DE2854334C3 - Thigh-hip joint endoprosthesis - Google Patents

Description

The invention relates to a thigh-hip joint endoprosthesis for cementless implantation with a Shank which runs in the longitudinal direction of the thigh bone and is inserted into a bore in the bone and a joint head associated with the joint socket and running in the direction of the femoral neck supporting femoral neck part, wherein the shaft has a cylindrical tube and a head area, which is provided with a threaded hole into which the femoral neck part is screwed.

Such an endoprosthesis is described in DE-OS 25 58 446. Before inserting this The entire femoral neck and essential parts of the trochanter massif are to be removed from the prosthesis. this represented a considerable loss of bone substance or substantial bone damage. Above that there is also the risk of positional errors in the femoral neck part. With the prosthesis according to the DE-OS 25 58 446, their firm fit in the longitudinal direction of the bone depends solely on the fit of the shaft. Through this the primary hold required for the prosthesis to grow in cannot be achieved. This makes one Permanent anchoring of the endoprosthesis in the bone unsafe.

In DE-OS 23 18 396 an endoprosthesis is described, which consists of a shaft, a shaft neck and a joint head is put together. In order to be able to use the shaft and the shaft neck, the entire femoral neck of the bone is removed.

In addition, a cavity must be created in the trochanter massif to accommodate the shaft neck. Of the The hold of the endoprosthesis in the bone depends solely on the seat of the shaft in the bone. A form-fitting There is also no connection here that could promote the ingrowth of the prosthesis.

In DE-OS 25 14 793 there is another endoprosthesis with a shaft and a femoral neck part described. To insert this endoprosthesis, the femoral neck of the bone must also be removed. And that The trochanter massif is largely hollowed out. Here, too, parts of the bone must be removed, which could be used to anchor the prosthesis. A form-fitting

The anchoring of the endoprosthesis in the pulling direction is primarily through a self-tapping external thread of the Given the shaft. The femoral neck part itself does not contribute to holding the prosthesis in the bone.

The object of the invention is to design an endoprosthesis in which the natural femoral neck to Insertion of the endoprosthesis does not have to be removed and the trochanter massif does not have to be hollowed out the femoral neck part in a bore in the femoral neck stump and the shaft through a bore in the Insert the trochanter massif and insert it into the inserted endoprosthesis for secure ingrowth Cancellous bone can be introduced, with the shaft and the femoral neck part and the endoprosthesis with the Bones should be connected.

According to the invention the above object is achieved in that the threaded hole in one of the natural Femoral neck angle corresponding angle is arranged in the head region of the shaft and the femoral neck part has a threaded portion which is screwed into the threaded hole that in the head area a Fübohrung is arranged, which in the Rohrbereäch opens out, and that the pipe area has outside in ^ longitudinal direction grooves at the bottom Breakthroughs are provided.

As a result of the invention, the endoprosthesis is firmly seated in the bone immediately after the operation guaranteed, since on the one hand the shaft lying in the medullary canal is seen in the longitudinal direction of the bone sits firmly in the bone and on the other hand the femoral neck part rigidly connected to the shaft enclosed on its circumference by the bore of the femoral neck stump and the trochanter massif is. A permanently firm fit of the endoprosthesis in the bone - without the use of cement - results from the positive fit of the endoprosthesis in all directions Bone and the ingrowth of the endoprosthesis in the bone, which is introduced by cancellous bone, which can be inserted into the inserted shaft and, if necessary, the inserted thigh neck part in such a way that it is distributed between these endoprosthesis parts and the bone.

During the operation, the femoral neck of the bone and especially the trochanter massif need for it Insertion of the shaft and the femoral neck part not to be removed, so an essential Bone damage, in particular a loss of bone substance with the insertion of the endoprosthesis, does not connected is. To insert the endoprosthesis, only two drill holes of different sizes are required, namely a larger axial and a smaller one laterally in the trochantet massif or the femoral neck stump. That Removal of the deformed or broken femoral neck head is an inevitable Need. However, this does not mean any significant loss of substance.

