Background: Displacement is an important risk factor for nonunion of
scaphoid wrist fractures. We compared computed tomography with radiographs
with regard to their ability to detect displacement.
Methods: Six blinded observers rated thirty scaphoid fractures (ten
displaced and twenty nondisplaced) with use of radiographs and computed
tomography. The radiographs were evaluated separately from the computed
tomography scans and then, in a third evaluation, the two imaging studies were
reviewed simultaneously. The evaluations were repeated four weeks later.
Observers were asked to evaluate specific measures of fracture displacement
and then to judge the fracture as being displaced or nondisplaced.
Results: Intraobserver reliability was better for computed
tomography alone and the combination of radiographs and computed tomography
than it was for radiographs alone (kappa values, 0.65, 0.63, and 0.54,
respectively; all p < 0.001). The interobserver reliability was also better
for computed tomography alone and the combination of radiographs and computed
tomography than it was for radiographs alone (kappa values, 0.43, 0.48, and
0.27, respectively; all p < 0.001). The average sensitivity was 75% for
radiographs alone, 72% for computed tomography alone, and 80% for both; the
average specificity was 64%, 80%, and 73%, respectively; the average accuracy
was 68%, 77%, and 75%, respectively. The positive predictive values (assuming
a 5% prevalence of fracture displacement) were low (0.10, 0.13, and 0.16) and
the negative predictive values were high (0.97, 0.98, and 0.99) for the
radiographs, computed tomography, and combined modality.
Conclusions: Computed tomography improves the reliability of
detecting scaphoid fracture displacement but has a more limited effect on
accuracy, which remains <80%. The utility of computed tomography scans for
diagnosing scaphoid fracture displacement is affected by the low prevalence of
fracture displacement. This study suggests that computed tomography scans are
useful for ruling out displacement but not for diagnosing it. We recommend
that all scaphoid fractures be evaluated with computed tomography in order to
rule out displacement.
Level of Evidence: Diagnostic Level III. See Instructions
to Authors for a complete description of levels of evidence.