The 'silent hip' of idiopathic ischemic necrosis of the femoral head in adults.

Fate of Untreated Asymptomatic Osteonecrosis of the Femoral Head

“…Therefore, the overall rate of progression of asymptomatic osteonecrosis in this study was 59%. These results are comparable with the overall rate of 66% (317 of 480) in the previous reports 5,[20][21][22][23][24][25][26][27][28] describing progression of asymptomatic disease. In our study, pain developed in most hips (83%; fifty of sixty) in which the lesion involved >50% of the femoral head, usually within three years (76%; forty-seven of sixty-two hips).…”

“…Discussion P revious studies of asymptomatic osteonecrosis of the femoral head have demonstrated various rates of disease progression 5,[20][21][22][23][24][25][26][27][28] . Differing opinions regarding the fate of asymptomatic disease have been attributed to several reasons, including differences in study populations, diagnostic modalities, follow-up periods, and the definition of disease progression 5,27 .…”

Untreated Asymptomatic Hips in Patients With Osteonecrosis of the Femoral Head

“…In our series large necrotic lesions were not observed in eight hips with Stage II sclerotic disease but were in five of 18 hips with Stage II cystic disease. Some investigators have suggested sclerotic changes in necrotic lesions indicate a repair process that inhibits bone resorption mechanism and provides structural integrity in the femoral head [13,18]. On the other hand, cystic changes within necrotic lesions may represent poor trabeculae and extensive bone resorption by osteoclastic resorption with greater potential for subsequent collapse [7,13].…”

“…However, there is no consensus regarding the natural history in patients with asymptomatic ON of the femoral head. The reported rates of progression in these hips have ranged from as low as 17% to as high as 100% [4,5,7,9,11,14,18,29].…”

Non-traumatic necrosis of the femoral head

“…Intraosseous pressure will be increased, run off at intraosseous phlebography will be delayed, and at histology characteristic features of ON is found. This is "the silent hip" of ON [24], that might be suspected in the contralateral hip of patients with ON.…”