Metarsophalangeal joint replacement device and methods

A device for the repair of a phalangeal joint comprises a first anchor, a second anchor, and a flexible spacer connecting the first and second anchors. The flexible spacer comprises a plurality of elongate fibers extending axially or criss-crossed between the first and second anchors and a polymeric matrix interspersed with the plurality of elongate fibers. Specifically, a prosthetic metatarsophalangeal joint device comprises a porous metallic metatarsal bone anchor, a porous metallic phalangeal bone anchor, and a polymeric spacer element comprising parallel or criss-crossed elongate fibers that can connect the metatarsal bone anchor and the phalangeal bone anchor. Methods for manufacturing prosthetic joint devices comprise using three-dimensional printing processes or molding processes. Methods for implanting prosthetic joint devices comprise positioning porous metallic anchor components adjacent resected bones at planar interfaces and between which a polymeric spacer having axial aligned elongate fibers embedded in a matrix can be disposed.

TECHNICAL FIELD

The present application relates generally to prosthetic implants for joints of a foot or hand. More specifically, the present application relates to flexible cartilage replacement devices that can be attached between two bones, as can be used in methods for arthroplasty of an interphalangeal joint, such as a metatarsophalangeal or metacarpalphalangeal joint.

BACKGROUND

Wearing down or wearing out of cartilage between bones of a joint can be characterized as osteoarthritis (“OA”). OA in the main joint of the great toe (i.e., the first metatarsophalangeal joint (“MTPJ1”) can cause sometimes unbearable pain and discomfort in a patient. A variety of metatarsophalangeal joint replacement devices have been developed for use in the first metatarsophalangeal joint (MTPJ1).

An example of a metatarsophalangeal joint replacement device rigidly connected components that are implanted between opposing bones of a joint in the intramedullary area of each bone. In such a configuration, the bones are typically fused together. An example of such a device is described in detail in U.S. Pat. No. 8,920,453 to Tyber et al.

Another type of metatarsophalangeal joint replacement device utilizes a pair of components that are implanted into opposing bones to abut each other. The components are configured to slide against each other to produce an articulating joint that is non-fused. An example of such a device described in detail in U.S. Pub. No. 2017/0367838 to Cavanagh et al.

Another type of metatarsophalangeal joint replacement device utilizes a pad or cushion inserted between the bones. The pad or cushion is typically attached via intramedullary inserts that extend into the opposing bones. Examples of such devices are described in detail in U.S. Pat. No. 5,480,447 to Skiba, U.S. Pat. No. 5,879,396 to Walston et al. and U.S. Pat. No. 6,007,580 to Lehto et al.

Another type of metatarsophalangeal joint replacement device utilizes a pad or cushion that is positioned between the bones in substitution of the cartilage and can be connected to the bones by minimally invasive means. An example of such a device described in detail in U.S. Pat. No. 9,907,663 to Patrick et al.

Issues in conventional metatarsophalangeal joint replacement devices persist and can cause discomfort for patients. There is, therefore, a need for interphalangeal, e.g., metatarsophalangeal, joint implants that reduce or eliminate pain, provide better comfort and performance for the patient.

OVERVIEW

The present inventors have recognized, among other things, that problems to be solved in MTPJ1 devices can include being too stiff, feeling too loose, over-intrusive implantation, and inadequate coupling to the bone. Conventional MTPJ1 devices can thus feel unnatural to the patient. Some conventional metatarsophalangeal joint replacement devices typically result in fusing of the joint, which causes stiffness in the joint and discomfort for the patient. Even when not fused, these devices may feel too tight (difficult to bend) or too loose (joint hypermobility as in Ehlers-Danlos syndrome: the joint unnaturally separates) to the patient and the implants may loosen due to inadequate fixation to the bone. Some devices also may require extensive intramedullary implantation into both bones of the joint, which can complicate the arthroplasty procedure.

In particular, polymeric or hydrogel pads or spacers inserted between the metatarsal bone and the phalange bone can be too stiff to reproduce natural flexion. Additionally, it can be difficult for these types of spacers to attach to the bone. For example, the spacer provides a small footprint for the facilitation of bone in-growth or the adhesion of bone cement, which can be difficult to deliver to the joint in the desired location.

The present subject matter can help provide a solution to these and other problems, such as by providing an interphalangeal joint device, such as an MTPJ1 device that can firmly attaches to the metatarsal (or metacarpal) bone and the phalange bone without requiring intrusive, intramedullary operations, while also providing a degree of flexibility and tightness that can more closely replicate the natural joint, thereby providing better patient comfort and performance. Furthermore, devices of the present disclosure can be manufactured in configurations that are simple to implant and that can be readily customized.

In an example, a device for the repair of a phalangeal joint can comprise a first anchor, a second anchor, and a flexible spacer. The flexible spacer can connect the first anchor and the second anchor, and can comprise a plurality of elongate fibers extending, axially or criss-crossed between the first and second anchors, and a polymeric matrix interspersed with the plurality of elongate fibers.

