Foot metatarsophalangeal joint height limiting type prosthesis

Abstract

The invention discloses a foot metatarsophalangeal joint height limiting type prosthesis which comprises a metatarsal bone prosthesis used for being combined with the end of a metatarsal bone and a phalanx prosthesis used for being combined with the end of a proximal phalanx, and a limiting groove is formed in the end, close to the phalanx prosthesis, of the metatarsal bone prosthesis in the moving direction of the proximal phalanx. A limiting groove is formed in the metatarsal bone prosthesis, a lining prosthesis is connected to the end, close to the metatarsal bone prosthesis, of the phalanx prosthesis, a stand column inserted into the limiting groove is arranged on the side, facing the metatarsal bone prosthesis, of the lining prosthesis, a blocking rod is arranged in the limiting groove, and when the stand column abuts against the blocking rod, the included angle between the center lines of the metatarsal bone prosthesis and the phalanx prosthesis reaches the maximum value. The rotation angle between the metatarsal bone prosthesis and the phalanx prosthesis can be limited through the arrangement of the limiting groove and the stand column, and inward turning and outward turning of the proximal phalanx are avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of medical prostheses, in particular to a high-restriction prosthesis for a metatarsophalangeal joint of a foot. Background Art

[0002] A variety of foot conditions affect the first metatarsophalangeal joint, including stiffness, severe hallux valgus, gout, or rheumatoid osteoarthritis. Traditional surgical treatment involves fusion of the first metatarsophalangeal joint, which results in loss of joint function and impacts walking and daily life. Newer treatments include interstitial packing arthroplasty and first metatarsophalangeal joint replacement (with either silicone or metal prostheses). However, clinical efficacy remains poor, with high revision rates, often accompanied by metatarsalgia and weakness in toe-start during walking. Prosthesis-related complications include silicone aging and wear, periprosthetic bone hyperplasia, and osteolysis. The normal first metatarsophalangeal joint requires significant internal and external valgus control. The numerous surrounding muscles, particularly the transverse head of the adductor muscles, can cause adduction of the first metatarsal and valgus of the proximal phalanx. However, existing prostheses cannot achieve this internal and external valgus control. Furthermore, surgical resection of the adductor muscles can easily lead to adduction of the proximal phalanx. Summary of the Invention

[0003] The present invention provides a high-restriction prosthesis for the metatarsophalangeal joint of the foot, which can solve the problem that the existing metatarsophalangeal joint prosthesis cannot achieve eversion and valgus restriction.

[0004] To achieve the above-mentioned objectives, the present invention provides the following technical solutions: a highly restricted prosthesis for the metatarsophalangeal joint of the foot, comprising a metatarsal prosthesis for combining with the end of the metatarsal bone and a phalangeal prosthesis for combining with the end of the proximal phalange, wherein a limiting groove is provided at one end of the metatarsal prosthesis close to the phalangeal prosthesis along the moving direction of the proximal phalange, an inner lining prosthesis is connected to one end of the phalangeal prosthesis close to the metatarsal prosthesis, a column inserted into the limiting groove is provided on the side of the inner lining prosthesis facing the metatarsal prosthesis, a shift lever is provided inside the limiting groove, and when the column and the shift lever are against each other, the centerline angle between the metatarsal prosthesis and the phalangeal prosthesis reaches a maximum value, and by providing the limiting groove and the column, the rotation angle between the metatarsal prosthesis and the phalangeal prosthesis can be limited, thereby avoiding inversion and eversion of the proximal phalange.

[0005] Preferably, the metatarsal prosthesis includes a spherical end and a first intramedullary plug arranged on the rear side of the spherical end for insertion into the interior of the metatarsal. The limiting groove is arranged at the end of the spherical end. The spherical end cooperates with the lining prosthesis to ensure the mobility between the metatarsal prosthesis and the phalangeal prosthesis. The first intramedullary plug can be inserted into the bone marrow of the metatarsal, thereby improving the connection strength between the metatarsal and the prosthesis.

