Reliability of Ultrasound Findings in Patients with Lumbar Multifidus Myofascial Pain Syndrome.

Background: Lumbar multifidus muscle provides stability to the spine. The present study aimed to evaluate the reliability of ultrasound findings in patients with lumbar multifidus myofascial pain syndrome (MPS). Methods: A total of 24 cases (7 females, 17 males, mean age: 40.13± 5.69, BMI: 26.48±4.96) with multifidus MPS were assessed. The variables were muscle thickness in rest and contraction, thickness changes, and cross-sectional area (CSA) in rest and contraction. Two examiners performed the test and retest sessions. Results: The active trigger points of lumbar multifidus on the right and left side of the cases were 45.8 % and 54.2%, respectively. The intraclass correlation coefficient (ICC) values for muscle thickness and thickness changes showed moderate to very high reliability for both within and between intra-examiner measurements. (ICC, 1st examiner: 0.78-0.96; ICC, 2nd examiner: 0.86-0.95). In addition, the ICC values of within and between-session intra-examiner for CSA were high. (ICC, 1st examiner: 0.83-0.88; ICC, 2nd examiner: 0.84-0.89). The ICC and standard error of measurement (SEM) of inter-examiner reliability ranged between 0.75 to 0.93 and 0.19 to 0.88 for multifidus muscle thickness and thickness changes. The ICC and SEM of inter-examiner reliability ranged between 0.78 to 0.88 and 0.33 to 0.90 for CSA of the multifidus muscle. Conclusion: The within and between-session reliability of multifidus thickness, thickness changes, and CSA was moderate to very high in patients with lumbar MPS when taken by two examiners. Furthermore, the inter-examiner reliability of these sonographic findings was high.