Retainer for tendons used in the reconstruction of the anterior cruciate ligament of the knee.

Abstract: The retainer for tendons used in the reconstruction of the anterior cruciate ligament of the knee comprises a cylindrical body (2) having a flange (3) at one end and an eyelet (5) at the other end; the tendons are engaged through the eyelet and are guided through a hole formed through the femoral and tibial condyles; the body (2) can be inserted until the flange (3) abuts against the femoral inlet of the hole.

Description: The present invention relates to a retainer for tendons used in the reconstruction of the anterior cruciate ligament of the knee. The conventional method for reconstructing the anterior cruciate ligament of the knee entails drilling a hole that passes through the tibial and femoral condyles. A frame, provided with slots for the passage of two tendons recovered from the tendinous muscle and from the gracilis muscle, is driven through the tibial inlet of the hole. When the frame has exited from the femoral inlet of the hole, it is orientated diametrically to said hole and the tendons are pulled and anchored to the tibial cortex. The retainer according to the prior art entails the substantial drawback that it does not allow to correctly tension the bundles of tendons. Tendon tensioning in fact occurs simultaneously with their fixation and can no longer be adjusted once fixation has been completed. A replacement plastic tendon retainer is known from DE 296 20 735 U1, which discloses an implant in the form of a convex disc, shaped as a button with an underside curved, convex region having two holes that provide for the passage of plastic filaments for replacing the tendons. The disc is placed so as to cover completely a duct made in a tibia with the convex part entering the duct inlet. On the underside of the disc protruding flaps with sharp ends are provided, which secure the disc to the tibia against rotation. The technical aim of the present invention is to provide a new retainer which allows to eliminate the above drawbacks. Within the scope of this aim, an object of the present invention is to provide a retainer which is capable of facilitating the operating technique for its installation. This aim and this object are achieved by a retainer for tendons according to the invention, as set forth in claim 1. Further particularities of the retainer according to the invention will become apparent from the following description on the basis of the accompanying drawings, wherein: figure 1 is a side view of a retainer according to a first embodiment; figure 2 is a sectional view, taken along the plane II-II of figure 1; figure 3 is a sectional view, taken along the plane III-III of figure 1; figure 4 is a partially sectional side view of a different embodiment of the retainer; figures 5 to 13 are views of various steps of the installation of the retainer. With reference to the above figures 1-3, the retainer is generally designated by the reference numeral 1 and comprises a cylindrical body 2 having, at one end, a cambered flange 3. A plurality of notches 4 are formed in the flange 3, are diametrically mutually opposite to the axis of the body 1 and are angularly mutually equidistant. A quadrangular eyelet 5 protrudes from the opposite side of the body 2 with respect to the flange 3. The eyelet 5 lies on a diametrical plane that passes through the axis of the body 1 and has a substantially ellipsoidal cross-section. The described retainer is completed by a hexagonal recess 6 which is formed axially in the body 1 and is open at the center of the flange 3. The recess 6 is meant for the engagement of a tool, for example an Allen wrench, whereby the retainer can be turned once it has been installed in the seat meant to receive it. The method for installing the described retainer is as follows. The semitendinous tendon B and the gracilis tendon C are first released through an incision A formed with an arthroscope; however, said tendons remain inserted on the tibia with one end. Two sutures D, for example of the type known as Brunnel suture, are then applied to the free ends of the two tendons B and C to allow the coupling of the thread E for pulling the tendons through the articulation of the knee. The arthroscope is then reinserted through a second supracondylar incision F and is used to form, according to conventional methods, the outer percondylar hole G and the tibial hole H (figure 5). By using a suitable ligature carrier I, the tendons B and C are then passed through the tibial hole H.and through the femoral hole G until they fully exit from the incision F (figure 6, 7). At this point, the tendons B and C are guided through the eyelet 5 of the retainer 1 (figure 8). By using a second traction wire L, the tendons are reinserted in the femoral hole G and in the tibial hole H, until they again exit from the tibial hole H (figures 8 and 9). The traction applied by the tendons to the retainer 1 causes the partial engagement of the retainer 1 in the inlet of the femoral hole G. By using a suitable boneset, the retainer is fully inserted in the femoral hole G until the flange 3 abuts against the outer cortex of the femur (figure 10). An adequate traction of the free ends of the tendons allows them to slide on the eyelet 5. When the pretensioning of all four bundles of tendons has reached a preset value, one and two staples M (figure 11) are arranged so as to straddle the tendons at the exit of the tibial hole H. At this point, valid stabilization of the knee has already been achieved. However, the retainer allows an additional and final tensioning by twining the tendon bundles inside the femoral hole G and the tibial hole H. For this purpose, an Allen wrench N is inserted in the recess 6 and turned through the necessary angle, for example approximately 360° (figure 12). The direction of rotation of the tendon bundles is clockwise for the right knee and counterclockwise for the left knee. The tensioning force of the tendons can be controlled with a torque wrench. When the tendons have reached the intended tension, the retainer 1 is fixed against possible rotary and axial displacements by positioning a staple O so as form a bridge on the flange 3, so that the teeth of the staple O engage the notches 4 (figure 13). It is evident that the described retainer perfectly achieves the intended aim and object. In particular, the retainer allows to simultaneously perform pretensioning and final tensioning of the tendons during the operation, at the chosen degrees of flexing and for the time deemed most suitable by the operator, allowing to take advantage of the visco-elastic properties of tendons. According to a different embodiment of the invention, illustrated in figure 4, instead of the hexagonal recess 3 a threaded hole 7 is provided which is suitable to receive a screw-on plug that, by preventing the growth of bone inside its internal hole, facilitates the optional engagement of a tool for the removal of the retainer, if and when required. In a further embodiment, the eyelet 5 is open so as to form a sort of hook. Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly such reference signs do not have any limiting effect on the interpretation of each element identified by way of example by such reference signs.

