Transient osteoporosis of the hip.

A 31-year-old male presented with pain in the right hip on activity which had persisted for the last 2 weeks. He denied any other joint pain and did not have any other co-morbid illness. On examination, range of hip movements was found to be painful in all directions. His investigation revealed normal acute phase reactants. Magnetic resonance imaging (MRI) revealed diffuse T2w-hyperintense signal in the head and neck of the right femur which is consistent with marrow edema (Figure 1a). No fracture or collapse of the femoral head or joint effusion was observed. These changes were consistent with transient osteoporosis of hip joint. Patient was advised conservative treatment and his symptoms completely subsided within 4 weeks. Follow-up MRI performed 2 months later showed complete resolution of the marrow edema in the right femoral head and no residual subarticular bone changes were observed (Figure 1b). The transient osteoporosis of hip (TOH) is an idiopathic and self-limiting disorder which is characterized by unexplained hip pain and was first reported by Ravault (1947) followed by Curtiss and Kincaid in 1959 (1). The TOH has been reported more frequently in healthy middle-aged males with a male: female ratio of 3:1 (2). The etiopathogenesis of TOH may include microvascular injury, nontraumatic reflex sympathetic dystrophy, metabolic factors, viral infection, neurological factors, and endocrine factors (3). An MRI is a sensitive test for diagnosing TOH and was described first in the radiology literature by Bloem (4). TOH is a self-limiting disease, a symptomatic and supportive treatment is recommended, and TOH should be included in the list of differential diagnoses of acute onset of hip pain.

Figure 1. a, b

Magnetic resonance imaging (MRI) showing diffuse T2w hyperintense signal involving the head and neck of the right femur which is in keeping with marrow edema (a); complete resolution of the marrow edema in the right femoral head and no residual subarticular bone changes (b)