[Entrapment of the synovium of the hip joint in children: a report of 15 cases].

15 cases, aged 4 to 14 years, experienced, a few days after a mild trauma, slight pain and limited motion of hip joint with the corresponding leg lengthened, a result of restrained adduction. Plane X-ray films of these hip joints showed nothing wrong, yet arthrography done on 4 cases and operative exploration in 1 patient found that a portion of synovium at the anteromedio-inferior part of the hip had been entrapped into the joint, on account of which the term entrapment of synovium of hip joint is coined. Under general anesthesia, gentle manipulation resulted in immediate relief in all hips but one, which failed to respond and then under went open operation, a very good chance of looking into the matter: a big portion of synovium incarcerated in the joint, the actual offender. There has been no recurrence found up to the time of writing. The pathogenesis and the related differential diagnosis have been discussed in detail.