Quality of lumbar paraspinal muscles in patients with chronic low back pain and its relationship to pain duration, pain intensity, and quality of life

Objectives: To examine the relationship between the quality of paraspinal muscles and pain intensity, duration, and quality of life in patients with chronic low back pain (cLBP).

Methods: Between January 2022 and December 2023, 119 individuals with no-back pain (no-BP) and 136 cLBP patients were enrolled. Both groups underwent health surveys and magnetic resonance imaging. Cross-sectional area (CSA), functional cross-sectional area (FCSA), and fat infiltration (FI) of multifidus (MF) and erector spinae (ES) were measured. Data were analyzed using multiple linear and binary logistic regression.

Results: Compared to the cLBP group, the no-BP group had smaller CSA influenced by FI of ES at L5/S1 (p = 0.01), higher FCSA of ES (p < 0.01) at L4/L5, and lower FI of ES and MF at L4/L5 and L5/S1 (p < 0.01). CSA, FCSA, and FI showed no significant correlation with cLBP intensity except for the CSA (p = 0.02) and FCSA (p = 0.03) of the L2/3 MF. Pain duration positively correlated with FI at L2/3, L3/4, and L4/5 of MF and ES (p < 0.05) and CSA of the L1/2 MF (p = 0.02). CSA (L3/4, L4/5, and L5/S1) and FCSA (L4/5, L5/S1) of MF correlated positively with SF36 scores (p < 0.05), while ES muscles did not (p > 0.05). FI of MF and ES showed no correlation with SF36 scores.

Conclusion: CSA and FI were significantly higher, and FCSA significantly lower in paraspinal muscles of cLBP patients compared to asymptomatic participants. Increased FI correlated with prolonged cLBP duration, indicating FI and FCSA alterations may play a significant role in cLBP development and duration.

Key points: Question What is the relationship between paraspinal muscle quality and cLBP, including its intensity, duration, and impact on quality of life? Findings cLBP patients had increased FI and reduced functional muscle area in paraspinal muscles, with FI correlating with prolonged pain duration. Clinical relevance Understanding the changes in lumbar paraspinal muscles provides insight into cLBP progression, guiding personalized interventions to improve pain management and patient quality of life.