Transient osteoporosis of the hip during pregnancy: a case report

Transient osteoporosis associated with pregnancy is a rare, self-limiting skeletal disorder, the origin of which remains unclear. We report the case of a 36-year-old Japanese woman who developed pain in the left hip, groin, and knee in the seventh month of pregnancy. The pain gradually worsened and prevented weight-bearing. The hip and knee pain progressed to bilateral involvement and persisted after an emergent cesarean section at 35 weeks. Radiographs after delivery revealed gross osteopenia of both the femoral heads, left distal femur, and proximal tibia, consistent with transient osteoporosis associated with pregnancy. The patient remained mostly wheelchair-dependent because of severe hip and knee pain. Several weeks later, the patient was started on alendronate, a biphosphonate, which provided dramatic relief of hip and knee pain. The patient's ambulatory function subsequently improved dramatically as a result of pain relief and assistance with gait training. This case is unique for several reasons. First, it is rare for transient osteoporosis associated with pregnancy to involve both hip joints, and it rarely involves the knee. Second, this is the first reported case of pain management of transient osteoporosis associated with pregnancy being successfully treated with an antiresorptive agent. Finally, the use of alendronate in transient osteoporosis associated with pregnancy may help shorten disability by providing pain relief and decreasing the fracture risk associated with this disease.