In another example, a prosthetic metatarsophalangeal joint device can comprise a metatarsal, or metacarpal, bone anchor that can comprise a porous metallic material, a phalangeal bone anchor that can comprise a porous metallic material, and a polymeric spacer element that can connect the metatarsal bone anchor and the phalangeal bone anchor. The polymeric spacer element can comprise a plurality of elongate fibers extending, parallel or criss-crossed, between the metatarsal bone anchor and the phalangeal bone anchor.

In an additional example, a method of manufacturing a device for the repair of a phalangeal joint can comprise fabricating first and second anchor components using a first additive manufacturing process (e.g., 3D printing) to produce a porous structure within each component, fabricating a flexible spacer component using a second additive manufacturing process or molding process to produce a plurality of elongate fibers extending straight across or criss-crossed through the flexible spacer, and attaching opposing ends of the flexible spacer component to the first and second anchor components.

DETAILED DESCRIPTION

FIG. 1is a diagram illustrating prosthetic joint device10implanted in foot12at first metatarsophalangeal joint (MTPJ1)14. Foot12includes five digitorum bones that each include one or both of a distal and medial phalange bone, a proximal phalange bone and a metatarsal phalange bone. For example, first metatarsophalangeal joint14includes distal phalange bone16, proximal phalange bone18and metatarsal phalange20. Prosthetic joint device10can include flexible spacer22, first anchor component24A and second anchor component24B.

Prosthetic joint device10can be used to reproduce the natural or anatomic operation of a joint between two bones of foot12. In the illustrated example, prosthetic joint device10is used in MTPJ114between proximal phalange bone18and metatarsal phalange bone20, but can be used in any of the digitorum bones of foot12. Additionally, prosthetic joint device10can be used to repair or replace other small-bone joints, such as metacarpal joints of a hand.

A healthy anatomic MTPJ1 joint includes cartilage that the epiphysis end of each bone (seeFIG. 6). The cartilage along with joint fluid provides a cushion between each bone that also facilitates flexion of the joint. The cartilage can become worn or can deteriorate with age, and trauma, thus causing pain and stiffness of the joint. Prosthetic joint device10can be implanted in the joint to alleviate the pain and restore proper joint flexibility and mobility. In particular, anchor components24A and24B can provide firm anchoring of prosthetic joint device10to bones18and20via osseointegration and flexible spacer22can hold MPJ114joint together in the anterior-posterior direction while also providing flexion in a sagittal plane.

First anchor component24A and second anchor component24B can be attached to proximal phalange bone18and metatarsal phalange bone20, respectively. In various examples, components24A and24B can be comprised of porous metallic material, such as porous titanium or tantalum. Flexible spacer22can be positioned between and connected to components24A and24B. In various examples, spacer22can comprise a polymeric component having anterior-posterior aligned fibers that can be embedded in a polymeric matrix to provide flexibility to the device.

FIG. 2is a schematic diagram illustrating prosthetic joint device30including flexible spacer32connecting first anchor component34A and second anchor component34B, which are connected to proximal phalange bone18and metatarsal phalange bone20, respectively. In general, device30, and other embodiments of the present application, can include two opposing anchor components, such as components34A and34B, that can be used to provide attachment to bone and a central cushion component, such as flexible spacer32, that can provide coupling of and flexibility to the joint.

In an example, device30can be manufactured in multiple processes such that device30is a single integrated body of multiple materials. In such a configuration, flexible spacer32can be produced using an additive manufacturing process or molding process using a polymer, while anchor components34A and34B can be produced using a separate additive manufacturing process using a metal. However, in various examples, prosthetic joint device30can be comprised of a single monolithic structure or a plurality of different components attached together. Prosthetic joint device30can also be comprised of a single type of material or a plurality of material types. For example, device30can be manufactured in a single process such that device30is a monolithic body of only a polymeric material. In another example, device30can be manufactured using a single process such that device30comprises a monolithic body of multiple materials.

Additive manufacturing processes, such as three-dimensional (3D) printing techniques, (such as electron beam or laser additive manufacturing) can be used to produce porous metallic structures of titanium alloys or tantalum, having geometries conducive to osteointegration and can additionally produce the intricacies of elongate fibers in a desired orientation. Furthermore, additive manufacturing processes allow one or more of the components of device30to be built directly onto one of more of the other components. As such, first anchor component34A and second anchor component can be made of a porous metallic material to facilitate attachment to bone, while flexible spacer32can be made of a polymeric material including fibers to facilitate flexing. The specific shape and geometry of anchor components34A and34B and spacer32can vary based on design needs. For example, anchor components34A and34B and spacer32can have circular, rectangular, square or polygonal cross-sectional profiles. In an example, anchor components34A and34B and spacer32have hexagonal cross-sectional profiles, as shown inFIGS. 4 and 5. Hexagonal profiles can facilitate implantation into bone by providing adequate planar surface areas for bone contact and also providing edges for resisting rotation within the bone.

