HK1019850A - Fixing element and ligament fixed with fixing element - Google Patents

Description

Fixing element and ligament fixed by means of a fixing element

The invention relates to a fixing element for attaching a ligament to a bone portion of a human being or an animal, and to a ligament which is fixed to a bone portion by means of at least one such fixing element.

When a ligament is damaged, such as a tear in the hamstring tendon (ligament rupture), a new ligament (plastic ligament) may be surgically installed. Ligament material that is removed from other parts of the body may be used for this new ligament, but plastic materials (plastic ligaments) may also be used for this purpose. Such a ligament can be fixed, for example, using bolts with toothed rings, staples, bone pegs, toothed pegs, etc. When using bone pegs for fixation, it is required to provide a continuous opening in the bone part through which the ligament to be fixed is placed. The bone segments of the bone parts for opening the continuous opening abut against the ligament so that the ligament is firmly held in the continuous opening by the bone segments or plugs. All of these fixation methods are often used individually or in combination.

A disadvantage of the known fixation methods is that it is difficult to bring and maintain the ligament in the correct tension. Thereby causing functional decline, pain and a feeling of instability. A particular disadvantage of ligaments made of ligament material removed from other parts of the body (homologues) is that ligaments installed in the correct tension during surgery tend to loosen over time, whereby their instability increases again. One disadvantage of plastic ligament material is that it has a limited life, so that it often breaks after years have elapsed. Therefore, the ligament must be replaced, which requires another major surgery.

The object of the invention is to fix a ligament to a bone part, so that it is simple to hold the ligament or to change the tension accordingly in order to replace a fixed ligament by another ligament.

To achieve this object, the present invention provides a fixation device for attaching a ligament to a bone portion of a human or animal, the fixation device comprising:

a hollow, substantially cylindrical member fixable in a continuous opening in a bone portion, an

An engagement element for a ligament which can be fixed to the cylindrical component at least at two mutually different axial positions. The outer wall of the cylindrical member preferably has a profile that facilitates stable fixation to the bone portions. The cylindrical member constitutes an alternative attachment solution for the attachment of the joint to the ligament. The engaging element can be attached to the cylindrical member in a relatively simple manner, whereby the displacement of the engaging element relative to the cylindrical member can be achieved relatively easily, or whereby the engaging element with the ligament fastened thereto can be detached from the cylindrical member for replacement with a new ligament which is likewise provided with the engaging element, and whatever type of ligament. It will be clear that here, it is of utmost importance that the cylindrical member must be rigidly connected to the bone parts. The operating techniques employed are not significantly different from those commonly employed. In order to simply achieve the connection between the cylindrical member and the engagement member, the inner wall of the cylindrical member preferably has a profile which co-operates with the engagement member for the ligament. The internal profile may preferably be constituted by an internal thread. In order to allow a simple and good connection of the engaging element to the cylindrical member, the outer side of the engaging element preferably also has a profile which cooperates with the inner side of the cylindrical member. This profile is preferably also formed by a thread. Ligament tension adjustment may be performed, for example, using limited surgery, such as incisions under local anesthesia. In a preferred embodiment, the fixed part may be provided with an adjustment device which can be remotely controlled. Here, it is conceivable to use, for example, a micromotor or the principle of electromagnetic induction. The ligament tension can then be adjusted "in situ" using a remote control, either on a production line or when the patient is connected to the knee laxity testing device. Other solutions are also possible in this connection, such as heat-sensitive materials or adjustment devices which can be controlled by means of a moving magnetic field.

With the structure of such a hollow cylindrical member permanently fixed to the bone, the operations that require possible revision are very limited, and the time required to make the revision can be significantly reduced compared to the existing ligament fixation means. Such a correction may be performed with an arthroscope.

Preferably, the inner side of the cylindrical member on at least one side thereof is smoothly moved into the end wall of the cylindrical member. Excessive wear of the ligament due to contact with sharp edges can be prevented when the cylindrical member is placed in the bone portion so as to move smoothly with the inside into the end wall of the cylindrical member forming the side along which the ligament is mounted in the cylindrical member.

The engaging member is preferably provided with means for gripping the ligament. Clamping the ligament has the advantage that the ligament material is not damaged or hardly damaged, while the length of the ligament required for a particular operation is kept as limited as possible. The engagement member can be used regardless of the type of implant (syngeneic ligament, plastic ligament or combination thereof).

In a preferred embodiment, the engaging member comprises a continuous opening in which a holding member for holding the ligament can be fixed. This clamping arrangement is very reliable and simple to use.

In another preferred embodiment, the joint may be connected to the cylindrical member by inserting an elastic member. By means of this elastic connection, the ligament tension can be kept constant, despite for example stretching of the ligament material over time. Another advantage is that peak loads on the ligament can be at least partially absorbed by the elastic member, so that damage to the ligament is not quickly caused.

In a further preferred embodiment the engaging member is provided with at least one recess and/or projection at a side remote from the ligament for engaging an adjustment means for changing the position of the engaging member relative to the cylindrical member. With this arrangement, the tension on the ligament can be changed after surgery using a small incision. By inserting an adjustment means, such as a wrench-like shape, in the cut-out such that it cooperates with the groove and/or the projection, the position of the engagement member relative to the cylindrical member can be changed. Thus, the tension on the ligaments can be changed without major surgery.

The invention also relates to a ligament which is fixed to a bone portion with at least one fixing element. According to the invention, the ligament can be fixed on both sides with fixing elements, but significant advantages are already obtained when one side of the ligament is fixed with a fixing element according to the invention, while the other side is fixed according to the methods of the prior art.

