In case of a knee joint filled distinctively with fluid and torn bone fragments the arthroscopy is recommended. As part of the Arthroskopy the joint is freed from blood and the cartilage surfaces are examined for possible damages. If a larger bony avulsion exists, it can be refixated arthroscopically or openly. In most cases though the main problem remains the tear in the area of the inner guiding ligament. Depending on the age of the patient, the injury and the false position I recommend one of the following methods of treatment:

• In case of a low-grade false position, which can be diagnosed via x-rays, MRT, but also via arthroscopy, a consistent physiotherapy is performed regardless of age and sex of the patient. The physiotherapy serves the improvement of the kneecap centering. Particularly the musculature which pulls the kneecap inwardly, is strenghtened here. A final clinical control and adequate x-rays are performed after 3 months. Then it will be decided whether the treatment can be finished.

• In case of a former injury, if the patient is already older or in case of a false position, which evens up well in a flexion position of only 20 degrees, the arthroscopic release of the external fixation apparatus (lateral release) is absolutely sufficient. Then an optimal control of the kneecap can be achieved by a physiotherapeutic after-treatment (like mentioned above). Here, a final clinical control including x-rays is performed as well.

• In case of a fresh dislocation (luxation), the kneecap is obviously crooked and an extended tear formation exists on the inside, then I recommend the arthroscopic suture and a tightening oft he inner ligament, either near the kneecap or a reattaching to the thigh. Sometimes a combination with a lateral release surgery can be considered. After the surgery the knee is supplied with a splint, which allows more flexion every week. The patients are not allowed to load during the first 14 days. After a few days the physiotherapeutic exercise can already begin. After a few weeks an accompanying strength training should be started. Here, a final clinical control including x-rays is obligatory as well.

• If the dislocation of the kneecap had occured several times before (recurring patellar luxation) and if , like mentioned above, an accompanying false position of the axis or the rotation of the legs with or without a false form of the slide bearing exist, simply an arthroscopic treatment is not possible. Therefore additional open interventions for bone correction are necessary.