IMAGING

PREDICTION OF COLLAPSE OF OSTEONECROSIS OF THE FEMORAL HEAD USING A NEW THREE-DIMENSIONAL QUANTIFICATION METHOD: SIGNIFICANCE OF LESION SIZE AND LOCATION

Takashi Nishii, Nobuhiko Sugano, Kenji Ohzono, Takashi Sakai, Nobuo Nakamura
Department of Orthopaedic Surgery, Osaka University Medical School E3, 2-2 Yamadaoka, Suita, Osaka 565-0871, JAPAN

Relevance of lesion size and location for prediction of collapse was evaluated quantitatively using new three-dimensional indexes. Sixty-five hips in 47 patients with osteonecrosis without collapse received MR imaging, and were followed up over 2 years. Lesion volume as well as latitude and longitude of the center of gravity of the lesion within the femoral head were calculated. Thirty-one hips developed collapse. Multiple logistic regression analysis showed a significant relationship between lesion volume and collapse. In 31 hips in which the lesion volume was less than 25%, only 6 collapsed, and those collapsed hips had a significantly higher sum of the latitude and longitude of the lesion, corresponding to the anterosuperior portion of the femoral head. We concluded that volume of the lesion is strongly correlated with risk of collapse, but that location of the lesion also plays an important role, especially when the volume is small but the lesion is located in the anteriorsuperior portion.