A 37-year-old woman with a history of Crohn disease presents for follow-up. She has been taking prednisone for the last 4 years at varying dosages and now has worsening left hip pain. The pain is aggravated during weight-bearing activities and is not relieved by rest. Physical examination is significant for a blood pressure of 148/82 mmHg and limited range of motion of her left hip. Dermatologic examination reveals purple striae and thinning of her skin in the lower abdominal region. Neurologic examination is within normal limits. Laboratory values (including ESR and TSH) are within normal limits.
Which of the following is the underlying mechanism of this patient’s left hip pain?
A. Cartilage erosionInterruption of bone vasculature. This patient is steroid-dependent and is presenting with signs and symptoms consistent with a diagnosis of avascular necrosis, also known as osteonecrosis. This condition results when there is necrosis of bone components due to interruption of the blood supply. Avascular necrosis manifests with progressive pain with a limited range of motion. Risk factors include chronic corticosteroid use, alcoholism, hemoglobinopathies (e.g., sickle cell disease), HIV, and chemotherapy. The best and most sensitive test for avascular necrosis is MRI. (A) Cartilage erosion occurs in osteoarthritis. (C) Excessive fluid production from inflamed synovium describes an inflammatory arthritis such as rheumatoid arthritis. (D) Peripheral nerve damage can occur in diabetic patients and results in Charcot joint, which manifests as a deformed foot that develops from an inability to detect pain, proprioception, and temperature.