JP3103639B2 - Artificial knuckle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an artificial finger joint for replacing a finger joint whose joint function has been reduced due to deformation and destruction due to chronic rheumatism, trauma or the like, and restoring the original joint function.

[0002]

2. Description of the Related Art Conventionally, arthrodesis and arthroplasty have been generally performed on deformed and destroyed finger joints.
However, in recent years, artificial finger joint replacement has been performed for the purpose of removing pain, improving the range of motion, and correcting deformation.

[0003] The artificial finger joint used in this replacement surgery includes:
U.S. Pat. No. 4,367,562 discloses a silicon artificial finger joint in which a stem and a main body are integrated into a medullary canal of a bone forming a joint without a sliding portion; Two members having a stem for insertion into the medullary canal of the bone to be bent comprise a hinged prosthesis that flexes and extends with a hinge; and a knuckle as disclosed in US Pat. No. 4,367,562. There has been a ball / socket type artificial finger joint in which a ball provided on one of two members having a stem inserted into a medullary cavity of a bone slides in a socket provided on the other.

[0004]

2. Description of the Related Art In addition to rocking in the bending and extension directions, a natural finger joint rocks slightly in the inner and outer directions. Among the above artificial finger joints, the hinge type artificial finger joint cannot swing inward and outward due to its structure. On the other hand, the ball / socket type artificial finger joint has a large range of motion in both the bending and extension directions; the inside and outside directions, but has a swing range that is more than necessary, which may hinder the reproduction of the original finger joint, Was dislocated from the socket. Further, the artificial finger joint made of silicon has an almost unlimited range of motion, and there is no possibility of dislocation, but there is a problem that silicon deteriorates after several years in the body.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a ball portion and a distal end member having a concave portion or a convex portion in a circumferential direction of the ball portion; It is an object of the present invention to provide an artificial finger joint comprising a sliding surface that slides and a proximal end member provided with a socket having a ridge or a concave groove combined with the concave portion or the convex portion on the sliding surface.

[0006]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of the present invention; FIG. 1 is an exploded perspective view showing an artificial finger joint 1 according to the present invention. Numeral 2 denotes a distal end member made of a titanium alloy, which has a spherical ball portion 2a and a circumferential direction of the ball portion 2a. Is provided with a convex portion 2b having a rectangular cross section over substantially the entire circumference, and a rod-shaped stem portion 2c for insertion into a bone. Reference numeral 3 denotes a proximal end side member, which is a substantially hemisphere made of polyethylene and overhanging its outer shape. Socket part 3
and a stem part 3b made of a titanium alloy which is fixed by an adhesive in a fixing hole (not shown) formed by drilling the socket part 3a and the vicinity of the pole thereof and inserted into a bone, and Reference numeral 4 denotes a sheath member made of a titanium alloy or ceramic, and a stem portion 3b of the proximal end side member 3.
Has an insertion hole 4a for inserting the inside.

As the distal end side member 2, a ceramic material such as alumina or zirconia which is excellent in sliding characteristics in addition to titanium alloy, or a metal material such as pure titanium or cobalt chromium alloy which is excellent in affinity with a living body, stainless steel or the like is used. And these materials may be used in combination.
The stem portion 2c may have a polygonal column shape and be further tapered for stable fixation to the bone.

FIG. 2 is a perspective view showing another embodiment of the distal end side member 2 constituting the artificial finger joint 1, and FIG. 3 is a sectional view taken along the line AA of FIG. 2, showing a ball portion 2a made of alumina ceramic. A ring made of polyethylene press-fitted into a groove 2d provided over the entire circumference except for the joint portion between the stem portion 2c and the ball portion 2a in the circumferential direction of the center and having a notch corresponding to the joint portion is press-fitted. FIG. By doing so, it is possible to prevent the risk of breakage of the artificial finger joint 1 due to the contact between the projection 0b and the wall surface of the concave groove 3f formed in the socket 3a of the proximal end side member 3.

