Implantable thumb prosthesis device & system

Abstract

An endoprostheses may include a bone anchor having a proximal end having an extension configured to be inserted into a residual portion of an amputated bone of a patient. The endoprostheses may also include a non-jointed endoprosthesis body configured to enclosed by soft tissue of the patient and having a proximal end configured to be coupled to a distal end of the bone anchor. The endoprostheses may also include a coupling configured to releasably engage the bone anchor and the non-jointed endoprosthesis body. The coupling may be configured to cooperate with the bone anchor and the non-jointed endoprosthesis body to maintain an axial and rotational arrangement of the non-jointed endoprosthesis body with respect to the bone anchor.

Description

Attorney Docket No. 05820.080W01IMPLANTABLE THUMB PROSTHESIS DEVICE & SYSTEMRELATED APPLICATIONS

[0001] This application claims the benefits of U.S. Provisional Patent Application No. 63 / 683,581, titled ‘ IMPLANTABLE THUMB PROSTHESIS DEVICE & SYSTEM,” filed August 15, 2024, U.S. Provisional Patent Application No. 63 / 798,707, titled “ORTHOPEDIC IMPLANT FOR SURGICAL THUMB RESTORATION,” filed May 2, 2025, the disclosures of which are incorporated herein by reference in their entireties.STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

[0002] This invention was made with government support under grant number 1944001 awarded by the National Science Foundation, and grant numbers R61 AR78096 and R33AR078096 awarded by the National Institutes of Health. The government has certain rights in the invention.BACKGROUND

[0003] The thumb is a critical component of human hand function, playing an essential role in a person’s quality of life. Its unique anatomy, such as its wide range of motion and the ability to oppose the fingers, allows for powerful and precise grips, making it possible to hold tools, write, button clothes, or handle delicate objects. This opposable movement is a key evolutionary7advantage that enables fine motor skills and complex manual tasks, setting humans apart from most other species. Without the thumb’s functionality, many everyday activities, from preparing food to using a smartphone, become significantly more difficult or even impossible. Beyond practical use, the thumb also contributes to balance and coordination in the hand, enhancing dexterity7and efficiency. In essence, the thumb is not only a structural part of the hand, it is a central enabler of independence, productivity, and the ability to interact with the world in both functional and creative ways.

[0004] Thumb amputations sever the physical connection between muscles and the thumb, causing severe, extensive sensorimotor impairment. An externally worn thumb or finger prosthesis is the standard means to restore part of the missing digit’s function. Unfortunately, thumb and finger prostheses still do not look, move, or feel like the biological intact limb.

[0005] Current prosthetics and prosthetic systems for fingers and thumbs are less than ideal for a number of reasons. For example, state-of-the-art prosthetic thumbs, whileAttorney Docket No. 05820.080W01 valuable in restoring some functionality after amputation are less than ideal for a number of reasons. One major limitation is the lack of true opposable movement, sense of touch, and fine motor control. Although many designs attempt to replicate the thumb’s range of motion, they often cannot match the intricate coordination and responsiveness of a biological thumb. This results in difficulty performing precision tasks like writing, fastening buttons, or delicately handling fragile objects, activities that a natural thumb makes intuitive and efficient. Grip strength is another shortfall. Prosthetic thumbs generally cannot generate the same power or endurance needed for sustained tool use or heavy' lifting, reducing overall hand function. Additionally, sensory' feedback, critical for judging pressure, texture, and positioning, is absent in most prosthetic models, meaning the wearer must rely heavily on visual cues, slowing down movements and increasing the risk of dropping or damaging items. Despite advances in ergonomics and materials, prosthetic thumbs can still feel bulky, awkward, or fatiguing over long periods, further limiting their role in restoring the full independence, dexterity, and nuanced control the natural thumb provides.

[0006] In light of the above, improved devices and methods that overcome at least some of the above limitations of the prior devices and methods would be helpful.SUMMARY

[0007] Embodiments of the present disclosure provide improved systems and methods including the use of muscle-driven, fully implanted, finger and thumb prosthesis that enables physiologic sensorimotor feedback and provide for improved outcomes for amputation patients.BRIEF DESCRIPTION OF THE DRAWINGS

[0008] A better understanding of the features, advantages and principles of the present disclosure will be obtained by reference to the following detailed description that sets forth illustrative embodiments, and the accompanying drawings of which:

[0009] FIG. 1 A depicts jointed endoprosthesis for a thumb or finger, in accordance with some embodiments herein;

[0010] FIGS. IB and 1C depict a muscle-driven, jointed endoprosthesis for a thumb or finger with artificial tendons for extension and flexion using residual tissue, such as muscles and tendons, in accordance with some embodiments herein;

[0011] FIGS, IB and 1C depict a jointed endoprosthesis for a thumb and index finger, respectively, in accordance with some embodiments herein;Attorney Docket No. 05820.080W01

[0012] FIGS. 2 A and 2B depict a non-jointed endoprosthesis for a thumb or finger, in accordance with some embodiments herein;

[0013] FIG. 3A and 3B depict a non-jointed endoprosthesis for a thumb or finger, in accordance with some embodiments herein;

[0014] FIG. 4 depicts aspects of a non-jointed endoprosthesis for a thumb or finger, in accordance with some embodiments herein;

[0015] FIG. 5A depicts a non-jointed endoprosthesis for a thumb or finger implanted in a thumb, in accordance with some embodiments herein;

[0016] FIGS. 5B and 5C depicts a non-jointed endoprosthesis for a thumb or finger implanted in a thumb and replacing two joints, in accordance with some embodiments herein;

[0017] FIG. 6A depicts a side view of an endoprosthesis for a thumb or finger, in accordance with some embodiments herein;

[0018] FIG. 6B depicts a top view of the anchor of the endoprosthesis for a thumb or finger of FIG. 6A, in accordance with some embodiments herein;

[0019] FIG. 6C depicts an end view of the anchor of the endoprosthesis for a thumb or finger of FIG. 6A, in accordance with some embodiments herein

[0020] FIG. 6D depicts a connector for an endoprosthesis for a thumb or finger, in accordance with some embodiments herein;

[0021] FIG. 6E depicts a connector and retention mechanism for an endoprosthesis for a thumb or finger, in accordance with some embodiments herein;

[0022] FIG. 7 depicts a cross-section of an endoprosthesis for a thumb or finger, in accordance with some embodiments herein;

[0023] FIG. 8 depicts a cross-section of an endoprosthesis for a thumb or finger, in accordance with some embodiments herein;

[0024] FIG. 9 depicts an anchor or bone stem implant connection to a digit prosthesis for an endoprosthesis for a thumb or finger, in accordance with some embodiments herein; and

[0025] FIG. 10 depicts surface treatments and features for an endoprosthesis for a thumb or finger, in accordance with some embodiments herein.DETAILED DESCRIPTION

[0026] The following detailed description provides a better understanding of the features and advantages of the inventions described in the present disclosure inAttorney Docket No. 05820.080W01 accordance with the embodiments disclosed herein. Although the detailed description includes many specific embodiments, these are provided by way of example only and should not be construed as limiting the scope of the inventions disclosed herein.

