WO2000067652A2 - Implant for operative treatment of femoral neck fractures and the like - Google Patents

Abstract

A two-part implant which is used to provide operative treatment of femoral neck fractures, comprising a sliding screw that has a threaded head on the front end thereof and a bolt which extends beyond the surface of the fracture, whereby a sliding bushing having an inserted thread on the outer periphery thereof is screwed into the other part of the bone. The two-part sliding screw is positioned in a minimally invasive manner. A stop device is arranged in between both parts to ensure that only one part can be displaced axially towards the other in a single direction.

Description

 Implant for the operative treatment of fractures of the femur and dql.

The invention relates to an implant for the operative care of z. B. Fractures of the femoral neck according to the preamble of claim 1. Such implants for the operative treatment of fractures, in particular fractures of the femoral neck, have proven themselves.

Although the implant according to the invention is suitable for the operative care of a wide variety of fractures, for the sake of simplicity only the use of an embodiment of the implant for the operative care of a femoral neck fracture in the form of a slide screw according to the invention is described below. However, the invention is not limited to this.

The surgical treatment of a fracture of the femoral neck is carried out in such a way that the fracture is first reduced and a Kirschner wire is inserted between the femoral head and the femur in the planned course of the screw channel to be created. Once the Kirschner wire has been inserted in the correct position, the Kirschner wire is drilled through with a two-step drill and the two-part sliding screw is inserted into the resulting drilling channel.

The front part of the sliding screw has a screw thread with which it is screwed into the femoral head. On the opposite side to the fracture surface, a sliding sleeve is used, which receives the bolt-side end of the sliding screw, and the sliding screw is supported in this sliding sleeve with axial play.

It is only known to screw the sliding sleeve laterally to the bone by means of a plate attached to it, in order to form the guide bearing for the sliding screw on the opposite bone.

However, the attachment of a sliding sleeve by means of a plate is not possible when using a minimally invasive technique.

CONFIRMATION COPY There is also the further disadvantage that the fracture surfaces are not compressed due to the constant axial play of the sliding screw in the sliding sleeve, which delays healing.

The invention is therefore based on the object of developing an implant of the type mentioned at the outset in such a way that it can be placed using a minimally invasive technique and that there is improved healing.

The technical teaching of claim 1 and / or 2 is used to solve the problem.

An essential feature of the inventive concept according to claim 1 is that the sliding pulse now at least partially has an external thread on the outer circumference with which the sliding sleeve can be screwed into the drilling channel.

There is therefore no need for an expensive attachment of the sliding sleeve to the bone by means of a perforated plate, and the sliding sleeve is screwed directly into the drilling channel.

The invention includes both a design of the sliding screw with a circumferentially provided thread on the outer circumference and another embodiment in which the screw thread is only partially present on the outer circumference.

Regardless of the special fastening of the sliding screw, the invention is also intended to protect a special locking device for implants. Protection in the form of independent independent claim 2 is sought for this locking device.

The basic principle of the locking device according to this feature of the invention is based on the fact that the guided sliding possibility of the implant causes the fracture to be subjected to compression when walking under weight. However, if the leg is relieved, the compression will undesirably decrease again. This is where the invention comes in, which ensures that the compression once achieved by loading remains secured in the long run. This is achieved by the locking device on the implant. The principle of the arrangement of a locking device can therefore be applied to all implants that allow a so-called dynamic compression.

In addition to the sliding screw described, the invention also provides an area of application which also includes self-locking interfragmentary tension screws or intramedullary nails.

Such an intramedullary nail consists of a solid material (e.g. implant steel or titanium) with cross holes arranged at both ends. It is used to stabilize fractures of long tubular bones (e.g. thigh or lower leg) in the medullary cavity of the bone. The intramedullary nail splits the fracture and allows axial compression of the bone fragments brought together and splinted through the intramedullary nail. However, the rotation of the bone fragments must be prevented by a turnstile on the intramedullary nail. For this purpose, bolts are provided in transverse bores of the intramedullary nail perpendicular to its longitudinal axis and act as a turnstile. In order to allow axial compression of the bone in the area of the fracture point, it is known that the transverse bores are each designed as an elongated hole oriented in the axial direction. The bolts are therefore guided with play in the respective elongated hole in the transverse bore.

It is disadvantageous here that compression (and desired) acting on the fracture is only applied during the duration of the load, but is not permanently maintained. This is where the invention comes in, which proposes to use the locking device according to the invention also with such an implant.

When the sliding screw is designed as an intramedullary nail, provision is therefore made for it to be telescopic and to have a locking device with which once compression is ensured and wound healing can thus be significantly improved.

Such a two-part implant consists of a sliding screw and the associated sliding sleeve. It can now be installed using a minimally invasive surgical technique because the sliding screw is anchored directly into the bone via the external thread. There is no screw-on plate. After the first pre-drilling with a Kirschner wire and after checking, the final drill channel can be drilled with a two-step drill over the lying Kirschner wire and the two-part sliding screw can be used immediately be screwed into the drilling channel via a skin incision. The screwing in is carried out in such a way that both the sliding screw itself and the sliding sleeve encompassing the sliding screw are screwed in together with a tool. This means that both the sliding screw is screwed into the femoral head in a single operation and at the same time - with the same rotation - the sliding sleeve is also screwed into the opposite femur, because the two parts are non-rotatably connected to each other by means of the tool and therefore the screwing movements in the screwing channel carry out.

