The ACL, or anterior cruciate ligament, in the knee connects the tibia, the lower leg bone, to the femur, the thigh bone. The ACL incurs injury more frequently than any other knee ligament. The symptoms of an ACL injury include a popping sound, pain, swelling and instability in the knee. Female athletes suffer ACL injuries two to four times as often as men playing the same sports, eOrthopod states. Around 200,000 ACL injuries occur each year in the United States, with around 100,000 ACL reconstructive surgeries performed, according to the American Academy of Orthopaedic Surgeons.
Causes
ACL tears occur most often as a result of trauma and they occur in conjunction with other knee injuries 50 percent of the time, the AAOS states. Sports that require frequent turns or sudden slowing or stopping often cause ACL tears. Since complete tears occur more commonly than partial tears, which might heal on their own, surgical repair is often necessary.
Repair
It's not possible to sew a torn ACL back together. Instead, the damaged ligament is replaced with a tendon taken either from a person's own body, called an autograft, or from a donor, called an allograft. A new ligament grows back using the tendon as scaffolding, according to the AAOS.
Procedure
Most ACL reconstruction surgeries are done arthroscopically, or through a small incision. A tiny camera inserted through the incision projects an image on a video screen so the surgeon can see the interior structures. Tools to remove the old ligament are inserted through additional small incisions in the knee. Most ACL repairs don't require an overnight hospital stay.
Recovery
A full recovery after ACL surgery can take four to six months, MedlinePlus reports. A knee brace and crutches may be used for the first one to four weeks after surgery. Physical therapy to prevent stiffness and restore strength and mobility begins right after surgery.
Complications
Like any surgery, ACL reconstruction surgery can have complications. The knee may still be stiff or may not regain full strength and range of motion in 5 to 25 percent of patients, according to the AAOS. Allografts fail more often than autografts, with a failure rate of 23 to 34 percent as compared to 50 to 10 percent of autografts in young active patients. Allografts also carry a small risk of infection transmission, including chronic infections such as hepatitis or HIV, the AAOS warns. Bacterial infections occur in less than 1 percent of cases, and the risk of contracting HIV or hepatitis C is estimated to be less than 1 in 1 million, the same source reports. Kneecap pain occurs commonly in people who had an autograft of the patellar tendon. Bleeding and blood clot development occur in less than 1 percent.
