Association of Multifidus Thickness with Disability, Lumbar Stability and Kinesiophobia in Movement Control Impairment Subgroup of Chronic Low Back Pain

Abstract

Background: Global burden of disease data shows low back pain as the fourth leading cause of disability. Lumbar multifidus muscle (LM) deficit is one of the underlying mechanisms for compromised spinal stability causing chronic low back pain (CLBP), particularly in the movement control impairment (MCI) subgroup. Although evidence demonstrated the association between CLBP and kinesiophobia, there is insufficient evidence regarding the roles of LM in lumbar stability, disability, and kinesiophobia. This study aimed to determine the associations between LM thickness and lumbar stability, disability level, and kinesiophobia. Methods: 33 participants with CLBP during remission and having MCI were recruited. Rehabilitative ultrasound imaging was used to measure LM thickness at rest and maximum voluntary isometric contraction and was further used to calculate percent LM thickness change (%LM). An electromagnetic motion tracking system was used to measure lumbar stability at lumbar levels L4 and L5 during rest and leg raise positions of prone instability test. These data were used for the lumbar stability index. Thai-version Oswestry disability index and Tampa scale of kinesiophobia were used to assess disability and kinesiophobia, respectively. Spearman’s rank correlation coefficient was used to assess statistical associations. Results: Findings demonstrated a significant moderate positive correlation between %LM and lumbar stability index at L5 (ρ = 0.42, P<0.05) and a trend at L4 (ρ = 0.32, P = 0.08), while %LM was not significantly associated with disability and kinesiophobia (P>0.05). Conclusions: Association between %LM and lumbar stability index suggests the role of LM in providing stability to the lower lumbar spine. No significant association between %LM and disability and kinesiophobia suggests clinicians should consider LM deficit might not be key to decreasing disability and fear of movement, and additional interventions may be needed to treat this subgroup of CLBP.