The Effect of Computed Tomography Scans Oriented Along the Longitudinal Scaphoid Axis on Measurements of Deformity and Displacement in Scaphoid Fractures.

Abstract

Reformatting computed tomography (CT) scans along the scaphoid longitudinal axis improves the ability to detect scaphoid fractures compared with reformats along the wrist axis. However, it remains unclear whether scaphoid axis reformats affect measurements of displacement or deformity, which are factors that drive the clinical decision to perform open reduction internal fixation. Our null hypothesis was that reformatting CT scans along the scaphoid axis does not affect measurements of fracture displacement and deformity. Thirty patients with CT scans demonstrating scaphoid fractures (4 proximal pole, 17 midwaist fractures, and 9 distal) were identified and reformatted along 2 axes: the longitudinal axis of the scaphoid and the longitudinal axis of the wrist. The reformatted scans were sent to 2 musculoskeletal radiologists and 2 orthopedic hand surgeons who made the following measurements: (1) fracture gap, (2) displacement of the articular surface, (3) intrascaphoid angle, and (4) height to length (H:L) ratio. The reliability of each of the measurements cited above was compared for all raters between the 2 axes using intraclass correlation coefficients. Measurement of fracture gap and articular displacement trended toward more reliability in the wrist axis, whereas measurement of H:L ratio and intrascaphoid angle trended toward more reliability in thescaphoid axis. However, no differences in measurements between the 2 axes were statistically significant. This study demonstrates that reformatting CT scans in line with the axis of the scaphoid does not result in more reliable measurements of displacement or deformity. Measurements of displacement and deformity in scaphoid fractures can be made in the wrist axis with comparative reliability to those in the longitudinal scaphoid axis.