CZ2015793A3 - Trapezium replacement - Google Patents

Abstract

Trapezium replacement for total trapeziometacarpal joint endoprosthesis consists of an implantable replacement body (1) with an internal antilux liner (2) in which a spherical recess (3) is formed for the endoprosthesis head, with the implanted body (1) having at least one transverse fixation an opening (4) for extending the fixation tendon. The replacement body (1) is preferably provided with two through-holes (5) for bone screws (6), one of which is intended to be inserted into the base of the second metacarp and the other into trapezoidea.

Description

Trapezoidal Replacement Technique

BACKGROUND OF THE INVENTION The present invention relates to a trapezium replacement for total endoprosthesis of the trapeziometacarpal joint of the thumb when it has to be extirpated.

Background Art

For total endoprosthesis, several types of these articular implants are currently used in a variety of designs, which can also be made of different materials. The metacarp base, the articular surface of the trapezium or the entire joint may be replaced. Silicone, ceramic, metal with polyethylene substitutes are known, with one or two stems and non-cemented or cemented substitutes. The entire assembly of such total endoprosthesis consists of a metacarpal component, respectively. shank, neck with head and trapezial components in the form of an articular hole. In its optimum design, the articulated hole for cementless replacement is made of cobalt-chromium-molybdenum alloy with an external porous titanium coating and an inner ceramic like diamond like carbon, usually made of a cemented replacement. polyethylene.

U.S. Pat. No. 4,955,916 discloses a total replacement of the trapeziometacarpal joint in which both the metal metacarpal and trapezium components are threaded on their surface to secure in the bone. The trapezoidal part has a conical surface and is fitted with a polyethylene insert and the articulated hole has a meshed titanium disc in its bottom to interact with the bone.

U.S. Pat. No. 5,507,822 discloses a two-part construction of this articular replacement, the metacarp-based replacement component of which is terminated by a well, and the component replacing the articulating surface of the trapezium is terminated by the head. This is the so-called reverse type replacement with the inverted head and hole.

FR 2 670 109 discloses a three-part construction of such an articulated restoration, which consists of a trapezoidal component in the form of an articulated cup-like joint, which is provided with peripheral ribs on its outer surface, and a central component in the form of a straight shaft provided at one end thereof. a spherical head for insertion into the trapezoidal component and at the other end a cone for connection to the metacarpal component, the metacarpal component having a central conical hole for the Morse cone of the central component and an end thread for the insertion rod. Another French patent publication FR 2 755 005 discloses a method of placing a total replacement of the trapeziometacarpal joint, a method of positioning it and selecting a length, wherein the actual construction of the implant is not further specified in this specification. The Czech utility model 21565 is known for the articulation of the base of the first metacarp of the thumb, consisting of a stem and a head, the stem being formed by a pair of consecutive bodies where the first has the shape of a truncated pyramid while the other is a self-cone shape. The detachable head is then provided with a recess in the form of a self-locking cone in which the second shaft body is fixed in a self-locking manner. However, this construction replaces only one articulating part of the joint and does not replace the articulating area of the trapezium. Furthermore, a modular articular implant for total replacement of the trapeziometacarpal joint is known from the Czech utility model 25733, in which the trapezoidal articular hole is provided with at least one conical stabilizing projection, which is arranged on its canopy and in which a central opening is formed, which can be closed with an inner plug. and, on the other hand, by an outer peripheral ring with a set of fixing transverse ribs with an anchoring edge at their edges. Here, the central hole serves to guide the well through the guide wire. If a cranked connecting shaft is used to connect the trapezoidal articulated well and the metacarpal anchoring stem, in which the articulated shaft and mounting cone axes are misaligned, for example, at an angle of 15 °, the locking shaft is provided with a locking element and a metacarpal shaft with a locking pawl to prevent mutual rotation. . The modularity of this articular implant then consists in the fact that all its components are arranged in sets into a series of graduated rows and are interchangeable.

However, a considerable disadvantage of virtually all of these known total endoprostheses for the replacement of trapeziometacarpal joint is the fact that none of them can be used in cases where total trapezoidal destruction has occurred and therefore the trapezial total endoprosthesis component cannot be anchored to it. This may occur especially during reoperations, but these complications must be taken into account also during primooperations.

SUMMARY OF THE INVENTION

This disadvantage of the prior art is largely eliminated by the replacement of the trapezium for total trapeziometacarpal joint endoprosthesis according to the present invention, which consists of an implantable replacement body with an inner antilux liner in which a spherical recess for the endoprosthesis head is formed, the implanted replacement body is provided with at least one transverse fixation, preferably oval, aperture for extending the fixation tendon to ensure stability of the trapezium replacement.

Of course, as is generally common in implants, the replacement body is made of a biocompatible material, such as a cobalt-chromium-molybdenum alloy, a polyether-ether ketone, referred to as PEEK, or titanium, and the like. usually made of polyethylene.

Furthermore, the essence of the invention is that the replacement body is further provided with two through holes for bone screws for one additional fixation, one of which is intended to be inserted into the base of the second metacarp and the other into trapezoidea. This additional fixation is very suitable and it is up to the surgeon to consider whether to use, for example, permanent or absorbable screws with a sufficiently long "full" load bearing capacity, while the two screws are mutually interchangeable in optimum performance of this additional fixation.

