The cruciate ligaments are found in the middle of your knee joint, forming an “X” configuration as they cross each other to connect the thigh bone (femur) and the shin bone (tibia). The anterior cruciate ligament (ACL) prevents the tibia from sliding out in front of the femur, as well as provides rotational stability to the knee.
The mechanisms of an ACL injury include quick changes in direction (pivoting/cutting), stopping suddenly, landing awkwardly from a jump, and direct collisions. Female athletes are more prone to ACL injuries than males due to a number of physiological and biomechanical factors.
ACL injuries are usually complete or near-complete ligament tears, with partial injuries being rare. Over half of ACL injuries are associated with additional damage to the knee such as cartilage damage, meniscal tears and injuries to other ligaments.
What are the symptoms of an (ACL) injury?
At the time of the ACL injury, your knee may have given way and many people feel or hear a “popping” sensation. The deep pain and rapid onset of swelling make it very difficult to carry on with the activity or bear weight on the leg. Once the pain and swelling have resolved your knee can feel unstable and may continue to give way. Returning to pivoting/cutting activities is often impossible. Each giving way episode can cause further damage to your knee.
How is an ACL injury diagnosed?
The symptoms and a careful examination will usually suggest the diagnosis. An x-ray can be useful, but an MRI scan is the investigation of choice.
How is an ACL injury treated?
The treatment of ACL injuries is individualised to each patient based on activity levels and demands, age and associated knee injuries. Initial treatment is aimed at managing the pain and swelling through rest, analgesia/anti-inflammatory medication and ice. Crutches may be used to help mobility and a knee brace can help prevent further instability. As the pain and swelling subside, specific rehabilitation is started to restore motion, function and strength to your knee and leg.
Although a torn ACL will not heal, not everyone requires surgery. Physiotherapy and rehabilitation, however, plays a crucial role for everyone. Less active, usually older, individuals with less demanding activity levels can achieve overall knee stability with a focussed rehabilitation programme. People with higher activity levels and sporting demands usually require surgical intervention to reconstruct the torn ACL.
ACL reconstruction involves replacing your torn ligament with a tissue graft. There are several potential options including hamstring tendons at the back of your knee, part of the patella tendon that runs between the kneecap and tibia, and quadriceps tendon that runs up from the kneecap into the thigh. Donated graft (allograft) may also be used. The advantages and disadvantages of each option will be discussed by the surgeon to choose the best graft option for each individual.
It takes time for the graft to incorporate and function efficiently. Return to sport can take at least 6-months; often longer. Consequently, physiotherapy and rehabilitation are pivotal to the success of the surgery. Although at times you may feel frustrated, commitment to therapy is the most important factor in getting back to the activities you enjoy.