The scintigraphic assessment of the scoliotic spine after fusion.

Scintigraphy using technetium-labelled methylene diphosphonate was performed on 110 scoliotic patients six months after an attempted fusion and the findings compared with those at exploration to detect the possible sites of pseudarthroses. The majority of patients (65 per cent) had a uniform uptake of isotope over the fused area and all but one had a solid fusion. A second group (35 per cent) had a more patchy uptake and eight of the nine patients with pseudarthroses were in this group. Pseudarthroses were detected as localised areas of increased uptake but there were also a number of false positives and scans that were difficult to interpret due to continuing new bone formation in immature fusions. In those scans performed after one year the pseudarthroses which had been missed were seen more clearly in contrast to the diminished generalised activity in the fused area.