JPH08651A - Artificial bone capital - Google Patents

Abstract

PURPOSE:To simply fix an inner ball holding member to an outer ball without requiring a snap ring in the artificial bone capital to hold an inner ball inside of the outer ball by an annular inner ball holding member so as to be capable of swinging. CONSTITUTION:A recessed part 7 is peripherally arranged on an inner peripheral surface 6 of a diametrically expansive part of an outer ball 2. In a cross section in the radial direction of the annular shape, an inner ball holding member 8 is formed in a bag shape having an outside annular part 12 and an inside annular part 13 through a bottom part 11, and a projecting part 14 formed so as to be lockable in the recessed part 7 is arranged outside of the outside annular part 12, and the outside annular part 12 is formed so as to be elastically deformable in a diametrically contracted shape, and when the inner ball holding member 8 is pushed in so that the projecting part 14 is locked in the recessed part 7 of the outer ball 2, it can be fixed to the outer ball 2 by the inner ball holding member 8 itself.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a human femoral head when the head is damaged due to fracture or osteoarthritis of the hip.
Regarding an artificial head (hereinafter, also simply referred to as “head”) that is replaced as a substitute, in more detail, a double-structured head with an inner sphere embedded inside the outer sphere that is a bowl-shaped hemispherical body Regarding

[0002]

2. Description of the Related Art A conventional artificial head of this type is shown in FIG.
A structure shown in FIG. 6 is known. This head 81
Incorporates the inner sphere 83 inside the outer sphere 82, and forms an annular shape so that the inner sphere 83 is swingably held (supported) on the inner peripheral surface (expanded portion) 84 near the open end thereof. The formed inner ball holding member 85 is set (fitted), and a snap ring 87 for a hole is fitted into a recess (annular groove) 86 provided along the lower surface of the inner ball holding member 85, Inner sphere holding member 8
5 is attached to the outer sphere 82. In this structure, the inner sphere 83 is configured to be swingably held by the spherical inner surface 85a of the inner sphere holding member 85. In the head of the figure, a large number of rolling balls (balls) 88, 88 are inserted in an annular cage 89 in the middle of the inner and outer spheres, and the inner sphere 83 with respect to the outer sphere 82.
The smoothing of the swing of the.

[0003]

[Problems to be Solved by the Invention] The above-mentioned conventional artificial head 8
The inner sphere holding member 85 in 1 has no fixing means for the outer sphere itself, and the fixing is by the snap ring 87. Therefore, when assembling the artificial head, the inner sphere 83 with the stem S is inserted inside the outer sphere 82 via the rolling spheres 88, 88 and the retainer 89, and the inner sphere is formed on the inner peripheral surface 84. The snap ring 87 must be fitted into the recess 86 under the condition that the holding member 85 is set and the inner ball holding member 85 is pushed in to hold the state. Therefore, when attaching the inner sphere holding member 85, a step of setting the inner sphere holding member 85,
The step of fitting the snap ring 87 is required separately, and the step of fixing the inner ball holding member 85 is complicated. Further, it has been a problem that the parts management of the snap ring 87 is required in manufacturing the artificial head.

The present invention has been devised in view of the problems of the above-described conventional head, and provides an artificial head in which the number of parts is reduced and the inner ball holding member can be easily and quickly attached. The purpose is to

[0005]

In order to achieve the above object, the present invention has an inner sphere inside an outer sphere, and the inner sphere is provided on the inner peripheral surface near the open end of the outer sphere. In an artificial bone head to which an annular inner sphere holding member for swingably holding is attached, a recess is formed along the circumferential direction on the inner peripheral surface near the open end of the outer sphere. The inner sphere holding member is integrally provided with a convex portion that can be locked in the concave portion on the outer side in a circular cross section in the radial direction, and a portion including the convex portion is elastically deformable in a reduced diameter shape. The inner sphere holding member is attached to the inner peripheral surface of the outer sphere by locking the convex portion with the concave portion.

