Artificial knuckle

The present invention relates to artificial knuckles used for the treatment of joint disorders such as rheumatoid arthritis. More specifically, the present invention relates to an artificial knuckle in which a plastic socket member and a metal head member are detachably combined.

Joint disorders such as rheumatoid arthritis, osteoarthritis, and other knuckle deformities are extremely painful. Patients suffering from such symptoms are treated by excising the knuckle and applying an artificial knuckle. As a conventional artificial finger joint, for example, a medical device approval number disclosed in Non-Patent Documents 1 to 3 is known. The artificial knuckle of Non-Patent Document 1 shown in FIG. 1 has a ball joint type joint between the head and the socket. The metal head component a1 is composed of the head b, the set screw c and the joint anchor d, and the socket component e1 is composed of a plastic substantially hemispherical socket f, the set screw c and the joint anchor d. In the operation of applying this artificial knuckle to the patient, the joint anchor d is implanted in the medullary cavity of the middle hand, and the head b is placed via the set screw c. After that, a joint anchor d is also embedded in the proximal phalanx, and a socket f is installed via the set screw c to form a cementless artificial finger joint. In the artificial knuckle of Non-Patent Document 2 shown in FIG. 2, the joint between the head and the socket is a surface contact type. This artificial finger joint consists of a metal head component a2 with a grooved stem g and a plastic socket component e2 with a cylindrical stem h, which is the joint or middle between the proximal and intermediate phalanx. It is applied to the finger joint between the proximal phalanx and the unphalanged bone. The socket component e2 is positioned within the medullary cavity of the distal phalanx and the head component a2 is positioned within the medullary cavity of the proximal phalanx and secured with bone cement.

The artificial knuckle of Non-Patent Document 3 shown in FIG. 3 is a surface contact type like the above-mentioned artificial knuckle shown in FIG. The artificial knuckles shown in FIGS. 3 (A) and 3 (B) consist of a component a3 for the metacarpal bone and a component e3 for the proximal phalanx. The artificial knuckle shown in FIG. 3 (C) consists of a component a4 for the proximal phalanx and a component e4 for the intermediate phalanx. The artificial knuckle of Non-Patent Document 3 shown in FIG. 4 is an integrated artificial knuckle made of silicone rubber having a hinge portion, and the state in which the distal stem is bent 90 ° with respect to the proximal stem is shown in FIG. 4 (Fig. 4). Shown in A). In the figure, the hinge portion i is cut out in the shape of a keyhole on the palm side (inside) of the middle portion in the thickness direction, and the outside of the hinge portion i is cut at 90 °. In addition, a rectangular distal stem j and a proximal stem k are integrally provided on the distal surface and the proximal surface of the hinge portion i, respectively, and the respective stems j and k are provided against the elasticity of the knuckle bone. An artificial knuckle is attached by pushing it into the knuckle cavity.<nplcit num="1"><text>Pamphlet on artificial knuckles with medical device approval number 21100BZZ00217000 (ME1000-7020BA-2)</text></nplcit><nplcit num="2"><text>Pamphlet on artificial knuckles with medical device approval number 20900BZZ00583000 (ME2000-2010BA-4)</text></nplcit><nplcit num="3"><text>Pamphlet on each artificial knuckle with medical device approval number 21000BZG00015000 and medical device approval number 20800BZY00746000 [06/01 / AVA003WIN (1.5)]</text></nplcit>

