Comparison of radiographic appearance and bone scintigraphy in fracture nonunions

Many surgeons assess the biological activity of fracture nonunions by the presence or absence of callus on radiographs. However, the assessment of biological activity by radiographic appearance alone is controversial. Bone scintigraphy reflects blood flow and new bone formation; therefore, it is useful in assessing such biological activity in nonunion cases. This retrospective study compared radiographs with Tc-99m bone scintigraphy in 48 patients with uninfected nonunions. Positive uptake was observed in all cases. The uptake patterns were classified into 4 types: type 1, intense, uniform uptake; type 2A, a definite photon-deficient cleft between 2 areas of intense uptake; type 2B, a photon-deficient area other than type 2A; and type 3, an intermediate pattern with uneven, distributed uptake. The percentage of type 1 with intense uptake does not decrease with time, and type 2 does not increase. When uptake was compared in patients with a nonunion and a united fracture, higher uptake in nonunion was seen in 46% and lower uptake was seen in 27%. All cases of hypertrophic and more than half of oligotrophic nonunions were type 1. Type 2 was seen in 17% of oligotrophic, 67% of comminuted, 100% of defect, and 57% of atrophic nonunions. Poor callus visualization may not preclude biological activity. Long duration from injury may not equate to declines in biological activity. Comparing uptake in nonunions and united fractures in the same patient may help to assess biological activity. The photon-deficient area is helpful to assess the necessity of bone graft or other osteogenic supplementation.