Reflex decalcifying algodystrophy of the hip in pregnancy (so-called transient osteoporosis). Review of the literature and four case reports.

Transient algodystrophy of the hip in pregnancy is a relatively rare condition, still unknown to many and easily overlooked. Diagnosis is important because of the related difficulties in natural delivery and the risk of fracture. Four unilateral cases are presented (two right and two left), characterised by pain, limping, limitation of the hip motion and demineralisation of the head and neck of the femur. Treatment was by rest and protected weight-bearing. Three were delivered by caesarean section. In one patient a fracture of the neck of the femur occurred a few weeks before delivery, requiring surgery. In all four cases the outcome was benign. Like algodystrophy occurring in adults of either sex the aetiology is unknown. In pregnant women the association with the right occiput anterior position of the fetus (documented in one patient where the affected hip was the right) suggests the possible involvement of one of the autonomic pelvic plexuses (right or left) in the unilateral cases.