[0006] Preferably, a limiting side block extending toward the metatarsal and fitting the metatarsal end is provided on the side of the spherical end away from the gear lever. The limiting side block and the first intramedullary column can simultaneously apply force to the metatarsal, thereby improving the firmness of the installation of the metatarsal prosthesis. Moreover, the limiting side block is integrated with the spherical surface of the spherical end, thereby achieving a relatively large contact area between the spherical end and the lining prosthesis, thereby improving the guiding effect.

[0007] Preferably, the phalanx prosthesis includes a base plate and a second intramedullary post arranged on one side of the base plate for insertion into the proximal phalanx. The second intramedullary post is inserted into the bone marrow of the proximal phalanx to improve the connection strength between the phalanx prosthesis and the proximal phalanx.

[0008] Preferably, a plurality of slots are provided on the side of the lining prosthesis facing the phalangeal prosthesis, and a snap-fitting boss matching the slots is provided on the side of the phalangeal prosthesis facing the lining prosthesis. Alternatively, the lining prosthesis is provided with a plurality of snap-fitting bosses on the side facing the phalangeal prosthesis, and the phalangeal prosthesis is provided with a snap-fitting groove matching the snap-fitting bosses on the side facing the lining prosthesis. By matching the snap-fitting bosses with the snap-fitting grooves, a limited connection between the lining prosthesis and the phalangeal prosthesis can be achieved, and the two will not slide relative to each other, thereby improving the bonding strength.

[0009] Preferably, a metal reinforcement component is provided inside the column to improve the strength of the column and prevent the column from breaking when it moves in the limiting groove.

[0010] Preferably, the gear lever is wrapped with a layer of polylactic acid cushion or polylactic acid-glycolic acid copolymer microsphere coating, and hyaluronic acid is embedded in the polylactic acid-glycolic acid copolymer microsphere coating. When the gear lever collides with the column, the microspheres rupture and release hyaluronic acid to form a lubricating buffer film.

[0011] Preferably, a groove is provided on the side wall of the column facing the gear lever, and a buffer block made of porous polyetheretherketone is embedded in the groove.

[0012] Preferably, the distal end of the base plate is provided with a plurality of positioning rods for being inserted into the proximal phalanges, so as to improve the connection strength between the phalangeal prosthesis and the proximal phalanges.

[0013] Preferably, the relative rotation angle range between the metatarsal prosthesis and the phalangeal prosthesis is not less than 90°, which can meet the angle requirements for the activities between the metatarsal prosthesis and the phalangeal prosthesis.

[0014] Compared with the prior art, the present invention has the following beneficial effects: The structure is simple. By setting limiting grooves and columns, the rotation angle between the metatarsal prosthesis and the phalangeal prosthesis can be restricted, avoiding inversion and eversion of the proximal phalanges. The end of the metatarsal prosthesis is spherical in design, and the lining prosthesis and the phalangeal prosthesis match the spherical curvature to ensure mobility. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic structural diagram of the assembled state of the present invention; Figure 2 This is a first-perspective three-dimensional structural diagram of the present invention in an assembled state; Figure 3 This is a second perspective structural diagram of the present invention in an assembled state; Figure 4 This is a first-perspective three-dimensional structural diagram of the present invention in an exploded state; Figure 5 This is a second perspective three-dimensional structural diagram of the present invention in an exploded state; Figure 6 It is a cross-sectional schematic diagram of the metatarsal prosthesis and the phalangeal prosthesis of the present invention in a state of relative rotation; Figure 7 It is a cross-sectional schematic diagram of the relative limiting state of the metatarsal prosthesis and the phalangeal prosthesis of the present invention; Figure 8 It is a schematic diagram of the present invention showing a metatarsal prosthesis and a phalangeal prosthesis with a buffer structure in a state of relative limitation.

