Anatomy-
- The anterior cruciate ligament is the primary restraint to anterior tibial displacement.
History
- The classic history of an anterior cruciate ligament injury begins with a noncontact deceleration, jumping, or cutting action. Obviously, other mechanisms of injury include external forces applied to the knee.
- The patient often describes the knee as having been hyperextended or popping out of joint and then reducing. A pop is frequently heard or felt.
- Within a few hours, the knee swells, and aspiration of the joint by injection reveals hemarthrosis. In this scenario, the likelihood of an anterior cruciate ligament injury is greater than 70%.
Physical Examination
- The Lachman test is the most sensitive test
- Anterior Drawer Test
- The pivot shift test
Diagnosis
Radiographic studies also are useful in diagnosis of anterior cruciate ligament injuries.
- Plain radiographs often are normal – however they may pick up some subtle fractures.
- MRI is the most helpful diagnostic radiographic technique. The reported accuracy for detecting tears of the anterior cruciate ligament has ranged from 70% to 100%.
Natural History-
It has been well documented that an individual with an anterior cruciate ligament–deficient knee who resumes athletic activities and has repeated episodes of instability will sustain meniscal tears and osteochondral injuries that eventually lead to arthrosis.
Treatment-
The treatment options available include nonoperative management, repair of bony avulsion of ACL and reconstruction with either autograft or allograft tissues or synthetics.
Nonoperative treatment is a viable option for a patient who is willing to make lifestyle changes and avoid the activities that cause recurrent instability. This can be achieved by a good physiotherapy protocol in selected patients.
Acute repair is appropriate when a bony avulsion occurs with the anterior cruciate ligament attached. The avulsed bone fragment often can be replaced and fixed with sutures or passed through transosseous drill holes or screws placed through the fragment into the bed.
Intraarticular Reconstruction
- The advances made in arthroscopy have led to the development of arthroscopic techniques
- The most common current graft choices are bone–patellar tendon–bone graft and the quadrupled hamstring tendon graft.
AFTERTREATMENT
Good physiotherapy is of utmost importance after ligament reconstruction. Place the knee in a controlled motion brace locked in full extension. Protected range-of-motion exercises are begun immediately.
After surgery, the thigh muscles atrophy quickly.
The early emphasis of strengthening is on the hamstrings, which function in concert with the anterior cruciate ligament to prevent anterior translation of the tibia. Also, their strengthening does not stress the graft.
Early quadriceps strengthening concentrates on quadriceps sets and straight leg raises.
Certain resisted quadriceps exercises are worrisome because they put some strain on the anterior cruciate ligament, especially in the last few degrees of extension of the knee if the limb is not bearing weight, so-called open chain exercises.
