JPS62254749A - Artificial hip joint - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an artificial hip joint for replacing and repairing a human joint.

[Conventional technology and its problems]

Conventionally used artificial hip joints are made of metal such as stainless steel or cobalt-chromium alloy, and the femoral head and stem are fixed integrally or by tapered fitting, and the stem is inserted into the femur and connected to the bone. The gap with the stem is fixed using cement. On the palatal side, a socket made of synthetic resin that receives the femoral head is similarly fixed to the pelvis using cement. In particular, on the femoral side, the stem is inserted into the long bone for a long time, but due to the difference in Young's modulus between bone and metal, the amount of deformation when loaded is greatly different, and the amount of deformation between cement and bone and cement differs greatly. Looseness between the metal stems is likely to occur, resulting in the artificial hip joint becoming detached from the living body, or looseness occurring between the parts, resulting in loss of joint function. In recent years, many attempts have been made to eliminate the occurrence of loosening between cement and bone or cement metal materials. Regarding stem materials, pure titanium and titanium alloys are now being used instead of the traditional cobalt chromium alloys and stainless steel.
Attempts have been made to follow the bending of bone by using materials with a Young's modulus closer to that of bone, but this alone has not completely solved the problem.

Design attempts have also been made to adapt the prosthesis to bones with complex shapes and to minimize the gap between the bone and the prosthesis. There is.

However, it is extremely difficult to make the entire outer peripheral surface correspond to the shape of the bone without using cement because of the individual differences between living organisms.

On the other hand, bone is also processed into the shape of a prosthesis and then inserted, but a lot of healthy bone is shaved off during processing.
This results in a deterioration in the strength of the entire pipe, which also poses many problems. Another major drawback is that when inserting and fixing the stem into the medullary canal of a bone, the cement as an adhesive is injected directly into the medullary canal, which can cause blood to get into the cement and deteriorate the strength of the cement itself. Ta.

[Specific Means for Solving the Problems] In order to solve the above problems, a thin metal sheath 4 that can follow the shape of the bone marrow cavity is used for fixation by following the shape of the bone.

At this time, there are many grooves or unevenness on the surface of the pod 4,
It is preferable that the device be firmly fixed to the bone, and it is even more effective if the surface is coated with ceramics, osteogenic factors, etc.

In addition, the stem is fixed in the sheath, which is firmly fixed to the bone, using cement or a biocompatible, elastic adhesive to provide long-term stability.

[Effect]

The operation of this system is as follows.

1. The shape and size differences caused by individual differences in bones can be followed (accommodated) by the deformation of the sheath, and the surface area in contact with the bones can be maximized, making it possible to disperse stress.

2. Since the sheath is deformable, the shape of the stem can be simple, making it very easy to manufacture.

3. Since the cement as an adhesive does not come into direct contact with the bone, the adverse effects on living cells caused by the polymerization heat of the cement are reduced.

4. Easily follows bone deformation.

〔Example〕

Embodiments of the present invention will be specifically explained with reference to the drawings.

In FIG. 1, l is a femoral ball made of alumina or zirconia, etc. This femoral ball 1 is tapered and fitted to a titanium alloy stem 2, and is inserted into a sheath 4 using cement 3. Fixed. This Saya 4 is
It has an external shape as shown in the perspective view in Fig. 2, for example,
It is made of titanium alloy, and its surface is coated with apatite, making it compatible with bone.

Furthermore, the thickness of this sheath 4 should be approximately 2 m to 1 Pm, so that it can be plastically deformed, and as many types of shapes and sizes as possible are prepared so as to match the size of the medullary cavity of the bone as much as possible. It's a good idea to keep it. During actual use, the surgeon selects and inserts the most suitable one according to the size of the medullary cavity, and then deforms it from the inside to match the shape of the medullary cavity as much as possible. After this operation, an adhesive 3 such as biocompatible cement, ultra-high molecular weight polyethylene, silicone rubber, etc. is injected into the inside, and the stem 2 is inserted and fixed. The material constituting the sheath 4 may be made of metals such as titanium, titanium alloy, aluminum, or synthetic resins such as polyethylene.

〔Effect of the invention〕

A metal sheath is placed between the stem and the inner wall surface of the medullary canal of the femur like a ridge, and the sheath is made to correspond to the shape of the medullary canal, and an adhesive is filled in the sheath to fix the stem. Because of this, the contact surface area between the bone and sheath can be increased regardless of the shape and size of the bone due to individual differences, and stress can be dispersed, so the bone and sheath, and ultimately the bone and stem, can form a stable bond. As a result, the state can be maintained,
There will be no separation or loosening for many years. Also, since the pod is deformable, the shape of the stem can be simple.
Manufacturing becomes extremely easy. Furthermore, since the bone does not come into direct contact with an adhesive such as cement, the adverse effects on living cells caused by polymerization heat and eluted components during fixation can be reduced. Moreover, since blood during surgery does not mix with the adhesive, it does not cause a decrease in adhesive strength, and it has a tremendous impact on human welfare, as it can repair the hip joint, that is, restore walking ability and ensure long-term stability. can do.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the state in which the stem of the artificial hip joint according to the present invention is attached to the femur, and FIG. 2 is a three-dimensional perspective view of only the sheath 4 shown in FIG. 1.

Claims (1)

[Claims] In an artificial hip joint comprising a stem inserted into the femoral medullary canal and a femoral ball integrally formed at the free end of the stem or fitted by a conical taper, there is a plastic bond between the femur and the stem. Thickness that can be deformed from 1μm to 2m
1. An artificial hip joint characterized by having a sheath of m, and a biocompatible adhesive being filled between the sheath and the stem.