DE2854334A1 - Anchoring members for artificial hip joint - has main shaft with enlarged top with hole tapped at angle for sloping pin - Google Patents

Abstract

The hip joint prosthesis with a spherical block (1'') mounted at the top, has a main member (2) which is inserted into the bone. This has a stem (5) with a larger diameter outer end (4) which carries the spherical block. A tapped hole passes through this larger diameter part at an angle to receive a pin (3) to the end of which is attached a further spherical portion. The smaller diameter part can be curved to match the natural curvature of the bone, and can curve away from the direction of the sloping topped hole. This part has channels (1') down it, and holes through it which communicate with the channels. The larger end has an equaliser hole down the middle and slots at right angles to this hole.

Description

Endoprosthesis

The invention relates to an endoprosthesis, in particular a thigh endoprosthesis for the hip joint, with a medullary shaft running in the longitudinal direction of the bone and with one of the joint socket running in the direction of the femoral neck associated femoral neck part bearing the joint head.

In the hip joint prosthesis they appear in the replacement of the joint socket occurring problems solved. With regard to that of the joint head, in the femur However, there are still difficulties with the fixed part of the prosthesis. It has shown, that with endoprostheses cemented into the thigh bone with at most one Life expectancy of around 15 years.

A one-piece femoral endoprosthesis is for example in the DE-OS 23 58 159 described. The medullary shaft of such an endoprosthesis runs conically so that it tends to emigrate from the start. In addition, must be at of such an endoprosthesis, in addition to the joint head to be replaced, also the femoral neck completely removed, resulting in a significant loss of bone substance or represents substantial bone damage and, moreover, the possibility of positional errors the prosthesis.

In DE-OS 23 56 los64 an endoprosthesis with a shaft is described, which has a slightly conical, straight shape with a prismatic thickening at the top Has part and which is to be inserted into the bone without the use of cement. The medullary canal shaft and the femoral neck part are also in such an endoprosthesis formed in one piece. Before inserting such an endoprosthesis is also the entire femoral neck of the bone removed. In addition, the trochanter massif are largely removed, so that the total loss of bone substance is significant is larger than the endoprosthesis according to DE-OS 23 58 159.

In the known endoprostheses, their tight fit depends in the longitudinal direction of the bone only depends on the seat of the medullary canal shaft. Therefore it can be a safe Anchoring of the prosthesis cannot be guaranteed. This makes it permanent Anchoring of the endoprosthesis in the bone is not secure.

The object of the invention is to provide an endoprosthesis of the type mentioned at the beginning To propose a type in which the femoral neck part is firmly supported in the trochanter massif is.

According to the invention, the above object is achieved in that the medullary cavity and the femoral neck part as one each inserted into a bore in the bone Component are formed and that the two components according to the anatomical Ratios set to each other in the angle corresponding to the cervical angle are.

This angle is usually around 1300.

The invention is already immediately after the surgery A firm fit of the endoprosthesis in the bone is guaranteed, because on the one hand the medullary shaft seen in the longitudinal direction of the bone and firmly seated in the bone with a force fit on the other hand, the femoral neck part rigidly connected to the medullary shaft on his The circumference of the bore of the femoral neck and possibly the lateral massif of the trochanter is enclosed.

The femoral neck of the bone and especially the trochanter massif do not need to insert the medullary shaft and the femoral neck part to be removed, leaving substantial bone damage, especially one Loss of bone substance, not associated with the insertion of the endoprosthesis. To insert the prosthesis, only two drill holes of different sizes are therefore required. The removal of the deformed or broken head is an inevitable Need.

A permanent fit of the endoprosthesis without the use of cement results from the positive fit of the endoprosthesis in the bone. Through advantageous developments of the invention, which emerge from the description of the drawings and subclaims result is the ingrowth of the endoprosthesis through the cancellous osteoblasts favored.

By not removing the femoral neck stump of the bone, Rotation and positional errors of the endoprosthesis are avoided from the outset, since the Bore into which the femoral neck part is to be inserted, corresponding to the femoral neck stump is aligned.

In a preferred embodiment of the invention, it sits down the on the medullary shaft fixed portion of the femoral neck part on the joint head opposite side into a peg that protrudes beyond the medullary shaft and in particular protrudes through the bone. This ensures that the most stuck The medullary shaft is attached to the femoral neck not only on the inside in the femoral neck stump lies, but is also anchored on the outside in the outer wall of the trochanter.