In this case, the inner sphere holding member is formed in a bag shape having an outer outer ring portion and an inner inner ring portion with a bottom portion in a cross section in the ring radial direction. A convex portion that can be locked in the concave portion is integrally provided on the outer side of the outer annular portion, and the outer annular portion is formed so as to be elastically deformable to a reduced diameter. It is preferable that the convex portion is attached to the inner peripheral surface of the outer sphere by locking the convex portion to the concave portion on the side closer to the opening end portion of the outer sphere or on the side opposite thereto. If the outer annular portion has cuts at intervals, the portion including the convex portion is easily elastically deformed in a diameter-reducing manner, which facilitates the assembling work.

[0007]

In the artificial bone head according to the present invention, since the inner ball holding member is attached to the outer ball by itself, no separate means such as a snap ring is required. Further, when assembling the inner sphere, the inner sphere is arranged inside the outer sphere, and the inner sphere holding member is provided on the inner peripheral surface of the outer sphere near the opening end, and the portion including the outer convex portion is reduced in diameter. When it is bent and deformed into a shape and pushed in, its convex portion expands and is locked at the portion of the outer sphere facing the concave portion. Thus, the inner sphere holding member can be easily and quickly attached to the outer sphere.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment in which the femoral head according to the present invention is embodied will be described in detail with reference to FIGS.

Example 1 In the figure, reference numeral 1 is an artificial bone head 1 of the present example, which is a bowl-shaped, hemispherical ceramic outer sphere 2 inside a substantially spherical ceramic sphere. Inner sphere 3 of the outer sphere 2 is incorporated, and the inner peripheral surface of the outer sphere 2 near the opening end 4 has a tapered step portion 5
To form a cylindrical expanded portion, and a semicircular concave portion (concave groove) 7 is circumferentially provided along the circumferential direction at the substantially center of the inner peripheral surface 6 of the expanded portion. There is. An annular inner sphere holding member 8 is attached to the inner peripheral surface 6 of the expanded diameter portion as described below, and holds the inner sphere 3 swingably. In this example, a large number of rolling balls 9 are incorporated and inserted in a swingable annular retainer 10 between the inner and outer balls 2 and 3.

The inner sphere holding member 8 is made of polyacetal resin in this example, and has a ring-shaped cross section in the radial direction, and an outer ring portion 12 on the outer side and an inner ring portion on the inner side via a bottom portion (upper part in the drawing) 11. Is formed in a bag shape (substantially inverted U-shape) including 13 and a protrusion 14 that can be locked in the recess 7 of the outer ball 2 is integrally provided around the outside of the outer annular portion 12. The outer annular portion 12 is formed so as to be elastically deformable in a radius (inner) direction in a radially contracted manner with the bottom portion 11 side as a base end.
However, the convex portion 14 is circumferentially provided around the center of the outer annular portion 12 along the circumferential direction in an arc shape substantially matching the cross section of the concave portion 7, and the inner sphere holding member 8 is arranged inside the outer sphere 2. When it is attached to the peripheral surface 6, the outer peripheral surface of the outer annular portion 12 is configured to be fitted and locked in the concave portion 7 of the outer ball 2. The surface 6 is formed so as to be slightly pressed by elasticity.

On the other hand, the upper inner peripheral surface 15 of the inner annular portion 13 of the inner sphere holding member 8 is formed in a spherical shape so as to swingably hold the lower outer periphery of the inner sphere 3. However, in this example, the inner peripheral surface 15 is formed so as to maintain a slight gap with the inner spherical surface when a compressive load is applied between the inner and outer spheres 2, 3. Further, in this example, between the inner sphere holding member 8 and the cage 10, a short tubular rubber tube 16 is provided as an elastic support means of the cage 10, and a concave step inside the upper surface of the inner sphere holding member 8 is provided. Part 17 and retainer 10 Reduced-diameter part 1 on the outer peripheral lower edge
0a, and the elasticity of the rubber tube 16 constantly urges the cage 10 and the rolling ball 9 toward the top of the outer ball 2. However, when the rubber tube 16 of this example is pushed by the retainer 10 and flexibly deforms into a buckling shape so as to have a V-shaped cross section, the intermediate portion of the inner peripheral surface thereof is cut into an arc shape so as to have a thin wall. It is formed to be flexible.

