Scapular Dyskinesis Assessment with Low Dose Three-Dimensional Wing Computer Tomography after Anatomical Union of Clavicle Fracture

Abstract

Purpose: Malunions after clavicle fractures are generally considered to cause scapular dyskinesis. This study aims to verify the incidence of scapular dyskinesis following anatomically reduced clavicle fracture and to verify the usefulness of low-dose three-dimensional (3D) scapular wing computed tomography (3D-scapula wing-CT) analysis. Methods: Twenty-four patients with mid-clavicle fracture and four patients with distal clavicle fracture were recruited. After anatomical reduction and bony union, scapular dyskinesis was assessed by history taking and physical examination by two orthopedic doctors. The mean follow-up period for the assessment was 14.3±10.1 months. Low-dose 3D-scapular wing-CT analysis in prone position was performed with calculated effective dose 2.35 mSv, which means approximately 25% dose of conventional setting. Four observers evaluated five angles (upward rotation, internal rotation, anterior tilting, superior translation, protraction) from 3D-reconstructed images on both shoulders of a patient. Authors analyzed the results between injured to normal shoulder. Results: Scapular dyskinesis or significant shortening of injured clavicle (mean clavicle length difference, − 1.77±6.36 mm) were not observed among the included 28 subjects. The difference values of the five angles between the fractured side and normal side showed no statistical significance (upward rotation: 1.51, p=0.13; superior translation: 0.89, p=0.327; anterior tilting: 1.7, p=0.096; protraction: 0.83, p=0.374; internal rotation: 0.98, p=0.406). As the interclass correlation coefficients of four observers was 0.988 (p=0.00), images from low-dose 3D-wing-CT are clear enough to assess scapular dyskinesis (interclass correlation coefficient, 0.996; p=0.00). Conclusion: It is important to make anatomical reduction and length restoration of clavicle fracture for preventing scapular dyskinesis. Low-dose 3D-scapular wing-CT is an effective tool for assessing scapular dyskinesis, which provides images of sufficient quality with little increase in morbidity from radiation hazard.