The invention will be further described with reference to some non-limiting examples and to the accompanying drawings, in which:

FIG. 1 is a sectional perspective view showing a knee equipped with a ligament fixed at one side by a fixing member according to the present invention;

FIG. 2 is a perspective view showing a fixing member according to the present invention; and

fig. 3 is a perspective view of another fixing member according to the present invention.

Figure 1 shows a partially sectioned human knee joint 1. The ligament 2 is fixed artificially in the knee joint 1. For this purpose, continuous openings 5,6 are provided in the upper skeleton part 3 and the lower skeleton part 4, respectively. The ligament 2 is fixed to the lower skeleton portion 4 by means of staples 7 known in the art. This connection of the ligament 2 to the lower bone portion 4 provides a rigid connection which can only be released by surgery. Here, it is difficult to re-fix the same staple 7 a second time at the same location on the lower bone part 4.

In the upper skeleton part 3, in the continuous opening 5, a fixing element 8 according to the invention is arranged. The side of the fixing element facing the ligament 2 is provided with an edge 9 which is rounded on the inside to prevent the ligament 2 from being worn when inserted into the fixing element 8. The following figures are provided to further illustrate the fixing member 8.

Fig. 2 shows a fixing element 10 which is placed into the bone part 3. The fixation means 10 comprise a cylindrical member 11, which is provided with a contoured edge on the outside for stable fixation of the cylindrical member 11 in the osseous material 3. The cylindrical member 11 has a hollow form such that its inner wall is provided with an internal thread 12. An engagement member 13 is located inside the cylindrical member 11, the engagement member 13 being provided with an external thread 14, which thread 14 cooperates with the internal thread 12 of the cylindrical member 11. The engaging piece 13 can be moved in the axial direction by rotating the engaging piece 13 relative to the cylindrical member 11. This axial movement of the engagement member 13 changes the tension of the ligament 2. By placing, for example, a wrench 15 in a recess 16 provided in the end wall of the engaging member 13, the tension of the ligament 2 can be changed in a very simple manner. The ligament 2 shown in these figures is made of a number of fibres 17. But other ligaments are possible. In order to fix the engaging member 13 to the ligament 2, the engaging member 13 is provided with a recess 18 in which a holding member 19 is placed. The clamping member 19 can be fixed in the groove 18 such that the fibres 17 of the ligament 2 are clamped between the clamping member 19 and the wall of the groove. In the figure, for this purpose, the holder is provided with threads which cooperate with internal threads provided on part of the length of the recess 18. However, other solutions are also easily imaginable.

Fig. 3 shows a fixing member 20 having a different structure from the fixing member 10 shown in fig. 2. The fixing part 20 shown here likewise comprises a cylindrical component 11 corresponding to the cylindrical component shown in fig. 2. On the side where the ligament 2 can be brought into contact with the cylindrical member 11, the latter is provided with a rounded edge 21. An adapter 22 with a hollow sleeve 23 is located inside the cylindrical member 11, the hollow sleeve 23 being provided with an external thread 24 for cooperation with the internal thread of the cylindrical member 11. The axial position of the sleeve relative to the cylindrical member 11 can be varied by rotating the fixing means 21, the rotation of which is simplified by the protrusions 25 mounted on the sleeve 23. A difference to the construction shown in figure 2 is that a holding block 26, which is quite similar to the holding member 19 in figure 2, is provided for free axial movement within the sleeve 23. The operation of the clamping block will not be further described in these figures. The clamping block 26 is supported by means of a spring 27 on the sleeve 23. Thus, the tension of the ligament 2 can be kept constant when slight variations occur in the length of the ligament 2; changes in the length of the ligament 2 can be absorbed by the spring 27. The fixing element 20 shown in this figure therefore has the advantage that, in the event of slight changes in the length of the ligament 2, no readjustment is necessary in order to keep the tension of the ligament 2 constant.

Claims (13)

1. Fixation element for connecting a ligament to a bone portion of a human or animal, comprising:

a hollow, substantially cylindrical member fixable in a continuous opening in a bone portion, an

-an engagement member for a ligament which is connectable to the cylindrical member at least at two mutually different axial positions.

2. The fixation element of claim 1 wherein the outer wall of said cylindrical member has a profile for stably securing it to a bone portion.

3. A fixing element according to claim 1 or claim 2 wherein the inner wall of the cylindrical member has a profile for co-operation with an engaging member of a ligament.

4. A fixing element according to claim 3, characterized in that the inner contour of the cylindrical member is constituted by an internal thread.

5. A mounting member according to any preceding claim, wherein the mounting member is provided with adjustment means allowing remote adjustment.

6. A fixing element according to any preceding claim characterised in that on at least one side of the cylindrical member its inner side smoothly translates into the end wall of the cylindrical member.

7. A fixing element according to any preceding claim wherein the engaging member is provided with means for gripping the ligament.

8. A fixing element according to any preceding claim wherein the outer side of the engaging member has a profile for co-operation with the inner side of the cylindrical member.

9. A fixing element according to claim 8 wherein the profile of the outer side of the engagement member is formed by a screw thread.

10. A fixing element according to any preceding claim wherein the engagement member comprises a continuous opening in which a retaining member for retaining the ligament can be secured.

11. A mounting device according to any preceding claim, wherein the engagement means is connectable to the cylindrical member by means of an interposed resilient member.

12. A fixing element according to any preceding claim wherein the engaging member is provided with at least one recess and/or projection on the side remote from the ligament for attachment of adjustment means for changing the position of the engaging member relative to the cylindrical member.

13. Ligament with at least one anchoring element according to any one of the preceding claims, the ligament and the anchoring element being anchored to bone parts.