<p> In the conventional artificial finger joints shown in FIGS. 1 to 4, the shape of the joint surface or the hinge portion between the head and the socket is elaborated to reproduce not a little natural finger movement. However, the ball joint type artificial knuckle whose joint between the head and the socket is shown in FIG. 1 requires a set screw to fix the head and the socket of each component, and has a large number of parts. In addition, although the installation of each component is cementless, it is very complicated to install it on the knuckle joint. The surface contact type artificial finger joints shown in Fig. 2 and 3, including the ball joint type, have frictional contact between the head and socket and there is no gap between the two components, so they only operate according to the shape of the joint surface. Can not. Moreover, since the degree of freedom of joining is too high, there is a problem that the joining surface is displaced and the component is easily dislocated, resulting in re-deformation after the operation. It is also necessary to inject bone cement into the medullary space after each component is positioned within the medullary space of the phalanx. In the integrated artificial knuckle shown in FIG. 4, the distal stem portion and the proximal stem portion cannot be separated, and it is complicated to attach the knuckle to the knuckle site during surgery. Further, the distal stem rotates with respect to the proximal stem with the portion between the keyhole-shaped inner notch and the outer cut as the rotation axis, and there is no play in the axial direction. It is not possible to operate in orthogonal directions.</p><p> As described above, the conventional artificial finger joint has a drawback that not only the delicate movement of the finger such as the smooth flexion movement of the finger cannot be reproduced, but also the attachment to the finger joint portion at the time of surgery is complicated. In addition, separable artificial knuckles with removable head and socket components may re-deform after surgery. Further, the conventional artificial knuckle has a drawback that one product can be applied to only one part of the knuckle and the versatility is poor. Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art, the movement of the finger close to that of a living body can be reproduced, the finger joint can be easily attached to the joint portion, and the components are separated from each other. It is an object of the present invention to provide an artificial knuckle that can prevent postoperative re-deformation while being possible and can be applied to any part of the knuckle.</p>

<p> In order to achieve the above object, the artificial finger joint of the present invention comprises a plastic socket member and a metal or alloy head member rotatably attached to the socket member, and the socket member includes a hinge portion and a first member. It is composed of one bulge and the first stem, and the head member is composed of a pivot that detachably fits in the hinge part of the socket member, a connecting part, a second bulge, and a second stem, and the first stem. And one of the first bulge and the second stem and the second bulge is inserted into the proximal medullary cavity of the knuckle, the other is inserted into the distal medullary cavity, and each bulge. The part is pressed against the inner surface of the bone and fixed in the medullary cavity. In the embodiment of the present invention, the hinge portion is composed of a hollow cylinder whose both end surfaces are closed, and the pivot is detachably attached to the hollow cylinder along the width direction of the first bulging portion in the longitudinal direction thereof. A first opening is formed, and a second opening that allows the head member to rotate relative to the socket member is formed in the circumferential direction of the central portion of the hollow cylinder in the longitudinal direction.</p><p> The artificial knuckle of the present invention is attached to the hinge portion of the socket member in a state in which the pivot of the head member is detachably and rotatably loosely fitted. Therefore, when the socket member and the head member are fixed to the medullary space of the knuckle adjacent to each other in the knuckle, not only the finger can bend and extend around the pivot, but also the pivot is attached to the hinge portion. On the other hand, since it is loosely fitted, it is possible to perform a displacement motion other than the bending and stretching motion, so that a motion similar to the finger motion of the living body can be reproduced. Further, the socket member and the head member are fixed to the knuckle joint portion by simply inserting the first stem and the bulging portion and the second stem and the bulging portion separately into the medullary cavity. Moreover, since it is a semi-restraint type artificial knuckle that is attached with the pivot loosely fitted to the hinge part, there is a risk that the knuckle member will come off or shift from the socket member after surgery and the artificial knuckle will re-deform. There is no. Further, in the artificial finger joint of the present invention, the metacarpal bone is adjusted by cutting the first stem and the second stem according to the length of the phalanx adjacent to the affected finger joint. It can be applied to any site between the proximal phalanx and the proximal phalanx, the proximal phalanx and the intermediate phalanx, or the intermediate phalanx and the unphalange.</p>

