JPS6134820B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a resurfacing elbow joint device for replacing an elbow joint.

Traditionally, metal hinge-type elbow joint devices have been used for many years to replace arthritic or injured elbow joints, but over time they tend to loosen or loosen.
Many complications occur due to wear of the hinge, and it is difficult to say that good treatment is being provided.
In addition, in recent years, attempts have been made to create partially joined or resurfaced elbow joints to improve the drawbacks of the hinge type, but bone cement is generally used to fix the prosthesis to the bone, and It is also a cause of looseness. Therefore, further improvements are desired in many respects, such as achieving normal flexion and extension movements of the formed joint, preventing the occurrence of loosening over time, and maintaining joint stability over a long period of time. There is.

The present invention was developed in view of the above circumstances, and provides sufficient initial fixation from the beginning of replacement without using bone cement fixation.
The objective is to provide an elbow joint device that has stable fixation over a long period of time and allows normal flexion and extension movements of the joint.

Hereinafter, one embodiment of the present invention will be specifically described with reference to the drawings.

In Figures 1a and b, 1 is a humeral bone member, 2
3 is a first protrusion of the humeral component 1; 3 is a second protrusion longer than the first protrusion; these first and second protrusions 2, 3 are connected by a curved surface 4.5. There is.
This second protrusion 3 has a notch 6 formed therein. Further, the curved surface 4 constitutes a recess 7 for accommodating the capitellum of the humerus, and the curved surface 5 is a convex curved surface in the section taken along the line A-A' at the articular joint of the humeral component.
- It has a concave curved surface in the cross section along the line B', and forms a sliding surface with the ulnar component. The opposing planes of the inner walls 2' and 3' of the first protrusion 2 and the second protrusion 3 are formed by partially resecting the trochlear part of the humeral capitellus and applying bone cement to the recess 7 of the humeral component. It is desirable that the parts be parallel to each other in order to directly and accurately fit the parts without using a crown, and to obtain stable fixation from the beginning of the crowning of the parts. In addition, the notch 6 of the humeral bone member 1 allows the ulnar head to be moved in the extended position of the joint.
A space that can be accommodated in the olecranon fossa of the humerus is secured, allowing for a large range of joint motion. Further, in FIG. 2, the other member of the elbow joint device is shown, 8 is an ulnar member, and 9 is a curved surface forming an articulation part, which articulates in a complementary manner with the curved surface part 5 of the humeral member 1. . The cross-sectional shape of the curved surface 9 is concave in the CC' cross section, and convex in the D-D' cross section as shown in FIG. 2C. Further, on the outer side of the ulnar component, there is a peg portion 11 for inserting and fixing the ulnar component into the ulnar canal.

Incidentally, the material constituting the peg part 11 of the humerus component and ulna part is preferably made of biocompatible metal or ceramic, but bone cement may be used for bone growth or regeneration. It is most preferable that the material is made of ceramics that have good biocompatibility in that good fixation can be obtained over a long period of time without causing any problems. Here, biocompatible ceramics include, for example, oxide ceramics such as aluminum oxide (alumina), or
This means calcium phosphate ceramics or glass, and the fact that it is composed of the biocompatible ceramics of the present invention means that it is composed only of such ceramics, or that it is composed of other materials such as titanium or stainless steel as a base material. Among the surfaces of metal members, at least the surface that comes into contact with bone when attached or fitted is coated with ceramics that have biocompatibility. When these members are composed of ceramic units, it is preferable to use high-purity alumina ceramics, which have excellent mechanical strength and wear resistance, and are physically and chemically stable in vivo.

Furthermore, the material constituting the sliding portion of the ulnar member that articulates is preferably a biocompatible plastic material, particularly high-density polyethylene, which has a low coefficient of wear and a small amount of wear. The sliding member of the ulnar member and the peck portion 11 may be connected by conventional screwing or fitting.