[0016] Reference numerals: 1. Metatarsal prosthesis, 11. Spherical end, 12. Limiting groove, 13. Stop rod, 14. First intramedullary column, 15. Limiting side block, 16. Polylactic acid-glycolic acid copolymer microsphere coating, 17. Polylactic acid cushion pad, 2. Phalanx prosthesis, 21. Base plate, 22. Positioning rod, 23. Second intramedullary column, 24. Snap-in boss, 3. Lining prosthesis, 31. Column, 32. Slot, 33. Buffer block. DETAILED DESCRIPTION

[0017] The technical solutions in the embodiments of the present invention will be described clearly and completely below with reference to the accompanying drawings in the embodiments of the present invention.

[0018] The present invention aims to solve the problem that the existing metatarsophalangeal joint prosthesis cannot achieve inversion and valgus restriction. Figure 1-7As shown, the following technical solution is provided: a high-restriction prosthesis for the metatarsophalangeal joint of the foot, comprising a metatarsal prosthesis 1 for combining with the end of the metatarsal bone and a phalangeal prosthesis 2 for combining with the end of the proximal phalanx, wherein the end of the metatarsal prosthesis 1 close to the phalangeal prosthesis 2 is provided with a limiting groove 12 along the moving direction of the proximal phalanx, and the end of the phalangeal prosthesis 2 close to the metatarsal prosthesis 1 is connected with a lining prosthesis 3, and the lining prosthesis 3 is provided with a column 31 inserted into the limiting groove 12 on the side facing the metatarsal prosthesis 1, and a shift rod 13 is provided inside the limiting groove 12. When the column 31 and the shift rod 13 are abutted against each other, the centerline angle between the metatarsal prosthesis 1 and the phalangeal prosthesis 2 reaches a maximum value. By providing the limiting groove 12 and the column 31, the rotation angle between the metatarsal prosthesis 1 and the phalangeal prosthesis 2 can be limited, thereby avoiding inversion and eversion of the proximal phalanx.

[0019] Specifically, the stop groove 12 cooperates with the post 31 to form a mechanical stop. When the post 31 contacts the stop lever 13, it precisely limits the maximum rotation angle of the metatarsal prosthesis 1 and the phalangeal prosthesis 2 (≥90°). This design controls the valgus / valgus angle within a physiologically safe range (e.g., ±10°), preventing proximal phalangeal deformities (such as recurrence of hallux valgus) caused by excessive valgus / valgus, while also preventing abnormal prosthetic wear and surrounding bone dissolution. By limiting the abnormal angle, the load on the metatarsophalangeal joint is evenly distributed, reducing concentrated pressure on the metatarsal heads, enhancing toe propulsion during walking, and improving the patient's gait.

[0020] In this embodiment, the metatarsal prosthesis 1 includes a spherical end 11 and a first intramedullary post 14 arranged on the rear side of the spherical end 11 for insertion into the interior of the metatarsal. The limiting groove 12 is arranged at the end of the spherical end 11. The spherical end 11 cooperates with the lining prosthesis 3 to ensure the mobility between the metatarsal prosthesis 1 and the phalangeal prosthesis 2. The first intramedullary post 14 can be inserted into the bone marrow of the metatarsal to improve the connection strength between the metatarsal and the prosthesis. The first intramedullary post 14 can adopt a conical or threaded design. After being inserted into the metatarsal bone marrow cavity, dual fixation can be achieved through bone cement (such as polymethyl methacrylate) or bone ingrowth (porous tantalum metal coating on the surface), thereby increasing the pull-out resistance by more than 40% and reducing the risk of prosthesis loosening.

[0021] The spherical end 11 of the metatarsal prosthesis 1 matches the curved surface of the lining prosthesis 3, limiting eversion and valgus while allowing the metatarsophalangeal joint to perform flexion and extension movements (such as dorsiflexion and plantar flexion). The range of motion can reach more than 90°, which is close to normal joint function.

[0022] The metatarsal prosthesis 1 and the phalangeal prosthesis 2 can be made of Ti-6Al-4VELI titanium alloy and formed by 3D printing. The porous structure of the surface (porosity 60%, pore size 500-800μm) promotes bone ingrowth, and the mechanical strength is ≥800MPa.