Base52A of anchor component44A can comprise a disk-like body for supporting flexible spacer42and facilitating attachment to proximal phalange bone18. Posterior surface58A can be flat or substantially flat to provide a base upon which interdigitation zone50A can be located and built-up from. Likewise, anterior surface60A can be flat to enhance bone contact with proximal phalange bone18, which can be resected to provide a flat bone surface. Fixation pegs54A and56A can extend from anterior surface60A in a location to allow fixation pegs54A and56A to be inserted into cancellous bone of proximal phalange bone18. Fixation pegs54A and56A therefore increase the surface area of anchor component44A in contact with bone to increase osseointegration, as well as provide initial fixation of anchor component44A with bone18.

Base52B of anchor component44B can comprise a disk-like body for supporting flexible spacer42and facilitating attachment to metatarsal phalange bone20. Anterior surface60B can be flat or substantially flat to provide a base upon which interdigitation zone50B can be located and built-up from. Likewise, posterior surface58B can be flat to enhance bone contact with metatarsal phalange bone20, which can be resected to provide a flat bone surface. Fixation pegs54B and56B can extend from posterior surface58B in a location to allow fixation pegs54B and56B to be inserted into cancellous bone of metatarsal phalange bone20. Fixation pegs54B and56B therefore increase the surface area of anchor component44B in contact with bone to increase osseointegration, as well as provide initial fixation of anchor component44B with bone20.

Anchor components44A and44B can be identical in geometry and can be interchangeable such that anterior surfaces60A and60B and posterior surfaces58A and58B can be reversed, respectively.

As discussed, bases52A and52B can have a variety of cross-sectional profiles. Additionally, the cross-sectional profiles of fixation pegs54A,56A,54B and56B can have a variety of cross-sectional profiles, such as circular, rectangular, square, polygonal, hexagonal and ribbed. As mentioned, posterior surface58A and anterior surface60B can be flat to facilitate adhesion with interdigitation zones50A and50B, respectively.

Interdigitation zones50A and50B can comprise solid bodies of material that can facilitate coupling of elongate fibers46to bases52A and52B, respectively. For example, interdigitation zone50A can comprise a disk of material having anterior surface62A that can be fused into pores of base52A and posterior surface64A from which fibers46can integrally extend. Likewise, interdigitation zone50B can comprise a disk of material having posterior surface64B that can be fused into pores of base52B and anterior surface62B from which fibers46can integrally extend.

Fibers46can extend from first interdigitation zone50A to second interdigitation zone50B. In an example, all of fibers46are parallel or substantially parallel to each other. Fibers46can extend parallel to axis A of device40. Axis A can extend along the longitudinal centers of anchor components44A and44B, which can coincide with the anatomic centers of bones18and20. Material of matrix48can be sandwiched between interdigitation zones50A and50B and filled-in between fibers46. Material of matrix48can be in contact with fibers46, but not bonded thereto. Coupling of interdigitation zones50A and50B to bases52A and52B, respectively, and fibers46provides axial, anterior-posterior stability and connection of device40. Fibers46additionally permit flexible spacer42to bend as material of matrix48can slide past and around fibers46under deflection. As such, device40can replicate the feel and flexibility of an anatomic joint.

FIG. 4is a cross-sectional view of flexible spacer42ofFIG. 3showing a plurality of fibers46disposed in matrix48. The size and spacing of fibers46relative to the depicted cross-section are not drawn to scale, and are shown for illustrative purposes. Fibers46can have circular cross-sectional profiles to facilitate bending, but other shapes can be used. In examples, fibers46can have diameters in the range of approximately 0.4 nm to approximately 100 nm. In other examples, fibers46can have other cross-sectional profiles. Fibers46can be separated from each other to provide space for matrix48. In examples, fibers46can be spaced at intervals in the range of approximately 0.01 mm to approximately 2 mm. Fibers46can be spaced uniformly or asymmetrically or crossed. Crossing and spacing of fibers46can be used to adjust stiffness of flexible spacer42. For example, as shown inFIG. 8, flexible spacer42can be more densely spaced near the bottom or inferior side of the device to facilitate bending in the superior direction. In an example, fibers46and matrix48can comprise polyethylene material. In examples, fibers46can comprise approximately 20% to approximately 70% of the area of the cross-section. Such a ratio can provide adequate stiffness to flexible spacer42for the purposes of compression, tension and torsion, but facilitates bending of flexible spacer42in a manner that realistically reproduces operation of a natural joint. Matrix48can comprise polymeric material that is loosely packed around and amongst fibers46. In an example, material of matrix48form pseudo-tubes round fibers46that assist in maintaining fibers46separated and provide resistance to axial compressing of fibers46, but that do not inhibit flexing of fibers46.

