The time course of 99Tcm-Sn-polyphosphate scintimetry of normally healing tibial fractures in man.

In 38 fractures of the human tibia showing radiological consolidation within 6 months, the amount of callus formed was assessed monthly by scintimetry following intravenous administration of 99Tcm-Sn-polyphosphate. The results of the scintimetry were expressed as a ratio (as radioactivity over the fracture divided by that over the contralateral area of the normal leg). The error of the scintimetric ratio within the period of measurements (20-60 minutes after the injection of isotope) was +/- 5 per cent. More isotope accumulated around the fracture in all patients. The scintimetric time course of transverse as well as longitudinal fractures showed a peak value (scintimetric ratio 3.6 +/- 0.6 s.d.) in the fourth to fifth week, whatever the primary treatment, and was of the same magnitude in the two types of fracture. A secondary increase of the scintimetric ratio was found in 70 per cent of the fractures following the start of weight bearing. Infection of a fracture induced a higher scintimetric ratio than that of an uninfected fracture. Re-fractures showed exceptionally high scintimetric ratios in the second to fourth week (twice the values of primary fractures), but the ratios decreased rapidly. Scintimetry is non-invasive, quantitative method of estimating the formation of callus. In this study the scintimetric time course of healing fractures of the tibia was determined. The results are to serve as a basic study of the method's suitability in early diagnosis of pathological healing.