Reliability of B-mode ultrasonography to measure lumbar multifidus muscle dimensions in patients with unilateral lumbar disc herniation

OBJECTIVES:To evaluate Ultrasound Imaging (USI) reliability for measurement of lumbar multifidus (LMF) muscle thickness and cross sectional area (CSA) at rest and during contraction in patients with unilateral lumbar disc herniation. SETTING:Laboratory. DESIGN:Reliability Study. PARTICIPANTS:Thirty patients, aged 25-50 years (37.55 ± 9.55), with unilateral L4-L5 lumbar disc herniation participated in this study. MAIN OUTCOME MEASURES:Thickness and CSA of LMF were measured using B-mode ultrasound by two raters in prone position. RESULTS:Same day and multiple day inter-rater and same day intra-rater reliability showed good to excellent reliability (intraclass correlation coefficients ranged from 0.70 to 0.91). Also standard error of measurement and minimal detectable change for USI reliabilities ranged from 0.06 to 0.57 and 0.16 to 1.31, respectively. CONCLUSIONS:Reliability of USI for measurements of LMF muscle thickness and CSA was high, and consistent with previous studies conducted on reliability of USI to measure LMF dimensions in other populations.