First-time patellar luxation appears typically in teenagers and young adults below the age of 16 years, with a prevalence of 45/100,000/year. This luxation is treated with brief limited mobility in a bandage, and with a complementary physiotherapy if the mobility is influenced afterwards. Risk factors for patellar instability are patellofemoral dysplasia, hyperlaxity, patella alta and valgus malalignment in the knee joint. In case of repeated luxation the treatment is surgical, i.e. reconstruction of the medial patellofemoral ligament recreating the medial patella-stabilizing structures. If the dysplasia is severe, tuberositas tibiae-osteotomy and trochlea plastic can correct a lateral tracking of the knee joint. Generally, patella-stabilizing surgery is successful with a reluxation rate of only a few per cent.