Then, inside the outer ball 2, the rolling ball 9,
Then, the cage 10 formed by attaching the rubber tube 16 to the reduced diameter portion 10a is inserted, the inner sphere 3 is inserted, and the inner sphere holding member 8 is placed on the inner peripheral surface 6 of the enlarged diameter portion of the outer sphere 2. If you press it too hard, as shown by the two-dot chain line cross section in FIG.
The circular arc portion, which is the outer peripheral surface of 4, hits the intersecting ridge between the inner peripheral surface 6 of the expanded diameter portion and the opening end portion 4, that is, the opening inner peripheral edge corner 6a, and is subjected to a wedge action, so that the front end side (lower side in the figure) of the outer annular portion 12 is mainly The convex portion 14 enters the inner peripheral surface 6 while being deformed in a diameter-reduced manner, is further pushed into the concave portion 7, elastically expands at that portion, and is locked as shown in FIG. As a result, the inner sphere holding member 8 is attached to the outer sphere 2, and the inner sphere 3 is held by the upper inner peripheral surface 15 thereof so as to be swingable. The step 5 is
It acts as a stopper when the inner ball holding member 8 is pushed in together with the recess 7.

With the above-mentioned structure, in this example, the outer sphere 2
The inner sphere holding member 8 on the inner peripheral surface 6 of the expanded diameter portion near the opening end 4 of the
The inner sphere 3 is attached to the outer sphere 2 so as to be swingable by pushing. At this time, in particular, in this example, the portion including the convex portion 14 (outer annular portion 12) is elastically deformed in a diameter-reduced manner in the process of pushing in the inner sphere holding member 8 without requiring a special device, so that only pushing in is required. Inner sphere holding member 8
Since it can be attached, not only is a snap ring unnecessary, but it is expected that the number of man-hours for assembling the bone head will be greatly reduced.
Further, in this example, when the human body (patient) is replaced (weared), the inner ball holding member 8 made of polyacetal is used in addition to the inner and outer balls.
Only the metal is exposed (contacted) to the body fluid side, so that metal ions are not eluted into the body by a conventional snap ring made of metal such as stainless steel. Therefore, the health of the patient is not impaired.

Further, when the snap ring is used, there is a gap (play) between the snap ring and the groove to be fitted therein, so that the snap ring moves in the width direction or the radial direction, or slips in the circumferential direction. On the other hand, the outer sphere is made of high-strength and high-hardness material such as ceramics, so the snap ring wears and metal abrasion powder is generated, which is mixed and absorbed in body fluids to improve patient health. However, in the case of this example, this problem is also solved. The material of the inner sphere holding member 8 may be any material as long as the portion including the convex portion 14 can be elastically deformed in a diameter-reduced manner and has human body compatibility and predetermined durability (corrosion resistance) and strength. , But is not limited to this example, but due to the problem of metal ion elution, it is made of metal (stainless steel, etc.)
It is better to use synthetic resin such as high-density polyethylene, Teflon, or nylon.

In the above embodiment, when the inner sphere holding member 8 is attached, the outer annular portion 12 is preliminarily outside the outer annular portion 12 by pressing the convex portion 14 against the inner peripheral edge corner 6a in the pushing process. The annular portion 12 may be pressed so that the diameter thereof is reduced so that the annular portion 12 is positively squeezed. In addition, the convex portion 14 is attached to the outer annular body 12
Although the entire circumference of the outer peripheral surface is provided, it may be provided at intervals if the attachment strength is expected to decrease. Further, in the present example, the step portion 5 positively acts as a positioning stopper, but such a step portion 5 may be omitted.

