Permanent post-traumatic patellar dislocation.

Permanent post-traumatic dislocation of the patella is an extremely rare condition, and is often confused with congenital dislocation. The anatomic abnormalities differ in the two conditions: in the former there is an adaptive flattening of the patella, in the latter there is a propensity for flexion contractures and incongruity of the patella and trochlea. Treatment options include observation, patellar realignment, and patellectomy. In the patient reported, surgical correction appeared to result in patellar alignment.