Ligaments in the knee include the anterior cruciate ligament (ACL), posterior cruciate ligament (PCL) and the medial cruciate ligament (MCL). One of the most common injuries to the knee is a torn ACL. Less common are PCL and MCL tears, which typically occur along with a traumatic ACL tear. The primary function of the ACL is to prevent the tibia from sliding forward on the femur. The incidence of ACL tears is higher in individuals who participate in basketball, football, skiing and soccer. It is estimated that only 30 percent of ACL tears are the result of a direct contact with another player or object. The majority of tears are due to non-contact mechanisms that result from cutting, pivoting or an awkward landing. Female athletes have a higher incidence of ACL tears, which may be due to differences in muscular strength, neuromuscular control, physical conditioning, lower extremity alignment, increased ligamentous laxity and possibly the effects of hormones.
Non-surgical and surgical treatment options are available for treatment of ACL, MCL and PCL tears. Non-surgical treatment may be considered based on a patient’s age (very young or elderly), activity level (low demand, sedentary lifestyle) and in cases such as a partial tear. The ACL does not heal with nonsurgical treatment, however symptoms of pain and instability can improve with a physical therapy program focused on muscle strengthening supplemented with a brace. Without surgery, activities involving cutting or pivoting movements should be eliminated as these put the knee at significant risk for further injury.
Surgical treatment is typically performed for patients who want to return to a full level of activity including sports and heavy manual labor. Surgery is performed arthroscopically and involves reconstructing (replacing) the ACL. Past studies have shown that simply repairing (stitching) the ACL back together does not work. During the same procedure, any associated injuries to the meniscus and/or articular cartilage will be treated. The meniscus can be “repaired” directly with sutures (stitches) or trimmed (partial meniscectomy) depending on the type of tear. The long-term success rate of ACL reconstruction ranges from 85-95 percent. The goal of ACL reconstruction is to restore the function of the knee by creating a stable joint therefore allowing a return to full recreational, sports and work activities.
In some cases, surgery is necessary to repair MCL and PCL tears, however these ligaments do not have a significant impact on the stability of the knee and in some cases can heal on their own or can be treated non-operatively.