Incidentally, in order to enhance the attachment strength (retaining performance), an annular space R formed by the outer annular portion 12 and the inner annular portion 13 is appropriately filled with a ring or a ring. You may fill with a filler. By doing so, the diameter-reducing deformation in the radial direction cannot be performed correspondingly, so that the attachment strength is improved. It should be noted that, as the filler, a substance obtained by mixing powdery polymethylmethacrylate (PMMA) with a predetermined solvent to form a paste (semi-liquid) (also called bone cement) and solidifying it, Although preferable in terms of strength and human compatibility, a thermosetting resin such as an epoxy resin may be loaded and solidified.

Embodiment 2 Next, another embodiment of the present invention will be described with reference to FIGS.
Will be described with reference to. However, in this example, the concave portion 7 of the inner peripheral surface 6 of the expanded diameter portion of the outer sphere 2 and the inner sphere holding member 8 in the previous example are used.
The cross-sectional shape of the convex part of is made to have a sawtooth shape, and the difference is that the diameter reducing property by the wedge action at the time of pushing the inner sphere holding member is increased and the retaining property is improved, and the others are different from the previous example. Since there is no difference, the same parts are designated by the same reference numerals, and detailed description thereof will be omitted.

That is, in this example, the concave portion 27 at the substantially center of the inner peripheral surface 26 of the expanded diameter portion of the outer sphere 2 is formed by denting in a saw-tooth shape, and the convex portion of the outer annular portion 22 of the inner sphere holding member 28 is provided. The vertical cross-sectional shape of 24 is a sawtooth shape that fits exactly when it is attached to the recess 27. In this example, since the convex portion 24 is formed in a sawtooth shape having a predetermined inclined surface 24a, the wedge action or the diameter reducing property when the inner sphere holding member 28 is pushed in is improved, which facilitates the attachment. Is effective,
It also has a high retainability. Also in this example, as in the previous example, if necessary, in order to increase the attachment strength, the outer annular portion 2
The space R formed by 2 and the inner annular portion 23 may be filled with an appropriate filling material (ring) or filler.

As can be understood from this example, the cross-sectional shapes of the concave portion of the outer sphere and the convex portion of the inner sphere holding member locked to the outer sphere according to the present invention are easy to assemble, and are easy to assemble after assembly. It is preferable that the fitting structure is such that the stop is not impaired. However, the shape is not limited to the circular arc shape in the previous example or the saw tooth shape in this example, and the concave portion has a U-shape (square groove) to which a normal snap ring is attached, and the convex portion has a square cross section to be fitted therein. Good. In this case, when attaching, the diameter of the outer sphere is positively reduced so that it faces the inner peripheral surface of the outer sphere near the opening end, and is pushed under it, or the convex portion faces the concave portion. It will be attached by inserting it with the diameter reduced to the position to be expanded and expanding it.

-Embodiment 3-A further embodiment of the present invention will be described with reference to FIGS.
However, also in this example, since it is essentially the same as that of FIG. 1 and only the shape of the inner sphere holding member 38 is partially changed, etc.,
Only this difference and the action and effect due to it will be described, parts common to those of the first embodiment will be designated by the same reference numerals, and description thereof will be omitted as appropriate.

That is, also in the present example, similarly to the previous example, the inner sphere holding member 38 is provided with the outer side outer ring-shaped portion 32 and the inner side inner ring-shaped portion 33 with the bottom portion 31 in the cross section in the ring-shaped radial direction. It is formed in a bag shape (U shape), and is formed on the outer side of the outer annular portion 32 in the substantially center of the inner peripheral surface of the outer sphere 2 near the open end 4 along the circumferential direction. Although the convex portion 34 that can be locked in the concave portion 7 is integrally provided, in the present example, the bag-shaped bottom portion that connects the inner annular portion 33 and the outer annular portion 32, contrary to the inner sphere holding member in FIG. The convex portion 34 is locked to the concave portion 7 with 31 being close to the open end 4 of the outer sphere 2, and the inner sphere holding member 38 is attached to the inner peripheral surface 6 of the outer sphere 2.

