Anterior cruciate ligament tear: A common knee injury
Knee injuries represent a very common orthopedic complaint and tears of the anterior cruciate ligament (ACL) are frequent among the active, athletic population. The ACL functions to limit forward movement of the tibia (shin bone) on the femur (thigh bone). Patients with tears of the ACL typically report a noncontact type of injury. Patients often sustain the injury when landing from a jump or changing direction while running. A pop may be heard or felt and onset of pain and swelling usually occurs following injury. Athletes may be unable to return to play, secondary to pain or a sense of looseness. A careful physical examination with comparison to the normal knee is usually diagnostic for ACL injuries. Plain radiographs (X-rays) are commonly normal but may show evidence of a capsular avulsion injury. An MRI scan is useful to confirm the ACL tear as well as to evaluate possible injuries to other ligaments, articular cartilage and menisci. In many cases of ACL injury an MRI scan will also show bone bruises to the front of the femur and the back of the tibia.
Treatment of an ACL tear is either operative or non- operative and depends on several variables including presence of other injuries, patient age, patient activity level and the ability of the patient to participate in a postoperative rehabilitation program. Older or more sedentary patients and those willing to forego certain activities and sports may be candidates for non-operative treatment. Patients who wish to return to sports that require running, jumping, cutting and pivoting movements require surgical reconstruction. Patients who choose to return to sports without surgical reconstruction of the ACL risk further damage to the knee. Surgery is usually performed under general anesthesia on an outpatient basis. Many choices exist for ACL grafts including autografts (from the patient) and allografts (from a cadaver donor).
The patellar tendon, hamstring tendons and the quadriceps tendon have all been used with success. Commonly, tunnels are created in the femur and tibia and the graft is stabilized in the tunnels using various fixation methods. Postoperative physical therapy is necessary to regain knee range of motion and restore muscle strength. A period of restriction from sports and other heavy activities is advised to allow graft healing. To properly diagnose and treat a knee injury, an evaluation by an orthopedic surgeon is necessary.