Other Ligaments Injuries

Medial Collateral Ligament (MCL) Injury

The main restraining ligament on the inside of the knee is the MCL. This is a ligament that is frequently injured when the lower leg is forcibly deviated laterally (away from the body).


Following an injury, pain is normally experienced over the medial aspect of the knee. It is usually associated with some swelling and there is tenderness on examination.

An MRI scan can be useful to confirm the clinical diagnosis and differentiate it from other injuries such as a meniscal tear and identify whether any other structures have been injured as the medial meniscus and ACL are often also inured at the same time as the MCL.


Diagram demonstrating the ligaments of the knee
Diagram demonstrating the ligaments of the knee

Fortunately, most MCL injuries will heal well and there is usually no need for surgical treatment. For mild sprains, rest, analgesia and physiotherapy is usually sufficient and for more severe sprains, the knee often needs to be supported in a brace to allow the ligament to heal in a good position.

The healing process following an MCL injury takes place over a period of six to twelve weeks depending on the severity of the injury.

Occasionally, after the ligament has healed, there can be significant laxity that can give instability symptoms similar to those that occur after an anterior cruciate ligament injury and these might occasionally require surgery.

In addition, the MCL is sometimes repaired or reconstructed acutely in the complex multi-ligament knee injury.



Posterior cruciate ligament injury

The posterior cruciate ligament (PCL) is the largest ligament in the knee and injury to it is rarer than injury to the ACL. PCL injuries often occur in front impact sports such as rugby league and serious road traffic accidents.

Following a PCL injury, the knee is usually painful and swollen with a reduced range of movement but often there is no tenderness. An MRI scan can be useful to confirm injury and identify any other associated injuries.

Unlike the anterior cruciate ligament, the posterior cruciate ligament injuries normally heal well over a period of six to eight weeks. The initial treatment for the acute PCL injury involves rest, analgesia and physiotherapy.

Most patients achieve good knee function and do not require any further treatment even though the PCL normally heals in  a slightly stretched position.

However unlike the ACL injury an isolated PCL injury only  occasionally lead to persistent instability symptoms that requires reconstruction.

If reconstruction is necessary then it is reconstructed along the same principles as with an ACL reconstruction, using the medial hamstring tendons with an arthroscopically assisted technique.

The post-operative regime is similar although the PCL needs to protected with  a hinged knee brace and crutches for six weeks to prevent it stretching out.

Risks.  The types and level of risk  associated with PCL reconstruction is very similar to that of an ACL reconstruction.

Lateral collateral ligament injury

Isolated lateral collateral ligament (LCL) injuries are relatively uncommon but can occur when there is forced medial deviation of the lower leg relative to the knee, however, most LCL injuries occur as part of a complex knee ligament injury.

Following an LCL injury, patients will typically experience pain, swelling and localized tenderness over the outside (lateral) aspect of the knee.

An MRI Scan is useful to confirm this injury and if there is a complete tear to the ligament, surgery is usually indicated to repair the injured ligament as when treated without surgery, injury to this ligament tends to lead to significant instability.

Complex knee injuries

A complex ligament injury is an injury where more than one of the major ligaments of the knee has been damaged. In addition to the four main ligaments the LCL has important associated structures grouped together and is referred to as the postero-lateral corner.

Patients who sustain a complex knee injury will usually have experienced a major accident or high energy twisting injury and often have associated meniscal, articular cartilage injures and sometimes associated fractures.


The diagnosis of complex knee ligament injuries is made both on the history of the mechanism of injury and the findings on clinical examination by the surgeon.

MRI scans are very helpful to determine precisely the structures injured and to plan the best form of treatment.

Treatment of complex knee ligament injuries

Fortunately, complex ligament injuries of the knee are quite rare and as would be expected, treatment is more complicated and is different for each patient and their individual pattern of injury.

Sometimes surgery is required as soon as possible after the injury, sometimes no surgery is required immediately but surgery is planned for a later date when the patient has recovered from the acute injury.

Surgery usually involves multiple ligament reconstruction and the rehabilitation process is usually longer and more complex.

The results of surgery for such injuries is, as one would expect, more unpredictable and tends to depend on the specific injuries sustained.