HSS Presents: Anterior Cruciate Ligament Injuries

Brian Feeley, MD
2007 Sports Medicine Fellow
Hospital for Special Surgery


Anterior cruciate ligament (ACL) tears are common injuries that occur at all levels of athletics, including the NFL. It is extremely common in sports with a lot of planting, cutting, and pivoting, such as soccer, basketball, skiing, and football. The ACL is one of four major ligaments in the knee, and has a primary role in maintaining knee stability.

Tears of the ACL often occur with a sudden twisting movement when a person stops quickly and changes direction, especially with pivoting or landing after a jump. Sudden impact to the knee may cause an ACL tear as well.


Athletes with an ACL injury often hear or feel a ‘pop’ at the time of injury. The knee will become swollen quickly, and will feel unstable in many cases. With ACL injuries, there are often other injuries to the knee, including injuries to the cartilage and other knee ligaments.

Diagnosis can usually be done by physical exam, although an MRI is very helpful in diagnosis of ACL tears. It is also important to look for other injuries in the knee that are more difficult to diagnose on physical exam.


Immediately after ACL injury, it is important to decrease the inflammation in the knee with ice and anti-inflammatory medications such as ibuprofen. Physical therapy is prescribed to strengthen the surrounding muscles and improve the range of motion of the knee.

Some people with ACL injuries can be treated with physical therapy and rehabilitation and can continue to lead an active and healthy lifestyle. However, for athletes that wish to continue to perform at a high level or participate in high demand activities such as football, basketball, soccer, and skiing, ACL reconstruction is often recommended.

Since the ACL cannot usually be repaired or reattached once it is torn, surgical reconstruction is required. A graft of replacement tissue, either from the patient’s own hamstring or patellar tendon, or an allograft (human donor tissue) is used to replace the ACL. The reconstruction is performed, using arthroscopic surgery, through several small incisions around the knee.


Return to sports after an ACL reconstruction usually takes six months, depending on the level of competition and the type of activity. Patients can walk with crutches and a leg brace on the day of surgery. Physical therapy is started immediately to work on range of motion exercises. Strengthening is started early in the recovery period, with progression to running at four months. Pivoting exercises are started around five months, with return to play at six months. Arthroscopy has made the post-operative period easier for the patient, but carefully supervised rehabilitation is critical for a successful outcome.


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