DE4407227A1 - Femoral prosthesis assembly - Google Patents

Abstract

The femoral prosthesis assembly comprises a femoral shank (1) designed to receive a series of necks (2) connected to a spherical head. Each neck consists of a conical base (2a) which fits into a matching recess in the proximal end of the shank, and has an adjustable positioning element (2b) on its end which can be set at different angles. The opposite end of the neck has a truncated conical tip (2c) which engages with a socket in the spherical head.

Description

The invention relates to the technical field of surgical implants, especially of the hip prostheses.

It is well known to those skilled in the art that a Hip prosthesis has a thigh shaft that leads to Driving into the medullary cavity of the femur is determined. The upper part of the shaft is through a angled as a neck piece that extends to the immediate or attached recording one together with the Osilium socket acting spherical femoral head is. Such prostheses are for driving into the Marrow cavity designed with or without binding agents.

One problem that arises here is regulation the anteversio of the neck piece, namely the prosthesis and especially the thigh shaft with a anatomical shape licher in the thigh bone in one of its large ellipses Angle jammed.

The anatomical angle corresponds in numerous cases the anteversio is not the anteversio angle of the neck piece in relation to the shaft. In certain cases the anatomical angle can range from 15 degrees is far larger than about 60 degrees. This results in a high risk of dislocation Prosthesis, because in this case the angle of the neck piece of the thigh shaft no longer the anatomy of the corresponds to the patient concerned.  

As an attempt to avoid these disadvantages, ins especially in the area of the neck piece modular hips prostheses proposed. For that purpose it is proximal part of the thigh shaft to each other inserted a number of neck pieces directed the different angular orientations to the Adjust to the anatomical angle in question have any pathological case to be treated. This state of the art can be achieved through the teaching of Patents FR 85 06 214, FR 89 00 871, FR 91 03 150, FR 89 11 677 and FR 86 15 930 are explained. This ver Different patents show different solutions for Adjustment of the neck piece in the area of the shaft.

However, the proposed solutions are not full always satisfactory, because on the one hand they are not the Obtaining various angular orientations in allow a horizontal plane and on the other hand if they allow such alignment, this are not controllable what is happening at the moment of on driving or selection by the user as can highlight problematic.

The invention aims to overcome these drawbacks safer, easier and more effective way too avoid.

The problem to be solved by the invention is after Choice of different angular orientations of the neck piece depending on the case to be treated, to be able to control the rotation of the Neck piece in relation to the thigh shaft itself the relevant anatomical anteversio angle to get complete stability.  

To solve this problem, a module unit for a hip prosthesis with a thigh shaft that fits in attachable and interchangeable way a number of for Interacts with a spherical femoral head designed neck pieces, proposed and executed. According to the invention, each neck piece has a common frustoconical base piece on the at an angle to the proximal part of the shaft and in an angled manner to its vertical axis formed recess with complementary truncated cone like shape can be inserted, the base piece is extended by a positioning element that for Engagement in various angular orientations complementary, based on the recess brought formations with the provision of the angled Blocking designed in the desired position is.

To solve the problem posed, a rotation inhibited Ensuring stability is the positioning element formed as a protrusion.

Advantageously, the projection piece is coaxial with that truncated cone-shaped base piece and extends essentially over the entirety of its size.

To solve the problem, various controllable, angular orientations in the hori to maintain the zonal level are those in the bottom of the Complementary recesses introduced in the recess formed by recessed impressions that are angled in Are arranged in relation to each other.

The impressions are advantageously in a Number of two by 90 degrees, with a number of three by  60 degrees or 45 out of four puts.

Based on this basic concept and the posed Taking into account problem, a variety of be corresponding anteversio corresponding angular Aus getting directions is either the conical Base piece of each neck piece the positioning element opposite coaxially through a thigh head receiving, frustoconical extension piece extended or the conical base piece under ver different angular orientations by a waiter femur head, frustum-like ver Extension piece extended.

The invention is hereinafter with reference to the Drawings described in more detail, wherein

Fig. 1 is a partial view of the proximal portion is one designed according to the invention femoral stem,

Fig. 2 is a plan view of the collar,

Fig. 3 is a side view according to Fig. 2,

Fig. 4 is an enlarged scale Fig. 1 corresponding bottom view showing the shape of the indentations,

FIGS. 4a and 4b further arrangements of embossings show

Fig. 5 is an enlarged scale Fig. 3 corresponding view from above, showing the Positioniervorsprungstück,

Fig. 6 the attachment of the neck piece in the area of the corresponding part of the upper leg upper displays,

FIGS. 7 and 8 in any way limiting examples of modular neck pieces in ver different angular orientations show and

FIGS. 9 and 10 in an enlarged scale sectional views along the line AA of Fig. 6 showing different angular orientations of the neck portion in the horizontal plane.

In a known manner, the module unit has a thigh shaft, which is identified in its entirety by the reference number 1 and which, in the attached manner, receives a number of neck pieces 2 . The neck pieces are provided with a spherical thigh head 3 (dashed line in Fig. 6).

Each neck 2 has a common frustoconical base piece 2 a. This base piece 2 a is designed for insertion into a truncated cone-like recess 1 a with a complementary shape, which is introduced into the proximal part of the thigh shaft 1 . In particular, the recess 1 a is arranged at an angle with respect to the vertical axis of the shaft ( FIG. 1).

