Aim: we aimed to investigate lumbar multifidus muscle (LMM) atrophy in patients with mechanical low back pain in terms of age and gender in larger study group. Furthermore, we evaluated the coexistance of LMM atrophy and disc hernia and investigated the prevalence of LMM atrophy independent of disc hernia in mechanical low back pain.
Material and Methods: In total, 2166 lumbar MRI of low back pain patients (age range, 18-88 years) were re-evaluated retrospectively. LMM atrophy was visually assessed in axial sections of L4-L5 and L5-S1 levels. The distribution was examined based on age and gender. Incidences of co-existence with disc hernia and alone were investigated.
Results: Irrespective of gender, LMM atrophy prevalence at both levels were significantly higher in subjects older than 40 years compared to younger adults (P<0.001). LMM atrophy was significantly higher in women than in men (P<0.001). The prevalence of LMM atrophy in low back pain patients without hernia was significantly higher than patients without atrophy (P<0.001). Frequency of LMM atrophy in LBP patients without disc hernia was 13%. Hernia was more frequent in patients with LMM atrophy compared to patients without atrophy (P<0.001).
Conclusion: LMM atrophy in women is observed more than men and its prevalence and severity increase with age. 40 years of age is especially important for LMM atrophy. Hernia is found more frequently in individuals with LMM atrophy. LMM atrophy was the only MRI finding in 13% of the patients and further studies with a control group may worth to consider.