Habitual dislocation of the hip. A new, simple classification and report of a case.

Habitual dislocation of the hip occurred in a nine-year-old girl. The nomenclature of the literature on this disorder and other related conditions is confusing. The following simple classification is therefore proposed: (1) recurrent dislocation (posttraumatic, nonvoluntary); (2) voluntary dislocation (nonhabitual, associated with ligamentous laxity or paralytic disease); (3) habitual dislocation (not associated with significant ligamentous laxity). The treatment significantly differs in each of the described conditions. The diagnosis of habitual dislocation precludes correct interpretation of the history and physical examination.