FIG. 5is a cross-sectional view of anchor component44A ofFIG. 3showing a metallic porous structure comprised of struts66and voids68. The size and spacing of struts66and voids68relative to the depicted cross-section are not drawn to scale, and are shown for illustrative purposes. struts66are configured to provide structural stability to anchor component44A, while producing voids68that reduce the weight of component44A and provide space for osseointegration with bone and fusion with interdigitation zone62A (FIG. 3). In the depicted example, struts66and voids can reproduce the geometries of anatomic bone. In other examples, struts66and voids68can have other or synthetic geometries.

Anchor component44A can be formed of a suitable material that promotes bone ingrowth and is biocompatible, such as porous metallic material, or a porous tantalum material having a porosity of approximately 20%-80% and pores sizes of approximately 50 μm-600 μm for example, or within any range defined between any pair of the foregoing values. An example of highly porous tantalum and titanium alloy materials are Trabecular Metal™ and OsseoTi™ generally available from Zimmer Biomet, of Warsaw, Ind. Both materials are trademarks of Zimmer Biomet.

Anchor component44A can be formed by a plurality of different processes. In an example, such a material may be formed from a reticulated vitreous carbon foam substrate which is infiltrated and coated with a biocompatible metal, such as tantalum, by a chemical vapor deposition (CVD) process in the manner disclosed in detail in U.S. Pat. No. 5,282,861 to Kaplan, the disclosure of which is expressly incorporated herein by reference in its entirety for all purposes. In addition to tantalum, other metals such as niobium, or alloys of tantalum and niobium with one another or with other metals may also be used. The open cell metal structures can be fabricated using the tantalum metal film and carbon substrate combination, with the film deposited by CVD, which mimics bone closely in having struts66interconnected to form open spaces or voids68.

In examples, anchor component44A and other prosthetic components described herein with metallic porous structures including struts and voids and the like, such as the ones described herein, can be provided by any number of suitable three-dimensional, porous structures, and these structures can be formed with one or more of a variety of materials including but not limited to polymeric materials which are subsequently pyrolyzed, metals, metal alloys, ceramics. In some instances, a highly porous three-dimensional structure will be fabricated using a selective laser sintering (SLS) or other additive manufacturing-type process such as direct metal laser sintering. In one example, a three-dimensional porous article is produced in layer-wise fashion from a laser-fusible powder, e.g., a polymeric material powder or a single-component metal powder, that is deposited one layer at a time. The powder is fused, remelted or sintered, by the application of laser energy that is directed to portions of the powder layer corresponding to a cross section of the article. After the fusing of the powder in each layer, an additional layer of powder is deposited, and a further fusing step is carried out, with fused portions or lateral layers fusing so as to fuse portions of previous laid layers until a three-dimensional article is complete. In certain embodiments, a laser selectively fuses powdered material by scanning cross-sections generated from a 3-D digital description of the article, e.g., from a CAD file or scan data, on the surface of a powder bed. Net shape and near net shape constructs are infiltrated and coated in some instances.

Complex geometries can be created using such techniques. In some instances, a three-dimensional porous structure will be particularly suited for contacting bone and/or soft tissue, and in this regard, can be useful as a bone substitute and as cell and tissue receptive material, for example, by allowing tissue to grow into the porous structure over time to enhance fixation (i.e., osseointegration) between the structure and surrounding bodily structures, for example, to provide a matrix approximating natural cancellous bone or other bony structures. In this regard, a three-dimensional porous structure, or any region thereof, may be fabricated to virtually any desired density, porosity, pore shape, and pore size (e.g., pore diameter). Such structures therefore can be isotropic or anisotropic.

Such structures can be infiltrated and coated with one or more coating materials. When coated with one or more biocompatible metals, any suitable metal may be used including any of those disclosed herein such as tantalum, titanium, a titanium alloy, cobalt chromium, cobalt chromium molybdenum, tantalum, a tantalum alloy, niobium, or alloys of tantalum and niobium with one another or with other metals. In various examples, a three-dimensional porous structure may be fabricated to have a substantial porosity, density, pore shape and/or void (pore) size throughout, or to comprise at least one of pore shape, pore size, porosity, and/or density being varied within the structure. For example, a three-dimensional porous structure to be infiltrated and coated may have a different pore shape, pore size and/or porosity at different regions, layers, and surfaces of the structure.

In some embodiments, a non-porous or essentially non-porous base substrate will provide a foundation upon which a three-dimensional porous structure will be built and fused thereto using a selective laser sintering (SLS) or other additive manufacturing-type process. Such substrates can incorporate one or more of a variety of biocompatible metals such as titanium, a titanium alloy, cobalt chromium, cobalt chromium molybdenum, tantalum, or a tantalum alloy.

