An injury to the anterior cruciate ligament can be a debilitating musculoskeletal injury to the knee, seen most often in athletes. Non-contact tears and ruptures are the most common causes of ACL injury.

The anterior cruciate ligament (ACL) is an important ligament for proper movement. ACL injury more commonly causes knee instability than injury to other knee ligaments. Injuries of the ACL range from mild such as small tears to severe when the ligament is completely torn. There are many ways the ACL can be torn; the most prevalent is when the knee is bent too much toward the back and when it goes too far to the side. Tears in the anterior cruciate ligament often take place when the knee receives a direct impact from the front while the leg is in a stable position, for example a standing football player is tackled sideways when his feet are firmly planted. Torn ACL’s are most often related to high impact sports or when the knee is forced to make sharp changes in movement and during abrupt stops from high speed. Research has shown that women involved in sports are more likely to have ACL injuries than men. ACL tears can also happen in older individuals through slips and falls and are seen mostly in people over forty due to wear and tear of the ligaments. An ACL tear can be determined by an individual if a popping sound is heard after impact, swelling after a couple of hours, severe pain when bending the knee, and when the knee buckles or locks during movement or gives way while standing still with weight on the affected knee.

Signs and symptoms

Symptoms of an ACL injury include hearing a sudden popping sound, swelling, and instability of the knee (i.e., a wobbly feeling. Pain is also a major symptom in an ACL injury and can range from moderate to severe. Continued athletic activity on a knee with an ACL injury can have devastating consequences, resulting in massive cartilage damage, leading to an increased risk of developing osteoarthritis later in life.

Causes

ACL injuries occur when an athlete rapidly decelerates, followed by a sharp or sudden change in direction (cutting). ACL failure has been linked to heavy or stiff-legged landing; as well as twisting or turning the knee while landing, especially when the knee is in the valgus (knock-knee) position.

Women in sports such as football, basketball, tennis and volleyball are significantly more prone to ACL injuries than men. The discrepancy has been attributed to differences between the sexes in anatomy, general muscular strength, reaction time of muscle contraction and coordination, and training techniques. A recent study suggests hormone-induced changes in muscle tension associated with menstrual cycles may also be an important factor. Women have a relatively wider pelvis, requiring the femur to angle toward the knees. Recent research also suggests that there may be a gene variant that increases the risk of injury. The majority of ACL injuries occur in athletes landing flat on their heels. The latter directs the forces directly up the tibia into the knee, while the straight-knee position places the lateral femoral condyle on the back-slanted portion of the tibia. The resultant forward slide of the tibia relative to the femur is restrained primarily by the now-vulnerable ACL.

Western Medicine Treatment

The ACL primarily serves to stabilize the knee in an extended position and when surrounding muscles are relaxed; so if the muscles are strong, many people can function without it. Fluids will also build the muscle.

The term for non-surgical treatment for ACL rupture is conservative management, and it often includes physical therapy and using a knee brace. Lack of an ACL increases the risk of other knee injuries such as a torn meniscus, so sports with cutting and twisting motions are strongly discouraged. For patients who frequently participate in such sports, surgery is often indicated.

Patients who have suffered an ACL injury should always be evaluated for other knee injuries that often occur in combination with an ACL tear. These include cartilage/meniscus injuries, bone bruises, PCL tears, posterolateral injuries and collateral ligament injuries.

A torn ACL is less likely to restrict the movement of the knee. When tears to the ACL are not repaired it can sometimes cause damage to the cartilage inside the knee because with the torn ACL the tibia and femur bone are more likely to rub against each other. Immediately after the tear of the ACL, the person should rest it, ice it every fifteen to twenty minutes, produce compression on the knee, and then elevate above the heart; this process helps decrease the swelling and reduce the pain. The form of treatment is determined based on the severity of the tear on the ligament. Small tears in the ACL may just require several months of rehab in order to strengthen the surrounding muscles, the hamstring and the quadriceps, so that these muscles can compensate for the torn ligament.

If the tear is severe, surgery may be necessary because the ACL can not heal independently because there is a lack of blood supply going to this ligament. Surgery is usually required among athletes because the ACL is needed in order to perform sharp movements safely and with stability. The surgery of the ACL is usually done several weeks after the injury in order to allow the swelling and inflammation to go down. During surgery the ACL is not repaired instead, it is reconstructed using other ligaments in the body. There are three different types of ACL surgery. Patella tendon-bone auto graft and hamstring auto graft are the most common and preferred and tend to produce the best results. For the Patella tendon-bone auto graft, the central 1/3 of the patella tendon is removed along with a piece of bone at the attachment sites on the kneecap and tibia. The advantages of using this method is that the patella tendon and ACL are relatively the same length and it uses a bone to bone attachment which most surgeons agree is much stronger than other healing methods. The disadvantages of this method is common anterior knee pain due to the removal of bone from the kneecap. For the hamstring auto graft, two tendons are taken from the hamstring muscles and wrapped together forming the new ACL. Advantages of this method are less pain associated with post surgery healing than that of the patella tendon-bone graft due to the fact no bone was removed and the incision is small. Disadvantages of this method is that it takes longer to heal since there is no bone to bone healing and the tendon to bone takes awhile to become rigid. After the surgery, rehabilitation is required in order to strengthen the surrounding muscles and stabilize the joint.

Adopted from mayoclinic.com