JPS6359950A - Artificial hip joint - Google Patents

Abstract

(57) [Abstract] 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 that is applied to the human body.

(Prior Art) A conventionally used artificial hip joint is composed of a socket implanted in the hip bone, and a stem having a femoral ball at its tip that rotatably fits into the socket.

Among these, the stem is made of metal such as stainless steel or alloys such as cobalt chromium, and is inserted into the femoral medullary canal and fixed with cement interposed between the stem and the bone, and one palatal side receives the femoral ball. The socket used for this purpose is also generally fixed to the pelvis using cement. Particularly on the femoral side, the stem is inserted deeply (long) into the long bone, but due to the difference in Young's modulus between bone and metal, the amount of deformation when loaded is greatly different. Looseness is likely to occur at the metal stem connection (in particular, sinking due to the loosening of the stem is a major problem, causing the artificial hip joint to separate from the bone and causing looseness between the parts.
This resulted in loss of joint function.

Therefore, many attempts have been made to prevent such loosening between cement and bone and between cement and metal stems. In addition, stem materials such as pure titanium and titanium alloys have been used instead of the conventional stainless steel mesh and cobalt chrono-alloys, and stem materials are being used that have a Young's modulus that is closer to that of bone, in an attempt to follow the bending of bone. Although attempts are being made,
That alone does not completely solve the problem.

In addition, attempts were made to improve the design by adapting the external shape of prostheses, such as palate and stem, to bones with complex shapes, minimizing the gap between them and the bone, and fixing the stem without using cement. has also been done.

However, it is extremely difficult to make the overall shape resemble the shape of a bone without using cement because there are individual differences among living organisms.

Therefore, as a new attempt, for example, U.S. Patent No. 4.58
As described in the specification of No. 9,883, many pores are created three-dimensionally on the surface of the metal stem by baking or diffusion bonding metal beads or wire onto the surface of the metal stem. The stem is also firmly fixed to the bone by allowing new bone to grow, proliferate, and enter into the cavity.

However, by forming three-dimensional holes on the surface,
When the material is made porous, the surface area increases dramatically, and as a result, a large amount of metal ions are eluted, and its adverse effect on living organisms has become a major problem.

This further leads to a decrease in strength, which can lead to stem breakage, which is becoming a major problem.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention is characterized in that a ceramic body having excellent affinity with bone is attached to the stem constituting the artificial hip joint, especially in the intertrochanteric region. .

(Functions) The functions of the artificial hip joint made of such a stem are as follows: 1. The adverse effects on the living body due to elution of metal ions are reduced.

2. Decrease in strength of the entire stem due to surface porosity can be avoided.

3. The shape of the stem can be simplified, which makes manufacturing easier.

4. It is not necessary to use cement for bonding and fixing with bone, and when cement is not used, the adverse effects on living organisms due to polymerization heat during cement solidification are reduced.

(Example) Embodiments of the present invention will be described with reference to the drawings.

Fig. 1 is a fractured cross-sectional view showing the state in which the femoral bone side member constituting the artificial hip joint is attached to bone B. 1 is the femoral head ball, which is fitted onto the tip of the stem 2 made of titanium alloy or cobalt chromium alloy. There is. Reference numeral 3 denotes a ceramic body attached to the stem 2, particularly in the intertrochanteric region, and the ceramic body 3 is fitted into a recess 2a formed in the stem 2 and firmly fixed by a dovetail groove 2b. There is. Further, on the outer surface of the ceramic body 3, alumina beads 3a are attached in one or more layers, and the average void size formed by the beads 3a is It has a particle size of about 50 to 500 microns, and this is based on reports from animal experiments that bone invasion and proliferation is most pronounced when the average pore size is around 300 microns.

Further, if necessary, the surface of the ceramic body 3 to which the beads 3a are attached may be coated with apatite, bone morphogenetic protein (BMP), etc. that promotes bone growth and invasion, to improve compatibility with the bone. You can also do it.

In addition, as shown in FIG. 2, a conical ceramic body 3 made of alumina ceramic is fitted and fixed in the stem 2 so that both sides are exposed, and a biocompatible material is attached to the outer surface of the ceramic body 3. The stem 2 may have a porous alumina ceramic body 4 attached thereto, or it may have a ceramic body 3 attached with alumina beads 3a fitted from both sides of the stem 2 as shown in FIG. good.

(Effects of the Invention) As described above, according to the present invention, a material having excellent biocompatibility and engagement with the bone is placed in the bone-contacting part of a joint component such as an artificial hip joint. By being a
Because it provides strong fixation and support with the bone without using bone cement, it not only eliminates all the disadvantages of using bone cement that have been pointed out in the past, but also improves the strength of the stem. It can provide long-term stability of the artificial hip joint without causing complications due to deterioration or ion elution.

[Brief explanation of the drawing]

FIG. 1(a) is a broken cross-sectional view of the stem as an artificial hip joint member according to an embodiment of the present invention attached to the femur;
Figure (n) is a sectional view taken along line X--X in figure (a). FIG. 2(A) and FIG. 3(A) are both side views of a stem according to another embodiment of the present invention, and FIG. 2(U) is the same view (A).
The Y-Y line sectional view of Figure 3 (II) is the 2-
It is a 2-line sectional view. 1: Epigephalon 2: Stem 3: Ceramic body 3a: Alumina beads Patent applicant Kyocera Co., Ltd. Figure 1 (a) Figure 2 (a) Figure 3

Claims (2)

[Claims] (1) In an artificial hip joint comprising a metal stem inserted and fixed into the medullary cavity of the femur and a femoral ball at the distal end of the stem, at least the surface of the intertrochanteric portion of the stem is biocompatible. An artificial hip joint characterized by having an excellent ceramic body. (2) The artificial hip joint according to claim 1, wherein beads or porous bodies made of alumina ceramic are attached to the surface of the ceramic body.