NL1009832C2 - Hip replacement. - Google Patents

Description

Title: Hip replacement

The invention relates to a hip prosthesis comprising a first fastening assembly which is intended to be mounted in the hip bone and a second fastening assembly which is intended to be mounted in the upper end of the femur, the first and the second fastening assembly are connected to each other by means of a hinged connection, all parts of the hip prosthesis being so small; and / or slender that they can each be placed in their intended: end position thereof via a bore in the femur, which bore extends from the lateral exterior of the femur through the femur neck substantially in the direction of the imaginary longitudinal axis of the femur neck to the femoral head.

The applicant has described such a prosthesis in the non-prepublished international patent application PCT / NL98 / 00084.

The present application aims to supplement the said international patent application with a number of possibilities for attaching the second l fixing assembly in the femur bore. The subject matter of PCT / NL98 / 00084 is incorporated in the present application by ^

reference to it (English: PCT / NL98 / 00084 is incorporated herein by reference). According to the invention it comprises I

Second securing assembly of the 1 hip prosthesis described in the preamble when mounted a tapered 2 part, wherein a wide, medial side of the tapered part is more close to the femoral neck, while a narrow, lateral side of the tapered 3 part is closer to the outside of the femur.

Since the hip prosthesis is to be placed using the i minimally invasive method, ie through a small incision in the leg through the bore 2 .4

in the femur, the second, fastening assembly from an I

1009832 - 2 number of parts must exist that have the tapered configuration that matches the tapered femoral bore only in an assembled condition. After all, it is not possible to bring a one-piece tapered fastening assembly to the end position via the narrow, lateral side of the tapered femoral bore. Hence, the second fixation assembly of the hip prosthesis according to the invention is only mounted in the femoral bore which has been tapered for this purpose. The tapered bore is tapered from the femoral head to the lateral side of the femur over all or at least part of the length of the bore. With normal loading of the hip prosthesis, for example when the leg is loaded when standing and walking, the tapered second fastening assembly will be pressed more and more tightly into the tapered bore. As a result of this tapered construction of the second mounting assembly, a self-locking action has occurred.

Since all parts of the hip prosthesis must be capable of being placed in their end positions from the lateral side of the bore, special measures must be taken to accommodate the second fastening assembly in the fully or partially tapered bore in the femur. According to a further elaboration of the invention, the hip prosthesis is for this purpose characterized in that the second fastening assembly is provided with a pin, the pin at a free, medial end being provided with means for forming at least a part of the hinged connection, the second The mounting assembly is also provided with at least two retaining elements, which in mounted condition define a hole in which the pin is at least partly received. Preferably, at least one of the retaining elements is provided with a tapered portion that tapers from a medial, pivotally connected end to a lateral end, the retaining elements being dimensioned such that they can be passed through the bore in the femur moved as long as the pin has not been inserted or pushed far into the hip joint cavity.

The locking elements can then be placed separately first in the femur bore, after which the pin can then be placed in the hole bounded by the locking elements. :

During or after placing the pin in the hole delimited by the retaining elements, the pin can be connected to the 10 retaining elements, so that they form one whole hip prosthesis can be provided with means for this purpose according to a further elaboration of the invention.

for connecting the retaining elements and the pin. This Z

Means can have different embodiments which are described in the subclaims and will be further elucidated hereinafter on the basis of a number of exemplary embodiments, with reference to the drawing.

Figure 1 shows a sectional view through the top of the femur in which the second ”

Fastening assembly of a first exemplary embodiment I

of the hip prosthesis is placed; Figure 2 shows a cross-sectional view along the line II-II of Figure 1;

Figure 3 shows a cross section similar to I.

25 shown in Figure 1, wherein a second embodiment of a hip prosthesis is provided; 2 figure 4 shows a cross-sectional view along line IV-“IV from figure 3; Figure 5 shows a detail of the sectional view shown in Figure 4;

Figure 6 shows a similar sectional view as shown in Figure 1 of a third embodiment Z

of a hip prosthesis; :

Figure 7 shows a similar sectional view Z

35 as shown in Figure 1 of a fourth embodiment Z

of a hip prosthesis; and 1009832 4 figures 8a-8e show the different steps of mounting the second fastening assembly in the femur of the embodiment shown in figure 1.