In examples, anchor component44A can comprise titanium that is fabricated using a rapid manufacturing process. In examples, the rapid manufacturing process can comprise an additive manufacturing process, such as a powder deposition process. In such a process, very thin layers (e.g., layers that are only as thick as several levels of particles of the powdered titanium) of powdered titanium can be laid down incrementally. At each increment, selective portions of the powdered titanium can be solidified to form a portion of anchor component44A, and the unsolidified particles can be left to support the next layer of powder. For example, a laser can be used to selectively melt portions of the powdered titanium layer that will form anchor component44A. Subsequently, a new layer of titanium powder particles can be laid down on top of the previous, partially solidified layer and an additional solidification process can occur. The steps can be repeated until anchor component44A is built-up from one end to the other. The unsolidified particles can then be removed. Other types of rapid manufacturing processes can be used to fabricate prosthetic joint device40, such as 3D printing processes.

The rapid manufacturing processes can be used to include a desired level of porosity directly into anchor component44A. Likewise, struts66can be made to have any desired shape, size, number and aggregate strength and density in order to generate sufficient bonding strength to survive implantation and operation of anchor component44A, while permitting infusion of bone and polymer material from interdigitation zone50A, as described herein.

FIG. 6is a diagram illustrating natural anatomy70of first metatarsophalangeal joint14ofFIG. 1, which can comprise proximal phalange bone18and metatarsal phalange bone20. Again, as discussed above, the devices and methods described herein can be applied to other anatomies, such as metacarpal joints of a hand. Anatomy70can include articular cartilage pads72A and72B located on ends of bones18and20, respectively. The joint capsule can be filled with synovial fluid74enclosed within synovial membrane76. In cases of osteoarthritis (“OA”), cartilage pads72A and72B can become worn down and/or hardened, potentially resulting in pain and discomfort for the patient, as ends of bones18and20rub against each other. As such, it can be desirable to reproduce the natural feel and action of cartilage pads72A and72B with a prosthetic joint device configured according to the embodiments and examples described herein. In order to initiate an arthroplasty for metatarsophalangeal joint14an incision can be made through skin78and synovial membrane76to expose cartilage pads72A and72B. Joint14can be flexed to expose the opposing ends of bones18and20, as shown inFIG. 7.

FIG. 7is a diagram illustrating positioning of resected bones18and20for the implantation of prosthetic joint device40of the present disclosure into first metatarsophalangeal joint14. Proximal phalange bone18can be flexed to be substantially transverse to metatarsal phalange bone20. Distal end80of metatarsal phalange bone20can be resected to form planar anterior surface82. Proximal end84of proximal phalange bone18can be resected to form planar posterior surface86. As such, cartilage pads72A and72B can be removed and cancellous bone within bones18and20can become exposed at surfaces82and86within the hard, cortical walls of bones18and20. Prosthetic joint device40can be flexed at flexible spacer42so that fixation pegs54B and56B can be press fit into the cancellous bone of surface82and fixation pegs54A and56A can be press fit into the cancellous bone of surface86.

FIG. 8is a diagram illustrating implanted prosthetic joint device40of the present disclosure implanted into resected bones18and20ofFIG. 7. Prosthetic joint device40can include first anchor component44A, second anchor component44B and flexible spacer42. Fixation pegs54A and56A of first anchor component44A can be inserted into cancellous bone of planar posterior surface86such that anterior surface60A of base52A abuts flush against planar posterior surface86. Fixation pegs54B and56B of second anchor component44B can be inserted into cancellous bone of planar anterior surface82such that posterior surface58B of base52B abuts flush against planar anterior surface82. Flush engagement between surface86and surface60A and surface82and surface58B, respectively, can facilitate stability of prosthetic joint device40and can promote bone ingrowth into anchor components44A and44B.

Prosthetic joint device40can be sized to fit within MPJ114. In examples, prosthetic joint device40can come in a single size that is configured to fit most or all of the different sizes of bones of the general population. In other examples, prosthetic joint device40can be come in a plurality of sizes, e.g., small, medium and large, to allow for semi-custom sizing. In other examples, prosthetic joint device can be custom sized for patient-specific applications, such as by measuring the size of bones18and20from preoperative imaging.

In examples, the length of prosthetic joint device40between surfaces58B and60A can be approximately equal to the length of the resected portions of bones18and20plus the thicknesses of cartilage pads72A and72B, such as the average of the general adult population. In examples, the diameter of bases52A and52B can be sized to be approximately equal to the diameter of bones18and20at joint14, such as the average of the general adult population.

FIG. 9is a line diagram illustrating steps of method100for manufacturing a prosthetic joint device, such as prosthetic joint device40, of the present disclosure. At step102, the size of joint14(FIG. 1) can be determined. For example, the diameters of proximal phalange bone18and metatarsal phalange bone20can be measured from pre-operative imaging of joint14. The pre-operative imaging can include x-ray images, CT images, MRI images and the like, as well as two-dimensional and three-dimensional computer-generated models derived from the pre-operative imaging. From such measurements, the diameters for bases52A and52B (FIG. 3) can be determined. Additionally, the joint length, e.g., the thickness of cartilage pads72A and72B, can be measured. From such a measurement, the combined length of flexible spacer42and bases52A and52B can be determined. The measured size of joint14can be used to custom manufacture prosthetic joint device40to fit a specific patient, or can be used to select from a range of predetermined sizes of prosthetic joint device40. Step102can be an optional step. For example, prosthetic joint device40can be manufactured from anatomic data of the general adult population and can be configured for use in the general adult population without measurement. In additional examples, measurement of joint14can be conducted intraoperatively by a surgeon or other person to determine a size from premanufactured prosthetic joint devices.