<p> According to the present invention, since the artificial knuckle is a quasi-restraint type drum joint, the component of the artificial knuckle performs a rotation motion and a displacement motion orthogonal to the rotation motion, and vector motions of both motions are also added to the component. , The movement that is close to the original movement of the finger can be reproduced. Further, in the artificial knuckle of the present invention, each stem and bulge are separately inserted into the medullary cavity to fix each knuckle in the medullary cavity, and the pivot of the head member is used as the hinge part of the socket member. Since it is a semi-restraint type that allows loose fitting, it is easy to attach the artificial knuckle to the affected part of the knuckle, and there is a risk that the knuckle member will come off or shift from the socket member after surgery and the artificial knuckle will re-deform. Nor. Furthermore, the artificial knuckle of the present invention can be applied to any part of the knuckle other than the thumb.</p>

Hereinafter, the present invention will be described in detail with reference to the drawings. In FIGS. 5 and 6, reference numeral 1 is a socket member of the artificial knuckle, and 2 is a head member. The socket member 1 is made of a plastic material, and the head member 2 is made of a metal or alloy material. For these materials, it is necessary to use a living body buried material that is harmless to the human body. Typical plastics include ultra-high molecular weight polyethylene, and metal or alloys include metallic titanium and cobalt-chromium alloys (Co-Cr-Mo), which are excellent in strength. The socket member 1 is composed of an integrally connected hinge portion 3, a first bulging portion 4, and an annular first stem 5. The hinge portion 3 is composed of a hollow cylindrical body 6 whose both end faces are closed by a wall body 6a. A first opening 7 is formed in the longitudinal direction of the hollow cylinder 6 adjacent to the first bulge 4 along the width direction thereof, and a second opening 7 is formed in the circumferential direction of the central portion in the longitudinal direction of the cylinder 6. An opening 8 is formed. The first opening 7 is formed over almost the entire length in the longitudinal direction of the cylindrical body 6 except for the wall body 6a. The second opening 8 extends from the central portion of the opening 7 in the longitudinal direction to the vicinity of the edge of the first bulge 4 opposite to the opening 7. The hollow cylinder 6 of the hinge portion 3 may be replaced with, for example, a polygonal cylinder having a quadrangular cross section or more. The head member 2 is composed of an integrally connected pivot 9, an annular connecting portion 10, a second bulging portion 11, and an annular second stem 12, and is rotatably attached to the socket member 1. Regarding the connecting portion 10, the length from the central axis of the pivot 9 to the end face on the pivot 9 side of the bulging portion 11 is slightly longer than the radius of the hollow cylinder 6.

A concave pivot bearing portion 13 larger than the diameter of both ends of the pivot 9 is recessed in the center of the inner surface of the wall body 6a that closes both end faces of the hollow cylindrical body 6, and is formed from both ends of the first opening 7. Guide grooves 14 for guiding both end faces of the pivot 9 are engraved on the inner surface of the wall body 6a in each bearing portion 13. Each bearing portion 13 and the guide groove 14 are formed as one continuous groove. Further, both ends of the pivot 9 have a tapered shape in which the end faces thereof are reduced in diameter, and the opening surface of the first opening 7 is slightly shorter than the length of the pivot 9 in the longitudinal direction of the first opening 7. It has almost the same shape as the cross section of the pivot 9 in the axial direction. Then, one end of the pivot 9 was first inserted into the hollow cylinder 6 from one end of the first opening 7, and then the other end of the pivot 9 was inserted into the cylinder 6 from the other end of the opening 7. After that, by locking both ends of the pivot 9 to the bearing portion 13 of the cylindrical body 6 in a loosely fitted state, the pivot 9 of the head member 2 can be detachably loosely fitted to the hinge portion 3 of the socket member 1. .. When the head member 2 is attached to the socket member 1 via the pivot 9, the head member 2 is rotatable along a second opening 8 formed in the hollow cylinder 6. As described above, the second opening 8 is formed in the circumferential direction of the cylindrical body 6, and the angle of the opening 8 with respect to the central axis of the cylindrical body 6 is in the range of 90 to 240 °. However, this angle may be secured at 90 ° or more, and is not particularly limited.