The invention furthermore relates to the fact that, in the replacement body, an inner recess is offset relative to the body axis for inserting the inner anti-adhesive sleeve, the mutual contact surfaces of the inner anti-adhesive sleeve and the internal recess being formed by self-locking tapered surfaces preventing their relative rotation. By displacing the anti-lining insert in the body of the restoration, the position of the ball joint of the insert and the inserted head is matched to the original joint anatomy. In this case, the misalignment is optimally carried out in the direction of the trapezoid and can usually be in the range of 0.5 to 3 mm, depending on the size of the replacement body.

Furthermore, the invention is based on the fact that the inner anti-adhesive liner, which, as mentioned above, is usually made of polyethylene, is preferably provided with an outer shoulder which engages when the anti-liner is pushed into the body of the restoration into a recess formed therein. internal recess. The outer shoulder of the anti-lining insert and the recess in the inner recess of the replacement body are arranged at the lower edge of their abutting self-locking conical surfaces. This measure further protects the position of the anti-liner in the body of the restoration and prevents the risk of falling out.

Finally, the essence of the invention is that the replacement body is preferably of a non-rotating shape, preferably a barrel-shaped oval or elliptical cross-section, thereby preventing possible rotation of the body of replacement in the surrounding tissue. A concave surface is also preferably formed into the interior of the body from the underside of the replacement body for optimum abutment on the scafoideum. In particular, this concave surface is rotationally shaped, for example in the form of a spherical cap, for manufacturing reasons. The advantage of this replacement is the fact that its implantation requires minimal trapezoid resection. In the event that the surgeon decides to exacerbate the trapezium, this replacement will fully replace the original trapezial component in the trapeziometacarpal total endoprosthesis assembly. The trapezium replacement of the present invention may be available in a graduated size series, depending on the need of the practitioner, typically three sizes are usually sufficient. BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be further illustrated by the exemplary embodiment of a trapezium replacement for a trapeziometacarpal joint endoprosthesis according to the invention, wherein:

FIG. 1 - Plan trap replacement

FIG. 2 - Trapezoid replacement in side view a

FIG. FIG. 1 and FIG. 2 show an enlarged cross-section of the trapezium replacement of FIG. 1 and FIG. 2. Embodiment of the trapezium for total trapeziometacarpal joint endoprosthesis in this particular embodiment consists of the implantable implant body 1 made of polyether according to FIGS. with a polyethylene inner antilux liner 2. In the polyethylene inner antilux liner 2, a 5 mm diameter recess 3 is formed to push the head of the endoprosthesis neck (not shown) into its interior. The body and the replacements are provided with an oval transverse fixation hole 4 of 4 mm in length and 2 mm in width for extending the fixation tendon and, on the other hand, two through holes 5 shown in FIG. 2 for two mutually different 2 mm bone screws 6 of which one is intended for introduction into the 2nd metacarp and the other into the trapezoidea. In the two through holes 5, a one-sided recess H for the heads of these bone screws 6 is formed in FIG.

As can be seen from FIG. 3, an offset inner recess 7 is formed in the body and the replacement of the inner antilux liner 2 with respect to the axis of the body, wherein the abutment surfaces of the internal antilux liner 2 and the internal recess 7 are formed by self-locking tapered surfaces 8.

3, the barrel-shaped body of the barrel-shaped oval cross-section is formed, and a concave surface 12 in the form of a spherical canopy with a radius of 10 mm and a depth of 1.5 mm is formed from the underside of the barrel. optimal abutment of the body 1 of the replacement on the scafoideum.

As can also be seen from FIG. 3, the inner antilux liner 2 is provided with an outer shoulder 9 engaging a recess 10 which is formed in the inner recess 7 of the body and the outer shoulder 9 of the anti-lining insert 2 and the recess 10 in the inner recess 7 are arranged beneath the upper edge of their abutting conical surfaces 8.

INDUSTRIAL APPLICABILITY The substitution of the trapezium according to the invention can basically be used for all existing types of modular total trapeziometacarpal joint endoprostheses instead of their original trapezial components. The condition is only the same diameter of the articulation surfaces of the trapezium replacement insert and the inserted neck endoprosthesis head.

Claims (5)

PATENT CLAIMS 1. Replacing a trapezium for total trapeziometacarpal joint endoprosthesis, characterized in that it comprises an implantable replacement body (1) with an internal antilux liner (2) in which a spherical recess (3) is formed for the neck of the endoprosthesis head, the implanted body (1). ) of the restoration is provided with at least one transverse fixation opening (4) for extending the fixation tendon. A trapezium replacement according to claim 1, characterized in that the replacement body (1) is further provided with two through-holes (5) for bone screws (6), one of which is intended to be inserted into the base of the second metacarp and the other into trapezoidea. Trapezoidal substitute according to claim 1 and 2, characterized in that an inner recess (7) is disposed relative to the body axis (1) in the replacement body (1) for inserting the inner anti-lining insert (2), wherein the inner surfaces of the internal antilux the inserts (2) and the inner recesses (7) are formed by self-locking conical surfaces (8). A trapeze replacement according to any one of claims 1 to 3, characterized in that the inner antilux liner (2) is provided with an outer shoulder (9) engaging the recess (10) which is formed in the inner recess (7) of the body (1) , wherein the outer shoulder (9) of the antilux liner (2) and the recess (10) in the inner recess (7) are arranged on their abutting self-locking conical surfaces (8). Trapezoid replacement according to at least one of the preceding claims, characterized in that the replacement body (1) is of barrel-shaped oval cross-section, a concave surface (12) for engaging the body from the underside of the body (1). (1) scafoideum substitutes.