Because the femoral neck or the femoral neck stump of the femur is not removed rotation and positioning errors of the endoprosthesis are avoided from the outset, since the hole in which the Femoral neck part is to be used, aligned according to the femoral neck stump.

In an advantageous development of the invention, has the head area has at least one pressure compensation bore which runs in the longitudinal direction of the head part And opens into the pipe part. That’s a biological one Pressure equalization guaranteed, on the one hand on the operated leg and on the other hand has a beneficial effect on the ingrowth of the endoprosthesis

In a preferred embodiment of the invention, the threaded section screwed into the shaft settles of the femoral neck part on the opposite side of the joint head continues into a pin that consists of the Shaft protrudes and towers over the trochanter massif. A cross anchoring is thus achieved, through which the femoral neck part is fixed to the shaft

ίο not only lies on the inside of the femoral neck stump, but is also anchored on the outside in the outer wall of the trochanter

Further advantageous embodiments of the invention emerge from the following description and the

Drawing. In the drawing shows

F i g. 1 a thigh bone in section with inserted endoprosthesis,

Fig. 2 the endoprosthesis with jaw and femoral neck part,

F i g. 3 is a view of the shaft along the line MI-IM according to FIG. 2 and

FIG. 4 shows a view of the femoral leg.
The endoprosthesis inserted into a femur 1 consists of a shaft 2 and a femoral neck part 3 screwed into it.

The shaft 2 has a cylindrical head area 4 and a cylindrical tube area 5. Of the Tube area 5 must be curved in accordance with the natural curvature of the medullary canal of bone 1

be (see Fig. 2). It reaches over you Markraumengstelle Γ addition.

The outside diameter of the head area 4 is slightly larger than that of the tube area 5. To avoid this The shaft 2 in the transition area 6 has sharp edges

rounded between the head region 4 and the tube region 5 (see FIG. 2) and at its lower end 7 of the pipe area 5 is slightly drawn in (see FIG. 1).

The drawn-in open end 7 of the pipe section 5 can be closed with a cap or plug, so that an exit of the cancellous bone to be filled into the tube region 5 is initially prevented by the cap or plug be: marriages from a mass that dissolves in the bone after about two to three weeks, which is the end of it 7 is open again.

The pipe area 3 is provided with channels 8. For example, there are six grooves 8 on the circumference of the Pipe area 5 distributed. On the head region 4, depressions 9 distributed around its circumference are provided. The grooves 8 and the recesses 9 extend in the longitudinal direction of the shaft 2. They promote a solid Growing of the shaft 2 into the thighbone 1. In addition, this can be done on the circumference of the head area 4 distributed, offset from one another, in the direction of impact of the shaft 2 tapering, narrow strips 9 'may be provided. These are wedge-shaped in cross section. They have at d'.m end, which is opposite their end merging into the head area 4, unites Waste flank 9 ″. As a result, these strips 9 'act as barbs to prevent the Shank 2. In Fig. 2, for example, there are two such Last 9 'shown,

In the head area 4 there are pressure equalization bores extending from its upper end 10 into the pipe area 5 11 provided. The pressure compensation holes 11 can be reinforced with appropriate plastic tubes before the wound is closed. These plastic tubes remain - provided with a marking - under the skin cover and can thus easily at any time

for any necessary measures inside the medullary canal or the tubular area 5 of the shaft 2 to be used. In addition, the head area 4 has a coaxial filling hole 12, which is used for filling Cancellous bone is used. The filling bore 12 opens into the interior at an extension 13 located in the pipe region 5 of the pipe area 5. The filling hole 12 thus opens below the pressure equalization holes U in the Pipe area 5, so that clogging of the Druckaus' equalization holes 11 when filling the cancellous bone is avoided.

The grooves 8 are at their bottom with a plurality of opening into the cavity of the pipe area 5 Provided openings 14 through which cancellous bone secretion can enter the grooves 8 and thus in Made contact with the bone 1.

