The Reliability of Rehabilitative Ultrasound Imaging Measurements of the Lumbar Multifidi Recorded by Physical Therapist Students With Minimal Training

Abstract

Background and Purpose. Retraining of the multifidus muscle is considered a crucial component of a lumbopelvic stabilization program. Rehabilitative ultrasound imaging (RUSI) is used for documenting muscle thickness as well as assisting with muscle re-education. The amount of training required for student physical therapists to be able to obtain reliable multifidus thickness measurements has not been reported. The purpose of this study was to determine if 6 hours of training time was sufficient to allow students in physical therapist professional education programs to produce reliable thickness measurements of the lumbar multifidus muscle using RUSI. Subjects. Twenty healthy subjects (5 males, 15 females) were chosen from a convenience sample of students enrolled in a professional Doctor of Physical Therapy (DPT) program. Methods. Multifidus thickness was measured utilizing RUSI at the L2-3 and L4-5 segmental levels of each subject with the subject in prone. Measurements were taken on each subject in the parasagittal view by 4 raters (3 student raters and 1 experienced clinician). Reliability was established using the intraclass correlation coefficient (ICC) and standard error of measurement (SEM) for the 4 raters. Results. On the basis of an average of 3 trials, the raters showed high interrater agreement on the measurement of thicknesses at the L4-5 vertebral level (ICC2,3 = 0.936; 95% CI: 0.874-0.972) and relatively lower, but still with a high level of agreement at L2-3 (ICC2,3 = 0.827; 95% CI: 0.658-0.924). The interrater reliability of the 3 novice raters (excluding the interrater reliability of the experienced rater) was high at the L4-5 level (ICC2,3 = 0.905, 95% CI: 0.800-0.959) and lower at L2-3, but still with good reliability (ICC2,3 = 0.760, 95% CI: 0.494-0.897). In addition, the experienced and novice raters produced reliable intrarater measurements at L2-3 (experienced rater, ICC3,1 = 0.975, 95% CI: 0.948-0.989; novice raters, ICC3,1 = 0.942, 95% CI: 0.879-0.975; ICC3,1 = 0.984, 95% CI: 0.966-0.993; and ICC3,1 = 0.966, 95% CI: 0.928-0.985) and at L4-5 (experienced rater, ICC3,1 = 0.993, 95% CI: 0.986-0.997; novice raters, ICC3,1 = 0.966, 95% CI: 0.927-0.985; ICC3,1 = .988, 95% CI: 0.975-0.995; and ICC3,1 = 0.964, 95% CI: 0.923-0.984). Discussion and Conclusion. The results of this study suggest that 6 hours of didactic training may be sufficient to provide second-year professional DPT students with the training necessary to make reliable thickness measurements of the multifidus using RUSI.