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 multi fidus 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.