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FIGURE 109.16 Radiographs depicting perilunate dislocation, best seen on the lateral
radiograph. (Courtesy of Children’s Orthopaedic Surgery Foundation.)

In addition to fractures, suspicion for ligamentous injuries should be high,
particularly in late childhood and adolescence. An important part of radiologic
evaluation is assessment of the distance between the scaphoid and lunate bones.
In a true scapholunate dissociation, this space is widened, often called the Terry
Thompson sign. This can be difficult to assess in children in whom this space is
naturally widened, as the carpals are not fully ossified. The normal plain
radiograph scapholunate interval decreases with age in children. It is also
important to note that dynamic scapholunate instability may not be shown on
routine x-ray, and may only be obvious under stressed view. Perilunate