POTENTIAL USE OF BONE MARROW SCINTIGRAPHY IN SUSPECTED PROSTHETIC HIP INFECTION EVALUATED WITH 99MTC-HMPAO-LEUKOCYTES

Aim. To evaluate the usefulness of Tc-99m-Sulphur colloid when combined with leukocyte scintigraphy in suspected prosthetic hip infection, comparing the results with information from Tc-99m-HMPAO-leukocyte scintigraphy alone. Materials and methods. Seventy patients (42 women, 28 men; mean age 68 13 years) with painful hip prostheses and suspicion of infection were evaluated prospectively. All patients had bone scintigraphy, Tc-99m-HMPAO-labelled white blood cell scintigraphy and Tc-99m-Sulphur colloid bone marrow scintigraphy. ESR and CRP levels were measured in all patients. The final diagnosis was made with microbiological Results. Infections were diagnosed in 12 of the 70 patients (3 coagulase-negative Staphylococcus, 2 Staphylococcus aureus, 2 Staphylococcus epidermidis, 2 enterococcus and 3 polymicrobial agents). ESR and CRP values were higher in patients with infection than in patients without infection (51.8 +/- 29.4 vs. 25.4 +/- 16.4 and 2.8 +/- 2.2 vs. 1.1 +/- 1.3, respectively; p < 0.05). Bone scintigraphy did not show a characteristic pattern to differentiate infection from aseptic loosening. The pool phase of the bone scintigraphy was positive in only 3/12 patients with infection (25%). Sensitivity and specificity of the leukocyte scintigraphy was 83% and 57%, respectively. When the results of the bone marrow scintigraphy were added, these values increased to 92% and 98%, respectively. Conclusion. Performing bone marrow scintigraphy significantly improves results when compared with leukocyte scintigraphy alone in the diagnosis of infected hip prostheses. Bone scintigraphy did not help to differentiate aseptic loosening from infection in this series.