The medical device can be any of the devices disclosed herein.

[0014] Additional embodiments and features are set forth in part in the following description. They will become apparent to those skilled in the art upon review of the specification, or may be learned by practicing the embodiments discussed herein. A further understanding of the nature and advantages of certain embodiments can be realized by reference to the remaining portions of the specification and the drawings that form a part of the present disclosure. Brief Description of the Drawings

[0015] Figure 1 is a top view of a diagram showing a pedicle screw implanted into the vertebral body of a vertebra through the pedicle.

[0016] Figure 2 shows a side plan view of an embodiment of a pedicle screw printed in titanium 3D.

[0017] Figure 3 shows Figure 2 the top plan view of the pedicle screw.

[0018] Figure 4 shows Figure 2 the bottom plan view of the pedicle screw.

[0019] Figure 5 shows a side plan view of an embodiment of a pedicle screw printed in 3D with a stent as disclosed herein.

[0020] Figure 6 shows Figure 5 the top plan view of the pedicle screw.

[0021] Figure 7 shows Figure 5 the bottom plan view of the pedicle screw.

[0022] Figure 8 Shows a side plan view of another embodiment of a pedicle screw 3D printed with a stent as disclosed herein.

[0023] Figure 9 Shows Figure 8 a top plan view of the pedicle screw.

[0024] Figure 10 Shows Figure 8 a bottom plan view of the pedicle screw.

[0025] Figure 11 Shows a side plan view of an embodiment of a porous pedicle screw.

[0026] Figure 12 Shows a Figure 11 exploded view of a porous pedicle screw having a tulip-shaped member and a pin.

[0027] Figure 13 Shows Figure 11 a top plan view of the cap of the porous pedicle screw.

[0028] Figure 14 Shows Figure 11 a side plan view of the cap of the porous pedicle screw.

[0029] Figure 15 Shows Figure 11 a perspective view of the saddle of the porous pedicle screw.

[0030] Figure 16 Shows Figure 12 a perspective view of the tulip-shaped member.

[0031] Figure 17 Shows a screw having a bone collection feature located along the distal portion of the screw rather than along the proximal portion of the screw.

[0032] Figure 18 Shows Figure 17 the proximal portion of the screw without a bone collection feature.

[0033] Figure 19 Shows Figure 17 the distal portion of the screw with a bone collection feature.

[0034] Figure 20 Shows Figure 17 cross-section A-A of the screw.

[0035] Figure 21 Shows Figure 17 cross-section B-B of the screw.

[0036] Figure 22 Shows a two-dimensional slice through the Schwarz diamond mathematical field.

[0037] Figure 23 Shows Figure 22 a three-dimensional cross-section of the non-thickened surface of

[0038] Figure 24 Shows a cylindrical remapping after conversion to the polar space of the non-thickened surface of Figure 23

[0039] Figure 25 Shows a shear-free Figure 24 remapping of

[0040] Figure 26 Shows a remapping of Figure 25 with shear

[0041] Figure 27 Shows the thickened surface of Figure 26 using the absolute value operation

[0042] Figure 28 Shows the sheet structure of the Schwarz diamond lattice after thickening and thinning.

[0043] Figure 29 Shows Figure 28 the thin-walled lattice field of intersecting a 3D geometric space that defines the location where the lattice exists to define a stent.

[0044] Figure 30 Shows a perspective view of a porous pedicle screw presenting a diamond structure lattice.

[0045] Figure 31 Shows Figure 30 the rear view of the porous pedicle screw of

[0046] Figure 32 Shows Figure 30 the front view of the porous pedicle screw of

[0047] Figure 33 Shows Figure 30 an enlarged inset of the front view of the porous pedicle screw of , highlighting the stent.

[0048] Figure 34 Shows Figure 30 the top view of the porous pedicle screw of

[0049] Figure 35 Shows Figure 30 the bottom view of the porous pedicle screw of

[0050] Figure 36 A perspective view of another embodiment of a porous pedicle screw presenting a diamond structure lattice is shown, the diamond structure lattice including bone harvesting features at the distal tip and textured threads at the proximal end.

[0051] Figure 37 Shows Figure 36 a rear view of the porous pedicle screw.

[0052] Figure 38 Shows Figure 36 a front view of the porous pedicle screw.

[0053] Figure 39 Shows Figure 36 an enlarged inset of the front view of the porous pedicle screw, highlighting the stent.

[0054] Figure 40 Shows Figure 36 a top view of the porous pedicle screw.

[0055] Figure 41 Shows Figure 36 a bottom view of the porous pedicle screw.

[0056] The present disclosure will be readily understood by the following detailed description in conjunction with the accompanying drawings, in which like reference numerals represent like structural elements. The drawings provide exemplary embodiments or aspects of the present disclosure and do not limit the scope of the present disclosure. Detailed Description

[0057] The present disclosure provides a medical device that includes a body, a stent located within the body, and means for concentrating bone growth disposed on the body. The device is designed such that it minimizes shear stress on the distal tip and distributes micromotion over the entire medical device, thereby promoting ingrowth of bone.

[0058] In certain embodiments, the means for concentrating bone growth in the medical device includes at least one trephine for harvesting bone inside the device.

[0059] In certain embodiments, the medical device (whether or not it includes a trephine) is constructed in an arcuate cross-sectional pattern that varies from the proximal end to the distal tip.

[0060] In certain embodiments, the medical device is configured to be placed into the lumen of a vertebral body. When the medical device is rotated coaxially, autograft is harvested within the stent.

[0061] In certain embodiments, the medical device includes threads having a concave profile, regardless of its other features.

[0062] In certain embodiments, a stent within a medical device includes a triply periodic minimal surface (TPMS) having a cubic repeating pattern that defines walls within the stent.

[0063] In certain embodiments, the TPMS is a Schwartz diamond that is helically wound about a central axis of the medical device and into the 3D geometric space of the stent.

[0064] In certain embodiments, the TPMS is helically wound into a single helix. In certain embodiments, the TPMS is helically wound into a double helix. In certain embodiments, the TPMS is helically wound into a triple helix. In certain embodiments, the TPMS is helically wound into a quadruple helix. In certain embodiments, regardless of whether the TPMS is helically wound into a single helix, each turn of the helix of the medical device includes three radial spokes.

[0065] In certain embodiments, the cubic repeating pattern within the medical device is between about 1 mm and 3 mm in the X / Y / Z dimensions, such as between about 1.5 mm and 2 mm in the X / Y / Z dimensions, or about 1.8 mm. In certain embodiments, the helical winding of the medical device is defined as having a period three times the size of the cubic repeating pattern. In certain embodiments, regardless of other features, the walls within the medical device are about 0.5 mm thick.

[0066] In certain embodiments, the threads near the proximal end of the medical device are textured to have a topography similar to that of the stent.

[0067] In certain embodiments, the medical device is configured to accommodate one or more biologic agents regardless of its other features. In certain embodiments, the medical device further includes at least one autologous product sprayed onto or injected through the device.

[0068] In certain embodiments, the body of the medical device is a shaft. In certain embodiments, the medical device is a bone screw. In certain embodiments, the medical device reduces one or more of the following: screw loosening, screw pullout, rod fracture, and bone mineral density reduction. In certain embodiments, the medical device includes a grooved tip.

[0069] In certain embodiments, the medical device is a pedicle screw.

[0070] The present disclosure also provides a method of treating a fracture in a patient in need thereof, the method including implanting the medical device into the bone of the patient. The medical device can be any of the devices disclosed herein.

[0071] Bracket

[0072] Surface curvature and Minkowski bone morphology curvature maps (functions that recover the notion of distance in linear space) indicate that the porous matrix in trabecular bone within the vertebrae is significantly different compared to other areas of the skeletal anatomy. The loads of conventional smooth-threaded pedicle screws may be too high for the vertebrae due to decreased bone mineral density after implantation.

[0073] The porous 3D printed scaffold promotes osseointegration, fusion and fixation within the bone. The open bone with the scaffold resembles natural bone. This similarity allows physicians to use other agents for patient-specific selection to promote bone formation and / or stabilize the device.

[0074] Triangular porosity sequences have been used in the prior art. Circular, square / rectangular shapes and variegated patterns more closely align with the natural vertebral bone structure. In addition, the structure of the scaffold reduces the likelihood of revisions to the medical device in which the scaffold is made, such as screw loosening, screw back-out, rod breakage and decreased bone mineral density.

[0075] In certain embodiments, the disclosed scaffolds and devices integrate orthopedic products with regenerative medicine to prevent the risk of delayed bone fusion to the implanted device.

[0076] In certain embodiments, the scaffold includes one or more structural prompts selected from porosity, pore size, granularity and surface topography. Porosity and pore size prompt mechanical strength, cell sedimentation and cell migration signals. Granularity prompts signal protein absorption, cell adhesion, cell proliferation and cell adhesion. Surface topography prompts signal specific surface area, cell adhesion and material tissue interface. Other scaffold features include pH and wall thickness. In certain embodiments, one or more structural prompts enhance at least one of multipotent mesenchymal stem cell (MSC) differentiation, osteoblast growth, extracellular matrix (ECM) deposition and new bone formation. In certain embodiments, new bone formation occurs after MSC differentiation, osteoblast growth, ECM deposition or a combination thereof.

