Aseptic necrosis of bilateral femoral heads after pregnancy

Aseptic necrosis, also known as avascular necrosis, ischemic necrosis, and osteonecrosis, is a pathological process caused by impaired blood supply to the affected bone that results in the death of osteocytes and bone marrow cells. Osteoclastic resorption of dead bone induces demineralization, trabecular thinning, and subsequent collapse of the joint surface with fracture of subchondral bone. A clinical diagnosis is made appropriately according to the patient’s symptoms, physical findings, and imaging results compatible with this disease. The precise prevalence of avascular necrosis is unknown; but in the United States, the number of newly diagnosed patients is estimated to be 10,000 to 20,000 per year [1]. Generally, most avascular necrosis of the femoral head is because of alcoholism, steroid use, and trauma. Excessive alcohol intake and usage of prolonged high doses of glucocorticoids are reported to account for more than 90% of cases [1]; other risk factors or conditions associated with avascular necrosis include Gaucher’s disease, pancreatitis, chemotherapy, decompression sickness (Caisson disease), and blood disorders, such as sickle cell disease and polycythemia. However, little is known about whether pregnancy is an etiological factor in femoral head osteonecrosis. We report the cases of two patients with bilateral osteonecrosis of the femoral head after pregnancy after ovulation induction and include a review of the literature. A healthy 27-year-old Taiwanese woman presented with right groin pain for 1 month after giving birth to a 2.8 kg female baby by normal spontaneous delivery (Gravida 1, Para 1, Abortion 0) at 40 weeks’ gestation 6 weeks before this episode. She had been treated with clomiphene citrate to increase the chance of becoming pregnant. The patient had no history of contraceptive drug use, trauma, alcohol drinking, steroid usage, hyperlipidemia, or ovarian hyperstimulation syndrome. Her weight gain during this pregnancy was 15 kg