The present invention relates to a tendon anchor to be used within the knee or other parts of the body.
The present invention is directed to the reconstruction of the anterior cruciate ligament (ACL) and the posterior cruciate ligament (PCL). The ACL helps stabilize the knee joint, and prevents posterior displacement of the femur on the tibia in hyperextension of the knee joint.
The ACL is sometimes torn during sports or as a result of traumatic stresses. Ligament reconstruction with allograft or autograft tissue has been shown to improve joint function and provide long term improvement in restoration of physical activity. A typical surgical procedure for ligament replacement and reconstruction involves obtaining a tissue graft or a suitable synthetic graft to replace the damaged ligament. A graft may come from either another part of the patient's body (autograft), from a cadaver donor (allograft), or the graft may be synthetically manufactured.
Structurally, the ACL attaches to a depression in the front of the intercondylar eminence of the tibia and extends posterior-superiorly to the medial wall of the lateral femoral condyle. Partial or complete tears of the ACL are common, comprising over a 120,000 cases annually in the United States.
The preferred treatment of the torn ACL is ligament reconstruction, using a bone-ligament-autograft. Methods for placement of such bone-ligament-bone grafts are generally described in Goble et al., U.S. Pat. Nos. 4,772,286; 4,870,957; 4,927,421; 4,997,433; 5,129,902; and 5,147,362. Other methods are shown in U.S. Pat. No. 4,400,833 to Kurland; U.S. Pat. No. 4,467,478 to Jurgustis; U.S. Pat. No. 4,597,766 to Hillal et al.; U.S. Pat. No. 4,668,233 to Seedhom et al.; U.S. Pat. No. 4,744,793 to Parr et al.; U.S. Pat. No. 4,834,752 to Vankampen; and U.S. Pat. No. 5,013,520 to Rosenberg.
Although the use of a bone-tendon-bone graft may provide the advantage of effective healing due to the efficient integration of the bone graft to the bone host, the harvesting of a bone-tendon-bone graft typically results in extensive morbidity to the donor knee joint. It is, therefore, often preferable to harvest grafts made up entirely of tendon tissue such as the hamstring. However, it has been found to be more difficult to effectuate and maintain accurate fixation of such grafts throughout the healing period where high-tension forces of the knee may act to disrupt the graft construct.
ACL reconstruction procedures generally include the formation of a tunnel through the patient's femur and tibia bones and implanting a natural ligament or tendon or a synthetic ligament in the bone tunnel which eventually attaches itself to the bone and holds the tibia and femur together.
In order to anchor the ligament within the bore or tunnel a device is necessary for grasping the ligament which can then integrate itself with the bone surrounding the bore. In the past, devices such as interference screws have been used when a bone-tendon-bone system has been used. See Mahony, U.S. Pat. No. 5,062,843; or Roger et al., U.S. Pat. No. 5,383,878; Steininger et al., U.S. Pat. No. 5,425,767; and Hubner U.S. Pat. No. 5,454,811. Interference screws function by creating a tight fit between the bone graft and the surrounding bone. Such a system may result in the tendon being damaged which can result in impeded healing or loosening of the interference fixation.
There has been a need for a ligament anchor which can fix the ligament in the bone bore which anchor includes a porous inner and outer surface for tissue ingrowth.