JP6071087B2 - Artificial knee joint - Google Patents

Description

The present invention relates to an artificial knee joint.

If the knee joint suffers from osteoarthritis of the knee, rheumatoid arthritis, bone tumor or trauma, etc., the damaged part of the joint of the femur and tibia is excised, and this part is prosthetic knee Replacement with a joint (knee implant) is performed. As in the conventional art, this artificial knee joint includes a femoral component having condyles corresponding to inner and outer condyles of the femur, and rotation and sliding of the two condyles (hereinafter referred to as rolling). It consists of a tibial component formed with an articular surface corresponding to the meniscus that can be received. In this case, various ligaments are connected to the femur and tibia that sandwich the knee joint, and are involved in the movement of the knee joint.

Above all, the cruciate ligament composed of the anterior cruciate ligament and the posterior cruciate ligament passes through the center of the knee joint. If this is preserved (unremoved) during the operation, it will become an obstacle during the operation, and the knee opening ( (Flexion) worsens and it is difficult to insert the knee implant. Therefore, when performing a replacement operation for an artificial knee joint, at least the anterior cruciate ligament, which is more obstructive, is removed in principle even if the degree of damage is low.

On the other hand, with regard to the posterior cruciate ligament, it is determined whether it is excised or preserved by comprehensively judging the degree of damage and the difficulty of the operation. If the degree of damage to the posterior cruciate ligament is large or if priority is given to ease of surgery, it is often removed, but if the anterior cruciate ligament and the posterior cruciate ligament are removed, the post-operative knee movement will worsen If the posterior cruciate ligament is healthy when the posterior cruciate ligament is healthy, the posterior cruciate ligament can be inserted into the U-shaped cut and preserved. Patent Document 1).

However, in reality, the posterior cruciate ligament is often excised in view of the ease of surgery. In such a case, the U-shaped cut is conventional and has little meaning. On the other hand, since the anterior cruciate ligament connects the anterior part of the tibia and the slightly rearward part of the femur, if it is left, it is difficult to perform the operation, and it is difficult to insert the knee implant as described above. In addition, since the presence of the U-shaped cut restricts the shape and strength of the artificial knee joint itself, in practice, as described above, in most cases, it is excised.

JP 2000-281707 A

In the present invention, at least the anterior cruciate ligament is preserved when the degree of damage is low, and the high one is excised and replaced with an artificial anterior cruciate ligament for reconstruction. In this case, the shape of the U-shaped cut formed in the center of the rear part of the tibial component is made more suitable, and by using this cut, it is possible to move closer to a living knee joint having an anterior cruciate ligament. . If the anterior cruciate ligament is preserved or reconstructed, surgery becomes difficult, but this will be covered by a surgical technique.

Under the above-mentioned problems, the present invention is attached to the distal end of the femur according to claim 1 and has an inner condyle and an outer condyle at the inner and outer sides, and at the rear end between the inner condyle and the outer condyle. A femoral component forming an open U-shaped cut, and an inner joint surface and an outer joint surface mounted on the proximal end of the tibia and rotatably and slidably receiving the inner condyle and the outer condyle respectively . A tibial component that forms a U-shaped cut that opens to the rear end between the articular surface and the external joint surface, and a U-shaped cut that is inserted between the tibial component and the tibia and is continuous to the U-shaped cut of the tibial component In an artificial knee joint comprising a formed base, the lower surface of the base has a U-shaped cross section comprising an anterior wall that is inserted into the anterior part of the tibia and two hanging walls that extend backward from both sides of the anterior wall into the tibia. A peg is formed, and the intercondylar bulge at the center of the proximal end of the tibia is not excised. The unexcised portion is taken into the U-shaped cut of the tibial component and the femoral component from between the anterior wall and the pit wall of the base, and the contact portion between the inner condyle of the femoral component and the inner joint surface of the tibial component And an artificial knee joint characterized in that a joint line connecting the lowermost ends of the contact portions between the external condyles and the external joint surface is tilted inward by adjusting the height of each contact portion and lowering the inside from the outside. Provided.

Moreover, this invention provides the structure as described in Claim 2 whose inclining angle is 1-5 degrees.

According to the first aspect of the present invention, the uncut portion of the tibia is taken into the U-shaped cut of the tibial component and the femoral component in addition to the anterior wall and the drooping wall of the base peg. Both the tibial component and the base are stable in posture and firmly fixed.

According to the invention of claim 2, the joint line is inclined inward, and the artificial knee joint can be made to move closer to the living body knee joint.

