Introduction

Tears of the anterior cruciate ligament (ACL) in the knee are not uncommon, they typically occur in footballers, netballers, basketballers and skiers. The ACL is the major stabilizing ligament of the knee, it functions to prevent buckling of the knee and thus is vulnerable to the pivoting action that occurs in the above sports and can lead to its injury. At the time of injury, in a complete rupture, the athlete usually hears a ‘pop’ or ‘crack’ sound, often this is associated with other injuries such as to the medial ligament or medial meniscus.

 

Anatomy and Physiology

 

The anterior cruciate ligament is one of a pair of ligaments in the knee joint that form a cross (this is where the name cruciate comes from), it is located in the centre of the knee joint and runs from the femur (thigh bone) posteriorly to the tibia (shin bone) anteriorly. The anterior and posterior ligaments function to stabilise the knee from front to back during normal and athletic activities. In general the ACL is the primary restraint to anterior (forward) tibial translation in all degrees of knee flexion.

When an ACL is completely ruptured an Orthopaedic Surgeon will often decide to fix this by taking a graft from another tendon in your body, usually from the hamstring or patella tendon. This graft is then attached to the femur proximally and the tibia distally to replicate the ACL.

 

Basic Management

 

A diagnosis of an ACL tear can usually be made clinically by a Physiotherapist or Sports Physician and is then supported by a MRI investigation.

Management of the torn ACL varies, a partial tear is usually managed conservatively, with a period of rest, physiotherapy, and gradual return to sport. A full tear is usually managed with surgery to repair the torn ligament, especially in the younger athlete. Some individuals may decide, along with their specialist, that they will not have surgery and instead maintain the strength around the knee with regular exercises. If this is decided the knee remains somewhat unstable making high-level sports difficult.

 

Following surgery, rehabilitation of the ACL is ongoing over a 6-12 month period.

Early stage rehabilitation can vary slightly depending on the surgeon, for example, whether a hamstring or patellar graft was used, or if other structures were damaged. Often you will be on crutches until you can walk comfortably. Physiotherapy at this stage is directed towards minimizing swelling, gentle knee mobility exercises and early activation of the quadriceps (particularly VMO), hamstrings and gluteals.

Mid-stage rehabilitation from the 2 to 12 week mark consists of progressive strengthening of the quadriceps, hamstrings, gluteals and calf using closed kinetic chain exercises (weight-bearing exercises where the foot is fixed and thus will not put a shearing force on the graft). Full range of motion of the knee joint, and gentle proprioceptive or balance exercises. Cycling can usually begin after 6-8 weeks, with swimming and running after 3 months depending on other variables such as muscle strength and knee range of motion.

 

End-stage rehabilitation and return to sport occurs usually after 6 months, and on your surgeons review. This is only after a period of ‘sport-specific exercises’ as dictated by your physiotherapist and depending on your particular sport demands (Grodski, Marks 2008)

Grodski M, Marks R. Exercises following anterior cruciate ligament reconstructive surgery: biomechanical considerations and efficacy or current approaches. Res Sports Med 2008; 16(2):75-96

http://orthopedics.about.com/od/aclinjury/tp/acl.htm

http://www.sportsinjuryclinic.net/cybertherapist/front/knee/anteriorcruciate.htm