Cup adapter

Abstract

This invention provides a cup adapter that allows for more secure press-fitting and fixation of the acetabular cup into the acetabulum. [Solution] The cup adapter 1 connects the acetabular cup 2 and the impactor 3 to each other and comprises a roughly cylindrical main body portion 11, a cup engagement portion 12 for engaging with the acetabular cup 2, and an impactor engagement portion 13 for engaging with the impactor 3. The impactor engagement portion 13 has an insertion hole 14 into which the tip 42 of the straight impactor 4 is inserted, and a fitting portion 15 into which the ring portion 52 of the oblique impactor 5 is fitted. With this configuration, the straight impactor 4 or the oblique impactor 5 can be appropriately selected and used for driving in depending on the positioning angle of the acetabular cup 2, so that the acetabular cup 2 can be pressed into and fixed to the acetabulum more reliably.

Description

Technical Field

[0001] The present invention relates to a cup adapter that connects a wide acetabular cup and an impactor to each other.

Background Art

[0002] In diseases such as osteoarthritis and osteonecrosis of the femoral head, surgery may be performed to replace the damaged hip joint with an artificial hip joint. In such surgery, generally, an artificial cup (wide acetabular cup) is attached to the wide acetabulum, and an artificial femoral head is fitted into the wide acetabular cup via a liner that substitutes for cartilage. The wide acetabular cup is placed in a depression formed by cutting the wide acetabulum with a hemispherical blade (reamer), and is press-fitted into the wide acetabulum by being driven through an impactor attached to the wide acetabular cup (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the wide acetabular cup as described above, depending on the placement angle, driving through the impactor may not succeed, and sufficient press-fitting to the wide acetabulum may not be achieved.

[0005] The present invention solves the above problems, and an object thereof is to provide a cup adapter that can more reliably press-fit a wide acetabular cup into a wide acetabulum.

Means for Solving the Problems

[0006] The present invention relates to a cup adapter for connecting an acetabular cup and an impactor, comprising a substantially cylindrical main body, a cup engagement portion provided at one end of the main body for engaging with the acetabular cup, and an impactor engagement portion provided at the other end of the main body for engaging with the impactor, wherein the impactor engagement portion has an insertion hole recessed in the other end face of the main body into which the tip of a straight impactor is inserted, and a fitting portion forming the outer circumference of the main body into which a ring portion provided at the tip of an oblique impactor is fitted.

[0007] The fitting portion preferably has planar portions arranged parallel to each other in a plan view, and these planar portions preferably engage with protrusions that protrude from the inner circumference of the ring portion of the oblique impactor.

[0008] The aforementioned insertion hole is preferably substantially polygonal in plan view and has an enlarged portion with rounded corners. [Effects of the Invention]

[0009] According to this invention, a straight impactor or an oblique impactor can be appropriately selected and used for driving in the acetabular cup depending on the positioning angle of the acetabular cup, thereby enabling more reliable press-fitting and fixing of the acetabular cup into the acetabulum. [Brief explanation of the drawing]

[0010] [Figure 1] An exploded perspective view of an acetabular cup insertion kit equipped with a cup adapter according to one embodiment of the present invention. [Figure 2] (a) is a side view of the cup adapter shown above, (b) is a cross-sectional view of (a) by line II, and (c) is a top view of the same cup adapter. [Figure 3] Figures (a)-(d) illustrate the process of pressing and fixing the acetabular cup into the acetabulum using the above-mentioned acetabular cup insertion kit. [Modes for carrying out the invention]

[0011] The cup adapter of this invention constitutes part of an acetabular cup insertion kit used to press-fit and fix an acetabular cup into the acetabulum. As shown in Figure 1, the cup adapter 1 connects the acetabular cup 2 and the impactor 3 in the acetabular cup insertion kit 10. The impactor 3 is composed of a straight impactor 4 and an oblique impactor 5.

[0012] The acetabular cup 2 has a hemispherical portion 21 formed in a hemispherical shape, and an adapter engagement portion 22 provided at the top of the hemispherical portion 21 that engages with the cup engagement portion 12 (see below) of the cup adapter 1. The hemispherical portion 21 is made of, for example, a titanium alloy or a cobalt-chromium alloy as the base material and has a coating portion 21a on its outer surface. The coating portion 21a has a porous three-dimensional mesh structure to improve biocompatibility. The adapter engagement portion 22 is formed, for example, by a screw hole.

[0013] In the illustrated example, the straight impactor 4 has a shaft 41 that is elongated in the vertical direction, a connecting part 42 provided at the lower end of the shaft 41 and connected to the cup adapter 1, a handle 43 attached to the upper end of the shaft 41, and a driving part 44 provided at the upper end of the handle 43 for driving with a hammer. In the illustrated example, the connecting part 42 is formed in the shape of a rectangular prism and is inserted into the insertion hole 14 of the cup adapter 1, which will be described later.

[0014] The oblique impactor 5, in the illustrated example, has a shaft 51 that is elongated in an upward diagonal direction, a ring portion 52 formed in the shape of a ring at the lower end of the shaft 51, a handle 53 provided at the upper end of the shaft 51, and a striking portion 54 provided at the upper end of the handle 53 to be driven in with a hammer. The ring portion 52 is formed in a cylindrical shape that extends along the vertical direction and is fitted onto the outer circumference of the fitting portion 15 of the cup adapter 1, which will be described later.

