Special Poster Session 50th International Society for the Study of the Lumbar Spine Annual Meeting 2024

IMPROVEMENT IN LUMBAR MULTIFIDUS MUSCLE COMPOSITION AFTER A 12-WEEK EXERCISE INTERVENTION IN PATIENTS WITH CHRONIC LOW BACK PAIN: A RANDOMIZED CONTROLLED TRIAL (#SP-7d)

Brent Rosenstein 1 , Meaghan Rye 1 , Alexa Roussac 1 , Neda Naghdi 1 , Luciana G Macedo 2 , James M Elliott 3 4 , Richard DeMont 1 , Michael H Weber 5 , Véronique Pepin 1 6 , Geoff Dover 1 , Maryse Fortin 1 6
  1. Department of Health, Kinesiology and Applied Physiology , Concordia University, Montreal, QC, Canada
  2. School of Rehabilitation Science, Faculty of Health Sciences , McMaster University, Hamilton, ON, Canada
  3. Faculty of Medicine and Health, School of Health Sciences, The Kolling Institute, University of Sydney, Sydney, NSW, Australia
  4. Northern Sydney Local Health District, St Leonards, NSW, Australia
  5. Department of Orthopedic Surgery , McGill University Health Centre, Montreal, QC, Canada
  6. PERFORM Centre, School of Health, Concordia University, Montreal, QC, Canada

Introduction: Paraspinal muscle fatty infiltration is elevated in people with chronic low back pain (LBP) compared to healthy-matched controls, and associated with higher levels of disability, LBP severity and muscle dysfunction. Exercise therapy is well-recognized to improve pain and disability in patients with chronic LBP, but its effect on paraspinal muscle composition remain elusive, particularly at the upper lumbar levels. We investigated the effect of a combined motor control and isolated lumbar strengthening exercise (MC+ILEX) versus a general exercise (GE) group on upper lumbar paraspinal muscle fatty infiltration in individuals with chronic LBP.

Methods: Fifty participants with chronic LBP were randomly allocated to each group (MC+ILEX, n=25; GE, n=25) and completed a 12-week supervised intervention program (2 sessions per week). IDEAL (lava-flex, 2-echo) fat and water magnetic resonance imaging (MRI) was acquired at baseline, 6-weeks and 12-weeks to examine the impact of each intervention on multifidus and erector spinae muscle fatty infiltration (% fat signal fraction) at L1-L2, L2-L3 and L3-L4.

Results: A mixed model ANOVA with repeated measures revealed no significant time*group for multifidus and erector spinae fatty infiltration at L1-L2, L2-L3 or L3-L4 (all p>0.05). Both groups showed a significant decrease in multifidus fatty infiltration at L1-L2 (MC+ILEX: -4.38[-6.07 to -2.70], GE: -3.23[-5.00 to -1.47]), at L2-L3 (MC+ILEX: -3.78[-5.52 to -2.04], GE: -2.55[-4.30 to -0.81]) and at L3-L4 (MC+ILEX: -3.71[-5.27 to -2.14], GE: -3.07[-4.74 to -1.39]) post-intervention. A significant decrease in erector spinae fatty infiltration was also observed at L1-L2 in both groups (MC+ILEX: -3.98[-6.58 to -1.38], GE: -5.10[-7.82 to -2.38]), with no significant changes in erector spinae fatty infiltration at L2-L3 or L3-L4.

Discussion: This study provided preliminary evidence suggesting that both a MC+ILEX and a GE intervention included in this trial may help improve multifidus muscle quality at the upper lumbar levels in participants with chronic LBP. The effect of fatty infiltration on muscle functional capacity is understudied and warrants further investigation.

  1. Fortin, M., Rye, M., Roussac, A., Naghdi, N., Macedo, L. G., Dover, G., Elliott, J. M., DeMont, R., Weber, M. H., & Pepin, V. (2021). The effects of combined motor control and isolated extensor strengthening versus general exercise on paraspinal muscle morphology and function in patients with chronic low back pain: a randomised controlled trial protocol. BMC musculoskeletal disorders, 22(1), 472. https://doi.org/10.1186/s12891-021-04346-x