In this example, as a result of this, the cage 1
The lower end of the rubber tube 36 for urging 0 is attached to the inner annular portion 3
Since it can be inserted into the space R between the outer ring 3 and the outer annular portion 32, the position of the rubber tube 36 is stabilized. The lower end (about half) of the rubber tube 36 is elastically fitted to the outer peripheral surface side of the inner annular portion 33 in the space R in this example. In the bone head embodying the present invention, including this example, the rubber tube 36
Is not mandatory. Instead of this, a spring material such as a coil spring (not shown) may be inserted.

-Embodiment 4-A further embodiment of the present invention will be described with reference to FIGS.
5, this embodiment is also essentially the same as that of FIG. 1 and is different only in that the shape of the inner sphere holding member is changed. Only the operation and effect of the same will be described, parts common to those in the first embodiment will be designated by the same reference numerals, and description thereof will be omitted.

That is, the inner sphere holding member 48 in this example.
The outer annular portion 42 is provided with two cuts k, k at substantially equal angular intervals (diameter direction) in plan view. This facilitates elastic deformation in the radial direction, further improving assembly.
It is formed to be simple. In this example, although the diameter of the outer annular portion 42 can be easily reduced, the attachment strength may be deteriorated. Therefore, although outlined above, the attachment of the inner ball holding member 48 to the outer ball 2 is omitted. After wearing, as a padding (ring) in the space R between the outer annular portion 42 and the inner annular portion 43, a short cylindrical ring as shown in FIGS. 14 and 15 (in this example, the same material as the inner sphere holding member is used). It is advisable to press in or press fit 51) for adhesion. A chamfer C is attached to the outer peripheral side of the upper end of the illustrated ring 51 to facilitate pressing (press-fitting), and two through holes 52 are provided in the diameter direction. The inner and outer diameters of this ring may be set to such a size that the outer ring portion 42 and the inner ring portion 43 of the inner ball holding member 48 are in a tight fit when pushed.

The number of breaks k of the outer annular portion 42 and the angular intervals may be set appropriately or may be unequal intervals. The present example can be embodied also in the inner sphere holding member shown in Examples 2 and 3, but when embodying in Example 3, a ring cannot be used. The material of the ring may be different from that of the inner ball holding member. By the way, in the ring of this example,
Since through holes 52, 52 are provided at two locations in the diametrical direction, if they are arranged and press-fitted according to the cuts k, k, they are indicated by a two-dot chain line in FIG. 11 at the time of resetting. As described above, the pulling tool h whose tip is bent like a hook is inserted from the cut k, the hook is inserted into the through hole 52 and pulled in the direction of the arrow, so that the inner sphere holding member 48 can be removed relatively easily.

Further, also in this example, the ring 51
Alternatively, the space R between the outer annular portion 42 and the inner annular portion 43 may be filled with bone cement. In this case, after the inner sphere holding member 48 is attached to the inner peripheral surface 6 of the outer sphere 2, bone cement is injected into the space R, so that after the solidification, the width of the cut k is reduced. , The outer sphere 2 is also adhered, so that the inner sphere holding member 48 is firmly attached to the outer sphere 2.

In the above embodiment, the inner sphere holding member is a bag-like (U-shaped) having an outer ring-shaped outer portion and an inner ring-shaped inner portion with a bottom portion in a cross section in the ring radial direction. Etc., and provided integrally with a convex portion that can be locked in the concave portion of the outer sphere on the outside of the outer annular portion, but the annular cross-sectional shape in the radial direction in the present invention is as follows. It is not limited to one. Further, in each of the above embodiments, the inner sphere holding member constituting the artificial bone head in the present invention is an endless annular member, but it can be embodied as an endless annular member in which a part of the ring is cut.