FIG. 6 is a side view of a femoral component. FIG. 6 is a plan view of a femoral component. FIG. 6 is a posterior view of the femoral component. It is a partial cross section side view of a tibial component (preservation type). It is a top view of a tibial component (preservation type). FIG. 6 is a posterior view of the tibial component (preservation type). It is a side view which shows the state of the flexion and extension of a femoral component and a tibial component (preservation type). It is a back slope view which shows the condition of extension of a femoral component and a tibial component (preservation type). It is a cross-sectional side view of a tibial component (reconstruction type). It is a top view of a tibial component (reconstruction type). It is a rear view of a tibial component (reconstruction type). It is a side view which shows the state of the flexion and extension of a femoral component and a tibial component (reconstruction type). It is a rear view which shows the condition of extension of a femoral component and a tibial component (reconstruction type). It is a perspective view of a living body knee joint.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 14 is a perspective view of the right knee of the living body as viewed from the inner rear, with the upper part being the femur 1 and the lower part being the tibia 2. The distal end of the femur 1 is formed with a substantially cylindrical inner condyle 1a and outer condyle 1b whose outer periphery is convex on the left and right. The proximal end of the tibia 2 is formed with an inner joint surface 2a and an outer joint surface 2b, which are concave meniscuses that receive the inner condyle 1a and the outer condyle 1b in a rollable manner. In addition, the front-rear central part between the inner joint surface 2a and the outer joint surface 2b of the tibia is slightly raised as an intercondylar bulge.

In this case, the bilateral joint surfaces 2a and 2b have a shape in which the center is recessed in the front and rear directions so as to receive the bilateral condyles 1a and 1b. The bilateral condyles 1a and 1b and the bilateral joint surfaces 2a and 2b are connected by a cruciate ligament, and the anterior cruciate ligament (ACL) is connected from the inside of the lateral condyle 1b and the center of the front side of the medial joint surface 2a. 3) and the posterior cruciate ligament (PCL) 4 is connected to the medial side of the medial condyle 1a and the posterior center of the bilateral joint surfaces 2a and 2b. When these ACL3 and PCL4 are viewed from the back, they cross to form a cross (X shape), which is why it is called a cruciate ligament.

The artificial knee joint is attached to the distal end of the femur 1 and the proximal end of the tibia 2, and is composed of a femoral component 5 and a tibial component 6, respectively. 1 is a side view of the femoral component 5, FIG. 2 is a plan view, and FIG. 3 is a posterior view. However, the femoral component 5 has a pentagonal shape (not limited to this) when the distal end of the femur 1 is viewed from the side. ) And attached to the inner surface of the femoral component 5. In this state, the front wall 5A and the rear wall 5B have a substantially parallel inner surface and are standing upright (the front wall 5A is higher), and they cover a wide range of the distal end of the femur 1 and are integrated. Strengthening.

The outer peripheral surface of the femoral component 5 has an inner condyle 5a and an outer condyle 5b imitated by the medial condyle 1a and the lateral condyle 1b on both the left and right sides. In order to further enhance the integration at this time, the femoral component One or a plurality of pegs (not shown) to be inserted into the femur 1 may be provided on the inner surface of 5. The femoral component 2 is made of a biocompatible metal such as a titanium alloy or chrome molybdenum steel that is harmless even when applied to the human body.

FIG. 4 is a cross-sectional side view of the tibial component 6 including the base, FIG. 5 is a plan view, and FIG. 6 is a posterior view. In many cases, the base 7 is laid, and in the form of a dish that can be placed on the base 7. In addition, on the back surface of the base 7, there is a type in which a peg 8 including a front wall 8 a that is inserted into the front portion of the tibia 2 to reinforce the fixing and a hanging wall 8 b that extends backward from both ends is projected. In general, the mating surface between the tibial component 6 and the tibial component 6 has a roughened surface or a concavo-convex fitting to enhance fixation. The tibial component 6 has an inner joint surface 6a and an outer joint surface 6b imitated by the inner joint surface 2a and the outer joint surface 2b.

In this case, both the inner joint surface 6a and the outer joint surface 6b are formed in a streak shape with the center depressed so that the inner condyle 5a and the outer condyle 5b can easily roll and are not displaced. The base 7 is made of the above-described metal, and the tibial component 6 is made of ultrahigh molecular weight polyethylene (UHMWPE) or the like having good sliding compatibility with the metal constituting the counterpart femoral component 5 and less wear. Usually it is.