[0027] Referring now to FIGS. 1 A-1D, muscle-driven endoprosthesis 100 for a thumb and finger are depicted. FIG. 1 A depicts a partial exploded view and an assembled view of the endoprosthesis 100. The endoprosthesis 100 may include one or more bone components 102, an anchor 104, joints 106, and artificial tendons 108. The bone components 102 may replicate the anatomical structure and function of the thumb or other digit and, in some embodiments, include a distal phalanx bone prosthesis 102C, a proximal phalanx bone prosthesis 102B, and a metacarpal bone prosthesis 102A. The dimensions, curvature, surface features, and proportions of each bone component 102 may be based on the corresponding amputated bone, pre-amputation imaging data, or on the contralateral, intact digit (e.g., the opposite thumb or finger) to ensure anatomical symmetry. In some embodiments, CAD modeling from CT or MRI scans may be used to replicate bone geometry. The distal phalanx bone prosthesis 102C may taper toward the distal end to simulate the shape of an anatomical fingertip and, in certain embodiments, may include a convex nail-bed-like surface, a textured grip pad, or soft-tissue-compatible overmolding to enhance functional and aesthetic realism.

[0028] Each bone prosthesis 102 may be pivotally coupled to an adjacent bone prosthesis 102 by way of joints 106. For example, the distal phalanx bone prosthesis 102C may be pivotably coupled to the proximal phalanx bone prosthesis 102B at a distal joint 106B to simulate the interphalangeal (IP) joint, and the proximal phalanx bone prosthesis 102B may be pivotably coupled to the metacarpal bone prosthesis 102 A at a proximal joint 106A to simulate the metacarpophalangeal (MCP) joint. In some embodiments, intermediate phalanx prostheses may be included to replicate multi -jointed fingers, and in certain designs, the MCP joint may also allow limited abductionadduction in addition to flexion-extension to better mimic natural thumb opposition.

[0029] In certain embodiments, the MCP and IP joints 106 may utilize a hinge-type design to positively connect the bone segments and constrain rotation to a single primary motion path, such as flexion-extension. The joints may be configured to rotate about a single axis of rotation or parallel axes of rotation. In one example, the joints 106 may include a hinge plate 110 having two apertures, each configured to receive a pin 112. Each bone component 102 may include corresponding apertures at proximal and / or distal ends, enabling the insertion of pins 1 12 to form pivot points. This arrangement mayAttorney Docket No. 05820.080W01 permit rotation about one or more longitudinal axes defined by the pins. In some variations, the hinge plate 110 may be curved or contoured to match the anatomical joint geometry and may include recesses or stops to limit motion to physiologically appropriate ranges, thereby preventing hyperextension or overflexion.

[0030] In certain embodiments, one end of the hinge plate 110, for example, the distal end, may be shaped to correspond to a recess 114 formed in a bone segment 102. Such mating geometries may include dovetail, tongue-and-groove, keyed, or conical shapes, which may serve to constrain movement about one of the pins 112 and thereby restrict motion to a single axis. In other embodiments, the joint 106 may pivot about a single axis by using a single pin 112 that extends through apertures in distal and proximal extensions 116 of adjacent bone components 102. In yet another variant, the pivot axis may be achieved with an integrated axle or journal -bearing assembly to reduce part count and simplify maintenance or revision surgery.

[0031] Bearing surfaces of the joints 106 may include a low-friction, wear-resistant material, such as ultra-high-molecular-weight polyethylene (UHMWPE), polyetheretherketone (PEEK), ceramics, or diamond-like carbon coatings, to minimize friction and prevent metal -on-metal contact. The low-friction material may be in the form of a coating, insert, washer, or bushing, and may be located on one or both mating surfaces of the joint. In some embodiments, self-lubricating polymer composites or hydrophilic coatings may be employed to reduce maintenance requirements and extend implant life.

[0032] As an alternative to rigid bearing j oints, the joints 106 may incorporate a flexible fiber-reinforced silicone band, such as the dovetail connector shown and descriebd with respect to FIGS. 6A and 6D. This band may act as both a pivot and an elastic restoring element. The fiber reinforcement may include high-strength, biocompatible, non-degradable materials such as polyester, polyethylene terephthalate (PET), aramid fibers (e.g., Kevlar®), or ultra-high-molecular-weight polyethylene fibers (e.g., Dyneema®). Such reinforcement may improve stiffness, tensile strength, and fatigue resistance compared to silicone alone. The silicone component may be medicalgrade and optionally embedded with antimicrobial or anti-inflammatory agents to reduce infection risk.

[0033] The anchor 104 may include an intramedullary stem 120 configured to anchor the endoprosthesis 100 into a residual bone 122 of the patient. For example, the stem 120 may be dimensioned for press-fit, cemented, or screw-threaded engagement within theAttorney Docket No. 05820.080W01 medullary' canal of a residual metacarpal bone. The anchor may be a separate component (see FIG. 7) or integrally formed with the metacarpal bone prosthesis 102A. The length of the metacarpal bone prosthesis 102 A may depend on the amount of residual metacarpal bone and may have a dimension that locates the joint 106A at the pre-amputation location.

[0034] When separate, the anchor 104 may be connected to the metacarpal segment by press-fitting, a connecting screw, a Morse taper, interlocking splines, or other mechanical coupling. The anchor 104 may include porous titanium, tantalum, or plasma-sprayed hydroxyapatite coatings to promote osseointegration. In other embodiments, bioresorbable coatings impregnated with growth factors or antibiotics may be used to encourage bone in-growth while reducing infection risk.

[0035] The endoprosthesis 100 may include one or more artificial tendons 108, such as an extension tendon 108A and a flexion tendon 108B. These tendons may be constructed from high-strength, fatigue-resistant synthetic fibers, including PTFE, UHMWPE, or braided polyester, and may optionally be coated with lubricants such as silicone or hydrophilic polymers to reduce wear. In some embodiments, the artificial tendons 108 may be actuated by attachment to residual or re-routed muscles. For example, in a thumb application, two extrinsic thumb muscles, the flexor pollicis longus and extensor pollicis longus, may be attached to provide primary flexion and extension at both MCP and IP joints. A third muscle, such as the opponens pollicis, may be attached to a medial portion of the proximal phalanx bone prosthesis 102B to enable opposition and enhance grasp function. The use of artificial tendons may eliminate the need for tendon autografts or allografts, reducing surgical complexity and eliminating donor-site morbidity.

[0036] To guide the artificial tendons 108, the bone components 102 may include integrated channels, sheaths, or pulley bars 124 on dorsal and palmar aspects. These pulleys may be positioned to replicate anatomical tendon paths, preventing bowstringing and maintaining efficient force transmission. In some embodiments, the pulleys may be made from ceramic-coated titanium or low-friction polymer inserts, and may be removable or adjustable to fine-tune tendon tension during or after surgery. The distal ends of the artificial tendons 108 may be affixed to the distal phalanx bone prosthesis 102C using crimped ferrules, threaded fasteners, adhesive bonding, or press-fit anchor posts.

[0037] Referring now to FIG. ID, an index finger endoprosthesis 100B may include bone components 102, an anchor 104, joints 106, and artificial tendons 108. The boneAttorney Docket No. 05820.080W01 components 102 may replicate the skeletal anatomy of the human index finger and, in some embodiments, include a distal phalanx bone prosthesis 102C, a middle phalanx bone prosthesis 102B, and a proximal phalanx bone prosthesis 102A. In certain designs, a metacarpal head interface component or a metacarpal bone prosthesis 102D may be included to connect with the residual metacarpal bone of the patient’s hand.

