Anterior cruciate ligament injuries occur most often in the sporting population. A torn anterior cruciate ligament is a common outcome from a major knee injury. The anterior cruciate ligament is the primary stabiliser of the knee joint. Thigh and calf muscles are secondary stabilisers of the knee joint.
If you have torn your anterior cruciate ligament you usually have a sudden twisting movement with your leg fixed on the ground. A snap or pop may be heard and the knee usually swells up within a few hours. The ligament either snaps in half or is pulled from the femoral or tibial surfaces. Once completely torn the ligament cannot repair itself. Partial tears may heal but the ligament is often stretched causing the knee to give way. The anterior cruciate ligament rupture will cause the knee to become unstable in certain movements. This occurs usually when one pivots such as a sudden change in direction. The knee feels like it is going to give way.
At the time of injury the other ligaments and cartilages in the knee may be damaged. Most commonly the medial collateral ligament may tear and either the medial or lateral meniscus may tear. This may result in locking of the knee joint.
Initial treatment is important to reduce swelling and improve range of motion by appropriate exercises. An x-ray is taken to exclude a fracture and occasionally an MRI scan is arranged to further assess the knee joint. It is quite common to see bone bruising on the MRI scan.
An anterior cruciate ligament reconstruction is recommended in patients whose knees give way on repeated occasions. If you have built up your thigh muscles and your knee does not give way then an anterior cruciate ligament reconstruction may not be necessary. There is a theoretical argument to do an anterior cruciate ligament reconstruction in order to preserve the knee for the future. It has been proven that torn cartilages result in long-term osteoarthritis. It is yet to be proven that a torn anterior cruciate ligament results in osteoarthritis but a torn anterior cruciate ligament with an unstable knee may lead to a torn cartilage and therefore in the end, an arthritic knee. Reconstructing the anterior cruciate ligament may not prevent long-term arthritic changes.