[0077] Bone

[0078] Bones can generally be divided into cancellous bone and cortical bone. "Cancellous bone" (also called "trabecular bone" or "spongy bone") is a lightweight, porous bone that encloses many large spaces, giving it a honeycomb or spongy appearance. The bone matrix or framework is organized into a three-dimensional grid of bony protrusions (called trabeculae) arranged along stress lines. The spaces between them are usually filled with bone marrow and blood vessels. In cross-section, the trabeculae of cancellous bone look like diaphragms. However, their topological structures in three dimensions are different, with trabeculae being roughly rod-shaped or columnar and diaphragms being sheet-shaped.

[0079] Cancellous bone accounts for about 20% of the human skeleton and provides structural support and flexibility in the absence of compact bone. Cancellous bone is present in most areas of the bone that are not subject to large mechanical stresses. It constitutes most of the expanded ends (epiphyses) of long bones and is a major component of the flat bones of the ribs, scapulae, skull, and various short flat bones in other parts of the skeleton.

[0080] Due to the increasing frequency of total joint replacements and their impact on bone remodeling, understanding the stress-related and adaptive processes of trabeculae has become a core concern for bone physiologists. To understand the role of trabecular bone in age-related bone structure and the design of bone implant systems, the relationship between the mechanical properties of trabecular bone and its anatomical location, density, and age has been studied. Therefore, mechanical factors including modulus, uniaxial strength, and fatigue performance have also been investigated.

[0081] High porosity gives trabecular bone compliance. The large differences in architecture result in a high degree of heterogeneity. Modulus and strength are inversely proportional to porosity and highly dependent on the pore structure. Generally, the percentage of porosity in cancellous bone is between 75% and 95%. The density is between 0.2 g / cm 3 and 0.8 g / cm 3 . Porosity can reduce the strength of bone but also lighten its weight.

[0082] Porosity and its structure affect the strength of the material. Therefore, the microstructure of trabecular bone is usually oriented. Where the mechanical stiffness and strength are greatest, the "grains" of the pores are aligned. Due to the directionality of the microstructure, the mechanical properties of trabecular bone are highly anisotropic. The Young's modulus of trabecular bone, including vertebrae, is between 800 Mpa and 14,000 Mpa. Its failure strength is between 1 MPa and 100 MPa.

[0083] "Cortical bone" or "compact bone" is much denser than cancellous bone. It forms the hard exterior (cortex) of the bone. Cortical bone gives the bone a smooth, white, and solid appearance. Cortical bone accounts for about 80% of the total bone mass of the adult skeleton. Cancellous bone is usually surrounded by a shell of compact bone, which provides greater strength and stiffness. The open structure of cancellous bone enables it to dampen sudden stresses, such as load transfer through joints. The ratio of space to bone in different bones also varies according to the need for strength or flexibility. Cancellous bone also has a relatively high level of metabolic activity.

[0084] "Wolff's law" states that the bone of a healthy person or animal can adapt to the loads it bears. For example, if the load on a particular bone increases, it will remodel itself over time to become stronger to resist that load.

[0085] Vertebra

[0086] In the vertebrate spinal column, each vertebra is an irregular bone with a complex structure composed of bone and some hyaline cartilage. The proportions vary according to the segment of the spine and the vertebrate species.

[0087] The basic configuration of the vertebra varies. Most of it is the body, and the central part is the vertebral body. The upper and lower surfaces of the vertebral body are attached to the intervertebral discs. The posterior part consists of eleven parts that form the vertebral arch, which is composed of two pedicles, two laminae, and seven processes. The laminae are attached to the yellow ligament (a spinal ligament). The shape of the pedicles forms vertebral notches, which form the intervertebral foramina when the vertebrae articulate. These foramina are the inlet ducts and outlet ducts for the spinal nerves. The vertebral body and the vertebral arch form the vertebral foramen, which is a large central opening that houses the spinal canal, and the spinal canal surrounds and protects the spinal cord.

[0088] The pedicles and laminae form the vertebral arch. Two pedicles extend from the sides of the vertebral body to join the vertebral body to the vertebral arch. The pedicles are short and thick projections that extend posteriorly from the junction of the posterolateral surfaces of the central upper surface, one on each side. From each pedicle, a wide plate (called the "lamina") projects posteriorly and medially to join and complete the vertebral arch and form the posterior boundary of the vertebral foramen, thus completing the triangle of the vertebral foramen. The upper surface of the lamina is rough for attachment to the yellow ligament. These ligaments connect the laminae of adjacent vertebrae along the length of the spine starting from the level of the second cervical vertebra. Above and below the pedicles are shallow depressions called vertebral notches (superior notch and inferior notch). When the vertebrae articulate, these notches align with the notches on adjacent vertebrae, thus forming the intervertebral foramen openings. The intervertebral foramina allow the spinal nerves and associated blood vessels to enter and leave each vertebra. The articulation of the vertebrae provides a strong support for the body.

[0089] Device

[0090] The present disclosure provides a device formed from the scaffolds disclosed herein. In certain embodiments, the device is hollow and porous and has a scaffold. In certain embodiments, according to the compressive force, the device includes a threaded distal region, optionally a threaded central region, and optionally a threaded proximal region.

[0091] In certain embodiments, the device is selected from pedicle screws, hollow pedicle screws, porous pedicle screws, large head screws, small head screws, headless screws, traumatic hip fracture devices, glenoid cages, glenoid cage screws, trauma plates, tibial stems, femoral stems, hammer toe implants, screw fusion systems, Charcot foot deformity correction, radial head fracture devices, high tibial osteotomy, deformity correction, vertebral resection cages, tumor correction, anchors, dental implants, maxillofacial implants, and sports medicine anchors.

[0092] In certain embodiments, the device is selected from a hip fracture system, reverse total shoulder, dental implant, upper extremity hardware, lower extremity hardware, total joint replacement implant, total joint revision implant, spinal fusion, spinal arthroplasty, regenerative therapy, cartilage implant, maxillofacial hardware, and cardiac implant.

[0093] In some embodiments, the screw is configured with features of a structure that facilitates bone growth through the screw from the opposite side, thereby allowing bone connection through the screw. In some embodiments, the structure is narrow (such as through the threads), allowing for rapid through-growth. In some embodiments, the structure is deeper (such as through the minor diameter), thus providing stronger adhesion. In some embodiments, the feature is a void in the screw or is porous or structured to promote bone growth. In some embodiments, the structure collects autograft in a channel inside the device. In some embodiments, the feature is impregnated with one or more polymers.

[0094] In some embodiments, the device is configured to enhance the stability and fixation of a bone screw within bone and improve bone mineral density. In some embodiments, the device includes a spinal implant configured to engage cortical and cancellous bone within a vertebra. In some embodiments, the device is configured to resist and / or prevent the bone screw from toggling when the bone screw engages dense cortical bone and less dense cancellous bone generated by the load on the bone screw. In some embodiments, the device is configured to resist and / or prevent the bone screw from loosening from the cortical bone and, in some cases, from being pulled out of the vertebra. In some embodiments, the device is configured to promote bone through-growth to improve the attachment of bone to the bone screw. In some embodiments, the bone screw is anchored in the bone, thereby reducing pull-out. In some embodiments, the bone screw is designed to dissipate micromotion and reduce shear to enhance bone mineral density.

[0095] In some embodiments, the device includes a bone screw having bone through-growth through the shaft of the screw to reduce kinking and potential failure of the screw. In some embodiments, the bone screw includes features of a structure that allows bone to grow through the bone screw from the opposite side, thereby allowing bone connection through those bone screw structures. In some embodiments, the bone screw includes a feature that can be narrow (such as through the bone screw threads), which will allow for rapid through-growth. In some embodiments, the bone screw includes a feature that may be deeper (such as through the minor diameter), which will provide a greater volume of bone through-growth. In some embodiments, the bone screw includes features that can be voids or cavities through opposite sides of the bone screw and / or voids or cavities entering and leaving the same or adjacent surfaces. In some embodiments, the void or cavity may contain a scaffold for bone attachment or a porous structure on the void surface.

[0096] In some embodiments, the bone screw includes features or structures that may be disposed along the shaft portion of the bone screw. In some embodiments, the bone screw includes features or structures that may be disposed continuously along the surface of the bone screw (such as, for example, along the distal end). In some embodiments, the bone screw includes features or structures that may be disposed discontinuously along a portion of the bone screw. In some embodiments, the bone screw includes features or structures that may include a scaffold or polymer.

[0097] In some embodiments, the device includes a spinal implant having a hybrid configuration that combines fabrication methods (such as, for example, one or more previously fabricated features and materials) and fabrication methods (such as, for example, one or more additive manufacturing features and materials). In some embodiments, additive manufacturing includes 3D printing. In some embodiments, additive manufacturing includes fused deposition modeling, selective laser sintering, direct metal laser sintering, selective laser melting, electron beam melting, laminated object manufacturing, and stereolithography. In some embodiments, additive manufacturing includes one or more selected from rapid prototyping, desktop manufacturing, direct manufacturing, digital manufacturing, instant manufacturing, and on-demand manufacturing. In some embodiments, the device includes a spinal implant fabricated and grown or otherwise printed by a fully additive process.