According to the second inventive concept, it is provided that the two-part implant is provided with a locking device between one and the other part. This locking device only allows an axial displacement of the two parts in the direction in which the two parts are subjected to thrust. However, if the two parts are subjected to tension, the shift is locked.

When designing the implant as a sliding screw, it is essential that the fracture surface is compressed, i. H. the slide screw should be constantly subjected to tension to allow compression of the fracture surfaces. In the opposite direction, however, axial play of the sliding screw in the sliding sleeve should be ensured. It is known that sintering occurs in the area of the fracture surfaces during the healing process, which therefore move and interlock with one another, as a result of which the sliding screw is subjected to thrust. This thrust is to be absorbed by the locking device and this ensures that no thrust forces acting on the fracture surfaces can occur.

The axial adjustment play of the sliding screw in the sliding sleeve should be selected so that the sliding, lateral end of the sliding sleeve does not come out of the sliding sleeve and leads to soft tissue irritation.

There are various embodiments for the design of the locking device, all of which are intended to be encompassed by the inventive concept.

In a first embodiment, the locking device consists of a ratchet and this in turn consists of a ring that is radially inward in the Sliding sleeve is attached and which cooperates with an associated sawtooth-like catch on the outer circumference of the sliding screw.

In a second embodiment, a locking blade is provided instead of the locking ring, which also interacts with a sawtooth-like external toothing of the sliding screw.

In a third embodiment, instead of the sawtooth-like external toothing, slots are arranged on the sliding screw, into which slots the locking ring or the locking blade engage.

In a further embodiment, a kinematic reversal of the aforementioned embodiments provides that the sawtooth-like toothing is arranged on the inner circumference of the sliding sleeve, while the locking ring or the locking blade is connected to the sliding screw.

In this latter embodiment as well, corresponding slots can be incorporated on the inner circumference of the sliding sleeve instead of the sawtooth-shaped latching.

Instead of the locking blade or locking ring described, spring-loaded bolts or other known machine elements can also be used, which implement such a locking mechanism.

The subject matter of the present invention results not only from the

Subject of the individual claims, but also from the combination of the individual claims with each other.

All information and features disclosed in the documents, including the summary, in particular the spatial depicted in the drawings

Education are claimed as essential to the invention, insofar as they are new compared to the prior art, individually or in combination.

In the following, the invention will be explained in more detail with reference to drawings showing several possible embodiments. Here, from the drawings and their description, further features and advantages of the invention that are essential to the invention emerge. Show it:

Figure 1: schematically shows a femoral neck fracture with explanation of the parts;

Figure 2: the supplied by the two-part slide screw according to the invention

Femoral neck fracture;

Figure 3: a two-part sliding screw in a first embodiment in

Cut;

Figure 4: a second embodiment of a two-part sliding screw;

Figure 5: the front view of an embodiment of a sliding screw;

FIG. 6: an embodiment of FIG. 4 modified from FIG

Locking device;

FIG. 7: an embodiment of a modified compared to FIG. 5

Sliding screw;

8 shows an embodiment of the FIG

Locking device;

Figure 9: another embodiment of a locking device.

A typical fracture of the femur is shown in FIG. 1, the femoral head 2 being broken off from the femur 1. The fracture surfaces that form are labeled 3 and 4.

The fracture is first repositioned in order to bring the fracture surfaces 3, 4 together as shown in FIG. 2, then a Kirschner wire is first drilled from position 21 in the course of the planned course of the screw and the position is checked. The Kirschner wire is then drilled through with a two-stage drill and the two-part sliding screw 5, 7 is screwed into the bore in each case. In the exemplary embodiment according to FIG. 2, two two-part sliding screws are thus arranged next to one another. It consists of the sliding screw 7 itself and the associated sliding sleeve 5. According to Figure 3, the sliding sleeve 7 consists of a screw 9 with a front threaded head 8, which is screwed into the femoral head 2. The rear part of the screw bolt 9 is axially displaceably mounted in the receiving bore 10 of a sliding sleeve 5, which according to the invention is provided with an external thread 6.

It is provided that the sliding screw 7 can move axially displaceably in the receiving bore 10 in the direction of the arrows 11, a sliding section 12 being provided which ensures that the rear end face of the screw bolt 9 does not protrude from the rear end face of the sliding sleeve 5, because otherwise this would lead to soft tissue irritation.

To screw in the two-part sliding screw according to FIG. 3, a tool is provided which engages both on the rear face of the sliding sleeve 5 and on the face of the screw bolt 9 and connects the two parts to one another in a rotationally fixed manner.

In this way, the two parts can be screwed simultaneously from position 21 in FIG. 2 into the screw channels aligned with one another.