[0023] In this embodiment, a side of the spherical end portion 11 away from the gear rod 13 is provided with a limiting side block 15 extending toward the metatarsal bone and fitting the metatarsal end portion. The limiting side block 15 and the first intramedullary plug 14 can simultaneously apply force to the metatarsal bone, thereby improving the firmness of the installation of the metatarsal prosthesis 1. Moreover, the limiting side block 15 is integrated with the spherical surface of the spherical end portion 11, so that a relatively large contact area can be achieved between the spherical end portion 11 and the lining prosthesis 3, thereby improving the guiding effect. Specifically, the limiting side block 15 adopts the same contact area as the spherical end portion 11. 1 The integrated titanium alloy casting structure fits the outer bone surface of the metatarsal end, which can disperse more than 20% of the lateral stress and prevent lateral displacement of the prosthesis. At the same time, the side mass and the spherical surface form a continuous curved surface, which increases the contact area with the lining prosthesis 3, improves the guidance accuracy, and reduces abnormal friction. The first intramedullary plug 14 is 30-40mm long and 4-6mm in diameter. The end inserted into the medullary cavity can be provided with 3-4 annular grooves to increase the bone cement anchoring area. A transition fillet is provided at the connection between the distal end and the spherical end 11 to reduce stress concentration.

[0024] Preferably, the phalangeal prosthesis 2 includes a base plate 21 and a second intramedullary column 23 arranged on one side of the base plate 21 for inserting into the interior of the proximal phalanx. The second intramedullary column 23 is inserted into the bone marrow of the proximal phalanx to improve the connection strength between the phalangeal prosthesis 2 and the proximal phalanx. Specifically, the distal end of the base plate 21 is provided with a plurality of positioning rods 22 for inserting into the proximal phalanx, which can improve the connection strength between the phalangeal prosthesis 2 and the proximal phalanx. Specifically, 3-4 barbed positioning rods 22 are provided at the distal end of the base plate 21, which can form a mechanical lock when inserted into the cortical bone of the phalanx, and cooperate with the intramedullary column to improve the initial stability of the prosthesis and the bone by 60%, which is particularly suitable for patients with osteoporosis; the second intramedullary column 23 has a length of 25-35 mm and a diameter of 3-5 mm. It can adopt a hollow design (inner diameter 1 mm) and can be implanted with antibiotic sustained-release particles to prevent postoperative infection.

[0025] In this embodiment, the lining prosthesis 3 is provided with a plurality of slots 32 on the side facing the phalangeal prosthesis 2, and the phalangeal prosthesis 2 is provided with a snap-fitting boss 24 matching the slots 32 on the side facing the lining prosthesis 3; Alternatively, the lining prosthesis 3 is provided with a plurality of snap-in bosses 24 on the side facing the phalangeal prosthesis 2, and the phalangeal prosthesis 2 is provided with a snap-in groove 32 matching the snap-in boss 24 on the side facing the lining prosthesis 3. The matching of the snap-in boss 24 and the snap-in groove 32 can achieve a limited connection between the lining prosthesis 3 and the phalangeal prosthesis 2, and the two will not slide relative to each other, thereby improving the bonding strength. Specifically, there are several snap-in bosses 24 and snap-in grooves 32, all of which are arranged at the edge position. The lining prosthesis 3 is made of UHMWPE material, sterilized by γ rays (dose 25-30kGy), and has a wear rate of ≤0.1mm / year after anti-oxidation treatment, and its service life is expected to be more than 15 years.

[0026] In this embodiment, a metal reinforcement component is provided inside the column 31 to improve the strength of the column 31 and prevent the column 31 from breaking when it moves in the limiting groove 12. Specifically, the metal reinforcement component is a titanium alloy or cobalt-chromium-molybdenum alloy core rod with a diameter of 1 / 3 of the outer diameter of the column 31. It can withstand a lateral force of ≥500N without breaking (traditional plastic columns can only withstand 200N), thereby avoiding prosthesis failure caused by column breakage due to long-term use.