At step104, porous anchor components44A and44B (FIG. 3) can be manufactured, such as by using a three-dimensional (“3D”) printing process. In an example, a selective laser sintering process can be used to build up bases52A and52B and fixation pegs54A-56B. Such components can include struts66and voids68. Components44A and44B can be manufactured from a variety of materials, such as polymeric material and metallic material. Bases52A and52B can be made to sizes, e.g., length and diameter, based on measurements taken at step102. In examples, components44A and44B are made from titanium alloys, stainless steel alloys and tantalum alloys.

At step106, flexible spacer42can be manufactured, such as by using a 3D printing process or molding process or combination of both. In an example, a fused filament fabrication process can be used to build up interdigitation zones50A and50B, fibers46and matrix48. In particular, one of interdigitation zones50A and50B can be directly built up on top of one of bases52A and52B, respectively. In such a process, for example, polymeric material of interdigitation zone50A can be deposited onto and/or melted into voids68of base52A, thereby causing adhesion of interdigitation zone50A to base52A. Interdigitation zone50A can be built up to a sufficient thickness to cover or substantially the desired surface area of base52A. As such, a planar surface of polymeric material can be built-up on base52A to support fibers46. In examples, interdigitation zone50A can be made from a polymeric material, such as polyethylene. In another aspect of the present disclosure, intercalated polymer of flexible spacer42between two metallic scaffolds formed by porous anchor components44A and44B can be 3D printed using a polymer and antibiotics powder mixture. The antibiotic can be eluted out of the polymer material and from the implant into the patient to, for example, prevent and treat possible infection. The antibiotic powder can be azithromycin, amoxicillin, gentamicine or other similar medicants.

At step108, fibers46can be built-up onto interdigitation zone50A. Fibers46can be built integrally with interdigitation zone50A. At step110, material of matrix48can be deposited around fibers46. Fibers46and matrix48can be simultaneously built-up on top of interdigitation zone50A to the desired length. Fibers46and matrix48can be made to a length based on measurements taken at step102. The material of matrix48can be positioned around, without attaching to, fibers46to facilitate flexing of flexible spacer42. In examples, fibers46and matrix48can be made from a polymeric material, such as polyethylene. In examples, fibers46and matrix48can be made from the same or different materials as each other.

At step112, interdigitation zone50B can be built-up on ends of fibers46and on top of matrix48. For example, a layer of the material of flexible component42can be formed to tie-up ends of fibers46and form a base for joining with second anchor component44B. In examples, interdigitation zone50B can be made from a polymeric material, such as polyethylene.

At step114, interdigitation zone50B and second anchor component44B can be attached to each other. In an example, interdigitation zone50B can be built-up to the desired thickness and anchor component44B can be attached to interdigitation zone50B, such as by being pushed into the material of interdigitation zone50B to cause the material to penetrate into voids68. In examples, interdigitation zone50B can be built-up directly on base52B and attached to fibers46and matrix48.

Steps102through114describe example method steps for forming prosthetic joint devices to include a plurality of elongate fibers. Such elongate fibers can be built up in a parallel or criss-crossed axial manner to extend between anchor components. The elongate fibers can be continuous between the anchor components to provide axial or anterior-posterior strength to the device. Additionally, the elongate fibers have diameters such that the device can readily flex in the sagittal plane. The presence of matrix material alongside the elongate fibers provides stabilization to the elongate fibers to prevent buckling of the device, e.g., collapsing together of the device in the anterior-posterior direction. However, the presence of matrix material does not stiffen the device in the sagittal plane. Such a fiber and matrix composition can be produced with additive manufacturing techniques described herein. However, in other examples, manufacturing processes that can produce the fiber and matrix composition described herein can be used, such as molding processes.

FIG. 10is a line diagram illustrating steps of method200for implanting a prosthetic joint device, such as prosthetic joint device40, of the present disclosure. Steps202-214provide a high-level overview of steps that can be taken to implant prosthetic joint device40and are not intended to be an exhaustive listing. In other examples, other steps can be used.

At step202, incisions in tissue of the patient can be made to expose bones18and20of MTPJ114. Specifically, skin78and capsule76can be cut open to expose cartilage pads72A and72B, if said pads are not worn away from osteoarthritis, as shown inFIG. 6.

At step204, MTPJ114can be flexed by the surgeon or other personal to expose the distal ends of proximal phalange bone18and metatarsal phalange bone20, as shown inFIG. 7. In such a position, cartilage pads72A and72B can be exposed and distal end80and proximal end84(FIG. 7) are readily viewable by the surgeon.

