Alterations in the micro-anatomy of paraspinal muscles in patients with non-specific chronic low back pain

Abstract

Objectives: Investigating: 1)difference in muscle fibre type percentage and/or size when comparing both research groups for both the m. multifidus and the m. erector spinae. 2)difference in muscle fibre type percentage and/or size when comparing m. multifidus with m. erector spinae in both research groups. 3)correlation between the CSA of m. erector spinae/m. multifidus and muscle fibre type CSA in both research groups. Measurements: Primary outcome measures were CSA, percentage and proportional area of different muscle fibre types. The secondary outcome measure was the total muscle CSA. Results: There was a significant difference in the CSA of muscle fibre type I, this for both research groups. The percentage of muscle fibre type I was significantly larger in the NSCLBP patients when compared with the controls, this for both muscles. In the m. multifidus the proportional area of muscle fibre type I was significantly larger for the NSCLBP group. Percentages of muscle fibre type IIx were significantly larger for both muscles. The proportional area of muscle fibre type IIx was significantly larger in the m. erector spinae. There was a correlation between the CSA of muscle fibre type IIa and total muscle area of the m. multifidus in healthy subjects. Conclusion: No significant atrophy of the m. multifidus could be found in NSCLBP patients. Results suggest that muscle fibre type II is most susceptible for atrophy. Fear avoidance behaviour of NSCLBP patients could explain an increase in muscle fibre type I.