According to an important feature of the invention, the truncated cone-like base piece 2 a has a positioning element 2 b that projects over its underside, which is designed to engage in the bottom of the recess 1 a that has complementary shapes 1 b. In particular, this positioning element 2 b, as shown in FIGS. 2, 3 and 5, is formed by a protrusion flattened in cross section. This projection piece 2 b is coaxial with the frustoconical base piece 2 a and extends essentially over the entirety of its small base area ( Fig. 5). The parallel, rectilinear edges 2 b1, 2 b2 of the projection piece 2 b are laterally connected to each other via a semicircle 2 b3.

The introduced in the bottom of the frustoconical recess 1 a of the shaft, complementary formations 1 b are formed by diametrically cruciform, with respect to each other angularly arranged impressions around the neck piece 2 different angular orientations in a horizontal plane depending on the engagement of the projection piece 2 b in one or the other of the imprints 1 b. Advantageously, as shown in Fig. 4, the impressions are arranged two in number and symmetrically at 90 degrees to form a cross.

However, other arrangements of the impressions 1 b are not excluded. For example, as shown in Fig. 4a, the impressions are three in number and offset by 60 degrees. According to FIG. 4b, the impressions are four in number and offset by 45 degrees.

It is therefore possible to obtain an alignment of the neck piece 2 with respect to the shaft 1 by successive jumps of 90 degrees, 60 degrees or 45 degrees. In the same way as for the flat piece 2 b, the lateral edges of the impressions are formed by a semicircle 1 b1.

The conical base piece 2 a of each cone is extended on the side opposite the flat piece 2 b by a truncated cone-shaped spacer 2 c, which is designed to receive the femoral head 3 . This frustoconical spacer 2 c can either be formed coaxially to the frustoconical base piece 2 a ( FIG. 6) or at an angle to this base piece. In the latter case, the frustoconical spacer 2 c in a variety of angular orientations α, β,. . . ( Fig. 2, 7, 8). It should be noted that, in a known manner, the frustoconical base piece 2 a and the spacer 2 b can be joined together directly or via intermediate spacers 2 d, 2 e.

Significantly, the intermediate areas 2 d, 2 e of the attachment can allow a variable, lateral offset δ, which is known under the name "ante position" (dashed line in FIG. 7). This lateral offset δ is independent of the modular principle of the angular orientation α, β,. . . , which is known as "Anteversio".

It is found that by combining different possible angular orientations of the neck piece 2 and its assembly in the thigh shaft under different controllable, angular orientations which result from the engagement of the flat piece 2 b in one of the impressions 1 b, a variety of receives angular orientations of the neck piece 2 with respect to the shaft 1 .

Of course, the thigh shaft 1 can have different cross-sectional profiles and other devices for driving into the medullary cavity with or without binders.

The advantages are clear from the description, in particular it should be underlined and stated:

• - the controlled angular alignment of the neck piece in terms of the shaft,
• - the rotationally inhibited stability,
• - The variety of angular orientations that are caused by combining different configurations of the Neck piece and its angular positioning in Regarding the shaft with the effects of the anteversio and the anteposition and
• - the simplicity of regulation around the axis of the Neck piece by using the play of the mov Lichen neck piece in trials before use.

Claims (9)

1. Module unit for a hip prosthesis with an upper leg shaft ( 1 ), which can be attached and replaced. A number of to cooperate with a spherical femoral head ( 3 ) from designed neck pieces ( 2 ), characterized in that each neck piece ( 2 ) has a common truncated cone-like base piece ( 2 a), which is at an angle to the proximal part of the shaft ( 1 ) and in an angular manner to its vertical axis formed recess ( 1 a) with a complementary frustoconical shape is insertable, the base piece ( 2 a) is extended by a positioning element ( 2 b) which for engagement in Different angular orientations in complementary, on the bottom of the recess ( 1 a) formed formations ( 1 b) is designed with the provision of the angular blocking in the desired position. 2. Module unit according to claim 1, characterized in that the positioning element is formed by a projection piece ( 2 b) with a flattened, symmetrical cross section. 3. Module unit according to claim 2, characterized in that the projection piece ( 2 b) is formed coaxially to the frustoconical base piece ( 2 a) and extends substantially over the entirety of its size. 4. Module unit according to claim 1, characterized in that in the bottom of the recess ( 1 a) of the shaft ( 1 ) introduced from complementary formations ( 1 b) are formed by angularly aligned from one another, cross-shaped impressions. 5. Module unit according to claim 4, characterized in that the impressions ( 1 b) are two, three or four in number and are offset by 90 degrees, 60 degrees or 45 degrees. 6. Module unit according to one of claims 2 to 5, characterized in that the straight edges of the projection piece ( 2 b) and the impressions ( 1 b) are connected to one another via a semicircle. 7. Module unit according to claim 1, characterized in that the conical base piece ( 2 a) of each neck piece, the positioning element ( 2 b) opposite is coaxially extended by a truncated cone from spacer ( 2 c) which receives the upper leg head. 8. Module unit according to claim 1, characterized in that the conical base piece ( 2 a) of each neck piece, the positioning element ( 2 b) opposite with different angular orientations is extended by a truncated cone-shaped spacer ( 2 c) which receives the femoral head. 9. Module unit according to one of claims 7 and 8, characterized in that the conical base piece ( 2 a) opposite the positioning element ( 2 b) is extended by intermediate connection spacers under different lateral displacements by a conical spacer and a truncated cone-like spacer ( 2 c) that picks up the thigh head.