The stem portion 2c is fixed to the distal bone using bone cement, or the outer surface is coated with hydroxyapatite or the like to form a porous bone-growth-inducing coating layer (not shown). To fix it in the medullary cavity.

The inside 3 of the socket 3a of the proximal end member 3
c has a dome-shaped sliding surface 3d and the ball portion 2a
A concave groove 3f having a cross section larger than the convex portion 2b and a substantially rectangular cross section is provided near the center of the sliding surface 3d.

The socket 3a is made of polyethylene,
It is preferable that the socket portion 3 is made of a ceramic material such as alumina or zirconia excellent in sliding characteristics, or a metal material excellent in compatibility with living bodies, such as titanium alloy, pure titanium or cobalt chromium alloy, or stainless steel.
When the outer surface of a is made porous by, for example, forming a porous bone growth inducing coating layer (not shown) by coating, for example, hydroxyapatite or the like, the fixing force to the bone is enhanced. Note that the above materials may be used in combination.

The stem portion 3b may be made of a ceramic material such as alumina or zirconia having excellent sliding characteristics, or a titanium alloy having excellent affinity with a living body, pure titanium or cobalt chromium alloy, stainless steel, or the like, in addition to a titanium alloy. It is preferably made of a metal material, and its outer surface is desirably smooth.

The sheath member 4 has an insertion hole 4a for inserting the stem 3b of the proximal end member 3. The stem portion 3b of the proximal end member 3 is inserted into the medullary cavity through the sheath-shaped member 4.
When the extension is performed, a force is applied to the proximal end side member 3 to pull it out of the medullary cavity, and this force is absorbed by the stem portion 3b sliding in the insertion hole 4a of the sheath-like member 4. It is. The sheath member 4 is fixed to the bone by applying bone cement to the outer surface or by forming a porous layer of apatite or the like to form an osteogenesis-inducing coating layer (not shown). As described above, since the stem portion 3b is inserted so as to slide in the insertion hole 4a of the sheath-shaped member 4, the proximal end member 3 absorbs the above-mentioned force, and thus is inserted into the medullary cavity of the sheath-shaped member 4. Early fixation is realized.

The operation of the artificial finger joint having the above configuration will be described below. FIG. 4 is a partially cutaway view showing the artificial finger joint 1 of the present invention. Since the concave groove 3f is larger than the convex portion 2b as shown in this figure, the distal end member 2 is the proximal end member 3 Swings inward and outward directions by θ ° = 5 to 60 °.
Incidentally, the width w ₂ of the convex portion 2b, the height h ₂ are each from 1 to 10
mm, 0.2 to 3.0 mm, also the width w ₃ of the recess _3f, depth h ₃ respectively 1.5~12mm, 0.5~5.0
mm. The movable angle of the original finger joint in the medial and lateral directions is 5 ° to 60 °, and therefore, w ₂ / w ₃ = 1.
It is preferably from 1 to 2.4.

In the direction of bending and extension, a conventional ball
It has a large movable range like a socket type artificial finger joint and a hinge type artificial finger joint, and has the above-mentioned convex portion 2b and concave groove 3f.
As a result, there is no fear of dislocation because the swing is controlled only in the movable range in the inner and outer directions like the original finger joint.

FIG. 5 is a partial cross-sectional top view showing the artificial finger joint 1 in which the interphalangeal joint of the index finger of the right hand is replaced. The distal end member 2 is connected to the medullary cavity T _{2 of} the second middle phalanx T _1. And fix it with bone cement C, and attach the proximal end member 3 to the second
It has been inserted to the insertion hole 4a of Sayajo member 4 and fixed with bone cement C is inserted into the medullary cavity L ₂ of the proximal phalanx L ₁ in the medullary cavity L ₁ so as to be slidable. Since the artificial finger joint 1 is made of a material that can withstand long-term use in a living body, it does not deteriorate in a short period of time unlike a conventional silicon artificial finger joint.

