One hundred sixty-nine patients with radiographic or histologic evidence of ischemic necrosis of bone (INB) were evaluated. Ninety-nine (59%) of the 169 patients had multiple sites of INB, with 310 bones affected. Two hundred sixty-three (85%) of the 310 ischemic bones were symptomatic. Routine radiography produced negative findings in 58 (20%) of the bones with histologically confirmed INB. Results of hemodynamic studies, including baseline bone marrow pressure, saline stress test, and/or intraosseous venography, were abnormal in 243 (94%) of 259 ischemic bones so evaluated. Most importantly, hemodynamic studies detected 51 (93%) of the 55 bones that were radiographically normal but had histologically confirmed INB.