Knee injuries sometimes involve more than one ligament. These severe knee injuries, which occur at high velocity during sport or traffic accidents, are called multi-ligament knee injuries.
The four major knee ligaments usually involved in this injury are:
- Anterior cruciate ligament (ACL). This ligament is situated in the middle of the knee.
- Medial Collateral Ligament (MCL). This ligament is commonly injured when the knee buckles inwards. Fortunately, MCL injuries often heal without the need for surgical repair or reconstruction.
- Posterior Cruciate Ligament (PCL). This is the ligament that stops the tibia (shin bone) from moving backwards on the femur. Commonly PCL injuries occur from a fall directly onto the knee (or the shinbone). Isolated PCL injuries often heal similarly to the MCL injuries. However, a prolonged period of bracing is often necessary.
- Lateral Collateral Ligament (LCL). Injuries to the LCL and other associated ligaments on the posterior and lateral aspect of the knee may result in ongoing symptomatic instability. Unfortunately these ligaments do not heal well. Surgery is often required for these injuries.
In a multi-ligament knee injury two or more of the above ligaments are torn. Surgery will be required in most cases to obtain the best possible result following this type of injury.
The knee usually becomes painful and swollen immediately following the injury. Frequently these patients are taken by ambulance to hospital for assessment. X-rays are often performed in the emergency department to exclude fractures. A Zimmer knee splint is often applied at this time and the patient is discharged on crutches.
Multi-ligament knee injuries are always treated with a hinged knee brace prior to and after surgery. This will allow a certain degree of movement as determined by the treating orthopaedic surgeon. The brace can be adjusted to gradually increase the available amount of movement.
The assessment of a patient with a multi-ligament knee injury involves a thorough history of the accident and of any associated injuries. A physical examination is performed of the knee to assess the instability of the knee. The nerves and the blood vessels that flow to the foot are also assessed as these can be damaged at the time of injury.
An MRI scan is required to determine which ligaments are involved and how severely they are injured. It will also indicate associated injuries to other structures in the knee, such as meniscal or cartilage tears. There may be damage to the lining of the knee, and there may be fractures to the knee that were not apparent on the original x-rays.
Often acute intervention with surgery is needed, however if the diagnosis has been missed or delayed, then multi-ligament knee reconstruction may be performed at a later date.
The assessment of multi-ligament knee injuries is complex. Often an examination under anaesthetic (EUA) is helpful. This involves the patient having an anaesthetic and the orthopaedic surgeon assessing the degree of laxity in the various ligaments.
There are many options for surgical treatment of multi ligament knee injuries. Primary repairs may be performed to some of the ligament injuries, especially if they are very recent. However, most multi-ligament knee injuries require surgical reconstruction and this includes the placement of grafts. Most often this involves the taking of grafts such as the hamstrings, the patella tendon or the quadriceps tendon from the injured patient. Sometimes donor tissue (allograft) is used. The LARS synthetic ligament is also sometimes used for more significant knee injuries.
The recovery from multi-ligament knee reconstruction surgery is prolonged. Bracing is necessary post-operatively, often for an extended period. Physiotherapy is very important and this may continue for 12 to 18 months. Regular review appointments will occur, until a satisfactory recovery is achieved.
While the goal of multi-ligament knee reconstruction is a return to full function, this may not always be possible. This is particularly so if there are other associated knee injuries to the menisci or to the lining of the knee.
The risks of multi-ligament reconstruction include:
- deep vein thrombosis (DVT)
- nerve damage
- stiffness of the knee
- failure of the grafts or the repairs
- compartment syndrome – this occurs when there is severe swelling in the leg, which can compromise the circulation to the muscles of the calf. This is very rare but requires urgent intervention to avoid permanent damage to the muscles.
Modern techniques of multi-ligament reconstruction have led to significantly improved outcomes. However, patients do not always return to their previous levels of sporting activities.
The surgeons at Knox Orthopaedic Group will discuss the risks as well as the benefits of surgery for multi-ligament knee injuries. A hospital stay of up to three nights may be necessary following the surgery.