Medial Collateral Ligament (MCL) injury is damage to the ligament on the inside of the knee. The MCL connects the inner (medial) surfaces of the femur (thigh bone) and the tibia (shin bone). It is often caused by twisting or an impact to the outside of the knee during rugby or football. Because part of this ligament attaches to the inner knee cartilage, injury to it can often cause a torn knee cartilage. The symptoms of a MCL injury include knee swelling, locking or catching of the knee, a sense that the knee is going to give way when stessed in any way and pain on the intside of the knee. In the early stage of the injury the PRICE protocol should be followed – protection, rest, ice, compression and elevation above the level of the heart. If walking is impeded, crutches may be necessary. A knee brace can be helpful by taking the strain off the injured ligament if walking is possible but difficult. Conservative treatment of a MCL injury includes soft tissue massge, electrotherapy and a full rehabilitation programme to encourage the return of a full range of motion, strength and balance. In severe case, surgery may be indicated.