[0098] In certain embodiments, the device includes one or more selected from demineralized bone matrix (DBM), pre-packaged DBM, pre-packaged synthetic DBM, unpackaged DBM, and magnesium-infused titanium.

[0099] In some embodiments, the device includes a spinal implant, such as, for example, a bone screw fabricated by combining traditional fabrication methods and additive manufacturing methods. In some embodiments, the bone screw is fabricated by applying an additive manufacturing material, where the bone screw may benefit from the materials and properties of additive manufacturing. In some embodiments, traditional materials are used, the benefits of which (such as physical properties and cost) are superior to the additive manufacturing features and materials.

[0100] In some embodiments, the device treats spinal disorders selected from degenerative disc disease, herniated disc, osteoporosis, spondylolisthesis, stenosis, scoliosis, other curvature abnormalities, kyphosis, tumors, and fractures.

[0101] "Treating / treatment" of a disease or disorder refers to performing a protocol that may include administering one or more drugs to a patient, using an implantable device, and / or using an instrument for treating a disease (such as a microdiscectomy instrument for removing a herniated or protruding disc and / or bone spur) to relieve the signs or symptoms of the disease or disorder. Treatment does not require complete remission of signs or symptoms, does not require a cure, and specifically includes protocols that have a marginal effect on the patient. For example, treatment may include suppressing the disease, such as preventing its progression, or alleviating the disease, such as causing regression.

[0102] "Prevention" refers to alleviation before the signs or symptoms of a disease or disorder appear. Thus, prevention includes preventing the occurrence of a disease in a patient who may be predisposed to the disease but has not been diagnosed as having the disease.

[0103] "Tissue" includes soft tissue, ligament, tendon, cartilage, and / or bone. In certain embodiments, the tissue is cancellous bone, cortical bone, or cortico-cancellous bone.

[0104] In some embodiments, the device is used with other bone and bone-related applications, including diagnosis and treatment. In some embodiments, the device is alternatively used for surgical treatment of a patient in the prone or supine position and / or using various spinal surgical methods, including anterior approach, posterior approach, posterior midline approach, lateral approach, posterolateral approach, and / or anterolateral approach, and for other body regions (such as the maxillofacial and extremities). The device may also alternatively be used in protocols for treating the lumbar, cervical, thoracic, sacral, and pelvic regions of the spine. The device may also be used in animals, bone models, and other non-living matrices, for example, for training, testing, and demonstration.

[0105] In certain embodiments, the device is a customized medical device. In certain embodiments, the device is applicable to sports medicine.

[0106] In certain embodiments, the device is temperature-sensing. In certain embodiments, the device is pH-balanced.

[0107] In certain embodiments, the device is made with a pore former to a certain porosity, and the pore former is spherical, cubic, rectangular, elongated, tubular, fibrous, disc-shaped, platelet-shaped, polygonal, or a mixed shape thereof. In some embodiments, the porosity is based on a plurality of macropores, micropores, nanopore structures, and / or combinations thereof.

[0108] In certain embodiments, the device is made of biocompatible materials suitable for medical applications, including metals, synthetic polymers, ceramics, bone materials, and composites thereof. In certain embodiments, the device comprises one or more selected from the group consisting of: metals, ceramics, rubbers, hydrogels, rigid polymers, fabrics, bone materials, and composites thereof.

[0109] In certain embodiments, the device comprises a metal selected from the group consisting of: stainless steel alloys, aluminum, commercially pure titanium, titanium alloys, grade 5 titanium, superelastic titanium alloys, magnesium-infused titanium, cobalt-chromium alloys, superelastic metal alloys (such as Nitinol), and superelastic-plastic metals (such as Gum ). In certain embodiments, the device comprises ceramics and composites thereof, such as calcium phosphate (e.g., Skelite TM ). In certain embodiments, the device comprises a rubber selected from the group consisting of: polyaryletherketone (PAEK), polyetheretherketone (PEEK), polyetherketoneketone (PEKK), polyethylketone (PEK), carbon-PEEK composites, PEEK-BaSO4 rubbers, polyethylene terephthalate (PET), silicone, polyurethane, silicone-polyurethane copolymers, and polyolefin rubbers. In certain embodiments, the device comprises a hydrogel. In certain embodiments, the device comprises a fabric. In certain embodiments, the device comprises a rigid polymer selected from the group consisting of: polyphenylene, polyimide, polyetherimide, polyethylene, and epoxy resins. In certain embodiments, the device comprises a bone material selected from the group consisting of: autografts, allografts, xenografts, or transgenic cortical bone and / or cortico-cancellous bone. In certain embodiments, the device comprises tissue growth or differentiation factors. In certain embodiments, the device comprises resorbable materials (such as composites of metals and calcium-based ceramics, composites of PEEK and calcium-based ceramics, composites of PEEK and resorbable polymers), fully resorbable materials (such as calcium-based ceramics, e.g., calcium phosphate, tricalcium phosphate (TCP), hydroxyapatite (HA)-TCP, calcium sulfate), or other resorbable polymers (such as polyketones, polyglycolide, polytyrosine carbonate, polycaprolactone, and other combinations).

[0110] In certain embodiments, the device comprises a rubber selected from the group consisting of: polyaryletherketone (PAEK), polyetheretherketone (PEEK), polyetherketoneketone (PEKK), polyethylketone (PEK), carbon-PEEK composites, PEEK-BaSO4 rubbers, polyethylene terephthalate (PET), silicone, polyurethane, silicone-polyurethane copolymers, polyolefin rubbers, synthetic collagen, and collagen matrix. In certain embodiments, the device comprises synthetic collagen. In certain embodiments, the device comprises a collagen matrix.

[0111] In certain embodiments, the device comprises magnesium, vitamins, and minerals. "Vitamins" refer to organic molecules (or a group of chemically closely related molecules, i.e., vitamers) that are essential micronutrients required by organisms to maintain the normal functions of their metabolism. Some sources list fourteen vitamins, including choline, but major health organizations typically list thirteen: vitamin A (all-trans retinol, all-trans retinyl esters, and all-trans-β-carotene and other provitamin A carotenoids), vitamin B1 (thiamine), vitamin B2 (riboflavin), vitamin B3 (niacin), vitamin B5 (pantothenic acid), vitamin B6 (pyridoxine), vitamin B7 (biotin), vitamin B9 (folic acid or folate), vitamin B 12 (cobalamin), vitamin C (ascorbic acid), vitamin D (calciferol), vitamin E (tocopherols and tocotrienols), and vitamin K (phylloquinone and menaquinone). In nutrition, "minerals" refer to the chemical elements that are essential nutrients required by organisms to maintain life, including potassium, chlorine, sodium, calcium, phosphorus, magnesium, iron, zinc, manganese, copper, iodine, chromium, molybdenum, selenium, and cobalt.

[0112] In certain embodiments, the device comprises a metal selected from the group consisting of iron, stainless steel alloy, aluminum, commercially pure titanium, titanium alloy, grade 5 titanium, superelastic titanium alloy, magnesium-infused titanium, cobalt-chromium alloy, superelastic metal alloy (such as nitinol), superelastic-plastic metal (such as Gum ). In certain embodiments, the device comprises titanium. In certain embodiments, the device comprises iron.

[0113] In certain embodiments, the device is manufactured or 3D printed from materials such as titanium, titanium alloy, cobalt-chromium alloy, carbon fiber, magnesium-infused titanium, iron, or stainless steel. In certain embodiments, the device is made of a shape memory alloy or a shape memory polymer, thereby allowing the device to conform to the anatomical shape of the patient's body.

[0114] In certain embodiments, the device comprises magnesium-infused titanium. In certain embodiments, the device comprises an angiotensin receptor blocker coating. In certain embodiments, the device comprises a type 1 cartilage collagen coating. In certain embodiments, the device is infused with an antibiotic.

[0115] In certain embodiments, the device is used to treat an affected segment of a vertebra. Medical personnel gain access to the surgical site (including the vertebra) in any suitable manner (such as by incising and retracting tissue). In certain embodiments, the device comprises bone screws to enhance surgical treatment. In certain embodiments, the device can be pre-assembled for delivery to the surgical site or assembled in situ. In certain embodiments, the device is fully or partially revised, removed, or replaced.

[0116] In certain embodiments, the device is used with surgical methods or techniques, including but not limited to open surgery, mini-incision surgery, minimally invasive surgery (MIS), and percutaneous surgical implantation, thereby providing a protected access to the vertebral body or sleeve through a mini-incision. Once access to the surgical site is obtained, surgical treatment (such as vertebrectomy or discectomy) can be performed to treat a disease or disorder.

[0117] In certain embodiments, the surface of the device includes a non-solid configuration, such as a lattice. In some embodiments, the non-solid configuration includes a porous structure or a trabecular configuration.

