Combined Knee Ligament Injuries

The knee is a complex hinge joint and is one of the most commonly injured joints

Anatomy of The Knee

knee ligament
Normal knee anatomy, front view (Image from

The knee joint is formed by three bones, namely: the femur or thigh bone, the shinbone or tibia and the patella or kneecap. The patella is found in front of the joint. Ligaments connect one bone to another and they are strong bands that stabilise the knee. The knee has four primary ligaments that keep it stable.

Collateral Ligaments

They are located on the sides of your knee. The LCL-lateral collateral ligament is located on the outside while the MCL-medial collateral ligament is on the inside. Collateral ligaments manage the sideways movement of the knee.

Cruciate Ligaments

They are located in the centre of the knee. The ACL (anterior cruciate ligament) and PCL (posterior cruciate ligament) cross each other to form an “X”. The ACL is found at the front while the PCL is found at the back. These ligaments control backward and forward, as well as rotational movements of your knee.

Description of Knee Ligament Injuries

Most knee ligament injuries occur during sporting activities. The most common mechanism of injury is a twisting injury that occurs with a sudden change in direction of the body while the lower limb stays in the same position or turns in the opposite direction. Multiple ligament injuries are usually a consequence of high-velocity trauma – eg in skiing, traffic accidents or a fall from height. There are usually associated with injuries such as meniscal tears. Meniscus tear injuries are serious injuries that require immediate attention to exclude and treat associated inuries to blood vessels and nerves to avoid a potential loss of the involved limb. The common combination of injury would be a combined ACL and MCL tear.

The degree of injury to the ligaments and knee pain can be graded on a severity scale.

Grade 1 Sprains: The ligament is mildly damaged in a Grade 1 Sprain. It has been slightly stretched but is still able to help keep the knee joint stable.

Grade 2 Sprains: A Grade 2 Sprain stretches the ligament to the point where it becomes loose. This is often referred to as a partial tear of the ligament.

Grade 3 Sprains: This type of sprain is most commonly referred to as a complete tear of the ligament. The ligament has been split into two pieces, and the knee is unstable.

knee ligament injuries
Tears of the anterior cruciate ligament (left) can occur along with injuries to the medial collateral ligament (right).
(Image from


The MCL is injured more often than the LCL. Due to the more complex anatomy of the outside of the knee, if you injure your LCL, you usually injure other structures in the joint, as well.

Treatment of Multiple Knee Ligament Injuries

The knee is unstable in this situation and the ligaments would have to be reconstructed once the patient has been stabilised and other life or limb-threatening injuries have been addressed. The knee surgery required depends on the extent of the injury. It may be a single or two stage surgery. If both the MCL and the ACL are torn or injured, the surgeon will reconstruct them through a single surgery. If 3 or more ligaments are torn or injured, Dr Lee will perform a 2-stage surgery to reconstruct them. We will reconstruct the PCL and LCL first and then work on the ACL at a later date.

Outcome of Surgery For Multiple Knee Ligament Injuries

Results from multiple ligament surgery are not as consistent as single ligament injury. These are severe injuries that are not just causing knee pain but potentially limb-threathening and will require a much longer rehabilitation period than single ligament injuries.

In the past, a multiple ligament injury usually meant an end to the sporting career of the athlete. With improvements in surgical techniques and rehabilitation protocols, most athletes can get back to an active, sporting life once they have fully recovered.