Claims: A retainer for retaining and tensioning tendons (B, C), comprising: a cylindrical body (2) having at one end a flange (3) provided with a plurality of notches (4) arranged in diametrically opposed positions thereof, and at the other end an eyelet (5) which has an opening such as to allow guided passage of the tendons (B, C) therethrough and, upon insertion of the body (2) in a bone hole (G) with said flange (3) abutting against the inlet of the hole (G), to allow pre-tensioning of the tendons (B, C); a recess (6) formed at said flange (3) and adapted, upon pre-tensioning of the tendons (B, C), for the engagement of a tool (N) that causes clockwise or counterclockwise rotation of said body (2) and eyelet (5) for twining and consequent additional/final tensioning of the tendons; and fixing means (O) adapted to engage said notches (4) so as to fix the retainer (1) against rotary and axial movements. A retainer according to claim 1, characterized in that said recess (6) has a hexagonal cross-section. A retainer according to claim 1, characterized in that said recess (6) is a threaded hole (7) suitable to receive a closure plug by screwing. A retainer according to one of the preceding claims, characterized in that said eyelet (5) is provided open so as to form a sort of hook. A retainer according to one of the preceding claims, characterized in that said flange (3) is cambered. A retainer according to one of the preceding claims, characterized in that said eyelet (5) is quadrangular and lies on a diametrical plane that passes through the axis of the body (2). A retainer according to one of the preceding claims, characterized in that said fixing means are constituted by a staple (O) adapted to be positioned so as to engage said notches (4) and to form a bridge on the flange (3). A retainer according to one of the preceding claims, characterized in that said recess (6) is shaped so as to be engaged for rotation actuation by an Allen wrench (N).

Inventors: CONTEDUCA FABIO, FERRETTI ANDREA, CONTEDUCA, FABIO, FERRETTI, ANDREA
Applicants: CITIEFFE SRL, CITIEFFE S.R.L.
Application year: 1998
Main classification: A61B17
IPC codes: A61B17, A61F2