The convex portion 2b may have a rounded corner as shown in FIG. 6 or may have a semicircular cross section. In this case, the convex portion 2b and the concave groove 3f are formed. The risk of damage to the artificial finger joint 1 due to the contact of the wall surface can be prevented.

FIG. 7 is a partially cutaway view showing another embodiment of the artificial finger joint 1 according to the present invention, and shows a ball portion 2a of the distal end member 2.
In the circumferential direction, a concave portion 2e having a rectangular cross section over the entire circumference excluding the joint portion with the stem portion 2c instead of the convex portion 2b, and the concave groove 3f inside the proximal end member 3. Instead, a ridge 3g having a smaller cross section than the recess 2e is provided.

The function of the ridges 3g and the recesses 2e is exactly the same as that of the protrusions 2b and the grooves 3f, and the choice of which one to use is left to the discretion of the practitioner.

As shown in FIG. 8, the sheath member 4 has the same outer shape and outer dimensions but has a different thickness of the main body 4b, or has a different wall angle of the insertion hole 4a. By doing so, the distance l from the rear end of the sheath-shaped member 4 to the distal end of the stem member 2c of the distal end side member 2 can be adjusted, so that the installation position of the artificial finger joint 1 itself can be adjusted. . Therefore, the main body 4
When a plurality of b having different thicknesses are prepared in advance, by selecting an optimal sheath-like member 4 for setting the artificial finger joint 1 at a correct position, it is possible to perform fine adjustment while applying trial sampling. It is not necessary to perform bone resection, and artificial knuckle 1
Therefore, it is not necessary to prepare various sizes, and it is possible to secure the replacement operation by shortening the operation time and to install the optimal artificial finger joint 1. The sheath member 4
When not using, the stem portion 3b of the proximal end side member 3 is fixed in the medullary cavity using bone cement, or the surface of the stem portion 3b is made porous by a method such as coting, and the inside of the pore is It is fixed in the medullary cavity by the growth and production of living bone.

The convex portion 2b or the concave portion 2e of the distal end side member 2 does not necessarily need to be located in the center circumferential direction of the ball portion 2a, and like the two convex portions 2b, 2b shown in FIG. The position may be shifted from the center circumferential direction, or only one of them may be provided.

[0022]

According to the present invention, an artificial finger joint implant which can reproduce the movable range of the original finger joint in the inward and outward directions and does not cause dislocation or short-term deterioration in a living body can be achieved. Is possible.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing an artificial finger joint of the present invention.

FIG. 2 is an exploded perspective view showing an artificial finger joint including a distal end member according to another embodiment.

FIG. 3 is a sectional view taken along line AA of FIG. 2;

FIG. 4 is a partially cutaway view showing the artificial finger joint of the present invention.

FIG. 5 is a partially cutaway view showing the artificial finger joint of the present invention.

FIG. 6 is a partially cutaway view showing an artificial finger joint including a distal end member according to another embodiment.

FIG. 7 is a partially cutaway view showing another embodiment of the artificial finger joint of the present invention.

FIG. 8 is a partially cutaway view showing a state of setting an artificial finger joint using a sheath-shaped member having a different thickness of a main body.

FIG. 9 is a partially cutaway view showing another embodiment of the artificial finger joint of the present invention.

[Explanation of symbols]

 Reference Signs List 1 artificial finger joint 2 distal end member 3 proximal end member 4 sheath member 2a ball part 2b convex part 2e concave part 3a socket part 3f concave groove 3g convex ridge θ taper angle

Claims (1)

(57) [Claims] 1. A ball portion, a distal end side member having a concave portion or a convex portion in a circumferential direction of the ball portion, a sliding surface in which the ball portion slides, and a concave or convex portion formed on the sliding surface. A prosthetic finger joint comprising: a convex portion and a proximal end member having a socket portion having a convex ridge or a concave groove combined with the convex portion.