Ligament pathology

Collateral ligaments injury

What is it ?

Collateral ligaments are located on the periphery of the knee joint and may be injured during sport activities or road accidents. It may be an isolated injury, but most of the time they are injured in conjonction with a cruciate ligament tear (ACL or PCL). The medial collateral ligament (MCL) stabilises the knee during valgus movements, and the lateral collateral ligament (LCL) stabilises the knee during varus movements. The knee joint capsula is reinforced by ligamentous complex: the postero-lateral corner (PLC) and the postero-medial corner (PMC) which act in conjunction with the cruciate and collateral ligaments.

Clinical presentation

Collateral ligaments are easily palpable and be painful during clinical examination, and are typically painful during few weeks after an injury. Sometimes, an hematoma appears and is seen where the collateral ligament has been torn. These collateral ligaments may be stretched (grade 1 injury), partially torn (grade 2 injury) or completely torn (grade 3 injury), according to the severity of the knee sprain. In case of grade 3 injury, the medial or lateral laxity is obvious at clinical examination and the patient feels easily the instability.

When to consult a specialist?

A specialist must be contacted in case of a severe knee sprain: if a “pop” may be felt during the accident, if an hematoma appears and the pain persists, or if the joint is unstable.

Non surgical treatment

Collateral ligaments are well vascularised and have a good healing capacity. Hence, grade 1 and grade 2 lesions are treated conservatively by a knee brace which allows flexion/extension of the knee but prevents valgus or varus movements. This brace has to be used during 3 to 6 weeks after the trauma, according to the severity of the sprain.

Surgical treatment

A surgical treatment is indicated for grade 3 injury, i.e when the collateral ligament is completely torn. The surgery should be 10 to 21 days after accident: if earlier the knee is generally too swollen and the risk is to have scar healing problems because of the swelling; if later, the healing process already began and the repair may be difficult or impossible, so a reconstruction using a ligament graft may be necessary. Most of the time, grade 3 collateral ligaments injury is combined to a cruciate ligament tear (ACL or PCL): in that case, surgery may be staged with a first surgery to repair the torn collateral ligament, and then a second surgery 6 weeks later to reconstruct the torn cruciate ligament. This two-step approach allows knee recovery in between the two surgeries and gives better conditions for cruciate ligament reconstruction and rehabilitation.

Postoperative follow-up

Collateral ligaments must be protected by motion knee brace which allows flexion/extension of the knee joint, in order to preserve knee mobility but prevents valgus/varus movements. Crutches are necessary to walk during 4 to 6 weeks after surgery. Physiotherapy begins the day after surgery.

Risks and complications

The most frequent complication after collateral ligament repair is knee stiffness, because of pain which may limit the rehabilitation protocol. Skin dysesthesia sometimes happen around the scars, mainly after medial collateral ligament repair because the skin incision crosses the sensitive branches of saphenous nerve. Ergotherapy is a good treatment in case of dysesthesia.