In a preferred embodiment of the invention, the marrow shaft a cylindrical head part lying in the trochanter massif and a cylindrical head part Pipe part whose outer diameter is smaller than that of the head part. Preferably the pipe part extends at least over the medullary constriction of the bone, the before inserting the medullary canal shaft, drilled or milled out accordingly will.

An endoprosthesis according to the invention can not only be used for thigh bones, Use probes on other links as well.

Further advantageous refinements of the invention emerge from the following description and drawing.

In the drawing: FIG. 1 shows a thigh bone in section with inserted endoprosthesis, FIG. 2 the endoprosthesis with medullary canal shaft and femoral neck part, 3 shows a view of the medullary canal shaft along the line III-III according to FIGS 4 is a view of the cervical part.

The endoprosthesis inserted into a femur 1 consists from a medullary shaft 2 and a femoral neck part screwed into this 3.

The medullary shaft 2 has a cylindrical head part 4 and a cylindrical pipe part 5. The pipe part 5 must correspond to the natural curvature of the medullary canal of the bone l be curved (see. Fig. 2). It goes beyond that Marrow constriction 1 'out.

The outer diameter of the head part 4 is slightly larger than that of the Tube part 5. To avoid sharp edges, the medullary canal shaft 2 is in the transition area 6 rounded between the head part if and the pipe part 5 (cf.

Fig. 2) and slightly drawn in at its lower end 7 of the tubular part 5 (see Fig. 1).

The retracted open end 7 of the pipe part 5 can #der with cap Plug closed sdfl, so that the to be filled into the pipe part 5 can escape Cancellous bone is initially prevented. Cap or plug consist of a mass, which dissolves in the bone after about two to three weeks, which is the end of it 7 is open again.

The pipe part 5 is provided with channels 8. For example, there are six Grooves 8 distributed on the circumference of the pipe part 5.

On the head part 4, depressions 9 distributed around its circumference are provided. The grooves 8 and the depressions 9 extend in the longitudinal direction of the medullary canal shaft 2.

They promote firm ingrowth of the medullary canal sheath 2 into the Thighbones 1. In addition, 4 distributed around the circumference of the head part, against each other offset, in the direction of impact of the medullary shaft 2 tapering, narrow strips 9 'may be provided. These are wedge-shaped in cross section. They point at the end which is opposite their end merging into the head part 4, a falling flank 9 ″. As a result, these strips 9 'act as barbs against migration of the medullary canal shaft 2. In FIG. 2, for example, there are two such strips 9 'shown.

In the head part 4 are from its upper end 10 in the pipe part 5 extending pressure compensation bores 11 are provided. The pressure equalization 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 therefore easily take any necessary internal measures at any time of the medullary canal or of the tubular part 5 of the medullary canal shaft 2 can be used. aside from that the head part 4 has a coaxial filling hole 12, which is used for filling cancellous bone serves. The filling bore 12 opens into an extension 13 located in the pipe part 5 the interior of the pipe part 5. The filling bore 12 thus opens below the pressure equalization bores 11 in the pipe part 5, so that clogging of the pressure compensation holes 11 when Filling the cancellous bone is avoided.

The grooves 8 are at their bottom with a plurality of in the cavity of the tubular part 5 opening through holes 14 provided by the cancellous bone secretion can enter the grooves 8 and thus come into contact with the bone 1.

In the area of the upper end of the head part 4 is still one continuous transverse bore 15 provided for the approach of a knockout device.

To fix the femoral neck part 3 is in the head ~ part 4 a Threaded hole 16 is provided. The axis of this corresponds to the natural angle of the femoral neck around 1300 to the longitudinal axis of the head part 4. The axis of the threaded hole 16 is not located exactly in the plane of the curvature of the pipe part 5, but is opposite to this accordingly the body's antetorsion of 150. The transverse bore 15 is on the circumference of the head part 4 is aligned in the same way as the threaded hole 16.

This ensures that when the medullary canal shaft is inserted into the bone is inserted into the transverse hole, he rod the position of the threaded hole indicates in the trochanter massif, so that the alignment of the medullary canal shaft 2 in the bone is possible in a simple way.

The femoral neck part 3 has a threaded hole 16 corresponding Threaded section 17. This is followed by a pin 18, which is the head part 4 and with inserted prosthesis the trochanter massif 1 "of the femur 1 protrudes by about 1 to 2 cm (see. Fig. 1).

The pin 18 can improve the fit in the bone with a External threads may be provided that have the same pitch as the threaded section 17 having.

