Figure 10b. Early pseudarthrosis in a 43-year-old man. (a) Anteroposterior radiograph demonstrates a linear lucency in the posterolateral bone graft material on the right (arrow), a finding indicative of early pseudarthrosis. (b) Technetium 99m methylene diphosphonate bone scan (reversed to correspond to a) shows an area of markedly increased activity at this level (arrow), a feature that helps confirm the diagnosis.