At step206, bones18and20can be resected to form planar posterior surface86and planar anterior surface82, respectively, as shown inFIG. 7. Bones18and20can be resected to form flat or planar surfaces against which surfaces of anchor components44A and44B can abut. Additionally, bones18and20can be resected to expose cancellous bone into which fixation pegs54A-56B (FIG. 3) can be implanted.

At step208, any desired measuring of bones18and20, surfaces86and82and the gap between surfaces86and82for the sizing of the prosthetic joint component can be conducted. For example, if non-custom or standard implants are to be used, a surgeon can measure or observe the size of bones18and20intraoperatively to determine which size of prosthetic joint device40is to be used from a set of standard sized devices.

At step210, any anchor members of prosthetic joint device40can be connected to bones18and20. For example, as shown inFIG. 8, fixation pegs54A and56A of anchor component44A can be inserted into cancellous bone at surface86at bone18, and fixation pegs54B and56B of anchor component44B can be inserted into cancellous bone as surface82of bone20. Flexible spacer42can be flexed or bent by the surgeon to simultaneously attach all of fixation pegs54A-56B. Thereafter, tension on flexible spacer can be released and fibers46of flexible spacer can relax and return to the natural unflexed condition so that bone18can be moved into axial alignment with bone20, as shown inFIG. 8.

At step212, any bone cement can be applied to anchor components44A and44B if desired. Application of bone cement can be optional if a surgeon can determine that adequate bone material exists to support fixation pegs54A-56B. Likewise, any other observations of the fit of prosthetic joint device40or the flexion of the repaired joint14can be observed and evaluated after implantation.

At step214, any incisions made at step202can be closed-up, if desired or deemed appropriate by the surgeon.

FIG. 11is a schematic diagram illustrating prosthetic joint implant300of the present disclosure including electronic circuit306. Electronic circuit306can be in communication with reader302and computer system304. Prosthetic joint implant300can comprise polymer layer308disposed between porous scaffolds310A and310B. Electronic circuit306can comprise capacitor layers312A and312B, insulator314and resistor316. Components of prosthetic joint implant300are not drawn to scale.

Porous scaffolds310A and310B and polymer layer308can be configured according to the devices described herein. Electronic circuit306can comprise an active version of a prosthetic joint implant that can communicate information from the patient. Electronic circuit306can include one or more capacitors formed by capacitor layers312A and312B and insulator314, as well as one or more of resistor316and other electronic components. The electronic components can be 3D printed onto the interfaces between metallic porous scaffolds310A and310B and polymer layer308to measure stresses and strains during activities of daily living. Capacitor layers312A and312B can comprise conducting plates that can be made of tantalum, silver or niobium, while insulator314can comprise a dielectric that can be made of polymer or ceramic materials. Resistor316can be printed from carbon and ceramic powders.

Information or data relating to the measurements taken by electronic circuit306can be transmitted to reader302. Reader302can be configured to wirelessly communicate with electronic circuit306. In examples, reader302can additionally have writing capabilities to send information to electronic circuit306. In such cases, electronic circuit306can include a receiver and an electronic memory device. As such, patient-specific information can be written to prosthetic joint implant300. Information obtained from electronic circuit306can be transmitted to computer system304where the data can be stored and analyzed. The stresses and strains can be analyzed to determine the condition of prosthetic joint implant300and to evaluate the lifestyle of the patient.

VARIOUS NOTES & EXAMPLES

Example 1 can include or use subject matter such as a device for the repair of a phalangeal joint that can comprise a first anchor, a second anchor and a flexible spacer connecting the first anchor and the second anchor. The flexible spacer can comprise a plurality of elongate fibers extending between the first and second anchors, and a polymeric matrix interspersed with the plurality of elongate fibers.

Example 2 can include, or can optionally be combined with the subject matter of Example 1, to optionally include a flexible spacer and first and second anchors that can be integral with each other.

Example 3 can include, or can optionally be combined with the subject matter of one or any combination of Examples 1 or 2 to optionally include the first anchor and the second anchor that can be comprised of a porous structure.

Example 4 can include, or can optionally be combined with the subject matter of one or any combination of Examples 1 through 3 to optionally include the first anchor being connected to a first end of the flexible spacer via a first interdigitation zone transitioning the porous structure of the first anchor into the plurality of elongate fibers and polymeric matrix of the flexible spacer; and the second anchor being connected to a second end of the flexible spacer via a second interdigitation zone transitioning the porous structure of the second anchor into the plurality of elongate fibers and polymeric matrix of the flexible spacer.

Example 5 can include, or can optionally be combined with the subject matter of one or any combination of Examples 1 through 4 to optionally include the first and second interdigitation zones extending into pores of the first and second anchors and are free of fibers of the plurality of elongate fibers.

Example 6 can include, or can optionally be combined with the subject matter of one or any combination of Examples 1 through 5 to optionally include the flexible spacer being comprised of a polymeric composition and the first and second anchors are comprised of porous metallic structures.