[0118] In various embodiments, the non-solid configuration is configured to provide one or more paths to facilitate bone growth within the device and through from one surface of the device to the opposite surface. In some embodiments, the lattice includes one or more portions, layers, or substrates. In some embodiments, one or more portions, layers, or substrates of the lattice are arranged side by side, offset, staggered, stepped, tapered, end-to-end, spaced apart, in series, or in parallel. In some embodiments, the lattice defines a thickness that can be uniform, wavy, tapered, increasing, decreasing, variable, offset, stepped, arcuate, angled, and / or staggered. In some embodiments, one or more lattice layers are arranged in a side-by-side parallel orientation within the wall. In certain embodiments, the lattice includes one or more material matrix layers.

[0119] In some embodiments, the lattice includes a plurality of nodes and openings arranged in rows and columns or randomly. In some embodiments, the plurality of nodes and openings are arranged in series. In some embodiments, the plurality of nodes and openings are arranged in parallel.

[0120] In some embodiments, the lattice forms a rasp-like configuration. In some embodiments, the lattice is configured to engage tissue. In certain embodiments, the engagement of the lattice is for cutting, shaving, shearing, incising, or disrupting tissue. In some embodiments, the lattice includes a configuration selected from the group consisting of cylindrical, circular, oval, rectangular, triangular, polygon with planar or arcuate sides, irregular shape, uniform shape, non-uniform shape, consistent shape, variable shape, horseshoe, U-shaped, or kidney bean-shaped. In some embodiments, for example, the lattice is rough, textured, porous, semi-porous, recessed, knurled, toothed, grooved, or polished to engage and cut tissue. In some embodiments, the lattice forms a tunnel that is configured to direct, drive, or guide the cut tissue into an opening, such as fusing the device to the tissue.

[0121] Screw

[0122] In certain embodiments, the device is a screw. In some embodiments, the screw is selected from pedicle screws, vertebral screws, bolts, bone screws for side plates, intervertebral screws, uniaxial screws, fixed-angle screws, multi-axial screws, side-loading screws, sagittal adjustment screws, lateral sagittal adjustment screws, tapered tips, double-rod multi-axial screws, midline lumbar fusion screws, and / or sacral bone screws.

[0123] In certain embodiments, the device is a bone screw. In certain embodiments, the device is a pedicle screw. Referring Figure 1 , a pedicle screw implanted into the vertebral body of a vertebra through the pedicle is shown. In certain embodiments, the pedicle screw has a cage, where the polymer is retained within the hollow and / or porous portion of the screw.

[0124] In certain embodiments, the inner core of the screw is a trephine to collect and harvest autograft during and / or upon insertion of the screw.

[0125] In certain embodiments, post-implant options prevent revision surgery by polymer injection through the screw.

[0126] In certain embodiments, the pedicle screw does not exhibit screw loosening, screw pullout, rod fracture, or reduced bone mineral density.

[0127] In certain embodiments, the pedicle screw reduces one or more of the following: screw loosening, screw pullout, rod fracture, and reduced bone mineral density.

[0128] The disclosed screws focus bone growth along the entire shaft to minimize shear stress at the distal tip and evenly distribute micromotion across the screw to promote bone ingrowth.

[0129] In certain embodiments, the pedicle screw scaffold provides options for patients with simple to complex bone mineral density and immunocompromised conditions. In certain embodiments, the scaffold is impregnated with one or more biologics, antibiotics, demineralized bone matrix, nanotechnology, or regenerative medicine therapies.

[0130] Referring Figures 5 to 16 , the structures of the pedicle screws 300, 400, 500 are specifically designed to assist bone ingrowth through the pedicle screws 300, 400, 500 by using the scaffold 280, which is similar to the natural trabecular bone in the vertebral body. In combination with the threads 230 and the scaffold 280, the core 260 helps with autograft harvesting during insertion to push the autograft into the built-in channels within the core 260 of the pedicle screws 300, 400, 500. The wall around the holes harvests the autograft and acts as a trephine. This structure also contributes to the structural integrity of the pedicle screws 300, 400, 500, resists bone mineral density loss, and reduces micromotion.

[0131] Reference Figures 2 to 16 , the pedicle screws 200, 300, 400, 500 disclosed herein overcome many of the failures of prior art pedicle screws. In certain embodiments, the pedicle screws lack a wiper effect. In certain embodiments, the pedicle screws resist pullout. In certain embodiments, the pedicle screws do not exhibit excessive micromotion. In certain embodiments, for example, due to individual screw sterilization and packaging, the pedicle screws have a lower frequency of weakly virulent microorganisms detected by ultrasonic treatment. In certain embodiments, the heads and shafts of the pedicle screws resist failure. In certain embodiments, the pedicle screws are suitable for each type of bone quality. In certain embodiments, the pedicle screws have sufficient thread depth. In certain embodiments, the pedicle screws withstand insertion torque, particularly at the head-screw junction. In certain embodiments, when the screw is fully inserted, the fatigue life of the pedicle screw is not reduced. In certain embodiments, the pedicle screws have good instrumentation. In certain embodiments, the pedicle screws achieve angulation for rod acceptance. In certain embodiments, the pedicle screws do not have cyclic loading based on physiological conditions during walking. In certain embodiments, the pedicle screws do not fail in long segment posterior cervical fusion and do not require the simultaneous use of C6 or T1 support pedicle screws. In certain embodiments, the pedicle screws distribute stress. In certain embodiments, the pedicle screws do not impair the patient's immune function. In certain embodiments, the pedicle screws do not include PEEK. In certain embodiments, the pedicle screws do not have tulip-shaped or locking cap stress.

[0132] In some embodiments, the distal tip 220 of the pedicle screws 200, 300, 400, 500 has a surface configuration selected from: angled, irregular, uniform, non-uniform, offset, staggered, tapered, arcuate, wavy, reticulated, porous, semi-porous, recessed, pointed, textured, or combinations thereof. In some embodiments, the distal tip 220 includes a nail configuration, barbs, expansion elements, raised elements, ribs, and / or spikes to provide a manufacturing platform for forming a portion thereon via additive manufacturing. In some embodiments, the distal tip 220 has a cross-sectional configuration selected from: oval, rectangular, triangular, square, polygonal, irregular, uniform, non-uniform, offset, staggered, tapered, or combinations thereof.

[0133] In some embodiments, the pedicle screws 200, 300, 400, 500 include threads 230 that extend between a proximal end 210 and a distal tip 220. In some embodiments, the threads 230 include an external thread form. In some embodiments, the thread form includes a leading edge 231 having a front surface 235 and a trailing edge 232 having a rear surface 236. The front surface 235 defines a first opening 251. The rear surface 236 defines a second opening 252. In some embodiments, the first and second openings 251, 252 are axially aligned. In some embodiments, the first and second openings 251, 252 are circumferentially disposed around the thread form.

[0134] In some embodiments, the front surface 235 and / or the rear surface 236 include at least one tissue aggregation member. In some embodiments, the tissue aggregation member includes a cutting edge. In some embodiments, the cutting edge is configured to be file-like. In some embodiments, the cutting edge is configured to engage tissue, e.g., to cut, shave, shear, incise, or disrupt tissue. In some embodiments, the cutting edge is configured to be cylindrical, circular, oval, rectangular, triangular, polygonal, having planar or arcuate sides, irregular, uniform, non-uniform, consistent, variable, horseshoe-shaped, U-shaped, or kidney bean-shaped. In some embodiments, the cutting edge is rough, textured, porous, semi-porous, recessed, knurled, toothed, grooved, or polished to engage and cut tissue. In some embodiments, the cutting edge forms a tunnel that is configured to direct, drive, or guide the cut tissue into a void, such as to fuse the screw with the tissue.

[0135] For example, the pedicle screws 200, 300, 400, 500 are manipulated, such as by rotation or translation, such that the cutting edges 271 of the screws cut tissue or bone and direct it into the core 260, thereby promoting bone growth and fusion to the pedicle screws 200, 300, 400, 500. In some embodiments, tissue is embedded into the core 260 to promote bone growth and fusion to the pedicle screws 200, 300, 400, 500. In some embodiments, a lattice is disposed within the core 260 to form a scaffold 280 for bone growth.

[0136] In some embodiments, the threads 230 are configured to be thin, closely spaced, or shallow for engaging tissue. In some embodiments, the threads 230 include an increased pitch and an equal lead between the thread turns. In some embodiments, the threads 230 include a smaller pitch or more thread turns per axial distance to securely fix to the tissue or resist tissue loosening. In some embodiments, the threads 230 are configured to be continuous along a portion. In some embodiments, the threads 230 are configured to be discontinuous, staggered, or non - continuous. In certain embodiments, the threads 230 include a single thread turn.

[0137] In certain embodiments, the threads include multiple discrete threads. In certain embodiments, the threads have a concave profile.

[0138] In some embodiments, the line 230 includes penetrating elements, e.g., selected from nail configurations, barbs, expansion elements, raised elements, ribs, or spikes. In some embodiments, the threads 230 are configured to be self - tapping or discontinuous at the distal tip 220. In some embodiments, the distal tip 220 is rounded. In some embodiments, the distal tip 220 is self - drilling. In some embodiments, the distal tip 220 includes a solid outer surface.