Next, as a procedure for installing the elbow joint device according to the present invention as described above, if the procedure is as described below, it will be properly inserted, firm initial fixation will be obtained, and long-term stable fixation will be achieved. Ru. In other words, the resection of the femoral bone is performed in the usual way from the posterolateral side, after which the radial head is removed from the neck, and the olecranon is then separated. Next, leave several mm, preferably 2 mm or more, from the humeral trochlear part to the inside of the humeral capitellum to a thickness that is sufficient to accommodate the humeral member in the recess 7 with the width of the humeral member of the elbow joint device. After removing the bone, the anterior and posterior surfaces are removed along the bone axis, and the articular surface is also trimmed to match the bone receiving area. After the bone removal, the humeral component is attached with the second protrusion on the rear side. Also,
In bone resection on the ulnar side, after removing the osteophyte of the coronoid process, a hole is dug in which the peg portion 11 of the ulnar component can be inserted, leaving the flexural bone cortex of the ulnar articular surface. After the bone is resected as described above, the ulnar component of the present invention is well inserted and installed, and then the olecranon that was previously separated is fastened.

By performing bone resection in the manner described above, it is possible to properly attach the elbow joint device without using bone cement, and to maintain sufficient initial fixation and good maintenance over a long period of time. Note that FIG. 4 shows a combination of the humeral component 1 and the ulnar component 8 in an articulated state, and FIG. 5 shows an outline of both ends of the range of motion, that is, during extension and flexion.

One of the embodiments of the elbow joint device of the present invention as described above is such that a saddle-shaped humeral member disposed on the trochlea of the capitellum of the humerus articulates with the humeral member disposed on the olecranon of the ulna. In an elbow joint device comprising an ulnar member having a sliding surface, the humeral member has a first protrusion and a second protrusion longer than the first protrusion,
The outer surfaces of the first and second protrusions are connected to each other by a curved surface, and the second protrusion has a notch at approximately the center thereof.

In addition, when a resurfacing joint component is installed without using bone cement, sufficient initial fixation can be obtained, and in order to maintain a good long-term attachment condition, it is necessary to minimize the contact area with the bone. It is necessary to take only a large amount. In order to increase the contact area and to sufficiently increase the range of motion of elbow extension and flexion after elbow joint device replacement, the humeral component is located on the anterior aspect of the humerus due to the anatomical structure of the elbow. The length of the first protrusion is 1 to 5 mm, preferably 2 to 4 mm, and the length of the second protrusion located on the rear side is 5 to 20 mm, preferably 7 to 15 mm, and the second protrusion It is necessary that there is a notch approximately in the center of the projection with a width of 5 to 15 mm and a length of 4 to 20 mm (but shorter than the length of the protrusion). Here, the opposing planes of the inner walls of the first protrusion and the second protrusion allow accurate bone resection of the trochlear part of the capitellum of the humerus and stabilize the humeral component from the initial stage of crown attachment without using bone cement. It is desirable that they be parallel to each other in order to obtain good fixation. In addition, the inner wall surface of the recess at the connecting portion between the first protrusion and the second protrusion has a radius of 3 to 7 mm in order to minimize the amount of bone resection of the articular surface of the trochlear part of the capitellum.
mm, preferably 4 to 6 mm, preferably in the form of a semi-cylindrical surface. Further, the outer surface of the connecting portion has a sliding surface for articulation, and is saddle-shaped for smooth and stable movement during extension and bending movements. That is, as mentioned above, A-- in the approximate center of the joint sliding surface in Fig. 1a.
A' cross section, convex curved surface, preferably radius 5-14
mm, preferably 7 to 11 mm, is a part of a circular arc, more preferably a semicircle, and the outer edge of the joint sliding portion has a curved surface with a larger curvature than the above-mentioned curvature. At the outer edge of the joint sliding part, there is an outer wall 5' for preventing the ulnar member from falling off, and its width is 0.5 to 10 mm, preferably 1 to 8 mm. Therefore, the cross section taken along the line BB' in FIG. 1b has a concave curve, and there is a protrusion on the outer side of the curve to prevent it from falling off.

In addition, other special skills are placed on the olecranon of the ulna,
The ulnar component having a sliding surface that articulates with the humeral component has a peg portion 11 that fits into the ulnar canal. With this peg part, sufficient initial fixation and long-term stable maintenance can be achieved.

