Hip fracture in a patient affected by transient osteoporosis of the femoral head during the last trimester of pregnancy

Few cases of hip fracture in pregnant women affected by transient osteoporosis of the femoral head have been reported in the literature, but its real incidence seems to be underestimated. During pregnancy, osteoporosis manifests itself with an insidious onset of hip pain and limp without any trauma or infective episode in clinical history. Its clinical course is characterized by spontaneous recovery a few weeks to several months after delivery. This article describes the case of a 35-year-old woman with a sudden onset of bilateral hip pain during the last trimester of her first pregnancy; she had neither history of steroid therapy nor alcohol abuse; her body temperature and serological parameters were normal. Bilateral transient osteoporosis of the femoral heads was suspected and confirmed by magnetic resonance imaging. Fifteen days postpartum, she was admitted to our clinic with a displaced femoral neck fracture. A cementless total hip arthroplasty was performed to quickly begin a rehabilitative program. She underwent antiresorptive therapy with alendronic acid 70 mg/week and vitamin D for 3 months. Three months after the fracture, a dual-energy x-ray absorptiometry scan showed osteopenia (T-score, -1.5). Risedronic acid 35 mg/week and vitamin D were then prescribed. The last physical examination at 3 months postoperatively revealed a gradual recovery of the autonomy in activities of daily life.