[0139] In certain embodiments, the screw is a 3D - printed porous pedicle screw. Its porosity mimics natural vertebrae to attach and retain stem cells, growth factors, and other proteins within the structure of the pedicle screw and promote bone growth through the screw, thus stabilizing the entire construct. During insertion into the vertebra, the built - in trephine collects autograft and regenerative cells within the porous matrix. The disclosed topography attracts bone - forming stem cells within and around the device, thereby reducing the macroscopic movement of the overall construct. In certain embodiments, the device enables the surgeon to meet patient - specific needs such as, but not limited to, options of spraying / injecting regenerative products to stimulate the osteogenic cascade for bone formation, actively injecting the screw scaffold with antibiotics to treat diabetes - susceptible infections, and injecting bone cement to further stabilize the construct in severely osteoporotic bone.

[0140] In certain embodiments, the screw reduces the revision rate, improves bone mineral density, and / or meets patient - specific needs during spinal fusion. In certain embodiments, the bone mineral density is improved, the construct is stabilized, and the likelihood of revision is reduced.

[0141] In certain embodiments, the screw is a 3D printed titanium porous pedicle screw, and the porous pattern throughout the screw is similar to natural bone. Without being bound by theory, the function of the porous pattern is to attach to the surrounding bone, hold osteoprogenitor cells in place, and collect autograft bone within its porous structure. The advantage of the porous structure is the ability to inject polymers and regenerative therapies through the screw. In certain embodiments, stem cell therapy is injected through the screw implant. In such embodiments, the likelihood of failure is reduced.

[0142] In certain embodiments, the surgeon may inject or spray autologous concentrated stem cells into the screw. Without being bound by theory, as the screw rotates during insertion into the vertebra, the holes in the screw use its built-in trephine to collect an autograft / stem cell mixture internally. Then, the osteoprogenitor cells combine with the concentrated blood stem cells and signal the mutation and replication process to form more osteoblasts within the screw, which then guide the bone healing cascade within and around the screw. In these embodiments, the combination of the (a) osteoconduction (bone growth on its surface), (b) osteoinduction (recruiting cells for bone healing), and (c) osteogenesis (development and formation of bone) healing cascades of the stem cells improves bone mineral density and supports excellent bone integration and pullout strength.

[0143] In certain embodiments, the patient has diabetes and is prone to infection. In these embodiments, the surgeon may inject a mixture containing a calcium sulfate product and an antibiotic through the screw or onto the screw within the pedicle before or after insertion to provide antibiotic delivery in the area. In certain embodiments, the antibiotic is delivered for two to six weeks. Thus, the likelihood of revision due to infection is reduced.

[0144] Manufacture

[0145] The devices disclosed herein can be manufactured using a variety of methods. In some embodiments, manufacturing includes machining, such as subtractive manufacturing, transformative manufacturing, or variant manufacturing. In some embodiments, manufacturing includes cutting, grinding, rolling, forming, molding, casting, forging, extruding, swaging, lapping, cold working, or combinations thereof. In some embodiments, manufacturing includes a portion of the device formed by medical machining processes. In some embodiments, the machining uses a computer numerical control (CNC) high-speed milling machine, Swiss machining device, CNC turning with live tools, wire EDM 4th axis, and combinations thereof. In some embodiments, the manufacturing for forming a portion of the device includes finishing processes, such as laser marking, tumble blasting, bead blasting, micro-blasting, powder blasting, or combinations thereof.

[0146] In certain embodiments, based on the digital rendering and / or data of the selected configuration, the device is manufactured via additive manufacturing according to instructions from a computer and a processor.

[0147] In some embodiments, additive manufacturing includes 3D printing. In some embodiments, additive manufacturing is selected from fused deposition modeling, selective laser sintering, direct metal laser sintering, selective laser melting, electron beam melting, laminated object manufacturing, stereolithography, and combinations thereof. In some embodiments, additive manufacturing includes rapid prototyping, desktop manufacturing, direct manufacturing, direct digital manufacturing, digital manufacturing, instant manufacturing, on-demand manufacturing, or combinations thereof.

[0148] In some embodiments, a portion of the device is manufactured by additive manufacturing and then mechanically attached to the surface of the device, for example, by welding, threading, adhesives, or riveting.

[0149] In one embodiment, the device is configured based on imaging of the patient's anatomy. Suitable imaging techniques include, but are not limited to, X-ray, fluoroscopy, computed tomography (CT), magnetic resonance imaging (MRI), surgical navigation, bone density (DEXA), or 2D or 3D images of the patient's anatomy that are available. Selected configuration parameters for the device are collected, calculated, or determined. Examples of configuration parameters include, but are not limited to, patient anatomy imaging, surgical treatment, historical patient data, statistics, treatment algorithms, implant material, implant size, porosity, and manufacturing method. In some embodiments, the configuration parameters include implant material and device porosity based on patient anatomy and surgical treatment. In some embodiments, the porosity is selected. In some embodiments, the configuration parameters of the device are patient-specific. In some embodiments, the configuration parameters of the device are based on a general configuration and are not patient-specific.

[0150] For example, a digital rendering or data of the device is generated for display from a graphical user interface or stored in a database attached to a computer and a processor. In some embodiments, the computer monitor saves, digitally manipulates, or prints a hard copy of the digital rendering or data via a monitor. In some embodiments, the device is virtually designed on a computer monitor using a CAD / CAM program. In some embodiments, the processor executes code stored in a computer-readable storage medium to execute one or more computer instructions, for example, to transmit instructions to an additive manufacturing device. In some embodiments, the database or computer-readable medium includes RAM, ROM, EPROM, magnetic, optical, digital, electromagnetic, flash drives, technologies, or combinations thereof. In some embodiments, the processor instructs a motor to control the movement and rotation of device components.

[0151] Regenerative medicine

[0152] ″Regenerative medicine″ refers to a branch of translational research in tissue engineering and molecular biology that involves replacing, engineering, or regenerating human cells, tissues, or organs to restore or establish normal function. This field holds promise for transforming damaged tissues and organs by stimulating the repair mechanisms within the patient's body to functionally cure previously irreparable tissues or organs. For example, during bone regeneration, new bone formation is primarily influenced by physicochemical cues in the surrounding microenvironment. Tissue cells exist within a complex scaffold physiological microenvironment.

[0153] In certain embodiments, regenerative medicine is combined with the scaffolds or devices disclosed herein. The integration of autograft occurs in five stages: inflammatory, angiogenic, osteogenic, osteoconductive, and remodeling.

[0154] Inflammation lasts for approximately 7 to 14 days. The initial injury to the local blood supply and decortication results in the formation of a hematoma around the bone graft, into which inflammatory cells invade. Fibroblast-like cells in the inflammatory tissue transform into a fibrovascular matrix. Perioperative anti-inflammatory drugs reduce the fusion rate due to the inflammatory process.

[0155] Vascular buds appear in the fibrovascular matrix, similar to scar tissue formation during angiogenesis. Primary membranous bone forms near the decorticated bone. Subsequently, minimal endochondral ossification and intramembranous ossification occur.

[0156] During the osteogenic period from week 4 to week 5, repair includes increased angiogenesis, resorption of necrotic tissue, and differentiation of osteoblasts and chondroblasts. Specifically, stem cells differentiate into osteoblasts. New bone extends towards the central region of the fusion mass. The cortical portion of the graft continues to be resorbed.

[0157] Osteoconduction is characterized by ingrowth into the host bone and creep substitution. Osteoblasts produce new bone while osteoclasts simultaneously resorb the transplanted bone. The central region of the endochondral interface is observed in the center of the fusion mass, thereby binding the lower and upper halves of the fusion together. Multipotent cells in this central region differentiate into cartilage tissue with less angiogenesis.

[0158] During the remodeling period from week 6 to week 10, a peripheral cortical rim forms around the fusion. Marrow activity increases, forming secondary cancellous bone. The cortical rim thickens. Trabecular projections extend towards the center of the fusion. Remodeling is typically completed one year after device implantation.

[0159] Pseudarthrosis (nonunion) is the main cause of postoperative pain, accounting for 45% to 56% of revisions. Bone fusion is directly related to successful clinical outcomes. Patients with pseudarthrosis are asymptomatic in approximately 30% of cases. The younger the age, the higher the incidence of symptomatic pseudarthrosis (43.8 years vs. 52.1 years, p < 0.01).

[0160] In certain embodiments, bone marrow aspirate (BMA) replaces autologous bone graft in posterior lateral lumbar fusion (PLF) revision with allograft. In certain embodiments, BMA with allograft is more cost-effective than recombinant human bone morphogenetic protein-2 (rhBMP). In certain embodiments, bone marrow-derived cellular allografts are compared to autograft in bone grafting and spinal fusion procedures. In certain embodiments, BMA increases the regenerative potential of cortico-cancellous allograft bone. When treating unicameral bone cysts, the healing rate is high (98.7%) for bone marrow with demineralized bone matrix injection.

[0161] When introducing elements of the present disclosure or its embodiments, the articles "a", "an", "the", and "said" are intended to indicate the presence of one or more elements. The terms "comprising", "including", and "having" are intended to be inclusive and mean that there may be additional elements in addition to the listed elements.