[0015] The cup adapter 1, in the illustrated example, comprises a roughly cylindrical main body portion 11 extending vertically, a cup engagement portion 12 provided at one end (lower end) of the main body portion 11 for engaging with the acetabular cup 2, and an impactor engagement portion 13 provided at the other end (upper end) of the main body portion for engaging with the impactor 3. The cup engagement portion 12 is composed of screw threads that screw into the adapter engagement portion 22 (screw hole). The impactor engagement portion 13 has an insertion hole 14 recessed in the upper end surface of the main body portion 11 into which the tip (connecting portion 42) of the straight impactor 4 is inserted, and a fitting portion 15 that forms the outer circumference of the main body portion 11 into which the ring portion 52 of the oblique impactor 5 is fitted. A flange portion 16 is provided between the fitting portion 15 and the cup engagement portion 12, extending radially from the main body portion 11.

[0016] As shown in Figure 2, the insertion hole 14 is formed in a roughly polygonal shape (roughly quadrilateral in the example shown) in plan view, and has enlarged portions 14a at each corner (see Figure 2(c)). Each enlarged portion 14a has a rounded shape that expands outward and extends from the top to the bottom of the insertion hole 14.

[0017] The fitting portion 15 has a pair of planar portions 15a arranged parallel to each other in a plan view. Each planar portion 15a has a plurality of grooves 15b provided parallel to the circumferential direction of the main body portion 11. These grooves 15b are arranged at equal intervals from each other along the vertical direction and engage with protrusions (not shown) that protrude from the inner circumference of the ring portion 52 when the ring portion 52 of the oblique impactor 5 is fitted into the fitting portion 15.

[0018] Next, the procedure for pressing and fixing the acetabular cup 2 into the acetabulum during total hip replacement surgery using the acetabular cup insertion kit 10 equipped with the cup adapter 1 described above will be explained with reference to Figure 3. First, as shown in Figure 3(a), a first incision C1 of about 10 cm is made in the skin S of the thigh at an oblique position from the acetabulum B (the bone portion is indicated by a dot), and the acetabular cup 2 with the cup adapter 1 attached is inserted through this incision.

[0019] Next, as shown in FIG. 3(b), after the acetabular cup 2 is placed in the acetabulum B, the shaft 51 of the oblique impactor 5 is inserted through the first incision C1, and the ring portion 52 is fitted into the fitting portion 15 of the cup adapter 1. The handle 53 is operated to place the acetabular cup 2 at an optimal angle with respect to the acetabulum B. At this time, by engaging a convex portion (not shown) of the ring portion 52 with a groove 15b (not shown) of the fitting portion 15, the ring portion 52 does not rotate freely with respect to the cup adapter 1, and the operability is good.

[0020] Thereafter, as shown in FIG. 3(c), a second incision C2 about 2 cm long is formed at a position directly above the acetabulum B on the skin S, and the shaft 41 of the straight impactor 4 is inserted therethrough, and a connecting portion 42 (not shown) is inserted into the insertion hole 14 of the cup adapter 1. At this time, since an enlarged portion 14a (not shown) is provided in the insertion hole 14, the connecting portion 42 is easily guided into the insertion hole 14. By the above operations, both the straight impactor 4 and the oblique impactor 5 are connected to the acetabular cup 2 via the cup adapter 1.

[0021] Then, as shown in FIG. 3(d), the acetabular cup 2 is press-fitted and fixed to the acetabulum B by driving the driving portion 44 of the straight impactor 4 with a hammer. At this time, depending on the arrangement angle of the acetabular cup 2 with respect to the acetabulum B, the acetabular cup 2 may be press-fitted and fixed by driving the driving portion 54 of the oblique impactor 5.

[0022] As described above, by adopting the cup adapter 1 that can be engaged with both the straight impactor 4 and the oblique impactor 5 at the same time, the straight impactor 4 or the oblique impactor 5 can be appropriately selected and used for driving according to the arrangement angle of the acetabular cup 2. As a result, it is possible to more reliably press-fit and fix the acetabular cup 2 to the acetabulum B, prevent the acetabular cup 2 from falling off from the acetabulum B, and improve the reliability of the total hip arthroplasty.

[0023] Note that the cup adapter according to the present invention is not limited to the above-described embodiment and can be variously modified. For example, the fitting portion does not necessarily have to have a flat portion, and the fitting portion may be formed in a polygonal shape in plan view, and the ring portion may be formed to conform to this. Further, the insertion hole does not necessarily have to have an enlarged portion, and it may be configured not to have an enlarged portion.

Explanation of Reference Numerals

[0024] 1 Cup adapter 11 Main body portion 12 Cup engaging portion 13 Impactor engaging portion 14 Insertion hole 14a Enlarged portion 15 Fitting portion 15a Flat portion 2 Wide acetabular cup 3 Impactor 4 Straight impactor 42 Connecting portion (tip) of straight impactor 5 Oblique impactor 52 Ring portion

Claims

1. A cup adapter that connects an acetabular cup and an impactor to each other, It comprises a roughly cylindrical main body, a cup engagement portion provided at one end of the main body for engaging with the acetabular cup, and an impactor engagement portion provided at the other end of the main body for engaging with the impactor, The cup adapter is characterized in that the impactor engagement portion has an insertion hole recessed on the other end face of the main body portion into which the tip of a straight impactor is inserted, and a fitting portion that forms the outer circumference of the main body portion into which a ring portion provided on the tip of an oblique impactor is fitted.

2. The cup adapter according to claim 1, wherein the fitting portion has planar portions arranged parallel to each other in a plan view, and the planar portions engage with protrusions that protrude from the inner circumference of the ring portion of the oblique impactor.

3. The cup adapter according to claim 1 or 2, characterized in that the insertion hole has a substantially polygonal shape in plan view and has an enlarged portion with rounded corners.

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