Ligaments are tough bands of tissue which serve to connect the articular extremities of bones, or to support or retain organs in place within the body. Ligaments are typically composed of coarse bundles of dense white fibrous tissue which are disposed in a parallel or closely interlaced manner, with the fibrous tissue being pliant and flexible, but not significantly extensible.
In many cases, ligaments are torn or ruptured as a result of accidents or overexertion. Accordingly, various procedures have been developed to repair or replace such damaged ligaments. For example, in the human knee, the anterior and posterior cruciate ligaments (i.e., the ACL and PCL) extend between the top end of the tibia and the bottom end of the femur. The ACL and PCL cooperate, together with other ligaments and soft tissue, to provide both static and dynamic stability to the knee. Often, the ACL is ruptured or torn as a result of, for example, a sports-related injury. Consequently, various surgical procedures have been developed for reconstructing the ACL so as to restore normal function to the knee.
In many instances, the ACL may be reconstructed by replacing the ruptured ACL with a graft ligament. More particularly, with such procedures, bone tunnels are typically formed in the top end of the tibia and the bottom end of the femur, with one end of the graft ligament being positioned in the femoral tunnel and the other end of the graft ligament being positioned in the tibial tunnel. The two ends of the graft ligament are anchored in place in various ways known in the art so that the graft ligament extends between the femur and the tibia in substantially the same way, and with substantially the same function, as the original ACL. This graft ligament then cooperates with the surrounding anatomical structures so as to restore normal function to the knee.
A number of devices are currently employed for anchoring graft ligaments in the femur, including the use of crosspins, interference screws, and buttons which seat against the cortex of the femur when tension is applied to the graft ligament. A number of problems result from these techniques. For example, the button is placed deep within the femoral tunnel and away from the joint line, which can cause the graft to move in a side-to-side motion, i.e., to have a windshield wiper effect, and to cause tunnel widening, potentially leading to joint laxity. Other common problems involved in femoral fixation include slippage of the device within the femoral tunnel, slippage of the graft ligament relative to the device, or damage to the graft ligament resulting from contact with the device itself, such as the graft ligament being lacerated or wound up causing the graft orientation to be altered by the device.
Accordingly, there remains a need for a graft ligament anchor which is simple, easy to install, and inexpensive to manufacture, while providing secure, trouble-free anchoring of the graft ligament.