In the area of the upper end of the head area 4 there is also a continuous transverse bore 15 for the Approach of a Äusschiaggeräts provided.

To fix the femoral neck part 3, a threaded bore 16 is provided in the head area. Its axis is corresponding to the natural femoral neck angle by 130 ° to the longitudinal axis of the Head area 4. The axis of the threaded hole 16 is not exactly in the plane of the curvature of the Pipe area 5, but this is offset by 15 ° in relation to the body's own antetorsion. The transverse bore 15 is aligned on the circumference of the head area 4 in the same way as the threaded bore 16. Thus it is achieved that when the shaft is inserted into the bone, a rod inserted into the transverse hole is the Indicates the position of the threaded hole in the trochanter massif, so that the alignment of the shaft 2 in the Bone is possible in a simple way.

The femoral neck part 3 has a threaded section 17 corresponding to the threaded bore 16. At This is followed by a pin 18, which the head area 4 and, when the endoprosthesis is inserted, the The trochanter massif 1 ″ of the femur 1 protrudes about 1 to 2 cm (see FIG. 1). The pin 18 can to improve the fit in the bone with an external thread that has the same pitch as the threaded section 17 has

On the side of the threaded section 17 opposite the pin 18 there is an undetachable spring ring 19 arranged, the threaded portion 17 screwed into the threaded hole 16, the threads keeps under tension For this purpose, a blind hole 20 is provided in the head area 4 Threaded hole 16, the base of the spring ring 19 is supported by one of the strips 9 'described is arranged below the blind hole 20 that the femoral neck part 3 rests on its sloping flank 9 ″ (cf. Fig. 2). This ensures additional support for the femoral neck part 3 while leaving it

On the Schenkeihalteil 3, a neck portion 21 is formed, the diameter of which is greater than that of the Threaded portion 17 is the neck portion 21 has in its region close to the threaded section 17 has grooves 23 distributed around its circumference. soft are provided with a plurality of openings 24 which are in a continuous inner bore 25 of the femoral neck part 3 open. As already described with reference to the channels 8 and the openings 14, can the Schenkethalsteü 3 inter alia by the The inner bore 25 and through the openings 24 in the grooves 23 are grown around. In his that The area facing away from the threaded section 17, the neck section 21 is provided with an external thread 26, which has the same pitch as the threaded section 17. The external thread 26 is anchored at Insertion of the femoral neck part in the femoral neck (see Fig. 1) and thus improves the fit.

The femoral neck part 3 has a shoulder 27 at its end opposite the pin 18 provided, which is designed so that a

ίο can be fitted with a commercially available swivel head. Should a metallic joint head are placed, then the projection 27 will be provided with a thread. Should a ceramic head are placed, then the projection 27 can be conical for this purpose. Approach 27 is cylindrical if a joint head is provided which is intended to be rotatable on the extension 27. Such a rotatable metallic head is functionally favorable, since it is not just a relative movement of the joint head in the joint socket, but also a relative movement between the joint head and the approach 27 is possible. In Fig. A joint head 28 is indicated.

The shaft 2 and the femoral neck part 3 are made of a body-friendly metallic alloy or a

other suitable material

The tubular region 5 can also be slotted in the longitudinal direction, so that it is in the medullary canal of the bone resilient.

A firm tightening of the femoral neck part 3 can for example, facilitate the fact that in the approach 27 a transverse boom 30 for a corresponding Socket wrench is provided.

With the endoprosthesis described, a multiple mechanical process is already possible immediately after the operation Anchoring is given so that functional loads are not subject to any particular restrictions. The endoprosthesis is immediately after insertion by frictional connection of its tube area 5 and their head area 4 in the femur 1 and

in particular by a form fit of the femoral neck part 3 screwed to the head region 4 in the femoral neck stump Γ "and held in the outer wall of the trochanter massif 1". Over time occurs According to medical experience, a definitive consolidation of the anchoring through the described Measures favored ingrowth of the endoprosthesis into the bone.

