Computed Tomography for Suspected Scaphoid Fractures: Comparison of Reformations in the Plane of the Wrist Versus the Long Axis of the Scaphoid

Abstract

Definitive diagnosis of occult scaphoid fractures remains difficult. We tested the null hypothesis that, for diagnosis of true fractures among suspected scaphoid fractures, computed tomography (CT) reformations along the long axis of the scaphoid have the same accuracy as reformations made relative to the anatomical planes of the wrist. In a prospective trial, 34 patients with a suspected scaphoid fracture underwent CT scanning within 10days after trauma. CT reformations along the long axis of the scaphoid (CT-scaphoid) and along planes relative to the wrist (CT-wrist) were made. We used radiographs obtained 6weeks after injury as the reference standard for a true fracture. A blinded panel including two surgeons and one radiologist came to a consensus diagnosis for each reformation plane. The reference standard showed six fractures of the scaphoid (prevalence, 18%). Using CT-wrist, a scaphoid fracture was diagnosed in five patients (15%), with three false positive, four false negative and two true positive diagnoses. Using CT-scaphoid, a scaphoid fracture was diagnosed in five patients (15%), with one false positive, two false negative and four true positive results. Sensitivity, specificity and accuracy were 33, 89 and 79% for CT-wrist and 67, 96 and 91% for CT-scaphoid, respectively. This resulted in positive predictive values of 36% for CT-wrist and 76% for CT-scaphoid. Negative predictive values were 87% for CT-wrist and 94% for CT-scaphoid. No significant differences were found with the number of patients available. For diagnosis of true fractures among suspected scaphoid fractures, the diagnostic performance characteristics of CT scans reformatted along the long axis of the scaphoid were better than CT scans in the planes of the wrist, but the differences were not significant.