Three phase bone scintigraphy with (99m)Tc-MDP and serological indices in detecting infection after internal fixation in malunion or nonunion traumatic fractures.

OBJECTIVE To evaluate the diagnostic efficacy of technetium-99m-methylene diphosphonate ((99m)Tc-MDP) three phase bone scintigraphy in detecting infection in malunion or nonunion traumatic fractures after internal fixation. SUBJECTS AND METHODS One hundred and eighty four patients with malunion or nonunion fractures after internal fixation (130 men and 54 women; age range, 16-79 years) underwent (99m)Tc-MDP three phase bone scintigraphy (3PBS). They were divided into the infection group (n=96) and the control group without infection (n=88) based on the final diagnosis after operation. The sensitivity, specificity, accuracy, positive prediction value (PPV) and negative prediction value (NPV) were calculated and compared. All patients carried out other laboratory tests related to infection such as complete serum blood cells count, C-reactive protein (CRP), and erythrocyte sedimentation rate (ESR). RESULTS The (99m)Tc-MDP 3PBS for the blood flow phase showed sensitivity, specificity, accuracy, positive predictive value and negative predictive value, 91.7% (88/96), 72.7% (64/88), 82.6% (152/184), 78.6% (88/112) and 88.9% (64/72), respectively and for the blood pool phase, 93.8% (90/96), 61.4% (54/88), 78.3% (144/184), 72.6% (90/124) and 90.0% (54/60) respectively. The semiquantitative indices of the ratio between the abnormal and the normal region of interest (ROI), called by us the A/N ratio, for both blood flow and blood pool phases as estimated between the infection group and the control group were statistically different. CONCLUSION It is the opinion of the authors that (99m)Tc-MDP 3PBS provided high predictive values in diagnosing infection in patients with malunion or nonunion traumatic fractures after internal fixation. The diagnostic value of blood flow and blood pool phases estimated of the 3PBS was better than the laboratory indices: white blood cell counts, CRP, and ESR.