Quantitative early phase scintigraphy in the prediction of healing of tibial fractures.

Imaging with technetium-99m methylene diphosphonate (99mTc-MDP) is established in the diagnosis of infection, neoplasia and ischaemic necrosis in orthopaedic practice, but its role in fracture healing is less well-defined. Previous studies have shown a relationship between fracture site activity (region A), activity in adjacent normal bone (region C) and time to union. The predictive value of the A/C ratio of the image obtained 300-800 s after injection was assessed in a prospective study of 50 patients with closed tibial fractures managed with plaster casts, external fixators and intramedullary nails. There were significant differences in absolute uptake and A/C ratio between the three groups (P less than 0.05), but this was not related to time to union. Reamed nailing alters the distribution of 99m-Tc-MDP uptake so as to reduce the A/C ratio (1.10 +/- 0.20), but there is a promising role for early phase bone scanning in non-operative (A/C = 1.40 +/- 0.21) or externally fixed (A/C = 1.26 +/- 0.22) fractures in conjunction with other non-invasive methods of monitoring the biomechanical environment.