[0027] like Figure 8 As shown, in order to reduce the vibration and wear when the gear rod 13 collides with the column 31, the gear rod 13 is wrapped with a layer of polylactic acid cushion pad 17 or polylactic acid-glycolic acid copolymer microsphere coating 16, and hyaluronic acid is embedded in the polylactic acid-glycolic acid copolymer microsphere coating 16. When the gear rod 13 collides with the column 31, the microspheres rupture and release hyaluronic acid to form a lubricating buffer film.

[0028] Among them, polylactic acid (PLA) is an important bio-based degradable polymer material with good biocompatibility and degradability. Therefore, PLA gradually degrades within 3 months after surgery. During this period, the cushion absorbs the initial impact force of the joint movement. After degradation, the metal stop surface is exposed, forming a permanent limit.

[0029] Among them, the polylactic acid-glycolic acid copolymer (PLGA) microsphere coating is composed of a polyester polymerized from two monomers, lactic acid and glycolic acid. It has good biocompatibility and can gradually degrade into lactic acid and glycolic acid in the body, and eventually metabolize into carbon dioxide and water, without the need for a second surgery to remove it. Therefore, PLGA gradually degrades in the first 6 months after surgery, during which time it continuously releases hyaluronic acid, which not only cushions the impact of early collisions but also promotes the formation of synovial fluid. After degradation, the metal gear rod is exposed, achieving a dual-stage function of early cushioning and later stabilization. This coating reduces the wear rate by 90% within 3 months after surgery and stabilizes at 0.1mm / year after 6 months, solving the problem that traditional cushioning structures cannot take into account both early healing and long-term stability.

[0030] In addition, if Figure 8 As shown, a groove can also be provided on the side wall of the column 31 facing the gear lever 13, and a buffer block 33 made of porous polyetheretherketone is embedded in the groove, wherein the buffer block 33 can be connected to the metal reinforcement component by screws, or can be pasted to the surface of the groove. The porosity of porous polyetheretherketone (PEEK) can be 60%, and the pore size is 100-200μm. During collision, porous PEEK realizes compressible buffering through pore collapse, and the air in the pore forms a damping effect, which prolongs the impact time, and the biocompatibility of PEEK avoids inflammatory response.

[0031] In this embodiment, the hallux valgus treatment scenario involves surgical resection of the metatarsal head osteophytes. After medullary expansion, the first intramedullary post 14 is inserted into the metatarsal bone marrow cavity, with the retaining lateral block 15 aligned with the lateral metatarsal bone surface. Following osteotomy of the proximal phalanx, the second intramedullary post 23 and the positioning rod 22 are inserted into the phalanx. The lining prosthesis 3 is secured to the phalanx prosthesis 2 via the engaging boss 24 and the engaging groove 32, with the upright post 31 inserted into the retaining groove 12 of the metatarsal prosthesis. Postoperatively, patients can recover 90° of joint motion within 6 weeks, and a one-year follow-up revealed a hallux valgus recurrence rate of less than 5%.

[0032] Application scenarios for rheumatoid arthritis: For patients with severe joint damage, the high-restriction design of the prosthesis can reduce joint instability caused by inflammation, and the low-friction interface between the spherical end and the lining prosthesis can reduce the inflammatory response; the metal reinforcement component column 31 can withstand abnormal stress under long-term inflammatory conditions, reducing the risk of prosthesis fracture. The clinically expected revision rate is 30% lower than that of traditional prostheses.

[0033] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0034] In addition, the terms "primary," "secondary," and so forth, used in this disclosure are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, features designated as "primary" or "secondary" may explicitly or implicitly include at least one such feature. In the description of this disclosure, "plurality" means at least two, such as two or three, unless otherwise specifically defined.

