The results of combined scintigraphy in which indium-111-labeled
leukocytes and technetium-99m methylene diphosphonate were used were
compared with the results of cultures of open bone at 102 sites of delayed
union or non-union, to determine the effectiveness of this combination as a
preoperative indicator of osteomyelitis. There were twenty-five
true-positive, fifty-nine true-negative, eleven false-positive, four
false-negative, and three indeterminate interpretations, yielding, for the
diagnosis of osteomyelitis, a sensitivity of 86 per cent, a specificity of
84 per cent, an accuracy of 82 per cent, a positive predictive value of 69
per cent, and a negative predictive value of 94 per cent. There were few
false-negative scans; false-positive results were most likely at a
metaphyseal site adjacent to a joint in which there was post-traumatic
arthropathy, at the site of a failed arthrodesis, and at the site of an
unstable delayed union or non-union.