[0038] The dimensions, contours, and articular geometries of the bone components 102 may be based on the amputated finger’s pre-injury anatomy, medical imaging data (e.g., CT or MRI scans), or measurements of the contralateral, intact index finger. The distal phalanx prosthesis 102C may be tapered toward its distal end to replicate the fingertip profile and may include surface texturing or an overmolded polymer pad to simulate the soft-tissue feel and enhance tactile grip.

[0039] The bone components 102 may be pivotally coupled by joints 106 to replicate the natural finger’s motion. The distal interphalangeal (DIP) joint 106C may pivotably couple the distal phalanx bone prosthesis 102C to the middle phalanx bone prosthesis 102B. The proximal interphalangeal (PIP) joint 106B may couple the middle phalanx bone prosthesis 202B to the proximal phalanx bone prosthesis 202A. The metacarpophalangeal (MCP) j oint 106A may couple the proximal phalanx bone prosthesis 102 A to the metacarpal bone prosthesis 102D or to the residual metacarpal head.

[0040] In some embodiments, the DIP and PIP joints 106 may employ hinge-type designs configured to constrain motion primarily to flexion-extension, reflecting the predominant motion of these anatomical joints. The MCP joint 106A, however, may optionally allow limited abduction-adduction to permit lateral precision movements and assist with object manipulation.

[0041] Hinge-type joints may include a hinge plate with one or more apertures configured to receive pivot pins. The pins may extend through apertures in proximal and / or distal bone segments to form a stable rotational axis. In some designs, the MCP joint may use a dual-axis or gimbal mechanism to replicate the MCP’s compound motion.

[0042] To reduce wear, the joints’ bearing surfaces may incorporate low-friction materials such as UHMWPE, PEEK, or ceramic coatings. Alternatively, a flexible band joint (e.g., fiber-reinforced silicone) may be used for one or more joints, particularly the DIP joint, to allow both pivot and limited elastic return without rigid hardware.

[0043] The anchor 104 may be configured to secure the endoprosthesis into the residual metacarpal bone of the patient. In some embodiments, the anchor may include anAttorney Docket No. 05820.080W01 intramedullary stem 120 designed for press-fit, cemented, or threaded engagement with the medullary canal. The anchor 104 may be integrally formed with the the metacarpal bone prosthesis 102D or be a separate piece connected by a Morse taper, spline interface, or locking screw. Surface coatings, such as porous titanium or hydroxyapatite, may be applied to encourage osseointegration.

[0044] The endoprosthesis 100B may include artificial tendons 108 to replicate the finger’s flexor and extensor mechanisms. In one embodiment, two tendons are used: a flexion tendon 108B to mimic the function of the flexor digitorum profundus and flexor digitorum superficialis, and an extension tendon 108 A to replicate the function of the extensor digitorum. In some designs, a third tendon may be included for intrinsic muscle contributions, such as lateral band motion or fine extension control.

[0045] The artificial tendons 108 may be routed through integrated channels or pulley bars 124 formed along the dorsal and palmar aspects of the bone components 102. The pulley system may replicate the A1-A5 pulley arrangement of an anatomical finger to prevent tendon bowstringing and maintain efficient force transfer. Pulley components may be formed of low-friction polymer, polished metal, or ceramic-coated elements, and may be removable or adjustable to fine-tune tendon tension.

[0046] Distal tendon fixation may be accomplished via press-fit anchors, crimped ferrules, or threaded posts embedded in the distal phalanx bone prosthesis 102C. Artificial tendon materials may include UHMWPE fibers, PTFE cords, or braided polyester, optionally coated to reduce friction and wear.

[0047] When actuated by residual or re-routed muscles, the index finger endoprosthesis 100B may provide functional pinch, grip, and precision movement, enabling activities such as typing, writing, or grasping small objects. The MCP joint’s optional abduction-adduction capability may allow the index finger to cooperate with the thumb or other digits in complex manipulations, such as lateral pinch or key pinch. In some embodiments, joint range of motion, tendon tension, and pulley positioning may be adjustable post-implantation to fine-tune performance based on the patient.

[0048] In certain embodiments, a finger endoprosthesis for a finger may be actuated by attachment of artificial tendons to one or more residual intrinsic or extrinsic muscles of the hand and forearm. The artificial tendons may be routed through the prosthetic structure to replicate the force vectors and motion patterns of the anatomical tendons they replace.Attorney Docket No. 05820.080W01

[0049] For flexion, the artificial tendons may be connected to the residual flexor digitorum profundus (FDP) and / or flexor digitorum superficialis (FDS) muscles. In natural anatomy, the FDP inserts at the distal phalanx to flex the distal interphalangeal (DIP) joint, while the FDS inserts at the middle phalanx to flex the proximal interphalangeal (PIP) joint. In some embodiments, the prosthesis may employ a single flexor tendon attachment to the FDP for simplified actuation of both joints, or separate tendon attachments to both FDP and FDS for independent DIP and PIP motion control.

[0050] For extension, the artificial tendons may be connected to the residual extensor digitorum communis (EDC) muscle. In some embodiments, supplemental artificial tendon connections to the extensor indicis proprius (for the index finger) or extensor digiti minimi (for the little finger) may be used to provide independent control of specific digits.

[0051] In some embodiments, intrinsic muscle contributions may also be replicated. The lumbricals and interossei muscles naturally insert into the extensor hood and contribute to coordinated extension at the interphalangeal joints while assisting with flexion at the metacarpophalangeal (MCP) joint. An endoprosthesis may mimic these contributions by incorporating secondary tendon paths that apply extension force dorsally while permitting MCP flexion. This arrangement may enhance dexterity, especially for coordinated grips and release motions.

[0052] Artificial tendons may be anchored proximally via surgical attachment to residual muscle tissue using suturing techniques, bioresorbable suture anchors, or integrated tendon-coupling devices. In cases where residual muscle function is inadequate, muscle-tendon transfers from adjacent functioning muscles (e.g., extensor carpi radialis longus for extension, brachioradialis for flexion) may be performed to provide sufficient actuation force.

[0053] The tendon pathways within the prosthesis may incorporate anatomically- inspired pulley systems to maintain proper moment arms, prevent bowstringing, and ensure smooth motion. Pulley placement may correspond to anatomical pulley locations (e.g., A1-A5 and cruciform pulleys), but may be adapted in position, size, or number for mechanical optimization in the prosthetic context.

[0054] In certain embodiments, tendon tension may be adjustable intraoperatively or postoperatively via integrated tensioning mechanisms, such as set screws, ratcheting devices, or crimp locks, enabling fine-tuning of the prosthetic digit’s movement profile to the patient’s functional needs.Attorney Docket No. 05820.080W01

[0055] With reference to FIGS. 2A and 2B, a non-jointed endoprosthesis 200 is provided. The endoprosthesis 200 may include a bone anchor 202, a distal bone prosthesis 204, a fastener 206, and, in some embodiments, an exterior coating 212, a spacer 214, and a coating 21 . The bone anchor 202 may be configured as an osseointegrated pin, post, or screw, such as a threaded metallic screw, a solid stem for press-fit fixation, or a modular abutment with a detachable platform. The anchor may be formed from titanium alloys, cobalt-chromium alloys, stainless steel, or high-strength ceramics, and may be surface-treated through porous plasma spray, hydroxyapatite or tricalcium phosphate coating, micro-texturing, or grit blasting to promote osseointegration. Other or additional fixation methods may include expansion sleeves, external thread patterns designed for cortical or cancellous bone, or cement fixation.