In the figures, only the second fastening assembly of different embodiments of hip prostheses according to the invention is shown in each case. For a complete example of a possible embodiment of a hip prosthesis, reference is made to the international patent application PCT / NL98 / 00084, the material of which is to be regarded herein as interposed. The figures show various embodiments for fastening the second fastening assembly in the femur F. As described in detail in PCT / NL98 / 00084, the parts of the hip prosthesis must be designed such that they can all be placed in the end position through a bore in the femur, which bore extends from the lateral outer side F0 of the femur F through the femoral neck FN substantially in the direction of the imaginary longitudinal axis from the femoral neck to the femoral head. When placing the hip prosthesis, a relatively small incision is made in the leg that provides access to the lateral outside of the femur F. Then, a bore as described above is made in the femur F. The femoral head is removed via this bore with a special tool described in the above-mentioned international patent application. Then, in the hip bone, the first mounting assembly can be mounted through the bore in the femur F. After placing the first mounting assembly, the second mounting assembly can then be mounted. In the present exemplary embodiments, the second mounting assembly when mounted includes a tapered portion C. A wide, medial side of the tapered portion C is closer to the femoral neck FN, while a narrow, lateral side CL of the tapered 1009832 5 tapering portion C is more near the outside FO of the femur F. Because the tapered part of the medial side tapers to the lateral side, the hip prosthesis is pressed more and more firmly into the bore 5 in the femur F during normal loading of the leg. The particular geometry therefore provides the second mounting assembly with a self-locking action. In all the exemplary embodiments shown in Figures 1-7, the second mounting assembly is provided with a pin 3, 10 and 13, 33, 43 respectively. The pin 3, 13, 33, 43 is provided at a free, medial end with means for forming of at least part of the hinged connection.

In the present exemplary embodiments, this part is designed as a ball 4, 14, 34, 44 of a ball joint. It goes without saying that other hinge connections are also possible. To this end - see PCT / NL98 / 00084. The second mounting assembly of the present exemplary embodiments also includes two: 20 retaining elements 1, 2, respectively; 11, 12; 31.32; [41.42. The retaining elements 1, 2; 11, 12; 31.32; 41,42 ~ when mounted, define a hole in which the pin 3,

13, 33, 43 is included at least in part. In the present I

exemplary embodiments are both locking elements 1, 2; 25, 11, 12; 31, 32; 41, 42 provided with a tapered part C which tapers from a medial end CM facing the pivotable connection to a lateral end CL. The retaining elements 1, 2; 11, 12; 31, 32; 41, 42 are dimensioned such that they can be moved through the bore in the femur ~ 30 F as long as the pin 3, 13, 33, 43 is not already inserted or is pushed far into the hip joint cavity. _

The exemplary embodiments of Figures 1-6 are provided with a pin 3, 13, 33 which has a constant cross-section profile at least over a part of its length. -

Also the hole created by the two retaining elements 1, 2; 11, 12; 1009832 6 31, 32 has a substantially constant cross-section profile in which the part of the pin 3, 33 with the constant cross-section profile is at least partly included. Such an embodiment has the advantage that the retaining elements 1, 2; 11, 12; 31, 32 can be brought into their end position, after which the pin 3, 13, 33 can then be placed.

Since in such an embodiment the pin 3, 13, 33 is still relative to the retaining elements 1, 2; 11, 10 12; 31, 32, means must be provided for connecting the retaining elements 1, 2; 11, 12; 31, 32 and pin 3, 13, 33.

In figure 1 these means are formed by screw thread 5 which is arranged on the pin 3. The retaining elements 1, 2 are provided on the lateral end with an internal screw thread which cooperates with the screw thread 5 on the pin 3. In order to prevent that after insertion When the pin 3 is rotated in a certain position a further displacement of the pin 3 occurs, locking means 20 are further provided, which in the present exemplary embodiment comprise a sleeve 6 which is provided with an end wall. The sleeve 6 engages around the lateral ends of the locking elements 1, 2. Furthermore, means are provided for connecting the sleeve 6 to the pin 3. In the present exemplary embodiment, the means for connecting the sleeve 6 to the pin 3 a bolt 7. An end wall bore 9 is arranged in the end wall of the sleeve 6. An extension of this end wall bore 9 is provided with a pin bore 8 in the pin 3. The bolt 7 extends through the end wall bore 9 and engages 30 in the pin bore 8. With the tightening of the bolt 7, the sleeve 6 is further extended over the lateral ends from the retaining elements 1, 2. Because these lateral ends 10 are slightly tapered and, moreover, the inner peripheral wall of the sleeve 6 is also tapered, the retaining elements 1, 2 are pressed together when the bolt 7 is tightened, so that the pin is clamped between the retaining elements. . In addition, the; the tensile force exerted by the bolt 7 prevents the pin 3 from rotating with respect to the retaining elements 1, 2 due to the friction occurring in the threaded connection 5.