On the side of the threaded section opposite the pin 18 17 is a non-removable spring ring 19 is arranged, which is in the threaded hole 16 screwed-in threaded section 17 holds the threads under tension.

For this purpose, a blind hole 20 is provided in the head part 4, at which merging into the threaded hole 16 Reason the spring washer 19 supports. One of the strips 9 'described is thus below the blind hole 20 arranged that the femoral neck part 3 rests on its sloping flank 9't (cf. Fig. 2). As a result, an additional support of the femoral neck part 3 is under load guaranteed.

On the hip part 3, a neck portion 21 is formed, the Diameter greater than that of the thread section 17 is. The neck portion 21 has distributed around its circumference in its region close to the threaded section 17 Grooves 23, which are provided with a plurality of openings 24, the Open into a continuous inner bore 25 of the femoral neck part 3. As already Described with reference to the grooves 8 and the openings 14, the femoral neck part 3 inter alia through the inner bore 25 and through the openings 24 in the Grooves 23 are grown around.

The neck section is located in its area facing away from the threaded section 17 21 provided with an external thread 26, which has the same pitch as the threaded section 17 has. The external thread 26 is anchored when the femoral neck part is inserted 3 in the femoral neck (cf.

Fig. 1) and thus improves the fit.

The Schenlcelhalteil 3 is opposite to the pin 18 on its The end is provided with a shoulder 27 which is designed so that a commercially available one is attached to it Can be attached Geleiildcopf. If a metallic joint head is to be attached, then the projection 27 will be provided with a thread. Should be a ceramic head are placed, then the projection 27 can be designed conically for this purpose. Of the Approach 27 becomes cylindrical formed when a joint head is provided is, which should be rotatable on the approach 27. Such a rotatable metallic one The head is functionally favorable because it does not only involve a relative movement of the gel head in the joint socket, but also a relative movement between the joint head and the approach 27 is possible. In Fig. 2, a Gelenlckopf 28 is indicated.

The medullary canal shaft 2 and the femoral neck part 3 are made of a body-friendly metallic alloy or other suitable material.

The pipe part 5 can also be slotted in the longitudinal direction, so that it lies resiliently in the medullary canal of the bone.

The introduction of the femoral endoprosthesis described is roughly as follows made: First, the damaged joint head is about 2 to 3 mm from the bone separated and approximately in the line 29 shown in FIG. 1 in the optimal direction removed. If there is a femoral neck fracture, only the edges of the fracture are affected easily equalized. If necessary, a joint socket is used.

Then the medullary canal is opened in the usual way and in a according to the X-ray findings, milled out in such a way that an even contact surface is necessary for the tubular part 5 of the medullary shaft 2 is achieved. The milling takes place according to the length of the medullary volume. In the example shown, it extends it extends beyond the area of the medullary volume 1 'of the femur 1 (see Fig. 1).

Then the trochanter massif lii according to the outer diameter of the head part 4 of the medullary canal shaft 2 milled out. It is milled out for this Medullary canal an auxiliary device, for example a medullary canal rod with a guide spike used.

Then the femoral neck stump is formed from the end (see line 29 in FIG. 1) 1 "'to the milled-out cylinder space of the trochanter massif for the head part 4 milled out according to the outer diameter of the neck section 21. As an aid can work with a mandrel inserted into the medullary canal of the femoral neck stump liii will.

Following this, the medullary canal shaft 2 is inserted into the femur 1 driven in so far that the threaded hole 16 with the milled recess in the femoral neck stump lt tt aligns. The upper end of the head part 4 then stands 1 to 2 cm above the trochanter massif 1 '' so that the protruding transverse hole 15 is exposed. This can be used if necessary the medullary canal shaft 2 from the femur using a knock-out device be beaten.

The medullary shaft 2 is now firmly seated in the femur with a frictional connection 1. When the medullary canal shaft 2 is hammered into the bone, excess pressure is generated reduced by the pressure equalization bores 11, which are always open.

It is now through the filling hole 12 cancellous bone into the interior of the pipe part 5 introduced. This occurs with its secretions through the breakthroughs 14 or

the channels 8 and the open lower end 7 in the medullary canal, so that the necessary conditions for the tube part 5 to grow into the bone 1 are created.

The femoral neck part 3 is now partially inserted into the threaded hole 16 screwed in. Through the coaxial inner bore 25, a twist drill is now used the outer landing of the trochanter massif 111 is pierced.

