Some of the most common injuries seen on the soccer field occur in the knee. This is because the knee is the primary shock absorber for the lower body during running, jumping, cutting and kicking.

A Medial Collateral Ligament (MCL) sprain occurs following an external valgus, or lateral, force to the knee. This commonly occurs when two players attempt to strike the ball simultaneously or if one player falls onto another athlete's knee with the foot planted.

There are three grades of ligament damage ranging from few fibers torn with minor swelling and dysfunction to a complete, full-thickness rupture. Symptoms of a MCL sprain may include swelling, pain, stiffness, point tenderness over the medial joint and possible instability with walking. Early intervention is crucial in Grade I sprains in order to allow for recovery and return to sport within 21 days following the injury. Grade II sprains require a longer recovery period and can expect to be back to full sport activity in six to eight weeks if treated appropriately including a strength and stability program. If the athlete suffers from a Grade III sprain, it will be treated conservatively with a longer period of RICE and immobilization and possible surgical intervention. Nonetheless, a good lower-extremity strengthening program targeting the quadriceps and hamstrings could assist the ligaments in maintaining the stability of the knee and may aid in preventing a knee sprain injury in the soccer athlete.