[0056] The distal bone prosthesis 204 may represent an unjointed tip replacing the distal phalanx, interphalangeal (IP) joint, and any missing portion of the proximal phalanx. It may be sized and shaped from imaging of the contralateral digit and optionally include an inherent bend of 0° to 30° with respect to the longitudinal axis of the residual proximal phalanx and / or the bone anchor, to mimic common arthrodesis positions for optimal grasping and functional use. The prosthesis may have a structural core of biocompatible materials, such as titanium, PEEK, stainless steel, or biocompatible carbon fiber-reinforced polymer. The fastener 206 may couple the distal bone prosthesis 204 to the anchor 202 through an aperture 214 that extends though the distal bone prosthesis 204, such as from a distal end to a proximal end. The aperture 218 may include a shoulder 216 against which the fastener holds the distal bone prosthesis 204 to the bone anchor 202.

[0057] An exterior coating 212 may be applied to the distal bone prosthesis 204 to promote integration with soft tissue, using materials such as bioinert silicone or degradable polymers like polygly colic acid, with surface textures ranging from smooth to micro-textured and may additionally or alternatively include it could have 3D pores for tissue ingrowth including microvascular and macrovascular invasion to promote sustainable living interface. The microvascular and macrovascular invasion promotes a sustainable living interface by allowing cells to turn over as part of the tissue cycle.

[0058] A coating 216 may be applied to the bone anchor 202 to enhance bone attachment and reduce immune response, with options including hydroxyapatite, bioactive glass, or porous metallic surfaces.Attorney Docket No. 05820.080W01

[0059] In some embodiments, a spacer 214 may be positioned between the anchor 202 and bone prosthesis 204 to adjust overall length, distribute mechanical loads, and achieve symmetry with the contralateral digit. The spacer may be expandable, using ratcheting or threaded mechanisms for intraoperative fine-tuning, and may be formed from titanium, PEEK, or UHMWPE.

[0060] This non-j ointed endoprosthesis 200 may be adapted for reconstruction of other digits beyond the thumb, including the index, middle, ring, and little fingers, with component geometry, length, and contour adjusted to match each digit’s natural anatomy and functional role. For example, in the index finger, the prosthesis may be shaped to optimize pinch and fine manipulation with the thumb, while in the ring and little fingers it may be contoured to support power grips. The design may also be scaled and adapted for partial toe reconstructions, including the great toe or lesser toes, where maintaining length and restoring push-off function are critical.

[0061] The endoprosthesis 200 may be used in amputations at various levels below the proximal interphalangeal (PIP) joint or the metacarpophalangeal (MCP) joint. For amputations below the PIP joint, the prosthesis may replace the distal and middle phalanges while anchoring into the proximal phalanx. For amputations below the MCP joint, the device may replace the entire finger shaft, anchoring into the residual metacarpal bone. In both scenarios, the bone anchor 202 may provide a stable, osseointegrated interface, and the distal bone prosthesis 204 restores digit length, contour, and load-bearing capacity without the complexity of jointed articulation.

[0062] With reference to FIGS. 3A, 3B, 4, and 5A, an embodiment of a non-jointed endoprosthesis 300 is depicted. The non-jointed endoprosthesis 300 includes a bone anchor 330 (also referred to as an abutment), a thumb tip prosthesis 310, and a coupling 320 (also referred to as a clip). The bone anchor 330 is configured for secure osseointegration within the residual bone of an amputated digit and serves as the primary’ load-bearing interface between the patient’s skeletal structure and the prosthesis. In certain embodiments, the bone anchor may be in the form of a threaded screw, post, or stem, optionally having cylindrical, conical, or multi-lobed cross-sections to improve rotational stability. Threads may be cut or formed to match cortical or cancellous bone profiles, such as M4 x 0.7 mm right-hand thread, with a length and diameter selected to optimize pull-out strength without excessive cortical disruption.

[0063] The thumb tip prosthesis 310 may include a proximal portion 311 (proximal phalanx portion) with a length, cross-section, and curvature corresponding to the missingAttorney Docket No. 05820.080W01 portion of the proximal phalanx, and a distal portion 313 (distal phalanx portion) shaped to replicate the patient-specific distal thumb anatomy. The distal portion 313 may be oriented at a defined angle 302 relative to the longitudinal axis 301 of the proximal portion 311 and / or the bone anchor 330. In certain embodiments, this angle may range from 0° to 30°, consistent with arthrodesis positions for enhanced grip strength and dexterity. The tip geometry may be generated from high-resolution CT or MRI imaging of the contralateral thumb, producing a patient-specific digital model for additive manufacturing. The prosthesis may be fabricated from titanium alloys, cobalt-chrome alloys, stainless steel, or high-performance polymers such as PEEK, and may incorporate porous or lattice zones to reduce weight while maintaining structural integrity.

[0064] The thumb tip prosthesis 310 may also include a slot 312 for receiving the coupling 320. The slot 312 may contain one or more grooves 315 that receive and retain the coupling. The fit between the coupling 320 and the slot 312 (and associated grooves 315) may be an press fit, a sliding fit, or a snap-fit, depending on desired surgical handling characteristics and retention strength. In some embodiments, the grooves 315 may have undercut profiles to resist pull-out forces.

[0065] The coupling 320 may be a C-shaped clip or a variation thereof, such as a “bread clip” shape. A bread-clip sty le coupling combines the general retention mechanics of a C-clip with the flat, tabbed profile of a bread clip, featuring an open section 322 that allows the clip to snap over a cylindrical or partially cylindrical feature, such as the head of the bone anchor 330. The access slot 324 or gap is narrower than the diameter of the open section 322, and shoulders or inward-facing lips 326 may extend partially into the open section to enhance retention. A protruding tab or grip 328 extends outward from the clip body opposite the slot 324, allowing for manual or tool-assisted installation and removal. The sides 329 of the clip may be parallel to each other to engage with the grooves 315 of the thumb tip prosthesis. The clip may be fabricated from titanium, stainless steel, or biocompatible polymers (e.g., PEEK, PPSU), with surface finishing or coatings to improve wear resistance and reduce friction.

[0066] The bone anchor 330 may include a shaft 332 for implantation into the medullary canal of the residual bone, such as the thumb’s proximal phalanx or metacarpal. The head 338 of the anchor may serve as an abutment portion for coupling with the thumb tip prosthesis 310 via the coupling 320. The abutment portion may include both axial retention features, such as circumferential grooves 336, and rotational constraint features, such as opposing flat, sloped surfaces 339. These flat surfaces 339Attorney Docket No. 05820.080W01 may mate with corresponding flat, sloped surfaces 319 within the aperture 314 of the thumb tip prosthesis 310, forming a keyed interface that resists rotational displacement under torsional loads.

[0067] Axial retention is achieved when the coupling 320 engages both the groove 336 in the head 338 of the bone anchor 330 and the slot 312 in the thumb tip prosthesis 310. This engagement constrains movement of the thumb tip prosthesis 310 along the proximal-distal axis, preventing disengagement during functional use.

[0068] Rotational containment is provided by the keyed engagement between the sloped surfaces 339 of the anchor head 338 and the corresponding surfaces 319 of the thumb tip prosthesis 310, thereby resisting twisting or shearing motions that could compromise stability. In some embodiments, additional anti-rotation measures such as spline profiles, hexagonal heads, or asymmetric tapers may be used.

