Reliability of Ultrasound Image–Based Measurements of the Vastus Medialis Oblique Muscle Structure and Function

Purpose:To assess test–retest reliability of vastus medialis oblique (VMO) pennation angle, muscle thickness, and changes in muscle thickness across different knee flexion angles in healthy participants across two sessions.Methods:Intraclass correlation coefficients between days for VMO muscle thickness and pennation angle and changes in muscle thickness and pennation angle while seated with the knee at 0°, 30°, 60°, and 90° flexion, standing, and during a 30° squat.Results:Twenty-three of 33 individual muscle thickness intraclass correlation coefficient values showed good reliability. Six of 33 individual pennation angle intraclass correlation coefficient values showed good reliability.Conclusions:Assessing muscle thickness during voluntary isometric knee extension may be a non-invasive way to assess VMO muscle function in individuals with patellofemoral pain syndrome.[[Athletic Training & Sports Health Care. 2018;10(5):217–226.]