Kinematic and muscular assessment of spinal stability and the connection to lower back pain

Abstract

Previous researchers have utilized computational models and human movement analysis to improve our understanding of spinal function. However, the causes and optimal treatments for nonspecific lower back pain (LBP) remain unclear. Previous motion analysis studies into spinal disease have focused primarily on tracking spinal movements, neglecting the connection between the lower limbs and spinal function. However, nonspecific LBP is not isolated to the spinal column. The human postural response requires a complex milieu of skeletal and muscle function and therefore pain often stems from deficiencies in other areas, such as the knees and pelvis. The current lack of knowledge surrounding the functional implications of LBP may explain the diversity in success from general treatments currently offered to LBP patients.

The purpose of this study was to evaluate both the kinematic differences and variation in muscle activation patterns between subjects with a history of LBP (hLBP) (n=10) and healthy individuals (n=16) in response to a balance perturbation. Further analysis aimed to integrate these datasets to provide a clinical picture of body position in both the trunk and lower limbs. The findings support the hypothesis that there are inherent differences in movement patterns between healthy and hLBP subjects. The results revealed the use of an upper body-focused strategy in the healthy cohort for balance control. Specifically, this involved activation of the erector spinae and external oblique muscles, thus resulting in a significantly smaller range of motion at the lumbar spine. The hLBP cohort implemented a lower limb-focused strategy, relying on activation of the semitendinosus and soleus muscles. Based on the findings in this study, further work is recommended to 1) better refine the spinal model, 2) compare hLBP subjects to patients acutely suffering from LBP, and 3) investigate a wider range of muscles to more robustly investigate muscle synergies.