[0069] The non-jointed endoprosthesis 300 may also include an expandable spacer 340 positioned between the bone anchor 330 and the thumb tip prosthesis 310. This spacer may allow intraoperative adjustment of overall prosthesis length to achieve symmetry with the contralateral digit. Expandable spacers may use ratcheting, threaded, or wedge mechanisms, and may be fabricated from titanium, PEEK, or UHMWPE.

[0070] The surfaces of the thumb tip prosthesis 310 and / or bone anchor 330 may be partially covered with a 3D porous coating engineered to promote soft-tissue and osseous ingrowth. Such coatings may feature graded pore sizes, microvascular channels of approximately 50-200 microns and macrovascular channels of approximately 300-800 microns, to facilitate both capillary and small-vessel infiltration. The interconnected pore network allows for sustained vascularization and cell turnover as part of the tissue cycle, wherein old cells are replaced and metabolic waste is removed while oxygen and nutrients are continuously supplied. Pore geometries may be spherical, ellipsoidal, or branched, and surface textures may be micro-roughened or chemically modified to enhance cellular adhesion.

[0071] While illustrated for a thumb application, the non-jointed endoprosthesis 300 may be adapted for reconstruction of other digits, including the index, middle, ring, and little fingers, or for partial toe reconstruction. The proximal and distal segments may be proportionally scaled, and the distal portion may be angled or contoured according to the functional role of each digit, e.g., a straighter, precision-oriented tip for the index finger; a slightly flexed, power-grip-optimized tip for the middle and ring fingers; and a medially swept tip for the little finger to facilitate hand cupping. In partial toe applications, theAttorney Docket No. 05820.080W01 distal portion may be reinforced for weight-bearing, particularly for the hallux, and contoured with a plantar curve to restore push-off function. The device may also be configured for amputations at various levels below the proximal interphalangeal (PIP) joint or the metacarpophalangeal (MCP) joint, replacing all missing segments while anchoring into the nearest viable bone.

[0072] FIGS. 5B and 5C depict embodiments of an unjointed endoprosthesis 300 configured for implantation at more proximal amputation levels in digits 2, 3, 4, or 5 of the hand, or in the first digit (thumb), where the bone anchor 330 is located in the residuum of the middle phalanx or the metacarpal bone. The amputation level may be through or distal to these bones. By way of example, the amputation may be through the metacarpal shaft, at the metacarpophalangeal (MCP) joint, through the proximal phalanx, or at other levels distal to the metacarpal, with the length and shape of the bone prosthesis 310 being adjusted to approximate the geometry' and / or posture of the missing portion of the digit.

[0073] FIG. 5B illustrates one example of a design for an unjointed endoprosthesis 300 configured to anchor into the first metacarpal bone. The device includes a bone anchor 330, a coupling 320, and a bone prosthesis 310, similar in general architecture to other unjointed endoprostheses 300 described herein. However, in this embodiment, the proximal portion 311 of the bone prosthesis 310 is significantly longer than in designs intended for more distal amputation levels. This increase in length allows the proximal portion 311 to span the distance from the coupling interface to the distal bend portion 313 in a manner that restores the full visible length of the digit despite the more proximal starting point.

[0074] In certain embodiments, the proximal portion 311 may be longer than the distal bent portion 313, particularly in thumb reconstructions anchored in the first metacarpal or in finger reconstructions anchored in the metacarpal or middle phalanx. This proportioning helps maintain the overall aesthetic length and functional reach of the digit while preserving natural anatomical proportions between the straight proximal segment and the angled distal segment. The extended proximal portion also provides additional surface area for soft tissue coverage and integration, as well as for possible surface treatments or coatings, such as porous structures for vascularized tissue ingrowth, along its length.

[0075] The distal bent portion 313 in FIG. 5B may be oriented at an angle relative to the longitudinal axis of the proximal portion 31 1 , with this angle selected to mimicAttorney Docket No. 05820.080W01 functional joint fusion positions — typically about 0° to 30° in the case of thumbs, or angles optimized for grip and precision functions in the case of the other fingers. The distal portion may include compliant pads, textured gripping surfaces, or other features as described, enabling the user to effectively participate in pinch, grasp, and push-off activities.

[0076] While FIGS. 5B and 5C show a thumb-specific design, the same design principles apply to digits 2, 3, 4, and 5. For example, when anchoring into the second metacarpal for an index finger reconstruction, the proximal portion may be lengthened to restore finger length up to the distal tip, with the distal portion angled slightly to facilitate key pinch with the thumb. In the case of the little finger, the distal portion may have a medially sweeping curvature to better conform to natural hand cupping.

[0077] FIG. 5C depicts the unjointed endoprosthesis 300 of FIG. 5B for thumb of a patient, demonstrating the restored overall thumb length and contour after proximal-level amputation. In this illustrated configuration, the bone anchor 330 is fixed within the intramedullary canal of the first metacarpal bone. The coupling 320 securely attaches the bone prosthesis 310 to the bone anchor, maintaining axial and rotational stability. The elongated proximal portion 311 restores the missing length from the anchoring point to the beginning of the angled distal portion 313, while the distal portion is proportioned and angled to mimic the natural functional posture of the thumb.

[0078] The implanted configuration shown in FIG. 5C shows the functional benefits of the proportionally elongated proximal portion 311 when the anchoring point is located farther from the fingertip than in more distal amputations. Functionally, the restored digit length improves leverage during grasp and pinch activities and maintains the spatial relationship between digits for coordinated hand motion.

[0079] With reference to FIGS. 6A-6E, an embodiment of a non-jointed endoprosthesis 600 with an updated coupling mechanism is depicted. In this embodiment, the coupling 320 is a dovetail connector having two lobes 622, 624 and a web 626 that extends between the lobes. The lobes 622, 624 may be symmetrically or asymmetrically shaped, and may have tapered, radiused, or chamfered leading edges to facilitate insertion. The proximal end of the thumb tip prosthesis 310 and the distal end of the bone anchor 330 each include respective dovetail slots 632, 634 that are open on one side of the bone anchor and thumb tip, allowing the lobes 622, 624 of the dovetail connector to be laterally slid into position for installation and removal. The slots may be undercut toAttorney Docket No. 05820.080W01 form a mechanical interlock with the lobes, and may include flared lead-in sections to guide installation.

[0080] The dovetail connector, as depicted in FIG. 6D, may be fabricated from a polymer, metal, ceramic, or composite material that is biocompatible and mechanically suitable for in vivo use. Examples include titanium alloys, stainless steel, PEEK, PPSU, or reinforced UHMWPE. In certain embodiments, the web portion 626 of the dovetail connector may be engineered as a sacrificial element, dimensioned and shaped such that it will preferentially fail under excessive load before damage occurs to the residual bone, the bone anchor 330, or the thumb tip prosthesis 310. This may be accomplished by reducing cross-sectional area, introducing stress concentrators such as necked regions or perforations, or by using a material with lower tensile strength relative to the other implant components. The sacrificial connector may be replaced through a minimally invasive incision, without the need to revise the bone anchor or prosthetic tip.