In the exemplary embodiment shown in figure 3, the pin 13 has a constant cross-section profile, viewed in the longitudinal direction of the pin 13. Figure 4 clearly shows that in the transverse direction the pin 13 is provided with tapered surfaces 15a, 15b which can be received in the hole bounded by the locking elements 11, 12. 7

In the present exemplary embodiment, the tapered surfaces 15a, 15b and the hole formed by the retaining elements 11, 12 7 are provided with snap edges which prevent an axial displacement of the pin 13 relative to the retaining elements 11, 12. In order to ensure that the tapered surfaces 15 of the pin 13 fit correctly in the:

associated opening in the retaining elements 11, 12 I.

This embodiment is also provided with I.

a sleeve 16 which is provided with an end wall in which an opening 19 is arranged. The sleeve 16 is tightened by means of a bolt 17 which engages in a pin bore 18. ”

Since this sleeve 16 is also provided with tapered I

peripheral walls 20, the retaining elements 11, 12 will be pressed together during tightening of the bolt 17. As the locking elements 11, 12 move towards each other, the tapered surfaces 15 of the pin 13 always come in =

to be more firmly engaged with the associated I.

tapered surfaces in the locking elements 11, 12. The snap-on edge 15 ~ in the tapered surfaces, clearly shown in the detail of figure 4 shown in figure 5,: 7 ensures a firm connection between the pin 13 and the _ confinement elements 11, 12. The tapered outer surface C of the confinement elements 11, 12 ensures that with a normal load on the hip prosthesis, the second: 35 mounting assembly becomes increasingly solid in the femur F ^

printed. I

1009832 '8

In the exemplary embodiment shown in Figure 6, the means for connecting the retaining elements 31, 32 and the pin 33 are formed only by a screw thread 35 provided on the pin 33 and 5 cooperates with the internal screw thread provided on the inside of the locking elements 31, 32.

In contrast to the previous embodiments, the exemplary embodiment shown in Figure 7 has a pin 43 which is tapered over at least part of its length. The tapered pendulum portion tapers from the medial end 43M to the lateral end 43L. The hole bounded by the two retaining elements 41, 42 has a tapered cross-section profile, seen from the medial to the lateral end of the hole, in which the tapered pin part 43 is at least partly received. The connection between the retaining elements 41, 42 and the pin 43 is here established by continuously pulling the pin 43 to the lateral side. This is accomplished in that the means for connecting the retaining elements to the pin include a pull plate 46 and a wire of memory metal 45. The memory metal wire 45 is connected at a first end to a medial end 43M of the pin 43. The second end of the wire 45 is connected to a pull plate 46. The pull plate 46 in mounted condition abuts the outside F0 of the femur F at the lateral end of the femur bore. The memory metal wire 45 is configured so that it tends to shorten at body temperature, so that a tensile stress occurs in the wire. During the placement of the wire 45 it is in a stretched state, so that during placement there is some leeway for the provision of the pin 43 and the retaining elements 41, 42. Although in the figure the retaining elements 41, 42 have a somewhat tapered configuration, this is not necessary since the tapered configuration of the second fastening assembly can also be fully accomplished by the pin 43.

In the exemplary embodiment shown in Figure 7, the retaining elements 41, 42 at the medial end 5 are additionally provided with a collar 47, 48, which is intended for engagement with the cortical bone edges which delimit the medial opening of the femur bore. Optionally, such a collar could also be provided in the other embodiments.

Figures 8a-8e show the successive steps for mounting the second fastening assembly shown in Figure 1. First, the retaining element 1 is placed (Figure 8a); the locking element 2 is then placed (figure 8b); the pin 3 is then inserted into the hole delimited by the retaining elements 1, 2 (figure 8c); the sleeve 6 is then slid over the lateral ends of the retaining elements 1, 2 (figure 8d). Finally, the bolt 7 is tightened, after which the second fastening assembly is mounted in the femur F (figure: 20 8e). It should be noted that before the pin is placed, the retaining elements may temporarily be pushed slightly deeper into the joint, so that the hole delimited by the retaining elements 1, 2 is slightly wider for inserting the pin 3. Then the r Retaining elements 1, 2 are retracted laterally into their end positions, after which the connection between the pin 3 and the retaining elements 1, 2 is established.

It will be clear that the invention is not limited to the described exemplary embodiments, but that various modifications are possible within the scope of the invention.