[0162] Having described the present disclosure in detail, it will be apparent that modifications and variations are possible without departing from the scope of the present disclosure as defined in the appended claims.

[0163] Although the disclosure described herein is susceptible to various modifications and alternative iterations, specific embodiments thereof have been described in more detail above. However, it should be understood that the detailed description of the compositions is not intended to limit the present disclosure to the specific embodiments disclosed. On the contrary, it should be understood that the present disclosure is intended to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure as defined by the language of the claims.

[0164] Example

[0165] The following examples are included to illustrate certain embodiments of the present disclosure. Those skilled in the art should understand that the techniques disclosed in the examples represent techniques that the inventors have found to function well in the practice of the present disclosure. However, according to the present disclosure, those skilled in the art should understand that many changes can be made in the specific embodiments disclosed without departing from the spirit and scope of the present disclosure and still obtain the same or similar results. Therefore, all matters are to be construed as illustrative and not restrictive.

[0166] Table 1 - Reference signs

[0167]

[0168]

[0169] Example 1 - Pedicle screw

[0170] Reference Figures 2 to 4 , the pedicle screw 200 is 3D printed with titanium. The pedicle screw 200 includes threads 230 disposed around a shaft 240 extending between a proximal end 210 and a distal tip 220. The threads 230 include an external thread form having a leading edge 231 and a trailing edge 232, the leading edge having a front surface 235 and the trailing edge having a rear surface 236. The front surface 235 defines a first opening 251. The rear surface 236 defines a second opening 252. The first opening and the second opening 251, 252 are axially aligned. The pedicle screw 200 has a core 260 extending from the proximal end 210 through the center of the pedicle screw 200 to the distal tip 220. The distal tip 220 includes two cutting members 270, each cutting member having a cutting edge 271.

[0171] Reference Figures 5 to 7 , an embodiment of the pedicle screw 300 is 3D printed with the bracket 280 disclosed herein. The pedicle screw 300 includes threads 230 disposed around a shaft 240 extending between a proximal end 210 and a distal tip 220. The shaft 240 includes two regions of the bracket 280 exposed to the outer surface of the pedicle screw 300. The threads 230 include an external thread form having a leading edge 231 and a trailing edge 232, the leading edge having a front surface 235 and the trailing edge having a rear surface 236. The front surface 235 defines a first opening 251. The rear surface 236 defines a second opening 252. The first opening and the second opening 251, 252 are axially aligned. The pedicle screw 300 has a core 260 filled with the bracket 280, the bracket extending from the proximal end 210 through the center of the pedicle screw 300 to the distal tip 220. The distal tip 220 includes three cutting members 270, each cutting member having a cutting edge 271.

[0172] Reference Figures 8 to 10, Another embodiment of the pedicle screw 400 is 3D printed with titanium and has the bracket 280 disclosed herein. The pedicle screw 400 includes threads 230 disposed around a shaft 240 extending between a proximal end 210 and a distal tip 220. The shaft 240 includes an area of the bracket 280 that is exposed to the outer surface of the pedicle screw 400 between an intermediate seven turns of threads 230. The threads 230 include an external thread form that has a leading edge 231 and a trailing edge 232, the leading edge having a front surface 235 and the trailing edge having a rear surface 236. The front surface 235 defines a first opening 251. The rear surface 236 defines a second opening 252. The first opening and the second opening 251, 252 are axially aligned. The pedicle screw 400 has a core 260 filled with the bracket 280 that extends from the proximal end 210 through the center of the pedicle screw 400 to the distal tip 220. The distal tip 220 includes three cutting members 270, each cutting member having a cutting edge 271.

[0173] Reference Figures 11 to 16 , Another embodiment of the pedicle screw 500 is 3D printed with metal and has the bracket 280 disclosed herein. The pedicle screw 500 includes a cap 510, a saddle 520, and a shaft 540, and, when present, a tulip 590 and a pair of pins 595. The cap 510 is configured to be coupled to the saddle 520 via cap threads 513 operatively disposed in a saddle groove 523. The saddle 520 is configured to be coupled to the shaft 540. In embodiments of the pedicle screw having a tulip, the distal tip 220 of the shaft 540 can be disposed through a bottom opening 592 of the tulip 590 and held in place with pins 595 disposed through side openings 596 of the tulip 590.

[0174] The pedicle screw 500 includes threads 230 disposed around a shaft 240 extending between a proximal end 210 and a distal tip 220. The shaft 240 includes an area of the bracket 280 that is exposed to the outer surface of the pedicle screw 500 between an intermediate thirteen turns of threads 230. The threads 230 include an external thread form that has a leading edge and a trailing edge, the leading edge having a front surface and the trailing edge having a rear surface. The pedicle screw 500 has a core filled with the bracket 280 that extends from the proximal end 210 through the center of the pedicle screw 500 to the distal tip 220. The distal tip 220 includes a cutting member 270.

[0175] Reference Figure 13 and Figure 14 , The cap 510 includes a cap body 514 that has cap threads 513 disposed in a helical manner around the outer surface of the cap body 514 between a cap top 511 and a cap bottom 512.

[0176] Reference Figure 15, the saddle 520 includes a saddle body 524 having a saddle top 521, a saddle bottom 522, and at least one saddle groove 523 disposed on an inner surface of the saddle body 524. The at least one saddle groove 523 is configured to receive and operatively couple to the cap thread 513. Similarly, the saddle bottom 522 is configured to receive and operatively couple to the proximal end 210 of the shaft 540.

[0177] Reference Figure 16 , when present, the tulip-shaped member 590 includes a tulip-shaped body 594 having: a top opening 591; a bottom opening 592; at least a pair of tulip-shaped grooves 593 disposed on an inner surface of the tulip-shaped body 594; a pair of side openings 596 between the at least a pair of tulip-shaped grooves 593; and a bottom opening 592. The at least a pair of tulip-shaped grooves 593 are configured to receive and operatively couple to the thread 230 of the shaft 540 when the distal tip 220 of the shaft 540 passes through the bottom opening 592 of the tulip-shaped member 590. After the thread 230 has engaged the at least a pair of tulip-shaped grooves 593, a pair of pins 595 can be operatively coupled to the tulip-shaped member 590 through the pair of side openings 596.

[0178] When present, the holes in the bracket 280 facilitate ingrowth of bone through the screws. Other materials for making pedicle screws include pre-packaged demineralized bone matrix (DBM), pre-packaged synthetic DBM, unpackaged DBM, and magnesium-infused titanium. During insertion, the built-in channels capture autograft. The screws have a double-ball angle and are thin. The screws include a locking cap with reverse-angle threads. The screws can be hollow or non-hollow.

[0179] The length of the screw is between 35 mm and 65 mm, and the diameter is between 4.5 mm and 8.5 mm. The acceptance criterion for the rod is 5.5 mm.

[0180] The built-in channels for autograft collection enhance the structural integrity of the implant. These built-in channels resist bone mineral density loss excellently and reduce micromotion. The randomized porosity pattern of the bracket 280 is typical of natural trabecular bone. In addition, the built-in struts provide structural integrity. The pedicle screws 200, 300, 400, 500 are made of cobalt-chrome, titanium, and magnesium-infused titanium.

[0181] The device is tested for cobalt-chrome and complies with American Society for Testing and Materials (ASTM) standards 543, 1798, and 1717.

[0182] ASTM Standard 543 evaluates the chemical reagent tolerance of plastic materials, including castings, thermoformed products, cold-formed products, laminated resin products, and sheets. Three procedures are presented, two under Practice A (immersion testing) and one under Practice B (mechanical stress and reagent exposure under standardized conditions of applied strain). These practices report changes in weight, dimensions, appearance, color, strength, and other mechanical properties. Standard reagents are specified to establish results on a comparable basis, without excluding other chemical reagents relevant to specific chemical resistance requirements. Provisions are made for reagent exposure at various exposure times, stress conditions, and elevated temperatures. The type of conditioning (immersion or wet patch / wiping method) depends on the end use of the material.

[0183] ASTM Standard 1798 covers the measurement of uniaxial static, fatigue strength, and resistance to loosening of the interconnect mechanisms of spinal fusion implant components. This test method provides a means to mechanically characterize different designs of spinal implant interconnects. Various components and interconnects can be combined for static and fatigue testing of spinal implant constructs. This test method does not involve the analysis of the structure or substructure of spinal implants, nor does it define the performance level of spinal implants.

[0184] ASTM Standard 1717 covers the materials and methods for static and fatigue testing of spinal implant assemblies in a vertebrectomy model. The test materials for the combination of spinal implant assemblies can be specific, depending on the spinal location and the intended method of application to the spine. These test methods provide a basis for mechanical comparison between past, present, and future spinal implant assemblies. They allow comparison of spinal implant constructs with different intended spinal locations and methods of application to the spine. These test methods are not intended to define performance levels. Instead, these test methods establish guidelines for methods of load type and applied load, measuring displacement, determining yield load, and evaluating the stiffness and strength of spinal implant assemblies. Methods for three static load types and one fatigue test are defined for the comparative evaluation of spinal implant assemblies.

