Instability and dislocation of the hip in Down syndrome: report of two cases and proposition of a diagnostic protocol.

The authors report two cases of children with Down syndrome presenting with different patterns of instability of the hip. A 4-year-old girl with delay in the acquisition of walking presented with a painless ''habitual dislocation''. An 11-year-old girl presented with ''subluxation'' of the hip, painful after long walks. Surgical treatment combining soft tissues and bone procedures (including reduction and plastic of the redundant capsule in both cases, differently associated with femoral varus and derotational osteotomy using Scaglietti screws and pelvic osteotomy according to Zanoli-Pemberton) provided excellent radiographic (improvement in radiographic indices) and functional (the first patient began walking without falls; pain disappeared in the second patient) result. With increasing life expectancy of patients with trisomy 21, the incidence of painful arthritis of the hip in adulthood is also rising, contributing to progressive loss of walking ability. Early diagnosis and correct treatment of young patients presenting with hip instability are mandatory to reduce this disabling pathologic condition. The authors review the literature about natural history and possible treatments of hip instability and dislocation, and propose a diagnostic protocol to use in the case of children with Down syndrome.