The first bulging portion 4 has a pyramid shape having a rectangular cross section on the side of the first stem 5. The lateral dimension of the bulge 4 on the hollow cylindrical body 6 side is shorter than the diameter of the cylindrical body 6, and the lateral dimension on the first stem 5 side is substantially the same length as the diameter of the first stem 5. The bulge 4 may be hollow or solid, and the annular first stem 5 may also be hollow or solid. Further, the bulging portion 4 may have a cylindrical shape or a cylindrical shape whose diameter is reduced toward the first stem 5. The diameter of the connecting portion 10 is shorter than the width of the second opening 8, and the connecting portion 10 has a slight degree of freedom corresponding to the pivot 9 loosely fitted in the bearing portion 13. The second bulge 11 has a similar shape slightly smaller than the first bulge 4. The bulging portion 11 may be hollow or solid. The surface of the bulging portion 11 excluding the end faces on the connecting portion 10 side and the second stem 12 side is subjected to a fine roughening treatment such as sandblasting so as to be familiar to the human body. Of course, it is not always necessary to perform the roughening treatment. Further, the second stem 12 having an annular cross section has a smaller diameter than the first stem 5, and may be hollow or solid. The first bulging portion 4 and the first stem 5 of the socket member 1 and the connecting portion 10, the second bulging portion 11 and the second stem 12 of the femoral head member 2 are orthogonal to the axial direction of the hollow cylindrical body 6. And each is substantially aligned coaxially.

For the knuckle, the first bulge 4 and the first stem 5 are inserted into the proximal medullary cavity, and the second bulge 11 and the second stem 12 are inserted into the distal medullary cavity. .. The first bulge 4 and the second bulge 11, which have a large cross-sectional area on the knuckle side, push the socket member 1 and the head member 2 into the medullary cavity, respectively, to push the knuckles such as the proximal phalanx. It is pressure-welded and fixed in the medullary cavity of the bone. At this time, the entire bulges 4 and 11 may be inserted into the medullary cavity, or a part of the large cross-sectional area thereof may be exposed from the knuckle bone, but the artificial knuckle joint may be inserted from the knuckle bone. The former is preferable because there is no risk of it being attached or detached. Here, with respect to the knuckle, the socket member 1 can be arranged on the distal side and the head member 2 can be arranged on the proximal side. In that case, it is preferable that the second bulging portion 11 has a similar shape larger than that of the first bulging portion 4, and the second stem 12 has a larger diameter than the first stem 5. The artificial knuckle of the present invention is formed by cutting the first stem 5 and the second stem 12 to adjust the length according to the size of the knuckle adjacent to the knuckle of the affected area to which the knuckle is applied. It can be applied to any part of the knuckle other than the thumb.

Next, an example of a procedure for inserting the artificial knuckle of the present invention into the knuckle of a patient suffering from joint disorders such as rheumatoid arthritis and osteoarthritis will be briefly described. First, an incision is made in the affected knuckle, leaving the ligaments and removing the proximal phalanx adjacent to the joint. Depending on the symptoms, the distal phalanx may also be removed. Next, with the first opening 7 on the volar side, the socket member 1 is pushed in to insert the first bulge 4 and the first stem 5 into the medullary cavity on the proximal side, and the head member 2 is pushed in to the second bulge. The exit 11 and the second stem 12 are inserted into the distal bone marrow cavity. When the entire first bulge 4 and the second bulge 11 are inserted into the bone marrow cavity and fixed, the pivot 9 is inserted into the hollow cylinder 6 of the hinge 3 and into the bearing 13. Free fit and lock. As a result, the head member 2 is restrained by the socket member 1 and does not detach from the socket member 1. After that, if the muscles around the affected area are sutured, the artificial knuckle implantation surgery is completed. As described above, the artificial knuckle of the present invention has an advantage that it is easy to attach to the affected part of the knuckle as compared with the conventional one.

