DE9402934U1 - Prosthetic handle for the replacement of the hip joint (thigh part) - Google Patents

Description

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Prof. Dr. med. K. Diehl Am Homburg 86, 21.02.1994

66113 Saarbrücken

Subject: Registration «in·· prosthetic stem for replacement of the hip joint·« for

User protection

The application covers the femoral part of an artificial hip joint. This consists of a stem which is anchored in the medullary cavity of the femur. A prosthetic neck with a conical end is attached to the stem to accommodate the hip joint ball. This joint ball is attached in the form of a metal or ceramic ball. The axis of the neck forms a neck-shaft angle of 140 degrees with the axis of the stem in the frontal plane (Fig. 1,3).

The handle is made of metal and is extra long.

The distal 2/3 of the stem is designed as a slightly tapered rod, which, after implantation in the thigh, is in line with its longitudinal axis (Fig. 1,2 and Fig. 1,3). The proximal part of the stem, close to the joint, widens in the frontal plane in a triangular shape, which takes a medial inclination of 14-0 degrees to the frontal axis of the remaining, distal part (Fig. 1,3).

In the sagittal plane, the 2/3 of the stalk furthest from the body run straight, rod-like, as in the frontal plane, with a constant, slight taper. The part of the stalk closest to the hip joint (proximal part) shows a backwards convex curve with a radius of the length of the stalk in the sagittal plane (Fig. 1,2). The long axis of this proximal stalk area forms an angle of 10 degrees in the sagittal plane with the long axis of the remaining stalk section (Fig. 1,2). This causes a displacement of one third of the stalk width there (in the sagittal plane) ventrally (front) at the base of the stalk's neck (Fig. 1,2). With this sagittal curve, the stalk follows the curve of the femoral shaft, which is also curved backwards convexly near the hip.

The stem has a rectangular cross-section in the section facing the hip joint (proximal section) (Fig. 1,1), the rest of the stem has a square cross-section (Fig. 1,1).

Parallel to the stem axis in the frontal plane, bars with a rectangular profile are inserted on both the ventral and dorsal surfaces of the stem (Fig. 1.3 and Fig. 1.1). One of the bars runs on both the ventral and dorsal surfaces of the stem exactly in the frontal axis over the entire length of the stem (Fig. 1.3). In the hip joint or proximal area of the stem, two further bars are attached, which run parallel to the first bar (Fig. 1.3).

-2-

The handle described represents a basic form, which can be rounded off by further processing so that, depending on the degree of further processing, both

a profiled handle with different profile shapes and profile depths as well as a slightly profiled or unprofiled handle can be produced.

The different possibilities of ready-to-implant stems after removal are shown as examples in Figure 2.

Figure 2.1 shows the cross-sections of the basic shape of the handle. Figure 2.4 shows a strongly profiled handle, which is created from the basic shape after rounding off the edges.

Figure 2.2 shows the cross-sections of a stem with reinforced rounding, which has medially and laterally rounded edges for even force transmission to the thigh.

Figure 2.3 shows the stem cross-section after further rounding by removal. The profile, which was still deep in Figures 2.4 and 2.2, has become increasingly flatter. Figure 2.5 shows the cross-section of the stem after extensive removal. What remains is an initially oval cross-section that becomes almost round further distally.

The basic shape of the handle (Fig. 2,1) is based on the idea of giving it special cross-sectional shapes for

cement-free anchoring

as well as for cementable implantation from the basic form.

The stem with the cross-sections shown in Figure 2.4 and Figure 2.2, with their deep profiles, have good prerequisites for cement-free implantation. The additional bars particularly absorb the torsional forces in the sagittal direction that occur when walking.

The stems with the cross-sections in Figure 2.3 and Figure 2.5, however, are suitable for cemented implantation.

In addition, the basic shape of the stem can be changed by K U r ζ e �eegr; so that less medullary space in the femoral shaft is filled during implantation.

-3-

Figure 3 shows such a handle in basic form, shortened to a standard size. The special profiles mentioned above for cement-free and cemented use can also be produced from the shortened basic handles by removing material.

Claims (3)

Generic term: Protection claims (two-part form) 1. Prosthesis style for replacement of the hip joint (thigh part) characterizing part: characterized in that the style is made of metal and has an extra length, a prosthetic neck with a conical end is attached to the stem to accommodate the metal or ceramic hip joint ball, the axis of the neck forms a neck-shaft angle of 140 degrees with the axis of the stem in the frontal plane (Fig. 1,3), the distal 2/3 of the stem are designed as a rod in a slightly tapered manner, which, after implantation in the thigh, is in line with its longitudinal axis (Fig. 1,2; 1,3), the proximal part of the stem near the joint widens in the frontal plane in a triangular shape, which takes on a medial inclination of 140 degrees to the frontal axis of the right, distal part (1,3), the distal 2/3 of the stem in the sagittal plane and in the frontal plane run straight in a rod-like manner with a constant slight taper, the part of the stem near the hip joint (proximal part) in the sagittal plane (Fig. 1,2) shows a backward convex curvature with a radius of the stem length, the longitudinal axis of the proximal stem area in the sagittal plane forms an angle of 10 degrees with the longitudinal axis of the remaining stem section (Fig. 1 _? 2), whereby a displacement of one third of the stem width there (in the sagittal plane) ventrally (front) occurs at the base of the neck of the stem (Fig. 1,2), the style follows the sagittal curvature of the femoral shaft, which is also curved backwards in a convex manner near the hip, the stem in the section facing the hip joint (proximal section) has a cross-section of rectangular shape (Fig. 1,1), the rest of the stem area has a square cross-section (Fig. 1,1), on the ventral and dorsal surfaces of the stem, bars with a rectangular profile are inserted parallel to the stem axis in the frontal plane (Fig. 1.3 u» 1.1), one of the bars on both the ventral and dorsal surfaces of the stem runs exactly in the frontal axis over the entire length of the stem (Fig. 1.3), two further bars are attached in the area of the stem near the hip joint, which run parallel to the first bar (Fig. 1.3), The style offers the possibility of both cementless anchoring and cementable implantation. General term of the sub-claim: 2. Prosthetic style according to claim 1, characterising part of the dependent claim: characterized in that - the basic form of the style described under No. 1 can be rounded off by further processing so that both a profiled style with different profile shapes and profile depths as well as a only slightly profiled or unprofiled style
can be produced (Fig. 2). General term of the sub-claim: 3. Prosthesis style according to claim 1 characterising part of the dependent claim: characterized in that the basic shape of the stem can be changed by shortening it so that less medullary space in the femoral shaft is filled during implantation (Fig. 3), the special profiles for cement-free or cemented use can be produced by removing them