[0081] In some embodiments, such as depicted in FIG. 6E, the dovetail connector may be further retained by a spring clip 660 seated in a grooved retaining slot 662. The clip 660, which may be formed from spring stainless steel, nitinol, or elastic polymer, is captured by the groove 662 and extends into the slot 634 to block the dovetail connector from sliding out. The clip may be removable with specialized surgical instruments, and may produce an audible or tactile "‘click'’ to confirm engagement. Other retention methods may include set screws, detent mechanisms, magnetic latches (with rare-earth magnets encapsulated in biocompatible coatings), or adhesive bonding in temporary fixation scenarios.

[0082] Referring to FIG. 6C, the dovetail slot 634 and the groove 662 for the retention clip are shown from a distal perspective, illustrating the relative alignment of the retaining features.

[0083] Referring to FIGS. 6B and 6C, a washer 650, such as a polymer washer, is depicted between the thumb tip prosthesis 310 and the bone anchor 330. The washer body may extend radially to fully isolate the mating surfaces, thereby preventing direct metal- on-metal contact and improving long-term use and biocompatibility. The washer 650 may include a coupling feature 652, such as a small dovetail or tongue, that engages with a slot 643 in either the thumb tip prosthesis 310 or the bone anchor 330 to retain the washer during assembly and prevent rotational migration in use. The washer may be fabricated from wear-resistant materials such as UHMWPE, PEEK, or ceramic composites.Attorney Docket No. 05820.080W01

[0084] As discussed elsewhere herein, the bone anchor 330 may include an implant portion and an abutment portion that are separable. The implant portion is configured for permanent osseointegration with the patient’s bone, while the abutment portion couples the prosthesis to the implant in a way that is replaceable or upgradable without disturbing the bone interface. FIGS. 7 and 8 depict examples of separable implant / abutment designs.

[0085] FIG. 7 illustrates a threaded connection embodiment in which the implant portion 710 includes an exposed threaded end 712 that extends from the residual bone. This threaded end receives a matching threaded portion 714 of the abutment 720. Thread geometries may include ISO metric, buttress, or square threads, with engagement lengths selected to balance ease of revision with mechanical stability. Anti-rotation features, such as flats or keyways, may be included in addition to the threads.

[0086] FIG. 8 illustrates a press-fit connection embodiment in which the implant portion 810 includes an exposed stud 812 configured to be received in a socket 822 of the abutment 820. The dimensions of the stud and socket are selected to achieve a secure interference fit, and may include tapered or barrel-shaped profiles to facilitate insertion and improve holding strength. Surface finishes may range from polished to microtextured, and optional circumferential grooves or barbs may be included to increase frictional retention.

[0087] In some embodiments, the bone anchor 330 and the thumb tip prosthesis 310 may be directly joined via a press-fit coupling 320. As depicted, the press-fit coupling may include a stud 922 that mates wi th a socket 924 in an interference fit. While the illustrated arrangement shows the socket as part of the thumb tip prosthesis 310 and the stud as part of the bone anchor 330, the configuration may be reversed. The press-fit may be supplemented with adhesives, cross-pins, or locking rings to enhance stability under cyclic loads. Press-fit geometries may be cylindrical, tapered, or polygonal, and may include surface treatments to further improve interface integrity7.

[0088] FIG. 10 depicts aspects of the thumb tip prosthesis 310 surface treatments and material zones. In some embodiments, the thumb tip prosthesis 310 may comprise a rigid structural portion that forms the internal core or load-bearing skeleton of the prosthesis. This rigid portion may be made from a metal, polymer, ceramic, or composite material that is biocompatible and mechanically suited for repeated loading during activities of daily living. Examples of suitable rigid materials include titanium alloys, stainless steel, cobalt-chromium alloys, carbon fiber-reinforced PEEK, and high-performance thermoplastics such as PPSU or PEKK. The rigid portion may be machined, injectionAttorney Docket No. 05820.080W01 molded, or additively manufactured, and may incorporate integrated lattice or honeycomb structures to reduce weight while maintaining structural strength.

[0089] The rigid portion may also include a porous surface structure designed to facilitate soft tissue integration. Such a surface may be formed directly during additive manufacturing (e.g., selective laser melting), by post-processing techniques such as laser texturing, acid etching, or bead blasting, or by applying a porous coating. The porous region may have interconnected pores with diameters ranging from about 50-200 microns to support microvascular invasion and cell migration, and larger macro-channels between about 300-800 microns to enable macrovascular invasion, promoting the establishment of a sustainable living interface. This integration allows fibroblasts, capillaries, and small blood vessels to penetrate and anchor the prosthetic surface, reducing the risk of soft tissue recession and providing ongoing metabolic support to the overlying tissue.

[0090] In some embodiments, the thumb tip prosthesis 310 may further include a compliant portion 1020 that is more compliant than the rigid structural portion. This compliant portion may serve to mimic the tactile feel, cushioning, and slight deformability of a natural fingertip pad, thereby improving comfort and functional performance in grasping and manipulating objects. The compliant portion 1020 may be positioned at or over the distal end 1030 of the prosthesis and may cover the tip and part of the volar (palmar) surface to provide a realistic interaction surface.

[0091] The compliant portion 1020 may be made from a polymer such as medicalgrade silicone, polyurethane elastomer, thermoplastic elastomer (TPE), or hydrogel-based materials. Shore A hardness values may be selected to replicate the softness of natural fingertip skin and subcutaneous tissue, ty pically in the range of 10A-40A for silicone- based formulations. The compliant portion may be bonded to the rigid portion mechanically (via undercuts, interlocking tabs, or dovetails), chemically (via surface primers or adhesives), or through co-molding processes.

[0092] Similar to the rigid portion, the compliant portion 1020 may also include a porous or textured surface to facilitate soft tissue integration. In some embodiments, the compliant portion may have a microporous outer skin with pore diameters of approximately 20-100 microns to allow dermal tissue anchoring.

[0093] The process parameters and sequence of steps described and / or illustrated herein are given by way of example only and can be varied as desired. For example, while the steps illustrated and / or described herein may be shown or discussed in a particular order, these steps do not necessarily need to be performed in the order illustrated orAttorney Docket No. 05820.080W01 discussed. The various example methods described and / or illustrated herein may also omit one or more of the steps described or illustrated herein or include additional steps in addition to those disclosed.

[0094] Although illustrated as separate elements, the method steps described and / or illustrated herein may represent portions of a single method.

[0095] A person of ordinary’ skill in the art will recognize that any process, system, or method disclosed herein can be modified in many ways. The process parameters and sequence of the steps described and / or illustrated herein are given by way of example only and can be varied as desired. For example, while the steps illustrated and / or described herein may be shown or discussed in a particular order, these steps do not necessarily need to be performed in the order illustrated or discussed.

[0096] The various exemplary methods described and / or illustrated herein may also omit one or more of the steps described or illustrated herein or comprise additional steps in addition to those disclosed. Further, a step of any method as disclosed herein can be combined with any one or more steps of any other method as disclosed herein.

[0097] Unless otherwise noted, the terms “connected to” and “coupled to” (and their derivatives), as used in the specification and claims, are to be construed as permitting both direct and indirect (i.e., via other elements or components) connection. In addition, the terms “a” or “an,” as used in the specification and claims, are to be construed as meaning “at least one of.” Finally, for ease of use, the terms “including” and “having” (and their derivatives), as used in the specification and claims, are interchangeable with and shall have the same meaning as the word “comprising”.

[0098] It will be understood that although the terms “first,” “second,” “third”, etc. may be used herein to describe various layers, elements, components, regions or sections without referring to any particular order or sequence of events. These terms are merely used to distinguish one layer, element, component, region or section from another layer, element, component, region or section. A first layer, element, component, region or section as described herein could be referred to as a second layer, element, component, region or section without departing from the teachings of the present disclosure.