Further, the sliding surface of the ulnar component that is articulated has a curved surface that is complementary to the joint sliding surface of the humeral component, and is a convex curved surface in cross section aC-C' in FIG. 2.

Furthermore, the relationship between the sliding surface 5 of the humeral component 1 and the sliding surface 9 of the ulnar component 8, which form the elbow joint joint, is as follows:
As shown in Figure 3, by making contact between the two at the center of the sliding part and by providing a gap of about 0.3 to 2 mm at the outer edge due to the difference in circumferential diameter, this creates play in the inward and outward directions and prevents the sliding part from forming. This is desirable because it provides good lubrication. Yet another feature is that the peg portions of the humeral and ulnar components that contact the bone are comprised of biocompatible ceramics. As a result, sufficient initial fixation and long-term crown attachment can be maintained without using bone cement. Here, the surface of each component that comes into contact with the bone should be roughened or a porous layer formed in order to ensure sufficient contact with the bone due to bone growth or regeneration and to obtain a good fixation state. .
In addition, in order to obtain low wear resistance, the surface roughness of the sliding surface of the humeral bone component that joins the joint is set to Rmax.
It is desirable to have a surface smoothness of 0.8μ or less, more preferably 0.1μ or less.

As an effect of using the elbow joint device of the present invention, the first protrusion of the humeral bone member and the second protrusion part that is longer than the first protrusion part are provided together, thereby physically fixing the humeral bone member to the bone. Significantly enhanced, stable and supportive joints are obtained. Further, during extension, the head of the ulnar side joint enters the notch provided in the second protrusion, making it possible to fully extend the elbow joint, while at the same time reliably preventing hyperextension.

Furthermore, by making the pegs of the humeral and ulnar components with biocompatible ceramics, attachment of new bone is promoted, and a strong bond with the bone can be achieved over a long period of time without the use of bone cement. Ru. As a result, we have obtained an elbow joint device that requires as little bone removal as possible, has a joint morphology that is close to physiological, and is easy to operate, and is also effective in clinical pain relief, muscle recovery, and functionality in daily life. The improvement was also very good, and the prosthetic device would be of great benefit to social welfare as an effective prosthetic device for elbow arthroplasty for rheumatoid arthritis.

[Brief explanation of the drawing]

FIG. 1a is a front view of a humeral component according to the present invention, FIG. 1b is a side view thereof, FIG. 2a is a front view of an ulnar component according to the present invention, FIG. 2b is a side view thereof, and FIG. Figure c is a cross-sectional view taken along line D-D' in Figure 2b, Figure 3 is a cross-sectional view perpendicular to the sliding direction of the sliding part between the humeral component and the ulnar component, and Figure 4 is a perspective view showing the assembled state. FIG. 5 is a schematic diagram showing the driving movement when the device is attached to a living body. 1... humerus member, 2... first protrusion, 3...
Second protrusion, 5... Sliding curved surface of humeral bone member, 6...
... Notch portion, 8... Ulna member, 9... Sliding curved surface of ulna member, 11... Peg portion.

Claims (1)

[Scope of Claims] 1. A saddle-shaped humeral component disposed on the trochlea of the capitellum of the humerus, and an ulna having a sliding surface disposed on the olecranon of the ulna and articulated with the humeral component. In the elbow joint device, the humeral bone member has a first protrusion and a second protrusion that is longer than the first protrusion, and the humeral bone member has a first protrusion and a second protrusion that is longer than the first protrusion. An elbow joint device characterized in that the outer surface is curved and the second protrusion has a notch at approximately the center thereof. 2. The elbow joint device according to claim 1, wherein the humeral bone member is made of biocompatible ceramics. 3. An elbow consisting of a saddle-shaped humeral component disposed on the trochlear part of the capitellum of the humerus, and an ulnar component disposed on the olecranon of the ulna and having a sliding surface that articulates with the humeral component. An elbow joint device, wherein the ulnar member has a peg portion that fits into the ulnar cavity. 4. A patent claim in which the portion of the ulnar component that constitutes the sliding surface that articulates with the humeral component is made of biocompatible plastic material, and the peg portion that fits into the ulnar cavity is made of biocompatible ceramics. The elbow joint device according to scope 3.