Avascular osteonecrosis of femoral head in a postoperative patient of pituitary Cushing's disease.

We describe a rare association of Cushing's disease causing avascular osteonecrosis of the femoral head in a patient with operated pituitary macroadenoma. Avascular necrosis of the femoral head (AVN) is not a common cause of musculoskeletal disability. Though AVN of the hip is a well-recognized complication of steroid treatment, it is rare in cases of endogenous hypercortisolism. To our knowledge, only 16 patients with AVN, associated with endogenous Cushing's syndrome (CS), have been documented in the medical literature. AVN associated with glucocorticoid use is more likely to manifest as bilateral disease than either idiopathic AVN or ethanol-associated AVN. We describe a 26-year-old woman who was diagnosed with Cushing's disease in 2007 and operated in the same year for an ACTH secreting pituitary adenoma, who was consequently given replacement dose steroid therapy for post operative panhypopituitarism. During follow up, she complained of bilateral hip pain and difficulty in ambulation. Magnetic resonance imaging showed multiple bony infarcts in the proximal femur and distal femur with femoral head collapse fractures bilaterally, consistent with AVN. She further underwent decompression surgery on bilateral hip joints. This case illustrates that AVN, an orthopaedic emergency, can be an alarming manifestation of Cushing's disease.