[0028]

According to the present invention, the inner ball holding member can be attached to the outer ball 2 by itself without the need for a snap ring. Therefore, the number of parts can be reduced, and the artificial bone head can be easily and quickly assembled, which is expected to reduce the cost.

[Brief description of drawings]

FIG. 1 is a central longitudinal front view and an enlarged view of essential parts of a first embodiment embodying an artificial bone head according to the present invention.

FIG. 2 is a front view of a half section of an inner sphere holding member used in the artificial bone head of FIG.

FIG. 3 is a bottom view of the inner sphere holding member of FIG.

4 is an explanatory view of a process of attaching the inner ball holding member of FIG. 2 to an outer ball.

FIG. 5 is a central longitudinal front view and an enlarged view of essential parts of a second embodiment embodying an artificial bone head according to the present invention.

6 is a front view of a half section of an inner sphere holding member used in the artificial bone head of FIG.

7 is a bottom view of the inner sphere holding member of FIG.

FIG. 8 is a central vertical sectional front view and an enlarged view of essential parts of a third embodiment embodying an artificial bone head according to the present invention.

9 is a front view of a half section of an inner sphere holding member used in the artificial bone head of FIG.

10 is a plan view of the inner sphere holding member of FIG.

FIG. 11 is a fourth embodiment in which the artificial head according to the present invention is embodied.
FIG. 2 is a front view of the central longitudinal section of FIG.

FIG. 12 is a front view, in half section, of the inner sphere holding member used in the artificial bone head of FIG. 11.

13 is a bottom view of the inner sphere holding member of FIG.

14 is a front view of a half section of a ring used for the artificial bone head of FIG. 11. FIG.

FIG. 15 is a plan view of the ring of FIG.

FIG. 16 is a central longitudinal front view and a partially enlarged sectional view of a conventional artificial bone head.

[Explanation of symbols]

 1 Artificial head 2 Outer sphere 3 Inner sphere 4 Open end of outer sphere 6 Inner peripheral surface of expanded portion of outer sphere (inner peripheral surface near opening end) 7,27 Recess of outer sphere 8, 28, 38, 48 Inner sphere holding member 11,31 Bottom part of inner sphere holding member 12, 22, 32, 42 Outer annular part 13, 23, 33, 43 Inner annular part 14, 24, 34 Convex part of inner sphere holding member k Outer annular part Break

Claims (3)

[Claims] 1. An inner sphere is provided inside the outer sphere, and an annular inner sphere holding member for swingably holding the inner sphere is attached to an inner peripheral surface of the outer sphere near an open end. In the artificial bone head formed as described above, a concave portion is formed along the circumferential direction on the inner peripheral surface near the open end of the outer sphere, while the inner sphere holding member is an outer side in a cross section in the annular radial direction. A convex portion capable of engaging with the concave portion is integrally provided, and a portion including the convex portion is formed so as to be elastically deformable in a diameter-reduced manner. An artificial bone head, characterized in that it is attached to the inner peripheral surface of the outer sphere by being locked to. 2. The inner sphere holding member is formed in a bag shape having an outer outer ring portion and an inner inner ring portion with a bottom portion in a cross section in the ring radial direction. A convex portion that can be locked in the concave portion is integrally provided on the outer side of the annular portion, and the outer annular portion is elastically deformable in a diameter-reduced shape, and the inner sphere holding member defines the bottom portion by The artificial body according to claim 1, wherein the convex portion is attached to the inner peripheral surface of the outer sphere on the side closer to the opening end of the outer sphere or on the opposite side thereof, and the convex portion is locked in the concave portion. Bone head. 3. The artificial head according to claim 2, wherein the outer annular portion has cuts at intervals.