Gliding Distance of the Extensor Pollicis Longus Tendon with Respect to Wrist Positioning: Observation in the Hands of Healthy Volunteers Using High-Resolution Ultrasonography

Study DesignCross-sectional experimental bench.IntroductionOptimal tendon gliding is necessary for normal thumb function.Purpose of the StudyMeasure the gliding distance of the extensor pollicis longus (EPL) tendons during passive thumb flexion from high-resolution echo images at four wrist positions.MethodsGliding distance of the EPL tendon in zone 4 of the thumb was measured during passive flexion in four different wrist positions in 25 healthy female volunteers. Tendon gliding was evaluated from high-resolution ultrasonography in a frame-by-frame cross-correlation analysis.ResultsMean gliding distance of the EPL tendon was 1.79, 2.45, 1.09, and 1.36 mm with the wrist positioned in neutral, 30 degrees of extension, 30 degrees of flexion, and 20 degrees of ulnar deviation, respectively. There were statistically significant differences in the gliding distance of the EPL tendon among all of four wrist positions except for that between the wrist flexion and wrist ulnar deviation conditions.ConclusionsWrist extension induces the greatest magnitude EPL tendon gliding.