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Interobserver reliability of computed tomography to diagnose scaphoid waist fracture union

journal contribution
posted on 2012-02-01, 00:00 authored by G Buijze, M Wijffels, T Guitton, R Grewal, C van Dijk, D Ring, Science of Variation Group, Richard PageRichard Page
Purpose : To determine the interobserver agreement and diagnostic performance characteristics of computed tomography (CT) for determining union of scaphoid waist fractures.

Methods : A total of 59 orthopedic and trauma surgeons rated for union a set of 30 sagittal CT scans of 30 scaphoid waist fractures. Of these fractures, 20 were treated nonoperatively, were imaged between 6 and 10 weeks after injury, and were known to have eventually achieved union. Ten were operatively confirmed to be ununited. We rated each scan as united or ununited using a Web-based rating application. We assessed interobserver reliability using Siegel's multirater Kappa. We calculated diagnostic performance characteristics using Bayesian formulas.

Results : The interobserver agreement among 59 raters was substantial. The average sensitivity, specificity, and accuracy of diagnosing union of scaphoid waist fractures on sagittal CT scans were 78%, 96%, and 84%, respectively. Assuming a 90% prevalence of fracture union of the scaphoid, the positive predictive value of a diagnosis of union on sagittal CT scan was 0.99 and the negative predictive value was 0.41.

Conclusions : Our results suggest that CT scans are accurate and reliable for diagnosis of union but inadequate for ruling out nonunion of scaphoid waist fractures between 6 and 10 weeks after injury.



Journal of hand surgery






250 - 254


W. B. Saunders


Philadelphia, Pa.





Publication classification

C1.1 Refereed article in a scholarly journal

Copyright notice

2012, W. B. Saunders


R Page