Thirty-five patients who were seen with non-traumatic aseptic
osteonecrosis of the femoral head were included in a study of the
contralateral hip to evaluate the incidence of bilateral disease. We used
not only conventional radiography and scintigraphy but also measurement of
intramedullary pressure and core biopsy. Pain was caused by 14.3 per cent
of the contralateral hips, a lesion was demonstrated on plain radiographs
in 51.4 per cent, and increased isotopic uptake was seen in 31.4 per cent.
Histological study of specimens obtained by osteomedullary biopsy (after
special procedure) showed bilateral necrosis in 88.5 per cent of the
patients. After a mean follow-up of thirty-four months, only one of nine
hips that were painless and had negative radiographic and isotopic
findings, but had positive findings on biopsy, became painful and
radiographically positive. The intramedullary pressure in the
intertrochanteric area was recorded in each hip, and no correlation was
found with the radiographic stage or with pain.