Correlation Between Dynamic 4-Dimensional Computed Tomography Data and Arthroscopic Testing of Scapholunate Instability: A Preliminary Study.

PURPOSE: The aim of this study was to test the validity and reliability of the assessments of scapholunate (SL) instability status on 4-dimensional (4D) computed tomography (CT) using wrist arthroscopy as a reference standard.

METHODS: Thirty-three patients (16 men, 17 women; mean age, 48 ± 13 years) with suspected SL instability were evaluated prospectively with 4D-CT and wrist arthroscopy. Based on the arthroscopic testing of SL joint, 2 groups were defined: group 1 (n = 8) consisted of patients who had no, or slight, SL malalignment in the midcarpal space and group 2 (n = 25) consisted of patients who had moderate or severe SL malalignment. Two independent readers, who did not know the arthroscopic findings, used 4D-CT to evaluate the SL gap, lunocapitate angle (LCA), and radioscaphoid angle (mean and range values) during radioulnar deviation.

RESULTS: The interobserver reliability was deemed good or excellent for most of the 4D-CT variables, except for the LCA range (moderate) and SL gap range (poor). For both readers, the SL gap mean, maximum, and minimum values were significantly higher (+67%, +78%, and +39%, respectively) and the LCA mean was significantly lower (-17%) in group 2 than in group 1. The radioscaphoid angle range values were lower (-34%) and the radioscaphoid angle mean values slightly higher (+4%) in group 2, but there was no significant difference between the 2 groups. The SL gap range values were also higher (+86% for R1 and +40% for R2) and the LCA range values also lower (-50% for R1 and -31% for R2) in group 2.

CONCLUSIONS: Quantitative 4D-CT data corresponded well with the arthroscopic dynamic analysis of the SL joint in patients with suspected chronic SL instability.

TYPE OF STUDY/LEVEL OF EVIDENCE: Diagnostic II.