Lindsey Vonn is out of the Olympics… Theo Walcott ruled out of the World Cup. Both ruled out because of Anterior Cruciate Ligament injuries. But what exactly is this ACL and why is it so important?
The ACL is one of the four main ligaments of the knee that help to keep the joint stable. It runs from the front of the shinbone and heads up and backwards to attach to the back of the thighbone. As with all ligaments it ‘s role is to provide stability between bones and resist external forces to prevent the knee from collapsing.
In reality the ligaments don’t do all of the work, strong and accurate muscle control aids to keep the knee aligned, but the role of the ACL cannot be underestimated. This can be demonstrated by the fact that in most cases it will be surgically reconstructed, it ‘s that important!
Unfortunately without the ligament the knee is considered unstable, and the joint is at risk of developing secondary arthritic changes.
An ACL injury can occur in several different ways, most notably by landing from a jump onto a bent knee then twisting, or landing on a knee that is over-extended. In collision sports, direct contact to the knee from opponents can cause an ACL injury. Because of the amount of force that is required to damage the ACL it is not uncommon for other structures within the knee such as the meniscus or medial ligament to also be damaged.
The reason the person is unable to carry on is that the restraining function of the ACL is absent and there is excessive rotation and forward movement of the shin in relation to the thigh, making the knee joint unstable. After a couple of hours the knee joint will become painfully swollen due to what is called a haemarthrosis (bleeding within the joint). This swelling provides a protective function by not allowing the person to use their knee but, if it persists, it can cause complications during the rehab stage.
People who do not play sports may be well able to function without the need for surgical reconstruction. Extensive rehabilitation is required though to strengthen the musculature around the knee to aid with stability. As in the majority of cases, elite athletes undergo reconstruction to enable them to compete at the highest level as is seen in all soccer and GAA players. During reconstruction a tendon graft is usually taken from the patella tendon or hamstring tendon. Doctors have recently discovered a new ligament the Anterolateral ligament (ALL) that may also be damaged along with the ACL during injury. Following ACL surgery some athletes still experience instability in the knee. Surgeons are hoping that by reconstructing the ALL ligament athletes will gain extra stability during twisting movements.
It will be interesting to see how quick Lindsey Vonn and Theo Walcott can return to competeing at the top level. Only time will tell!