[0185] In certain embodiments, the pedicle screws 200, 300, 400, 500 are individually packaged in double Tyvek TM peel trays.

[0186] In certain embodiments, the pedicle screws 200, 300, 400, 500 are injected or sprayed with materials such as BMA concentrate, calcium phosphate, biologics, and / or antibiotics. The filled or coated screws are allowed to sit for 10 to 15 minutes before insertion to allow material absorption.

[0187] Example 3 - Bone harvesting screw

[0188] Reference Figure 17, the bone collection feature (spoon) is located on the minor diameter of the screw. When the screw is inserted, these bone collection features pull bone and cells into the lattice structure.

[0189] In some embodiments, the bone collection features are positioned along the entire length of the screw.

[0190] In some embodiments, the bone collection features are located only along the distal portion of the screw ( Figure 19 ). Cross-section A-A shows the bone collection features at the leading edge of each opening such that during insertion, the bone collection features pull cells into the porous (lattice) structure of the screw ( Figure 20 ). In this embodiment, the proximal portion does not have these features ( Figure 18 ), allowing for a tight fit in the cortical bone located at the proximal end of the screw. Cross-section B-B shows the area without bone collection features ( Figure 21 ).

[0191] In some embodiments, the spoon-shaped feature rises obliquely from the minor diameter to a diameter slightly larger than the minor diameter on the surface between the porous structures. In such embodiments, the spoon-shaped feature is offset in the insertion direction.

[0192] In some embodiments, the spoon-shaped feature is angled or has a radius to assist in collection. In some embodiments, the leading edge is angled.

[0193] In some embodiments, for example, the screw includes a thickened neck-head junction below the hole to reduce the likelihood of rod breakage during screw installation.

[0194] Example 3 - Diamond lattice structure

[0195] The bone screw is 3D printed and tested with a diamond lattice structure. In some embodiments, for example, the spoon-shaped features are positioned along a helical pattern corresponding to the helical pattern of the openings into the internal lattice structure.

[0196] The design is based on a triply periodic minimal surface (TPMS), which is a minimal surface that is invariant under a rank 3 translation lattice. These surfaces have the symmetry of a crystallographic group. Many examples with cubic, tetragonal, rhombohedral, and orthorhombic symmetries are known.

[0197] Specifically, the Schwartz diamond TPMS is used for the lattice, formed by symmetry parameters, remapped from Cartesian coordinates to spherical polar coordinates about the central axis of the screw shaft (the screw shaft is sheared to form a helical winding), thickened, thinned, and intersected with the 3D geometric space of the stent.

[0198] Generating surfaces using symmetric parameters: Given a solution to the Plateau problem for a polygon, the reflection of the surface across a boundary line also produces a valid minimal surface that can be continuously joined to the original solution. If the minimal surface intersects a plane at a right angle, the mirror image in the plane can also be joined to the surface. Thus, given a suitable initial polygon inscribed in a unit cell, a periodic surface can be constructed.

[0199] Equation 1 approximately calculates the TPMS of these bone screws:

[0200] cos(x)cos(y)cos(z) - sin(x)sin(y)sin(z) = 0 (1)

[0201] This is the specific fundamental equation for this embodiment of the bone screw. The x, y, and z variables define the periodicity (i.e., the pattern) on X / Y / Z, similar to the way a cubic lattice is defined. This surface is called a "diamond" because it has two intertwined congruent labyrinths, each with a shape that is an inflated tubular version of a diamond bonding structure. For ease of discussion, a regularly repeating unit has been assumed, although the TPMS geometry is topologically affected to become pseudo-random. There are exact expressions based on elliptic integrals from the Weierstrass-Ennepar parameterization.

[0202] As an equation, it defines the Schwarz D surface that passes through infinite real space. Such a surface divides real space into two identical volumes, and the entry of positive space into negative space defines the isosurface or the medial surface. Figure 22 A two-dimensional slice through the Schwarz diamond mathematical field is shown, where the cyan space is "positive" and the purple space is "negative". Figure 23 Shown is Figure 22 a three-dimensional cross-section of the non-thickened surface of , where light gray represents the positive side of the surface and dark gray represents the negative side, as defined by the surface normal vector. In some embodiments, the cubic repeating pattern is 1.8 mm on X / Y / Z.

[0203] After creating the Schwarz equation, it is helically remapped (i.e., distorted) to create the base of the final shape. To do this, the equation is mapped from Cartesian space to polar space using conventional methods. The periodicity is mapped cylindrically. That is, the number of "spokes" remains radially a multiple of the selected unit size. Figure 24 Shown is the cylindrical remapping after conversion to polar space. This remapping is around the central axis of the screw shaft.

[0204] After remapping, the shear space is created to form a helical wrap, similar to the way an inclined plane wraps around a cylinder to create a screw. To form the shear, the Schwarz D equation is remapped from the X / Y / Z coordinate space by shearing one (or more coordinates): x → x, y → y, and z → z + x, where the Schwarz diamond is sheared in the XZ plane. This shear operation preserves the continuous field.

[0205] After the field is sheared and cylindrically remapped, it is thickened using an absolute value operation that converts the negative space of the equation to positive space in three dimensions ( Figure 25 ). The helical wrap of the medical device is defined as having a period three times the size of the cube repeat pattern (5.4 mm), thereby forming a single helix with a circumferential count of three and three radial spokes. Thereafter, a subtraction mathematical operation offsets the central geometry to create a sheet-like structure, as Figure 26 shown, where the thin-walled geometry is represented by the thin pink walls of the cylindrical radiation. In some embodiments, the walls are approximately 0.50 mm thick. Once the thin-walled lattice field intersects the 3D geometric space defining the lattice's existence location, the model of the stent is generated ( Figure 29 ).

[0206] The above diamond lattice was generated for two embodiments of the bone screw. Figure 30 A perspective view of an embodiment of a porous pedicle screw is shown, which presents such a helical pattern in the diamond structure lattice. Figure 31 The back of the porous pedicle screw is shown, Figure 32 The front of the porous pedicle screw is shown, Figure 34 The top of the porous pedicle screw is shown, and Figure 35 The bottom of the porous pedicle screw is shown. Figure 33 An enlarged inset of the front view of the porous pedicle screw is shown.

[0207] Figure 36 A perspective view of another embodiment of a porous pedicle screw is shown, which presents a diamond structure lattice that includes a bone harvesting feature at the distal tip and textured threads at the proximal end. The texture is similar to the surface topography of the diamond lattice structure. Figure 37 The back of the porous pedicle screw is shown, Figure 38 The front of the porous pedicle screw is shown, Figure 40 The top of the porous pedicle screw is shown, and Figure 41 f shows the bottom of the porous pedicle screw. Figure 39 An enlarged inset of the front view of the porous pedicle screw is shown.

[0208] Example 4 - Sheep bone integration and pullout strength study

[0209] In vivo evaluation, ex vivo evaluation, and data from this six-sheep study will determine how this treatment modality affects bone mineral density, polymorphonuclear cells (PMN), lymphocytes, plasma cells, macrophages giant cells, necrosis, osteoblasts, osteoclasts, signs of bone remodeling, neovascularization, fibrosis, signs of implant degradation, and particulate debris.

[0210] The first specific aim is to determine whether porous pedicle screws promote bone integration and pullout strength compared to the gold standard pedicle screw / rod construct in a sheep model of posterior lumbar interbody fusion. The topography of the 3D printed porous pattern has higher adhesion of stem cells to titanium. Additionally, mesenchymal stem cells and hematopoietic stem cells have therapeutic effects on bone. By combining these two approaches, the disclosed porous pedicle screws may achieve superior effects in terms of bone integration and pullout strength compared to current pedicle screws.

[0211] Bone mineral density (BMD) of 84 vertebral bodies (L1-L6) in six sheep will be measured one week preoperatively and at 24 weeks and 36 weeks postoperatively. Each subject will undergo two separate lumbar interbody fusion (LIF) procedures at the L2-L3 and L4-L5 joints. L1 and L6 will be native controls for comparison of changes with and without hardware.

[0212] Table 2 - Animal subjects

[0213]

[0214]

[0215] In each subject, a titanium interbody cage and bone void filler packed into the interbody cage will be placed between the L2-L3 and L4-L5 segments. Then, screws with diameters of 4.5 mm, 5.5 mm, or 6.5 mm and lengths of 45 ± 10 mm will be inserted into the right and left pedicles of the L2, L3, L4, and L5 vertebral bodies. This configuration represents a traditional fusion device and surgical technique. Prior to insertion, the porous pedicle screws (treatment) will be sprayed with autologous stem cell concentrate along the length of the porous portion of the screw.

[0216] All animals will have live lumbar X-rays immediately postoperatively (PO) and at the time of sacrifice. Throughout the study, animals will be visually evaluated at least once daily. Abnormalities, such as signs of infection at the surgical site, will be recorded. Six animals will be sacrificed in total 36 weeks after surgery.