Different femoral neck parts with different sizes can be used for different bone dimensions Have lengths of their neck portions 21 ready.

The shaft 2 consisting of the head area 4 and the tube area 5 can also be kept ready as a blank - without bores 16, 20 -. The threaded hole 16 and the blind hole 20 and, if necessary, the transverse beaning 15 are then made in the head area 4 according to the respective morphological conditions with regard to the femoral neck angle and anteversion angle of the patient
However, for special cases in which the anteversion angle of the patient is not 15 ° but, for example, 30 °, the head area 4 and the tube area 5 of the shaft 2 can be designed as two components that can be fixed to one another. It is thus possible to align the threaded hole of the head area with respect to the curvature of the pipe area; that the mutual position of curvature and threaded hole is to be adapted to the respective conditions

For this purpose 2 sheets of drawings

Claims (13)

Patent claims: 1. Thigh-hip joint endoprosthesis for cementless implantation with a lengthways of the thigh bone and inserted into a bore in the bone a joint head which runs in the direction of the femoral neck and is assigned to the joint socket supporting femoral neck part, wherein the shaft has a cylindrical tube and a head area, which is provided with a threaded hole into which the femoral neck part is screwed, thereby characterized in that the threaded bore (16) in one of the natural femoral neck angle corresponding angle in the head region (4) of the shaft (2) is arranged that the femoral neck part (3) has a threaded portion (17) which is screwed into the threaded bore (16) that in Head region (4) a filling hole (12) is arranged which opens into Λ, η pipe region (5), and that the Pipe area (5) has grooves (8) running on the outside in the longitudinal direction, on whose grand openings (14) are provided. 2. Endoprosthesis according to claim 1, characterized in that the tube region (5) on the Marrow constriction (Γ) of the bone (1) extends out, corresponding to the natural curvature of the Thigh bone is curved and that the plane of curvature against the axis of the threaded hole (16) is offset in the natural antetorsion angle. 3. Endoprosthesis according to claim 1 or 2, characterized in that the Rohi area (5) in the longitudinal direction is slotted. 4. Endoprosthesis after a previous one Claims, characterized in that the pipe area (5) at its head area (4) opposite end (7) is provided with a plug that dissolves after some time. 5. Endoprosthesis according to one of the preceding claims, characterized in that the head region (4) at least one pressure compensation hole (11), which in the longitudinal direction of the head area (4) runs and opens into the pipe area (5). 6. Endoprosthesis according to claim 5, characterized in that the mouth of the filling bore (12) closer to the head area (4) opposite one another The end (7) is the opening of the pressure compensation bore (ll). 7. Endoprosthesis according to one of the preceding claims, characterized in that the head region (4) is provided with depressions (9) on its outer circumference. 8. Endoprosthesis according to claim 7, characterized in that the depressions (9) are in Extend longitudinally. 9. Endoprosthesis according to one of the preceding claims, characterized in that on the the pipe area (5) facing away from the end of the Head area (4) a transverse bore (15) is provided, corresponding to the circumference of the head area (4) the threaded hole (16) is aligned as an orientation aid when inserting the shaft (2). 10. Endoprosthesis according to one of the preceding Claims, characterized in that the threaded section (17) screwed into the shaft (2) of the femoral neck part (3) on the side opposite the joint head (28) into a pin (18) continues, which protrudes from the shaft (2) and whose length is dimensioned so that it The trochanter mass (1 ") protrudes for further anchoring 11. Endoprosthesis according to one of the preceding Claims, characterized in that the femoral neck part (3) with a continuous, concentric Inner bore (25) and is provided with openings (24) 12. Endoprosthesis according to claim 11, characterized characterized in that the openings (24) of the femoral neck part (3) at the bottom of grooves (23) are provided which run on the neck section (21) in the longitudinal direction of the femoral neck part (3). 13. Endoprosthesis according to one of the preceding Claims, characterized in that the femoral neck part (3) adjoins the threaded section (17) a spring ring (19) is placed on the pair of threads (16, 17)