What should you know about MCL and LCL sprain?

The medial collateral ligament runs along the inner knee, while the lateral collateral ligament supports the outer knee. A force pushing the knee inward can strain the MCL; a force pushing it outward can strain the LCL. A sprain may involve stretched fibres or a partial or complete tear. Pain is often localised to the affected side and can worsen with turning, cutting or walking on uneven ground. A clinician may examine tenderness, movement and looseness, and may request imaging when another injury is suspected.

Protect the knee from movements that reproduce pain, and use a comfortable walking pattern rather than forcing activity. Cold packs wrapped in cloth may ease early swelling, and elevation can be useful after activity. Do not return to running, tackling or pivoting until strength, balance and knee control have improved. A clinician may recommend a hinged support, guided exercises or [Physiotherapy](/treatments/physiotherapy-and-rehabilitation/physiotherapy/). [Kinesiology Taping](/treatments/physiotherapy-and-rehabilitation/kinesiology-taping/) or [Splinting](/treatments/trauma-and-fracture-care/splinting/) may be considered for selected situations.

Arrange prompt assessment if the knee gives way, cannot fully straighten, becomes markedly swollen, or you cannot bear weight after an injury. Seek urgent help for a visibly deformed knee, a cold or pale foot, new numbness, or severe pain that is rapidly worsening. These features can indicate a more significant injury than an isolated ligament sprain.

Which ligament and degree of sprain do you suspect? Do I need imaging to check the meniscus, cruciate ligaments or bone? What movements should I avoid, and what signs show that strengthening can begin? When can I safely resume work, driving or sport?