Patella dislocation is either traumatic or spontaneous. In the traumatic one, the medial patello-femoral ligament is usually torn due to sudden rotation of the knee or due to a direct trauma. In the spontaneous dislocation, there is an anatomic variation which causes sliding of the patella easier. The increased Q angle, which is the angle formed by the quadriceps tendon origin and the patellar tendon insertion, is one of the causes of spontaneous dislocation. Also high located patella and narrow patellar sulcus are the other anatomic variations that predisposes to patella dislocation.
Patella dislocation must be treated promptly since untreated cases may lead to recurrent dislocations. The first dislocation is treated by conservative methods unless there is a cartilage damage. If there is a big cartilage separation, it must be fixed urgently. At the same setting, the traumatized structures like medial patella-femoral ligament is restored. But if the dislocation is the first time without cartilage separation, conservative methods like knee bracing, physical therapy and muscle strengthening exercises should begin.
Despite appropriate conservative treatment, recurrence of patella dislocation is approximately 60%. In recurrence surgery is mandatory since recurrent dislocation causes irreversible patellar cartilage destruction. There are many surgical methods that differs according to the etiologic factor. If there is an increased Q angle, tubercle osteotomy may be done. If a shallow sulcus is the cause of dislocation, trochlear deepening operations can be chosen. Reconstruction of the medial patello-femoral ligament is almost always is a part of any chosen surgery.