Between the inner condyle 5a and the outer condyle 5b of the femoral component 5, a U-shaped cut 9 (hereinafter referred to as a cut) that opens to the rear is formed. Although it is not particularly necessary in terms of function, it is convenient for passing through the intercondylar bulge of the tibia 2, the ACL 3 and the PCL 4, or for raising the post on the tibia 2 described later. Similarly, cuts 10 and 11 are formed between the inner condyle 6a and the outer condyle 6b of the tibial component 6 and the base 7 as well. These cuts 9 to 11 avoid interference of PCL4. However, when performing artificial knee joint replacement surgery (TKA) as described above, these ACL3 and PCL4 are often excised. 9-11 are probably more customary.

Although not shown, instead of the cut 11 between the inner joint surface 6a and the outer joint surface 6b of the tibial component 6, a post is erected here, and this post is connected to the inner condyle 5a of the femoral component 5 and the outer surface. Some of them are inserted into the cut 9 between the condyles 5b to restrict the lateral displacement of the femoral component 5.

The present invention provides an ACL-preserving type (hereinafter simply referred to as a preserving type) that retains ACL3 during TKA and an ACL reconstructing type (hereinafter simply referred to as a reconstructing type) artificial knee joint that replaces ACL3 with an artificial anterior cruciate ligament. Is. PCL4 is preferably preserved or reconstructed regardless of whether it is a preserved or reconstructed type of ACL3 (this will be described later). Since ACL3 is present, it is preferable to preserve or rebuild PCL4, which is not as problematic as ACL3, in order to ensure good movement of the knee prosthesis. is there.

In the preservation type knee prosthesis, the cuts 10 and 11 of the tibial component 6 described above are extended deeper forward (the one-dot chain line is the end line of the conventional cuts 10 to 11). As long as it is a preserving type, the anterior portion of the tibia 2 to which the ACL is attached must also be left uncut. Therefore, since the unexcised tibia 2 becomes an obstacle, it is accommodated in the cuts 10 and 11. That is, the osteotomy of the tibia 2 is performed in accordance with the cuts 10 and 11.

FIG. 7 is a side view showing a state of bending and stretching when an artificial knee joint in which PCL 3 is also preserved is mounted, and FIG. 8 is a posterior slope view, which shows the approximate center of tibial component 6 and base 7 (cut 9 of femoral component 5). (Same position) is present only in a small part in front (both sides have a normal shape). The unexcised tibia 2 is slightly higher than the inner and outer joint surfaces 6a and 6b due to the intercondylar protuberance, but is accommodated in the cut 9 of the femoral component 5, and there is no problem such as interference. At the front end of the base 7 in this example, a front wall 8a of a peg 48 inserted into the tibia 2 is provided to protrude downward, thereby strengthening the fixation.

The (artificial) knee joint bends and stretches over a range of bending positions where the femur 1 and the tibia 2 bend 90 degrees (or more) relative to the straight extension position. In the extended position, ACL3 contracts and PCL4 extends. On the other hand, in the bent position, ACL3 extends and PCL4 contracts. The preserved or reconstructed ACL3 and PCL4 help to make the movement smoother and closer to the living body. Note that the cut 9 of the femoral component 5 is formed to a position where ACL3 and PCL4 do not interfere even when the artificial knee joint is bent and extended.

Accordingly, the strength of the tibial component 6 may be weakened. However, since the tibial component 6 is originally only to receive the load of the inner condyle 5a and the outer condyle 5b of the femoral component 5, the cut 10 , 11 is slightly deeper (longer), there is no problem in strength. In addition, it is possible to compensate for the strength of the material, the width of the cuts 10 to 11 and the presence of the peg 8. At the time of TKA, a procedure for inserting the ACL 3 is required, but a conventional method for inserting the PCL 4 may be applied to the ACL 3 as well.

On the other hand, in the reconstructed artificial knee joint, the above-described cuts 10 to 11 are left as they are, the artificial anterior cruciate ligament ACL3 artificially manufactured in the tibial component 6 can be inserted, and fluctuations due to flexion and extension occur. A hole 12 having a size that does not hinder the opening is formed (the same applies to the base 7). Note that the PCL 4 can be inserted with the conventional cuts 10 to 11 in both the preservation type and the reconstruction type. 9 is a cross-sectional view of the tibial component 6 in this case, FIG. 10 is a plan view, and FIG. 11 is a rear view. Naturally, the hole 12 is formed obliquely in the direction in which the ACL 3 is inserted. According to the structure in which the hole 12 is formed, the reduction in the area can be reduced as compared with the structure in which the cut is deepened, which is advantageous in strength.

