SummaryLoss of motion following knee ligament surgery is a common and potentially serious complication. Loss of extension is most common following anterior cruciate ligament reconstruction, and loss of flexion is most common after posterior cruciate ligament reconstruction. The aetiology of loss of motion is multifactorial and includes impingement and capsulitis. The risk for loss of motion can be minimised by appropriate preoperative, intraoperative and postoperative intervention. Management of loss of motion depends on the cause and length of time following surgery.