[0035] In the present invention, unless otherwise specified or limited, the terms "connection" and "fixation" should be understood in a broad sense. For example, "fixation" can mean fixed connection, detachable connection, or integration; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; internal communication between two elements or interaction between two elements, unless otherwise specified. Those skilled in the art will be able to understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0036] In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that ordinary technicians in this field can implement it. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

Claims

1. A high-constraint prosthesis for the metatarsophalangeal joint of the foot, characterized in that: The invention comprises a metatarsal prosthesis (1) for combining with the end of a metatarsal bone and a phalangeal prosthesis (2) for combining with the end of a proximal phalangeal bone, wherein a limiting groove (12) is provided at one end of the metatarsal prosthesis (1) close to the phalangeal prosthesis (2) along the moving direction of the proximal phalangeal bone, and an inner lining prosthesis (3) is connected to one end of the phalangeal prosthesis (2) close to the metatarsal prosthesis (1), and a column (31) inserted into the limiting groove (12) is provided on the side of the inner lining prosthesis (3) facing the metatarsal prosthesis (1), and a stop rod (13) is provided inside the limiting groove (12). When the column (31) and the stop rod (13) are in contact with each other, the centerline angle between the metatarsal prosthesis (1) and the phalangeal prosthesis (2) reaches a maximum value.

2. The high-constraint prosthesis for the metatarsophalangeal joint of the foot according to claim 1, characterized in that: The metatarsal prosthesis (1) comprises a spherical end portion (11) and a first intramedullary plug (14) arranged at the rear side of the spherical end portion (11) for insertion into the interior of the metatarsal bone, and the limiting groove (12) is arranged at the end of the spherical end portion (11).

3. The high-constraint prosthesis for the metatarsophalangeal joint of the foot according to claim 2, characterized in that: A side of the spherical end (11) away from the shift rod (13) is provided with a limiting side block (15) extending toward the metatarsal bone and fitting with the end of the metatarsal bone.

4. The high-constraint prosthesis for the metatarsophalangeal joint of the foot according to any one of claims 1 to 3, characterized in that: The phalanx prosthesis (2) comprises a base plate (21) and a second intramedullary plug (23) arranged on one side of the base plate (21) and used for being inserted into the interior of the proximal phalanx.

5. The high-constraint prosthesis for the metatarsophalangeal joint of the foot according to claim 4, characterized in that: The side of the lining prosthesis (3) facing the phalangeal prosthesis (2) is provided with a plurality of slots (32), and the side of the phalangeal prosthesis (2) facing the lining prosthesis (3) is provided with a snap-fitting boss (24) matching the slots (32); Alternatively, a plurality of snap-fitting bosses (24) are provided on the side of the lining prosthesis (3) facing the phalangeal prosthesis (2), and a snap-fitting slot (32) matching the snap-fitting bosses (24) is provided on the side of the phalangeal prosthesis (2) facing the lining prosthesis (3).

6. The high-constraint prosthesis for the metatarsophalangeal joint of the foot according to claim 4, characterized in that: A metal reinforcement component is provided inside the column (31).

7. The high-constraint prosthesis for the metatarsophalangeal joint of the foot according to claim 4, characterized in that: The gear lever (13) is wrapped with a layer of polylactic acid cushioning pad (17) or polylactic acid-glycolic acid copolymer microsphere coating (16), and hyaluronic acid is embedded in the polylactic acid-glycolic acid copolymer microsphere coating (16). When the gear lever (13) collides with the column (31), the microspheres rupture and release hyaluronic acid to form a lubricating buffer film.

8. The high-constraint prosthesis for the metatarsophalangeal joint of the foot according to claim 7, characterized in that: A groove is provided on the side wall of the column (31) facing the shift lever (13), and a buffer block (33) made of porous polyetheretherketone is embedded in the groove.

9. The high-constraint prosthesis for the metatarsophalangeal joint of the foot according to claim 4, characterized in that: The distal end of the base plate (21) is provided with a plurality of positioning rods (22) for inserting into the proximal phalanges.

10. The high-constraint prosthesis for the metatarsophalangeal joint of the foot according to claim 1, characterized in that: The relative rotation angle range between the metatarsal prosthesis (1) and the phalangeal prosthesis (2) is not less than 90°.

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