Specifically, in the side view, from the rear wall 5B of the femoral component 5 toward the front surface of the tibial component 6 (including the base 7; the same applies hereinafter), and in the rear view, from the external condyle 5b of the femoral component 5. The tibial component 6 is directed toward the inner joint surface 6a. When the hole 12 is formed in this direction, the surface of the tibial component 6 is closer to the outer joint surface 6b side than the center. The femoral component 5 may be a normal one regardless of whether it is a preservation type or a reconstruction type.

TKA may be performed by a well-known method, but an artificial ACL 3 prepared in advance after the femoral component 5 and tibial component 6 (knee implant) are attached is passed through the hole 12, and both ends thereof are fixed. To do. Any method may be used for this fixation. For both the femur 1 and the tibia 2, the extension of the hole 12 is perforated and penetrated, and the end thereof is fixed to the bone surface. It is easy and preferable. The artificial ACL 3 is made of a tough and flexible resin material that is harmless to the human body.

FIG. 12 is a side view showing a state of bending and stretching of an artificial knee joint of the ACL3 reconstruction type in which PCL3 is preserved, and FIG. 13 is a rear view. As described above, ACL3 and PCL4 expand and contract with each other during bending and stretching. In this example, the PCL 4 is preserved, but when the degree of damage is high, it may be excised and replaced with the artificial posterior cruciate ligament 4 for reconstruction. The material and surgical technique in this case may be the same as those of the artificial anterior cruciate ligament 3 described above. As described above, the artificial knee joint moves more smoothly like a living knee joint.

By the way, the inner condyle 5a and the outer condyle 5b are convex, and the inner joint surface 6a and the outer joint surface 6b are concave as described above. However, a line connecting the lowest points of the contact portions is shown. This is referred to as a joint line JL (FIG. 13). The joint line JL is as described above so that the inner and outer condyles 5a and 5b are substantially in the same position when rotating on the inner and outer joint surfaces 6a and 6b, and are translated along the shape of the inner and outer joint surfaces 6a and 6b when sliding. It is formed on a convex surface and a concave surface. Note that when viewed from above, the joint line JL is directed in the left-right direction.

In the present invention, it is a preferable example that the joint line JL is inclined inward by lowering the inner side with respect to the horizontal horizontal line SEA. This is the case with living knee joints, which keeps the collateral ligament tension, especially the balance of relaxation and induction of ankle rotation during flexion. That is, by inclining the joint line JL, the artificial knee joint can be made to move closer to the living knee joint. The inclining angle of the joint line JL in the living knee joint is approximately 1 to 5 °, and is 3 ° on average, although there are individual differences depending on the shape of the femur 1 and the tibia 2 of the patient. But 3 ° is suitable.

DESCRIPTION OF SYMBOLS 1 Medial condyle 1b of the femur 1a 外側 Lateral condyle 2 of the tibia 2a Medial joint surface 2b of the heel 3 Articular joint surface 3 of the heel 4 Anterior cruciate ligament 4 Back cruciate ligament 5 Endocondyle 5b前 Anterior wall 5B の 後 Back wall 6 Tibial component 6a 内 Inner joint surface 6b 外 Outer joint surface 7 Base 7a Anchor 8 Peg 9 U-shaped cut of femoral component 10 U-shaped cut of tibial component 11 U-shaped of base Cut 12 hole

Claims (2)

A femoral component attached to the distal end of the femur and having a medial and external condyle inside and outside to form a U-shaped cut that opens to the posterior end between the internal and external condyles, and a proximal tibia U-shaped cut that is attached to the end and has an inner joint surface and an outer joint surface that receive the inner condyle and outer condyle so as to be rotatable and slidable, and opens at the rear end between the inner joint surface and the outer joint surface In a knee prosthesis comprising a tibial component that forms a base and a base that is inserted between the tibial component and the tibia and has a U-shaped cut that is continuous with the U-shaped cut of the tibial component. A U-shaped peg consisting of an anterior wall that is inserted into the anterior part and two sag walls extending backwards into the tibia from both sides of the anterior wall is formed, and the intercondylar bulge in the central part of the proximal end of the tibia Uncut the uncut part from between the front wall and the base wall of the base Incorporate into the U-shaped cut of the tibial component and femoral component, and connect the lower end of the contact part between the inner condyle of the femoral component and the inner joint surface of the tibial component and the contact part of the outer condyle and outer joint surface An artificial knee joint characterized in that the joint line is tilted inward by adjusting the height of each contact portion and lowering the inside from the outside . The artificial knee joint according to claim 1, wherein the inward inclination angle is 1 to 5 °.