[Dislocations of the patella]

Dislocation of the patella represents a frequent knee problem in childhood and adolescence. There are traumatic, recurrent, habitual and chronic forms. Many anatomical variations, which promote patellar dislocation, are known. The first traumatic dislocation is primarily treated conservatively with the exception of concomitant osteochondral fragments or very large soft tissue damage which justify surgical interventions. Recurrent, habitual and chronic dislocations are best cured surgically by vastus medialis advancement, reconstruction of the medial patellofemoral ligament, strengthening of the medial retinaculum together with a lateral release and by fixation of the patella using tendon grafts or medialisation of the insertion of the patellar ligament. To improve the femoropatellar groove by trochleoplasty is a different surgical concept. The long-term results following medialisation of the patellar ligament insertion or trochleoplasty are good with regards to patellar stability but mediocre in terms of avoiding degenerative changes in the patellofemoral joint.