[0099] As used herein, the term “or” is used inclusively to refer items in the alternative and in combination.

[0100] As used herein, characters such as numerals refer to like elements.

[0101] Embodiments of the present disclosure have been shown and described as set forth herein and are provided by w ay of example only. One of ordinary skill in the art willAttorney Docket No. 05820.080W01 recognize numerous adaptations, changes, variations and substitutions without departing from the scope of the present disclosure. Several alternatives and combinations of the embodiments disclosed herein may be utilized without departing from the scope of the present disclosure and the inventions disclosed herein. Therefore, the scope of the presently disclosed inventions shall be defined solely by the scope of the appended claims and the equivalents thereof.

[0102] The disclosure includes the following clauses and embodiments:

[0103] Clause 1. An endoprostheses comprising: a bone anchor having a proximal end having an extension configured to be inserted into a residual portion of an amputated bone of a patient; a non-jointed endoprosthesis body configured to be enclosed by soft tissue of the patient and having a proximal end configured to be coupled to a distal end of the bone anchor; and a coupling configured to releasably engage the bone anchor and the non-jointed endoprosthesis body, wherein the coupling is configured to cooperate with the bone anchor and the non-jointed endoprosthesis body to maintain an axial and rotational arrangement of the non-jointed endoprosthesis body with respect to the bone anchor.

[0104] Clause 2. The endoprostheses of any one of the preceding clauses, further comprising: a cavity7formed in the proximal end of the non-jointed endoprosthesis body, the cavity shaped to receive the distal end of the bone anchor; and a slot formed in the non-jointed endoprosthesis body extending from an outer surface of the non-jointed endoprosthesis body to the cavity, the slot configured to receive the coupling.

[0105] Clause 3. The endoprostheses of any one of the preceding clauses, further comprising: a circumferential groove formed in the proximal end of the bone anchor and configured to receive the coupling and constrain axial movement of the non-jointed endoprosthesis body.

[0106] Clause 4. The endoprostheses of any one of the preceding clauses, wherein axial movement is movement in the proximal-distal direction.

[0107] Clause 5. The endoprostheses of any one of the preceding clauses, wherein the inner surface of the cavity and an external surface of the distal end of the bone anchor are keyed to constrain rotational movement of the of the non-jointed endoprosthesis body.

[0108] Clause 6. The endoprostheses of any one of the preceding clauses, wherein the inner surface of the cavity is defined by one or more surfaces shaped to engage with one or more surfaces of the distal end of the bone anchor to constrain rotational movement of the of the non-jointed endoprosthesis body.Attorney Docket No. 05820.080W01

[0109] Clause 7. The endoprostheses of any one of the preceding clauses, wherein the one or more surfaces of the inner surface of the cavity are planar surfaces and the one or more surfaces of the distal end of the bone anchor are planar surfaces.

[0110] Clause 8. The endoprostheses of any one of the preceding clauses, wherein the coupling includes an open portion configured to receive the distal end of the bone anchor therein.

[0111] Clause 9. The endoprostheses of any one of the preceding clauses, wherein a pair of opposing shoulders define an opening into the open portion.

[0112] Clause 10. The endoprostheses of any one of the preceding clauses, wherein the non-jointed endoprosthesis body includes a proximal portion configured to have a longitudinal axis parallel to the longitudinal axis of the residual portion of the amputated bone.

[0113] Clause 11. The endoprostheses of any one of the preceding clauses, wherein the non-jointed endoprosthesis body includes a distal portion configured to have a longitudinal axis having an angle of between 0 and 30 degrees with respect to the longitudinal axis of the residual portion of the amputated bone.

[0114] Clause 12. The endoprostheses of any one of the preceding clauses, wherein the angle is between 5 and 30 degrees.

[0115] Clause 13. The endoprostheses of any one of the preceding clauses, wherein the angle is between 10 and 30 degrees.

[0116] Clause 14. The endoprostheses of any one of the preceding clauses, wherein the coupling is a flexible coupling configured to be engaged by the proximal end of the bone anchor and the distal end of the non-jointed endoprosthesis body.

[0117] Clause 15. The endoprostheses of any one of the preceding clauses, wherein the coupling includes a web that extends between a first end configured to engage with the bone anchor and a second end configured to engage with the non-j ointed endoprosthesis body.

[0118] Clause 16. The endoprostheses of any one of the preceding clauses, wherein the coupling is a sacrificial coupling configured to fail at the web under a first load on the non-jointed endoprosthesis body that is lower than a second load under which the residual bone, bone anchor, or non-jointed endoprosthesis body is configured to fail.

[0119] Clause 17. The endoprostheses of any one of the preceding clauses, wherein the flexible coupling includes a first lobe and the distal end of the non-jointedAttorney Docket No. 05820.080W01 endoprosthesis body includes a first slot and wherein the first slot is configured to retain the first lobe.

[0120] Clause 18. The endoprostheses of any one of the preceding clauses, wherein the first slot is open on a first side of the non-jointed endoprosthesis body and configured to slidingly receive the first lobe in an ulnar-radial direction.

[0121] Clause 19. The endoprostheses of any one of the preceding clauses, wherein an outer surface of the non-jointed endoprosthesis body includes a porous structure configured to facilitate soft tissue integration.

[0122] Clause 20. The endoprostheses of any one of the preceding clauses, wherein the outer surface of the non-jointed endoprosthesis body includes first pores having a dimension of between 50 and 200 microns and second pores between 300 and 800 microns.

[0123] Clause 21. An endoprostheses comprising: a bone anchor having a proximal end having an extension configured to be inserted into a residual portion of an amputated bone of a patient; a jointed endoprosthesis including a proximal portion pivotably coupled to a dital portion by ajoint, the jointed endoprosthesis configured to be enclosed by soft tissue of the patient, the proximal portion having a proximal end configured to be coupled to a distal end of the bone anchor; and a coupling configured to releasably engage the bone anchor and the non-jointed endoprosthesis body, wherein the coupling is configured to cooperate with the bone anchor and the non-jointed endoprosthesis body to maintain an axial and rotational arrangement of the non-jointed endoprosthesis body with respect to the bone anchor.

[0124] Clause 22. The endoprostheses of clause 21, further comprising: a cavity formed in the proximal end of the proximal portion of the jointed endoprosthesis, the cavity shaped to receive the distal end of the bone anchor; and a slot formed in the proximal portion of the jointed endoprosthesis extending from an outer surface of the proximal portion of the jointed endoprosthesis to the cavity, the slot configured to receive the coupling.

[0125] Clause 23. The endoprostheses of any one of clauses 21-22, further comprising: a circumferential groove formed in the proximal end of the bone anchor and configured to receive the coupling and constrain axial movement of the proximal portion of the jointed endoprosthesis.

[0126] Clause 24. The endoprostheses of any one of clauses 21-23, wherein axial movement is movement in the proximal -distal direction.Attorney Docket No. 05820.080W01

[0127] Clause 25. The endoprostheses of any one of clauses 21-24, wherein the inner surface of the cavity and an external surface of the distal end of the bone anchor are keyed to constrain rotational movement of the of the proximal portion of the jointed endoprosthesis.

