Unusual acute crystal-induced hip arthritis: hydroxyapatite deposition of the round ligament.

Hydroxyapatite (HA) crystal deposition disease is a common cause of acute inflammatory articular or periarticular pain. Here we report a patient with an acute hip arthritis due to HA crystal deposition of the round ligament. Therefore, HA crystal deposition in periarticular tendons and ligaments of the hip should be added to the differential diagnosis of an acute hip arthritis. Computed tomographic scan may be useful when standard radiographs do not evidence the calcification.