1009832

Claims (12)

1. Hip prosthesis provided with a first mounting assembly intended to be mounted in the hip bone and a second mounting assembly intended to be mounted in the upper end of the femur (F), the first and second mounting assemblies using a hinged connection are connected to each other, with all parts of the hip prosthesis being small and / or slender such that they can each be placed in its curved end position via a bore in the femur (F), which bore extends from the lateral outside (Fo) = from the femur (F) through the femoral neck (Fn) substantially in the direction of the imaginary longitudinal axis from the femoral neck (Fn) to the femoral head, the second mounting assembly being mounted in a tapered portion (C) wherein a wide, medial side (CM) of the tapered portion (C) is closer to the femoral neck (Fn) while a narrow, lateral side (CL) of the The tapered portion (C) is more near the outside (Fo) of the femur (F). Hip prosthesis according to claim 1, characterized in that the second fastening assembly is provided with a pin (3; 13; 33; 43), the pin being provided at a free, medial end with means (4; 14; 34; 44) to form at least a part of the hinged connection, wherein the second mounting assembly is also provided with at least two locking elements (1, 2; 11, 12; 31, 32; 41, 42), which in the mounted state have a hole boundaries in which the pin (3; 13; 33; 43) is at least partly included. Hip prosthesis according to claim 2, characterized in that at least one of the retaining elements (1, 2; 11, 12; 31, 32; 41, 42) is provided with a tapered part (L) which is 1009832 11! tapers from a medial pivotable end (CM) to a lateral end (CL), the retaining members (1, 2; 11, 12; 31, 32; 41, 42) being dimensioned by the 5 bore in the femur (F) can be moved as long as the pin (3; 13; 33; 43) has not yet been inserted or pushed far into the hip joint cavity. Hip prosthesis according to claim 2 or 3, characterized in that the pin (3; 13; 33) has at least a part of its length of a substantially constant cross-section profile, the hole containing the at least two locking elements ( 1, 2; 11, 12; 31, 32) have a substantially constant cross-section profile in which the part of the pin (3; 13; 33) with the constant cross-section profile is at least partly included. Hip prosthesis according to claim 2 or 3, characterized in that the pin (43) over at least part of the; length thereof is tapered, with the tapered pendulum portion tapered from the medial end to the lateral end, the hole bounded by the at least two retaining members a tapered as viewed from the medial to the lateral end of the hole. cross-section profile in which the tapered pendulum section is at least partly included. Hip prosthesis according to any one of claims 1 to 5, characterized in that the second fastening assembly is provided with two locking elements (1, 2; 11, 12; 31, 32; = 41, 42), each of which is provided with a tapered portion (C) that tapers from a medial end (CM) to a lateral ~ 30 end (CL). Hip prosthesis according to any one of claims 2-6, characterized by means (5-10; 15-20; 35; 45, 46) for connecting the locking elements and the pin. Hip prosthesis according to claim 7, characterized in that the means (5-10; 15-20; 35; 45, 46) for connecting the locking elements and the pin thread, 1009832 tapered clamp connections, snap and / or snap connections and / or the like. Hip prosthesis according to claim 7, characterized in that the means for connecting the locking elements 5 and the pin (3; 13) comprise a sleeve (6; 16) provided with an end wall, the sleeve (6, 16) engages the lateral end of the retaining members (1, 2; 11, 12), means (7-9; 17-19) being provided for connecting the sleeve (6; 16) to the pin (3; 13), the circumferential wall (10; 20) of the lateral ends of the retaining elements (1, 2; 11, 12) being slightly tapered with the inner circumferential wall of the sleeve being slightly tapered so that when fixing the means (7 -9; 17-19) for connecting the sleeve (6; 16) to the pin (3; 13) the 15 retaining elements (1, 2; 11, 12) are pressed together so that the pin (3; 13 ) is clamped between the retaining elements (1, 2; 11, 12.). Hip prosthesis according to claim 9, characterized in that the means (7-9; 17-19) for connecting the sleeve 20 (6; 16) to the pin (3; 13) a bolt (7; 17) the end wall having an end wall bore (9; 19) which is in line with a pin bore (8, -18) arranged in the pin (3; 13), the bolt (7; 17) extending through the end wall bore (9; 19) and engages the pin bore (8; 18). Hip prosthesis according to any one of claims 2-10, characterized in that the retaining elements (41, 42) at the medial end are provided with a collar (47, 48) intended for engagement with the cortical bone edges (Fn) 30 defining medial opening of the femoral bore. Hip prosthesis according to claim 7, characterized in that the means (45, 46) for connecting the locking elements (41, 42) to the pin (43) comprise a pull plate (46) and a thread of memory metal, the thread Memory metal (45) with a first end is connected to a medial end of the pin (43) and a second 1009832 end is connected to the pull plate (46), the pull plate (46) abutting in abutment against the outside ( Fo) of the femur (F) at the lateral end of the femur bore, the wire 5 of memory metal (45) tending to shorten at body temperature, so that a tensile stress in the wire (45) occurs. 1009832 z