The lateral collateral ligament is a thin band of tissue running along the outside of the knee. It connects the thigh bone (femur) to the fibula, which is the small bone of the lower leg that runs down the side of the knee and connects to the ankle. Like the medial collateral ligament, the lateral collateral ligament's main function is to keep the knee stable. There are 2 main regions of the lateral collateral ligament which can be affected: the posterolateral and the anterolateral regions.
Lateral collateral ligament - posterolateral corner
The posterolateral corner is perhaps the most complicated anatomical area of knee injury and anatomy. It comprises of a number of structures which help knee stability throughout the range of movement in side-to-side and rotational movements.
The posterolateral corner is comprised of primary and secondary stabilisers. The three major static stabilisers of the posterolateral corner are the lateral collateral ligament, popliteus tendon and the popliteofibular ligament.
There are secondary stabilisers such as the iliotibial band, the long head of biceps femoris tendon, the fabellofibular ligament, the joint capsule and the coronary ligaments. All these complex structures work together to provide side-to-side and rotational stability to the posterolateral corner of the knee.
The posterolateral corner is very rarely injured in isolation and usually forms part of a constellation of injuries including ACL and sometimes PCL. Failure to recognise and treat posterolateral corner injuries results in ongoing instability around the knee and can jeopardise anterior cruciate ligament reconstruction which usually results in failure if the posterolateral corner is not treated at the same time.
Anterolateral ligament
The anterolateral ligament is a newly discovered structure which is closely related to the origin of the lateral collateral ligament. It arises around the lateral femoral condyle and attaches to the tibia in between Gerdy’s tubercle and the fibula head. It is thought to help stabilise the knee especially around anterolateral rotatory instability.
Anterolateral ligament reconstruction is a new operation which helps to provide extra stability to ACL reconstructions. It is also now routinely carried out as part of revision ACL reconstruction. The anterolateral ligament can be reconstructed using a gracilis tendon autograft, it can also be reconstructed using synthetic material such as fibre tape.