Dislocation of the patella refers to when the kneecap (patella) moves out, and stays out of its normal position in the grove of the thigh bone. There are two forms of dislocation: acute traumatic dislocation and habitual dislocation.
Primary function of the patella is during knee extension, as the patella is functioning as a leverage so the tendon can exert on the femur by increasing the angle at which it acts.
The patella is dislocated when forces acting on the kneecap are too great for the supporting muscles and fascia to resist. This can occur with a direct blow to the knee cap which pushes it out to the side of the leg out of the
Patellofemoral joint. It typically results from a sports injury and occurs in about ⅔ of the time in young (61% sports), active patients under the age of 20 (Tsai et al., 2012).
Knee flexion in combination with knee valgus is named the leading injury mechanisms (Tsai et al., 2012) associated with patella dislocation.
Physiotherapy: strengthening and leg axis training in combination with proprioception. In case of repetitive dislocations, stabilizing surgery is necessary in order to prevent further instability. However, according to current literature ( Tsai et al., 2012), treatment and outcome measure vary.
Tsai C.H. et al., 2012, Primary traumatic patellar dislocation, Journal of Orthopaedic Surgery and Research, 7 (21), p: 21