Knee Ligament Injuries


There are many ligaments in the knee which connects the lower leg bone (tibia) to the thigh bone  (femur). Ligaments are strong, band-like connective structures that stabilise the knee and prevent excessive motion but can become sprained or torn if large and sudden forces are placed upon them. There are 4 major ligaments that are commonly injured, the Anterior Cruciate Ligament (ACL), Posterior Cruciate Ligament (PCL), Medial Collateral Ligament (MCL) and Lateral Collateral Ligament (LCL).

The ligament injured depends on the mechanism of injury. The ACL and PCL form a “cross” in the middle of the knee joint and prevents excessive forward and backward translation, respectively, of the tibia, and they both prevent twisting forces as well. Therefore, sudden twisting injuries such as landing and turning during a jump or strong blow to the knee from the front or back can stretch or tear these ligaments. The collateral ligaments lie on the inner (MCL) and outer (LCL) knee joint and are strained during excessive angular forces in the knee.

Ligament injuries are classified into 3 grades depending on severity. A Grade 1 ligament sprain is a mild injury where the ligament fibres are stretched but are minimally or not torn. With a Grade 1 sprain, there is usually some knee pain but swelling is usually not present and the individual is able to continue activity.

In a Grade 2 sprain, the ligament fibres are partially torn and the joint may be less stable. The individual usually experiences more swelling and pain. Knee movements may become restricted and weight-bearing is difficult.

In a Grade 3 tear, the ligament is completely torn and the knee joint becomes unstable. The knee will become quite swollen and bruised, and the individual may complain of pain (some may have no pain at all since all the nerve fibres in the ligament have been completely disrupted).

With a complete ligament tear, individuals often report a sense of knee instability (episodes of giving way when walking or when trying to change direction on the affected knee). A torn ligament can be diagnosed with clinical assessment but your physiotherapist or doctor may send you for an investigation (such as an MRI) to identify the extent of injury and to see if there is any other injury to surrounding structures.

Management of a knee ligamentous injury depends on what level the individual was before the injury, age, extent of the knee instability, and what goals he/she has after injury. If you do not plan to return to high level sports or do not have significant instability, the injury can be managed with a comprehensive and graded rehabilitation program. However, if you are a young, high level athlete and wish to return to intensive sports, you may consider surgical repair of the torn ligament.

Whether you decide to go for surgery, if it important to see a Physiotherapist who can teach you how to manage the injury in the acute phase and create a suitable rehabilitation program for you as you recover. Your rehabilitation program will consist of lower limb strengthening, proprioception and agility training with sport-specific exercises. Even with a torn ligament, you may be able to return to certain sports after proper rehabilitation.