When the femoral neck part 3 is screwed in completely, it unscrews the thread of the pin 18 in the trochanteric wall. It can also be done through the inner hole 25 a Kirschner wire can be shot in until it protrudes on the opposite side. This serves as a guide for a milling head with which the trochanter wall accordingly the outer diameter of the pin 18 is opened.

The latter is anchored in the trochanter wall by means of its external thread.

After the femoral neck part 3 has been fully screwed in, it is seated this is fixed by the spring ring 19 on the head part 4. The external thread 26 is in the Femoral neck stump l screwed in. In addition, cancellous bone secretion can occur through the Openings 24 in the grooves 23 get into the femoral neck stump 1 "'.

By screwing in the threaded section 17 of the cervical part 3 in the threaded hole 16, the filling hole 12 is closed. Complications Any pressure differences occurring in the bone marrow space are not to be expected because the pressure equalization channels 11 are still open.

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

Finally, the joint head provided can be placed on the shoulder 27 put on.

According to the state of the art surgical technique, it is common when in the medullary canal Infections occur by introducing a Palacos necklace, whose pearls with Penicillin are soaked, which diffuses into the medullary canal. Have the pearls usually a diameter of 3 mm.

Insert and pull out this chain even with the endoprosthesis in place to be able to, the diameter of at least one of the pressure equalization channels is dimensioned in such a way that that it is a little larger than the diameter of the pearls.

With the endoprosthesis described is already immediately after Operation given multiple mechanical anchoring, so that functional loads are not subject to any particular restriction. The endoprosthesis is immediately after the insertion by frictional connection of their tubular part 5 and their head part 4 in the thigh holes 1 and in particular by a form fit of the femoral neck part screwed to the head part 4 3 in the femoral neck blunt 1 '' 'and in the outer wall of the trochanter massif 1' ' held. According to medical experience, a definite solidification occurs over time the anchoring through the ingrowth promoted by the measures described the endoprosthesis into the bone.

Numerous modifications and others are within the scope of the invention Embodiments. For special morphological conditions special Refinements that make use of the features of the invention with regard to of the medullary shaft or provide with regard to the femoral neck part. For example, different bone dimensions can be used Have femoral neck parts with different lengths of their ilal sections 21 ready.

The medullary canal shaft consisting of the head part 4 and the tube part 5 can also be used 2 as a blank - without holes 16, 20 - are kept ready. The threaded hole 16 and the blind hole 20, and optionally the transverse hole 15 are then in front the operation according to the respective morphological conditions with regard to the femoral neck angle and Antetorsionswinlcel of the patient manufactured accordingly in the head part 4.

But it is also possible for special cases where the angle of antetorsion of the patient is not 15 °, but for example 30, the head part 4 and the Form the tubular part 5 of the medullary canal shaft 2 as two components that can be fixed to one another. It is thus possible to adjust the threaded hole of the head part against the curvature of the Align the pipe part so that the mutual position of curvature and threaded hole is to be adapted to the respective circumstances.

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Claims (34)