Example 7 can include, or can optionally be combined with the subject matter of one or any combination of Examples 1 through 6 to optionally include the flexible spacer comprising fibers of the plurality of fibers in the range of approximately 20% to approximately 70% of the volume of the flexible spacer.

Example 8 can include, or can optionally be combined with the subject matter of one or any combination of Examples 1 through 7 to optionally include the first anchor and the second anchor each including one or more fixation pegs.

Example 9 can include, or can optionally be combined with the subject matter of one or any combination of Examples 1 through 8 to optionally include fibers of the plurality of elongate fibers that are spaced apart from each other by the polymeric matrix.

Example 10 can include, or can optionally be combined with the subject matter of one or any combination of Examples 1 through 9 to optionally include fibers of the plurality of fibers extending parallel to center axes of the first anchor and the second anchor in an unflexed condition.

Example 11 can include, or can optionally be combined with the subject matter of one or any combination of Examples 1 through 10 to optionally include fibers of the plurality of fibers extend criss-crossed relative to each other and center axes of the first anchor and the second anchor in an unflexed condition.

Example 12 can include or use subject matter such as a prosthetic metatarsophalangeal joint device that can comprise a metatarsal bone anchor that can comprise a porous metallic material, a phalangeal bone anchor that can comprise a porous metallic material, and a polymeric spacer element that can connect the metatarsal bone anchor and the phalangeal bone anchor, the polymeric spacer element can comprise a plurality of elongate fibers extending between the metatarsal bone anchor and the phalangeal bone anchor.

Example 13 can include, or can optionally be combined with the subject matter of Example 12, to optionally include first and second fixation pegs extending from the metatarsal bone anchor and the phalangeal bone anchor, respectively, a polymeric matrix material interspersed with fibers of the plurality of elongate fibers, and interdigitation zones fusing struts of the porous metallic material of the metatarsal bone anchor and the phalangeal bone anchor with the fibers of the plurality of elongate fibers.

Example 14 can include or use subject matter such as a method of manufacturing a device for the repair of a phalangeal joint. The method can comprise fabricating first and second anchor components using a first additive manufacturing process to produce a porous structure within each component, fabricating a flexible spacer component using a second additive manufacturing process or a molding process to produce a plurality of elongate fibers extending across the flexible spacer, and attaching opposing ends of the flexible spacer component to the first and second anchor components.

Example 15 can include, or can optionally be combined with the subject matter of Example 14, to optionally include fabricating the first and second anchor components using the first additive manufacturing process and fabricating the flexible spacer component using the second additive manufacturing process or the molding process by printing the components from different materials.

Example 16 can include, or can optionally be combined with the subject matter of one or any combination of Examples 14 or 15 to optionally include printing the first and second anchor components by selective laser sintering or electron beam based three-dimensional printing the first and second metallic porous anchor components from a metallic powder.

Example 17 can include, or can optionally be combined with the subject matter of one or any combination of Examples 14 through 16 to optionally include fabricating the flexible spacer component using the second additive manufacturing process by three-dimensionally printing or molding the flexible spacer from polyethylene.

Example 18 can include, or can optionally be combined with the subject matter of one or any combination of Examples 14 through 17 to optionally include fabricating a flexible spacer component using a second additive manufacturing process or a molding process to produce a plurality of elongate fibers extending across the flexible spacer by extending the fibers straight across or extending the fibers across in a criss-cross manner.

Example 19 can include, or can optionally be combined with the subject matter of one or any combination of Examples 14 through 18 to optionally include fabricating the flexible spacer component using the second additive manufacturing process or the molding process by fusing a first interdigitation zone into the first anchor component, building a plurality of elongate fibers out of the interdigitation zone, interspersing a matrix layer between fibers of the plurality of fibers, building a second interdigitation zone onto the plurality of elongate fibers and the matrix layer, and fusing the second interdigitation zone into the second anchor component.

Example 20 can include, or can optionally be combined with the subject matter of one or any combination of Examples 14 through 19 to optionally include fabricating the first and second anchor components using the first additive manufacturing process to produce the porous structure within each component by producing a plurality of struts interconnected to form open spaces.

Example 21 can include, or can optionally be combined with the subject matter of one or any combinations of Examples 14 through 20 to optionally include fabricating the flexible spacer component using the second additive manufacturing process by three-dimensionally printing or molding the flexible spacer to include an antibiotic powder.

Example 22 can include, or can optionally be combined with the subject matter of one or any combinations of Examples 14 through 21 to optionally include fabricating the flexible spacer component using the second additive manufacturing process by three-dimensionally printing or molding the flexible spacer to include an electronic circuit.

Example 23 can include, or can optionally be combined with the subject matter of one or any combinations of Examples 14 through 22 to optionally include fabricating the flexible spacer component using the second additive manufacturing process by three-dimensionally printing or molding the flexible spacer to include an electronic circuit that can measure stress and strain in the device. Each of these non-limiting examples can stand on its own, or can be combined in various permutations or combinations with one or more of the other examples.