Comparison of sagittal computed tomography and plain film radiography in a scaphoid fracture model.

Purpose: To compare computed tomography (CT) in the sagittal plane and plain film radiography in the diagnosis of scaphoid fracture and displacement.

Methods: Three groups of scaphoids (no fracture, undisplaced fractures, fractures with displacement > 1 mm) from 11 cadaver wrists were prepared. Each wrist then was imaged by using sagittal plane CT scans in the long axis of the scaphoid and plain film imaging using 6 standard scaphoid views. Eight readers from 3 specialties read each group of images. The sensitivity and specificity for the presence of fracture and fracture displacement were calculated in addition to interobserver and intraobserver reliabilities for each.

Results: Both x-ray and CT scans showed a high sensitivity and specificity in detecting the presence of a fracture with no interspecialty differences. The sensitivity for displacement greater than 1 mm was lower for both modalities with no inter-specialty differences. The specificities for x-ray and CT for detecting displacement greater than 1 mm were 84% and 89%, respectively. The poor sensitivity for detecting displacement was explained by the low sensitivity of CT in the diagnosis of radial/ulnar displacement compared with x-ray and the low sensitivity of x-ray in the diagnosis of volar/dorsal displacement compared with CT scans. When fellowship-trained hand surgeons reviewed CT scans and plain films together the sensitivity and specificity for fracture displacement increased significantly. Intraobserver and interobserver reliability for both x-ray and CT scans was excellent except for the reading of CT scans among emergency physicians and for the reading of plain x-rays among senior house staff, representing moderate agreement.

Conclusions: Based on these results both CT scans in the sagittal plane and plain films accurately detect fractures with a high degree of interobserver and intraobserver reliability, but they fall short in detecting displacement greater than 1 mm.