Claims for protection 1. Endoprosthesis, in particular thigh endoprosthesis for a hip joint with an anesthetic shaft running in the longitudinal direction of the bone and one which runs in the direction of the cervical neck and is associated with one of the gel pan The femoral neck part carrying the joint head, characterized in that the narcotic shaft (2) and the femoral neck part (3) as one each in a hole in the bone (1) used component are formed and that the two components according to the anatomical relationships at an angle equal to the femoral neck angle are set. 2. Endoprosthesis according to claim 1, characterized in that the Medullary shaft (2) has a cylindrical head part located in the trochanter mass (111) (4) and a cylindrical tube part (5), the outer diameter of which is smaller than that of the head part (4). 3. Endoprosthesis according to claim 1 or 2, characterized in that the head part (4) of the medullary shaft (2) is provided with a threaded hole (16) is, into which a threaded section (17) of the femoral neck part (3) is screwed. 4. Endoprosthesis according to one of the preceding claims, characterized in that that the tubular part (5) is curved according to the natural curvature of the bone (1) is. 5. Endoprosthesis according to claim, characterized in that the plane of curvature is offset from the axis of the threaded hole (16) in the antetorsion angle. 6. Endoprosthesis according to one of the preceding claims, characterized in that that the pipe part (5) is slotted in the longitudinal direction. 7. Endoprosthesis according to one of the preceding claims, characterized in that that the pipe part (5) has grooves (8) on its circumference. 8. Endoprosthesis according to claim 7, characterized in that the base the grooves (8) openings (14) are provided. 9. Endoprosthesis according to one of the preceding claims, characterized in that that the pipe part (5) is drawn in at its end (7) opposite the head part (4) is. 10. Endoprosthesis according to one of the preceding claims, characterized characterized in that the tubular part (5) at least up to the lower end of the medullary narrowing point (1 ') of the bone (1) is enough. 11. Endoprosthesis according to one of the preceding claims, characterized characterized in that in the head part (4) at least one pressure compensation hole (11) runs. 12. Endoprosthesis according to one of the preceding claims, characterized characterized in that a filling hole (12) runs in the head part (4). 13. Endoprosthesis according to claim 12, characterized in that the The mouth of the filling hole (12) lies deeper in the pipe part (5) than the mouth of the pressure compensation hole (11). 14. Endoprosthesis according to one of the preceding claims, characterized characterized in that the head part (4) on its outer circumference with recesses (9) is provided. 15. Endoprosthesis according to one of the preceding claims 7 to 14, characterized in that the grooves (8) and the depressions (9) extend in the longitudinal direction of the medullary shaft (2) extend. 16. Endoprosthesis according to one of the preceding claims, characterized characterized in that on the head part (4) in the direction of the pipe part (5) tapering, wedge-shaped strips (9 ') are distributed offset, which at the other end has a sloping flank (9). 17. Endoprosthesis according to claim 16, characterized in that on the sloping flank (9 ″) of one of the strips (9) rests against the femoral neck part (3). 18. Endoprosthesis according to one of the preceding claims, characterized characterized in that on the head part (4) at the end facing away from the pipe part (5) at least a transverse bore (15) projecting beyond the bone (1) is provided. 19. Endoprosthesis according to claim 18, characterized in that the Cross hole (15) on the circumference of the head part (4) corresponding to the threaded hole (16) is aligned. 20. Endoprosthesis according to one of the preceding claims, characterized characterized in that the on the medullary shaft (2) fixed portion (17) of the Cervical part (3) on the side opposite the gel head (28) in a pin (18) continues which protrudes beyond the medullary shaft (2). 21. Endoprosthesis according to claim 20, characterized in that the Length of the pin (18) is dimensioned so that it protrudes through the trochanter mass (1 '). 22. Endoprosthesis according to claim 20 or 21, characterized in that that the pin (18) is provided with a thread which has the same pitch has, such as the threaded section (17) of the collar neck part (3). 23. Endoprosthesis according to one of the preceding claims, characterized characterized in that the femoral neck part (3) with a continuous, coaxial Inner bore (25) is provided. 24. Endoprosthesis according to one of the preceding claims, characterized characterized in that the femoral neck part (3) has a neck section (21), at its end opposite the threaded section (17) a shoulder (27) for Attachment of a Gelenldçopfes (28) is provided. 25. Endoprosthesis according to one of the preceding claims, characterized characterized in that the neck portion (21) has a larger outer diameter, than the threaded portion (17). 26. Endoprosthesis according to one of the preceding claims, characterized characterized in that the femoral neck part (3) adjoins the threaded section (17) a non-removable spring ring (19) is attached, which the thread pairing (16, 17) strained. 27. Endoprosthesis according to one of the preceding claims, characterized characterized in that the neck portion (21) is provided with at least one groove (23) is. 28. Endoprosthesis according to claim 27, characterized in that on The base of the grooves (23) is provided with openings (24) reaching into the inner bore (25) are. 29. Endoprosthesis according to one of the preceding claims 24 to 28, characterized in that the neck portion (21) at least partially with a External thread (26) is provided, the pitch of which is equal to that of the threaded portion (17) and its outer diameter is larger than that of the neck portion (21) in the rest is. 30. Endoprosthesis according to one of the preceding claims, characterized characterized in that the extension (27) has a thread for screwing on a Gelenlckopfs (28). 31. Endoprosthesis according to one of the preceding claims 24 to 29, characterized in that the extension (27) for placing a joint head (28) is conical. 32. Endoprosthesis according to one of the preceding claims 24 to 29, characterized in that the extension (27) for freely rotatable placement of a joint head (28) is cylindrical. 33. Endoprosthesis according to one of the preceding claims 24 to 32, characterized in that the extension (27) is provided with a transverse bore (30) is. 34. Endoprosthesis according to one of the preceding claims, characterized characterized in that the head part (4) and the pipe part (5) of two can be assembled Components are formed.