The anterior cruciate ligament (ACL) and the posterior cruciate ligament (PCL) cross in the centre of the knee. A tear of these ligaments can be partial or complete, and results from overstretching of this ligament within the knee. Cruciate ligament repair is carried out by an orthopaedic surgeon, using a combination of open surgery and arthroscopy. The operation can be carried out as a day case, or may require a day or two in hospital.