In order to additionally enable the fracture surfaces 3, 4 to be under compression, a locking device is provided, which is shown in several exemplary embodiments in FIGS. 4 to 9.

In a first embodiment of the locking device, it consists of a locking ring 13 which is fixedly connected to the sliding sleeve 15, the radially inner part of the locking ring 13 being seated on barb-like locking teeth 14. In this way, it is ensured that the screw bolt 9 is under tension, because when the fracture surfaces 3, 4 are sintered, the screw bolt is displaced in the direction of arrow 11 'into the sliding sleeve 15, whereby the locking ring 13 jumps over a projection of the locking teeth 14 , and engages in the nearest locking teeth.

FIG. 5 shows that the locking teeth 14 need not be circumferentially arranged, it can also be provided that the locking teeth 14a are only partially provided on the circumference of the screw bolt 9.

FIG. 5 also shows indicated cannulas 19 which are arranged on the outer circumference of the sliding screw 7 and which are open to the outside in order to receive the Kirschner wire. FIG. 6 shows as a modified exemplary embodiment that one or more latches 16 can be used instead of a latching ring 13.

The respective locking pawl is chamfered in its own direction and interacts with the steep flank of the locking teeth 14.

It is possible here, for. B. to use two opposing locking pawls 16 and a non-rotating locking teeth 14a according to Figure 5. In one rotational position between the sliding screw 17 and the sliding sleeve 5, the locking pawls 16 are out of engagement with the locking teeth 14a, while in the other rotational position this Latches 16 are in engagement with the locking teeth 14a.

In this way, by simply rotating the two parts 5, 17 relative to one another, it is possible to bring the locking teeth into the functional position and the non-functional position.

In comparison to the sliding screw 17 according to FIGS. 4 and 6, a sliding screw 27 can also be formed in that, instead of the locking teeth 14, slots 18 are machined in the surface of the space bolt 9, into which the locking ring 13 or the locking pawls 16 engage.

Of course, the bolt 9 does not have to be fully formed, it can also consist of a hollow material, so that the two-part sliding screw can be inserted over the lying Kirschner wire.

FIG. 9 shows the kinematic reversal of the function of the locking device compared to the locking devices according to FIGS. 4 to 8 described there. It is shown that the locking ring 13 or the locking pawls 16, which are associated with the locking teeth, can be connected to the screw bolt of the sliding screw 17 24 or slits cooperate on the inner circumference of a sliding sleeve 25.

It is important in all embodiments, however, that a screw thread 20 is arranged on the outer circumference of the respective sliding sleeve 5, 15, 25, with which it is possible to insert and remove the two-part sliding screw by a minimally invasive intervention. Drawing legend

1. hip bone

2. femoral head

3. fracture surface (femoral head)

4. Fracture surface (hip bone)

5. Sliding sleeve

6. Male thread

7. Slide screw

8. Threaded head

9. Bolt

10. Location hole

11. Arrow direction 11 '

12. Glide route

13. Locking ring

14. Latching teeth

15. Sliding sleeve

16.Latch

17. Slide screw

18th slot

19. Cannula

20.Screw thread

21st position

22.

23rd

24th

25. Sliding sleeve

26th

27. Slide screw

Claims

claims 1. Implant for the operative care of z. B. fractures of the femoral neck with a sliding screw (7, 17, 27), which has a sliding head (8) at the front end, which is screwed into one of the bone parts (e.g. the femoral head 2) and the screw bolts (9) of which fracture surface ( 3, 4) penetrates and engages with axial play in a sliding sleeve (5, 15) anchored in the other bone part (e.g. the hip bone 1), characterized in that the sliding sleeve (5, 15) at least partially on the outer circumference with a screw thread (20) is provided. 2. Implant for the operative care of z. B. femoral neck fractures, which is designed as an elongated, at least two-part part, one part of which is anchored in one part of the bone and the other part in the opposite, separated by the fracture, other part of the bone, characterized in that between the two Share a locking Device (13, 16) is arranged, which only allows an axial displacement of one part to the other in only one direction, (Fig. 4 to 9). 3. Implant according to claim 1 or 2, characterized in that the locking device is designed as a ratchet mechanism. 4. Implant according to claim 3, characterized in that the ratchet consists of a locking ring (13) which is fixed radially inward on the sliding sleeve (15) and which is associated with an associated sawtooth Locking teeth (14, 18) on the outer circumference of the sliding screw (17, 27) cooperates. 5. Implant according to claim 4, characterized in that the locking teeth (14) extend over the entire circumference of the screw bolt (9), (Fig. 4). 6. Implant according to claim 4, characterized in that the locking teeth (14a) extend only partially on the circumference of the screw bolt (9) (Fig. 5). 7. Implant according to claim 4, characterized in that the locking teeth are designed as slots (18) in the screw bolt. 8. Implant according to one of claims 1 to 7, characterized in that the equal screw (7 17, 27) has one or more cannulas (19) extending in the axial direction and open radially on the outer circumference. 9. Implant according to one of claims 1 to 8, characterized in that it is designed as a sliding screw. 10. Implant according to one of claims 1 to 8, characterized in that it is designed as an intramedullary nail.