Bilateral subcapital femoral fractures associated with transient osteoporosis of the hip in pregnancy: a case report.

Bilateral femoral neck fractures associated with transient osteoporosis of the hip (TOH) during pregnancy are rare. We report a case of a 46-year-old woman at 35 weeks of gestation who presented with progressive bilateral hip pain and impaired mobility without preceding trauma. Only a limited number of similar cases have been reported, underscoring the importance of considering TOH in the differential diagnosis of pelvic girdle pain in pregnant and postpartum women. Magnetic resonance imaging (MRI) remains the gold standard for diagnosis. Initial conservative management with analgesia and supportive care was unsuccessful, and the patient's condition deteriorated, resulting in immobility and severe pain. Delivery was performed via cesarean section based on a multidisciplinary team decision. Postpartum MRI revealed bilateral subcapital femoral neck fractures. Surgical treatment consisted of bilateral closed reduction and internal fixation using the Femoral Neck System (FNS), achieving satisfactory reduction and stable fixation. Six months postoperatively, clinical deterioration of the left hip required implantation of a non-cemented total hip arthroplasty due to partial avascular necrosis of the weight-bearing portion of the femoral head. Identified risk factors included advanced maternal age, obesity, pregnancy achieved through assisted reproductive technology (IVF), hypothyroidism, and presumed osteopenia. This case highlights the diagnostic and therapeutic challenges of TOH and emphasizes the importance of early recognition to prevent severe complications.