In the artificial knuckles shown in FIGS. 5 and 6, both ends of the pivot 9 are loosely fitted to the bearing portion 13 of the hollow cylindrical body 6, and the central portion of the cylindrical body 6 in the longitudinal direction with respect to the connecting portion 10 of the head member 2. The second opening 8 formed in the circumferential direction of is provided with some play. That is, since the artificial knuckle is a semi-restraint type, not only the head member 2 can rotate about the pivot 9 along the second opening 8, but also as shown in FIG. 7 (A), A motion of slightly swinging to the left and right with respect to the central axis of the head member 2 is also added to the head member 2. The swinging motion is restricted to the width of the second opening 8. Specifically, the range of the swing operation is restricted by the connecting portions 10 coming into contact with both side edges of the opening 8. Therefore, the swing range of the head member 2 can be adjusted by adjusting the width of the opening 8 and the diameter of the connecting portion 10, the diameters of both ends of the pivot 9 and the diameter of the concave bearing portion 13 as necessary. It is possible. This swing range is 5 ± 1 ° (θ) to the left and right with respect to the central axis of the head member 2.₁= 10 ± 2 °) is preferable. Further, the angle θ of the second opening 8 with respect to the central axis of the hollow cylinder 6.₂Is in the range of 90 to 240 °, and ligaments that suppress joint movement are left on both sides of the finger bone after surgery, so the rotation range of the head member 2 around the pivot 9 is shown in Fig. 7 (B). ), It is suppressed to about 90 °, which is the same as normal joint movement. In the above description, it is assumed that the socket member 1 is in a fixed state. However, assuming that the head member 2 is in a fixed state, the socket member 1 conversely performs the above movements, and the swinging and rotating movements of the head member 2 and the socket member 1 are relative to each other. Relationship. In this way, since the femoral head member 2 is drum-joined to the socket member 1 in a semi-restrained state, the femoral head member 2 or the socket member 1 has a rotational movement centered on the pivot 9 and the center of both members 1 and 2. In addition to the left and right swinging motions with respect to the axis, the vector motions of both motions are also added. Therefore, not only can the finger bend and stretch around the pivot 9, but it is also possible to perform a swinging motion, so that a motion similar to the movement of the finger of a living body is possible.

The artificial knuckle of the present invention can be used for chronic rheumatoid arthritis, osteoarthritis, and other knuckles by mounting a socket member and a head member in the bone marrow cavity of a knuckle adjacent to a joint with a disability other than the thumb. It can be used to treat patients suffering from knuckle disorders such as deformity.

<figref num="1">(A) is an exploded perspective view of a conventional artificial knuckle, and (B) is a perspective view of its head component and socket component.</figref><figref num="2">(A) is a perspective view of another conventional artificial knuckle, and (B) and (C) are front views and side views of the head component and the socket component thereof.</figref><figref num="3">(A) is a perspective view of a component in another conventional artificial knuckle, and (B) is a plan view and a side view thereof. Further, (C) is a plan view and a side view of the artificial knuckle of a portion different from that shown in (B).</figref><figref num="4">(A) is a perspective view of yet another conventional artificial knuckle, and (B) is a side view and a plan view of the hinge portion closed.</figref><figref num="5">It is an exploded perspective view which shows one Example of the artificial knuckle of this invention.</figref><figref num="6">(A) is a plan view of the artificial knuckle in a state where the head member and the socket member shown in FIG. 5 are combined, and (B) is a side view thereof.</figref><figref num="7">(A) is a plan view explaining the operation of the artificial knuckle of the present invention, and (B) is a side view thereof.</figref>

Code description

1 ... Socket member, 2 ... Bone head member, 3 ... Hinge part, 4 ... First bulging part, 5 ... First stem, 6 ... Hollow cylinder, 6a ... Wall body, 7 1st opening, 8 2nd opening, 9 Pivot, 10 Connecting part, 11 2nd bulging part, 12 No. Two stems, 13 ... pivot bearings, 14 ... guide grooves.