The knee is the largest joint in our body and depends on it’s ligaments for stability and proper function. The stabilizing ligaments of the knee are Anterior Cruciate Ligament (ACL) which connect the front part of the tibia (shin bone) to the back part of the Femur (thigh bone), Posterior Cruciate Ligament (PCL) which connects the back part of the tibia (shin bone) to the back part of Femur (thigh bone), Medial Collateral Ligamnet (MCL) which connects the inner side of the lower part of the femur (thigh bone) to the inner and upper part of the tibia (shin bone) and finally lateral Collateral Ligament which connect the lower and outer part of the femur (thigh bone) to the upper part of the Fibula (small bone of the leg).
The knee joint has a complex function and are used when one wants to pivot, change direction, crawl, kneel, stoop, jump and kick. If any of these ligaments are injured the function and motion of the knee joint is compromised.
Anterior Cruciate Ligament (ACL) can be injured as a result of a direct blow to the out side of the knee (direct injury) or in process of deceleration, jumping and landing and twisting/turning when foot is planted.
Tear of the ACL usually is associated with a loud “pop”, knee giving out and swelling within the first 24 hours. Pain usually is not very intense and in fact will improve in 2-3 days. As time goes on walking and range of motion may become more difficult.
Generally the pain and discomfort and functional disability is to the extent where an individual with injured ACL will seek medical attention. The examining physician in most cases is able to make a diagnosis of injury to the ACL, however dpending on the time of injury and the interval between injury and visit to the doctor physical examination by the examining physician may be inconclusive due to associated swelling or muscle spasm. In these situations there may be a need for an Magnetic Resonance Imaging (MRI) and or diagnostic arthroscopy.
Depending on the degree of damage to the ACL (partial or total) and presence or absence of other injuries (other ligaments and menisci) treatment may be surgical or non-surgical (conservative).
Non-surgical treatment usually include activity modification for a period of time, physical therapy and muscle strengthening exercises and use of stabilizing brace.
The decision to proceed with surgery depends on variety of factors including:
Patient’s age and occupation/sport, presence or absence of associated injuries, the degree of knee looseness/laxity and finally patient’s expectation.
A 55 year old Lawyer with minimal knee looseness/laxity who is not involved in any sporting activities and only wishes to be able to walk for 2 miles three times a week and has no associated injury and has no pain may not be a good candidate for surgery.
On the other hand a 17 year old football player who has a great potential for football scholarship and has moderate looseness/laxity and his knee frequently gives way, even in absence of associated injuries is a good candidate for surgery.
ACL reconstruction has been modified over the last two decades and these days are mostly done arthroscopically assisted (closed). There are two major sources of new ligament,
Autograft ( this is usually taken from patient’s patellar tendon or hamstring tendon) and Allograft (donor tissue from a tissue bank).
If there are other injuries to the knee it can also be repaired at the time of ACL reconstruction.
On rare occasions the severity of injury to the knee is as such that repair and reconstruction need to be performed in two stages.
Post operative physical therapy and rehabilitation is critical in the case of ACL reconstruction and adherence to the post operative ACL rehabilitation protocol will be a crucial part of the successful ACL surgery.
The rehabilitation protocol also depends on the type of surgery (closed vs open) and the type of tissue (autograft vs allograft) utilized for reconstructing of the ACL.