[0128] Clause 26. The endoprostheses of any one of clauses 21-25, wherein the inner surface of the cavity is defined by one or more surfaces shaped to engage with one or more surfaces of the distal end of the bone anchor to constrain rotational movement of the of the proximal portion of the jointed endoprosthesis.

[0129] Clause 27. The endoprostheses of any one of clauses 21-26, wherein the one or more surfaces of the inner surface of the cavity are planar surfaces and the one or more surfaces of the distal end of the bone anchor are planar surfaces.

[0130] Clause 28. The endoprostheses of any one of clauses 21-27, wherein the coupling includes an open portion configured to receive the distal end of the bone anchor therein.

[0131] Clause 29. The endoprostheses of any one of clauses 21-28, wherein a pair of opposing shoulders define an opening into the open portion.

[0132] Clause 30. The endoprostheses of any one of clauses 21-29, wherein the coupling is a flexible coupling configured to be engaged by the proximal end of the bone anchor and the distal end of the non-jointed endoprosthesis body.

Claims

Attorney Docket No. 05820.080W01Claims1. An endoprostheses comprising: a bone anchor having a proximal end having an extension configured to be inserted into a residual portion of an amputated bone of a patient; a non-jointed endoprosthesis body configured to be enclosed by soft tissue of the patient and having a proximal end configured to be coupled to a distal end of the bone anchor; and a coupling configured to releasably engage the bone anchor and the non-jointed endoprosthesis body, wherein the coupling is configured to cooperate with the bone anchor and the non-jointed endoprosthesis body to maintain an axial and rotational arrangement of the non-jointed endoprosthesis body with respect to the bone anchor.

2. The endoprostheses of claim 1, further comprising: a cavity formed in the proximal end of the non-jointed endoprosthesis body, the cavity shaped to receive the distal end of the bone anchor; and a slot formed in the non-jointed endoprosthesis body extending from an outer surface of the non-jointed endoprosthesis body to the cavity, the slot configured to receive the coupling.

3. The endoprostheses of claim 2, further comprising: a circumferential groove formed in the proximal end of the bone anchor and configured to receive the coupling and constrain axial movement of the non-jointed endoprosthesis body.

4. The endoprostheses of claim 3, wherein axial movement is movement in the proximal-distal direction.

5. The endoprostheses of claim 4, wherein the inner surface of the cavity and an external surface of the distal end of the bone anchor are keyed to constrain rotational movement of the of the non-jointed endoprosthesis body.

6. The endoprostheses of claim 2, wherein the inner surface of the cavity’ is defined by one or more surfaces shaped to engage with one or more surfaces of the distal end of the bone anchor to constrain rotational movement of the of the non-jointed endoprosthesis body.Attorney Docket No. 05820.080W017. The endoprostheses of claim 6, wherein the one or more surfaces of the inner surface of the cavity are planar surfaces and the one or more surfaces of the distal end of the bone anchor are planar surfaces.

8. The endoprostheses of claim 3, wherein the coupling includes an open portion configured to receive the distal end of the bone anchor therein.

9. The endoprostheses of claim 8, wherein a pair of opposing shoulders define an opening into the open portion.

10. The endoprostheses of claim 1, wherein the non-jointed endoprosthesis body includes a proximal portion configured to have a longitudinal axis parallel to the longitudinal axis of the residual portion of the amputated bone.

11. The endoprostheses of claim 1, wherein the non-jointed endoprosthesis body includes a distal portion configured to have a longitudinal axis having an angle of between 0 and 30 degrees with respect to the longitudinal axis of the residual portion of the amputated bone.

12. The endoprostheses of claim 11, wherein the angle is between 5 and 30 degrees.

13. The endoprostheses of claim 11, wherein the angle is betw een 10 and 30 degrees.

14. The endoprostheses of claim 1, wherein the coupling is a flexible coupling configured to be engaged by the proximal end of the bone anchor and the distal end of the non-jointed endoprosthesis body.

15. The endoprostheses of claim 14, wherein the coupling includes a web that extends between a first end configured to engage with the bone anchor and a second end configured to engage with the non-jointed endoprosthesis body.

16. The endoprostheses of claim 15, wherein the coupling is a sacrificial coupling configured to fail at the web under a first load on the non-jointed endoprosthesis body that is lower than a second load under which the residual bone, bone anchor, or nonjointed endoprosthesis body is configured to fail.Attorney Docket No. 05820.080W0117. The endoprostheses of claim 14, wherein the flexible coupling includes a first lobe and the distal end of the non-jointed endoprosthesis body includes a first slot and wherein the first slot is configured to retain the first lobe.

18. The endoprostheses of claim 17, wherein the first slot is open on a first side of the non-jointed endoprosthesis body and configured to slidingly receive the first lobe in an ulnar-radial direction.

19. The endoprostheses of claim 1 , wherein an outer surface of the non-j ointed endoprosthesis body includes a porous structure configured to facilitate soft tissue integration.

20. The endoprostheses of claim 19, wherein the outer surface of the non- jointed endoprosthesis body includes first pores having a dimension of between 50 and 200 microns and second pores between 300 and 800 microns.

21. An endoprostheses comprising: a bone anchor having a proximal end having an extension configured to be inserted into a residual portion of an amputated bone of a patient; a jointed endoprosthesis including a proximal portion pivotably coupled to a di tai portion by a joint, the jointed endoprosthesis configured to be enclosed by soft tissue of the patient, the proximal portion having a proximal end configured to be coupled to a distal end of the bone anchor; and a coupling configured to releasably engage the bone anchor and the non-jointed endoprosthesis body, wherein the coupling is configured to cooperate with the bone anchor and the non-j ointed endoprosthesis body to maintain an axial and rotational arrangement of the non-jointed endoprosthesis body with respect to the bone anchor.

22. The endoprostheses of claim 21, further comprising: a cavity formed in the proximal end of the proximal portion of the jointed endoprosthesis, the cavity shaped to receive the distal end of the bone anchor; and a slot formed in the proximal portion of the jointed endoprosthesis extending from an outer surface of the proximal portion of the jointed endoprosthesis to the cavity, the slot configured to receive the coupling.

23. The endoprostheses of claim 22, further comprising:Attorney Docket No. 05820.080W01 a circumferential groove formed in the proximal end of the bone anchor and configured to receive the coupling and constrain axial movement of the proximal portion of the jointed endoprosthesis.

24. The endoprostheses of claim 23, wherein axial movement is movement in the proximal-distal direction.

25. The endoprostheses of claim 24, wherein the inner surface of the cavity and an external surface of the distal end of the bone anchor are keyed to constrain rotational movement of the of the proximal portion of the jointed endoprosthesis.

26. The endoprostheses of claim 22, wherein the inner surface of the cavity is defined by one or more surfaces shaped to engage with one or more surfaces of the distal end of the bone anchor to constrain rotational movement of the of the proximal portion of the jointed endoprosthesis.

27. The endoprostheses of claim 26, wherein the one or more surfaces of the inner surface of the cavity are planar surfaces and the one or more surfaces of the distal end of the bone anchor are planar surfaces.

28. The endoprostheses of claim 23, wherein the coupling includes an open portion configured to receive the distal end of the bone anchor therein.

29. The endoprostheses of claim 28, wherein a pair of opposing shoulders define an opening into the open portion.

30. The endoprostheses of claim 21, wherein the coupling is a flexible coupling configured to be engaged by the proximal end of the bone anchor and the distal end of the non-jointed endoprosthesis body.

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