RELATION BETWEEN INESPECIFIC LOW-BACK PAIN AND GLUTEUS MEDIUS MUSCLE THICKNESS MEASURED BY M-MODE ULTRASOUND

S. Macias-Garcia¹, S. Fernandez-Carnero¹, F. Naranjo-Cinto¹, R. Fernandez-Matias¹, D. Pecos-Martin¹, T. Gallego-Izquierdo²

Background: Nonspecific low back pain (NSLBP) is one of the most prevalent painful syndromes and a great cause of absenteeism. The gluteus medius muscle (GM) is a good hip stabilizer and has an important role in the performance of the lumbo-pelvic rhythm. Some authors have found disturbances in the lumbo-pelvic rhythm in subjects with NSLBP which could be due to a loss of functional activation of the gluteal muscles. Previously studies have determined that ultrasound M-mode, which provides information collected along time from the middle point of the transducer as an image, is one of the most reliable tools for the measurement of the GM thickness.

Purpose: To evaluate the change in GM thickness from rest to contraction in subjects with NSLBP compared to healthy controls. To analyze between-groups differences in hip abductor strength. Finally, to evaluate the reliability of the ultrasound measurements.

Methods: A convenience sample of participants was recruited. Hip abductor strength was measured with a hand-held dynamometer and GM thickness at rest and contraction was measured with ultrasound M-mode. Strength and GM thickness were measured three times in each lower limb with a 30-second rest period in between them. All the dependent variables were collected by a blinded evaluator who was unaware of the subject’s group allocation. The reliability of the ultrasound measurements was analyzed in a random subgroup of 10 subjects. Pain intensity was measured with a visual analogue scale, low back pain related disability was measured with the Oswestry Scale and Rolland Morris questionnaire, and kinesiophobia was measured with the Tampa Scale of Kinesiophobia 11. The differences between groups were analyzed with a 2x2x2 mixed-model analysis of variance (ANOVA). Post hoc pairwise comparisons were analyzed with student t-test with Bonferroni correction. The reliability of the ultrasound measurements was analyzed with the intraclass correlation coefficient (ICC).

Results: Two groups were compared, the healthy subjects group (n = 17) mean age of 22.82 years and the NSLBP group (n = 12) with a mean age of 24.25 years. Good reliability was obtained at rest in the healthy (ICC = 0.9) and NSLBP (ICC = 0.96) groups, and at contraction in the healthy (ICC = 0.93) and NSLBP (ICC = 0.9) groups. The mixed-model ANOVA revealed a statistically significant decrease in the GM thickness at rest (mean difference = -0.33 and -0.35; p < .05) and at contraction (mean difference = -0.44 and -0.46; p < .05) in subjects with NSLBP. However, there were non-statistically significant differences for GM thickness change from rest to contraction and hip abductor strength (p > .05).

Conclusion(s): This study shows that subjects with NSLBP have less GM thickness at rest and contraction compared to healthy subjects. However, there are no differences in the GM thickness change from rest to contraction and hip abductor strength. Further research would be develop with more sampling for strengthening the results.

Implications: Regarding the results obtained could be some implications between the NSLBP and gluteus medius and should be taken into account in rehabilitation process.

Funding, acknowledgements: No fundings

Keywords: Gluteus medius, Nonspecific low back pain, M-mode ultrasound

Topic: Musculoskeletal: lower limb

Did this work require ethics approval? Yes

Institution: Alcalá University

Committee: Ethical Committee of Alcalá University

Ethics number: CEI/HU/2019/47