[0217] After euthanasia, the lumbar spine segment (L1-L5) was freshly dissected into individual functional spinal units (FSUs) (i.e., L4-L5) for postmortem assessment. After meticulous dissection in the sagittal and coronal planes, high-resolution biplanar digital radiographs and photographs were taken at the time of euthanasia. All samples were subjected to non-destructive range of motion (ROM) biomechanical measurements, including ROM biomechanics under flexion-extension, lateral bending, and axial rotation to a pure moment load of 6.0 N-m, resulting in range of motion (degrees), construct stiffness (degrees / N-m), and neutral zone (degrees).

[0218] Destructive pedicle screw pullout tests were to be performed. Quasi-static failure ramp tests were to yield construct stiffness (N / mm), yield force (N), ultimate failure force (N), and visually observed failure mode (MOD). Destructive pedicle screw unscrewing was to be tested for 1 screw out of N = 4 screws, and counterclockwise rotation of the quasi-static torque to loosen the screw was to result in the final torque (Nm).

[0219] Other tests were to include micro-computed tomography (MicroCT) of each FSU and associated pedicle screws, quantitative assessment (bone volume and bone density) of the posterior lumbar fusion (PLF) region, qualitative assessment of bone ingrowth around the pedicle screws, pedicle screw histology, organ histology, and static histomorphometric measurements of regions of interest (ROIs) of the screws, including percentage of bone area within the ROI, percentage of fibrous tissue within the ROI, percentage of void space within the ROI, percentage of the screw within the ROI, and percentage of bone growth onto the device.

[0220] Slides were to be delivered to a certified pathologist for histopathological analysis. The pathologist was initially to be unaware of the treatment parameters for each site. Then, when applicable, the sections were to be analyzed and graded according to the grading scheme in Table 3, based on each cell type and response. After all slides were scored for data post-processing, the pathologist was to be unblinded so that the data could be compared to control samples.

[0221] Table 3 - Histological evaluation scoring system for bone slice cell types and responses

[0222]

[0223] Reference: ISO 10993-6 Annex E (Biological evaluation of medical devices - Part 6: Tests for local effects after implantation)

[0224] The histopathology report will include, but not be limited to, a summary of methods and materials, tables and qualitative data and conclusions as of the last time point, low-power images, and representative microphotographs to illustrate the findings. An unpaired t-test with an alpha (α) value of 0.05 will be performed to determine the statistical significance of the biomechanical and histomorphometric outcome parameters. Then, the data will be compared with similar retrospective studies.

[0225] The second specific objective of this study is to demonstrate that the injection and spraying of autologous concentrated stem cells within and around pedicle screws is safe. Porous 3D-printed titanium intervertebral cages are typically impregnated with autologous stem cells during surgery. They have been proven to be safe and are the gold standard for assisting vertebral fusion after disc removal. This study aims to demonstrate that it can be performed within the vertebrae of sheep to provide confidence in safety for human clinical trials.

[0226] After sacrifice, histology will be compared with previous studies to determine the differences and similarities in polymorphonuclear cells (PMNs), lymphocytes, plasma cells, macrophages ), giant cells, necrosis, signs of bone remodeling in osteoblasts +, osteoclasts, neovascularization, fibrosis, signs of implant degradation, and particulate debris. The histology reports will also be compared and contrasted between the control, native, and treatment sites. An unpaired t-test with an alpha (α) value of 0.05 will be performed to determine the statistical significance of the biomechanical and histomorphometric outcome parameters. Injection of autologous stem cells within and around porous pedicle screws is expected to be safe compared to control screws, native screws, and previous studies.

[0227] The third specific objective of this study is to show that porous pedicle screws have topographies and porous patterns for promoting stem cell adhesion. Human mesenchymal stem cells have the strongest adhesion affinity for titanium surfaces with a porosity between 50% and 70%, with more robust and denser internal cell migration patterns and high cell viability. Therefore, the porous patterns and topographies of porous pedicle screws should have adhesion similar to that of stem cells.

[0228] After sacrificing the sheep, the screws will be removed from the vertebrae and stem cell adhesion will be studied. Cell viability on the implant surface will be performed using a LIVE / DEAD assay. Conditioned medium assays will be used to study bone morphogenetic protein 2 (BMP2) expression levels, vascular endothelial growth factor (VEGF), osteocalcin, osteoprotegerin expression, DNA, and alkaline phosphatase activity.

[0229] The correlation between cell adhesion with 3D-printed titanium patterns and porous pedicle screws will be shown. Porous pedicle screws exhibit better stem cell adhesion than the control group and subjects who have not undergone the experiment, as well as an adhesion rate similar to previous studies.

[0230] Example 5 - Sheep infection study

[0231] Another study involving six animals will focus on testing the feasibility of injecting a mixture of calcium sulfate and antibiotics as a means of reducing the infection rate after spinal fusion. The primary objectives of this project are to confirm (1) whether the tested pedicle screws contribute to achieving excellent bone integration and pullout strength compared to the gold standard pedicle screw / rod construct in a sheep model of posterior lumbar interbody fusion; (2) injecting a mixture of calcium sulfate and antibiotics reduces the infection rate after spinal fusion; and (3) the tested pedicle screws have a morphology and porous pattern for injection to support the above objectives.

[0232] For the first objective, the rationale is that if the patient's bone is infected, the surgeon can protect the hardware by injecting an antibiotic mixture via the device. Through the proposed animal study, it will be confirmed that in an infected and controlled area (e.g., vertebra), (1) compared to the control group, the pedicle screws will protect the surgical hardware (i.e., confirm that the infection has not spread to the hardware), and (2) the pedicle screws reduce the infection in the bone.

[0233] The sheep model was chosen because the sheep spine is most similar to the human spine. The sheep vertebrae are large enough to accommodate the pedicle screws disclosed herein. Smaller animals are not feasible because the screws are too large for their bones.

[0234] This sample size was chosen to realistically evaluate feasibility and achieve proof of concept within the first phase scope and timeline. To be consistent with the project objectives, the first phase results will be interpreted as preliminary results, and the tentative conclusions will be used to inform the expected second phase, in which a large-scale, controlled, and powerful animal study can be proposed to evaluate the efficacy endpoints in a scientifically rigorous manner.

[0235] The experimental design and methods will be substantially the same as the sheep study in Example 4 above, including Tables 2 and 3.

[0236] All references, patents, or applications (whether U.S. or foreign) cited in this application are incorporated herein by reference as if their entire contents were written herein. In the event of any inconsistencies, the materials disclosed herein shall prevail.

[0237] From the foregoing description, those skilled in the art can readily ascertain the basic characteristics of the present invention, and without departing from the spirit and scope of the present invention, various changes and modifications can be made to adapt it to various uses and conditions.

Claims

1. A medical device, the medical device comprising: A body; A stent in the body; And A device disposed on the body for concentrating bone growth over the entire body to minimize shear stress at the distal tip and spread micromotion over the entire medical device to promote bone ingrowth.

2. The medical device according to claim 1, wherein the device for concentrating bone growth comprises at least one trephine for harvesting bone inside the medical device.

3. The medical device according to claim 1 or 2, the medical device being constructed in an arcuate cross-sectional pattern that varies from a proximal end to a distal tip.

4. The medical device according to claim 3, the medical device being configured to be placed into the lumen of a vertebral body such that when the medical device is rotated coaxially, an autograft is harvested within the stent.

5. The medical device according to any one of claims 1 to 4, wherein the threads have a concave profile.

6. The medical device according to claim 1 or 5, wherein the stent comprises a triply periodic minimal surface (TPMS), the TPMS having a cubic repeating pattern that defines the walls within the stent.

7. The medical device according to claim 6, wherein the TPMS is a Schwartz diamond that is helically wound around the central axis of the medical device and into the 3D geometric space of the stent.

8. The medical device according to claim 7, wherein the TPMS is helically wound into a single helix.

9. The medical device according to claim 7 or 8, each turn of the helix of the medical device having three radial spokes.

10. The medical device according to any one of claims 6 to 9, wherein the cubic repeating pattern is approximately 1.8 mm in the X / Y / Z dimensions.

11. The medical device according to any one of claims 7 to 10, wherein the helical winding of the medical device is defined as having a period three times the size of the cubic repeating pattern.

12. The medical device according to any one of claims 6 to 11, wherein the walls are approximately 0.5 mm thick.

13. The medical device according to any one of claims 1 to 12, wherein the threads near the proximal end are textured to have a morphology similar to that of the stent.

14. The medical device according to any one of claims 1 to 13, the medical device being configured to accommodate one or more biological agents.

15. The medical device according to any one of claims 1 to 14, the medical device further comprising at least one autologous product sprayed onto the medical device or injected through the medical device.

16. The medical device according to any one of claims 1 to 15, wherein the body is a shaft.

17. The medical device according to claim 16, the medical device being a bone screw.

18. The medical device according to claim 17, the medical device reducing one or more of the following: screw loosening, screw extrusion, rod fracture, and reduced bone mineral density.

19. The medical device according to claim 17 or 18, the medical device comprising a grooved tip.

20. The medical device according to any one of claims 17 to 19, the medical device being a pedicle screw.

21. A method for treating a fracture in a patient in need, the method comprising: Implant the medical device according to any one of claims 1 to 20 into the bone of the patient.

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