Age and activity but not lumbar spinal stenosis and muscle fatigue affect sagittal spinal alignment: A pilot study.

Abstract

Ageing is associated with changes in spinal alignment. Lumbar spinal stenosis may alter spinal alignment due to pain, muscle atrophy and fatigue. While spinal alignment and motion are crucial in lumbar spinal stenosis, the effects of age, activity, and muscle fatigue on spinal alignment remain unclear. This study investigates these factors using motion capture analysis. In 11 patients with lumbar spinal stenosis (5 M/6 W; age, 71 ± 9 years; body mass index, 29 ± 5 kg/m²), 10 older controls (5 M/5F; 65 ± 5 years; 25 ± 6 kg/m²), and 10 young controls (5 M/5F; 26 ± 2 years; 22 ± 2 kg/m²), spinal alignment was assessed during standing and walking before and after a modified Biering-Sørensen test using reflective markers. The curvature of the thoracic and lumbar spine was modelled using a cubic polynomial. Spine inclination, thoracic kyphosis, lumbar lordosis and pelvic tilt were used to describe spinal alignment. The effects of group, activity and paraspinal muscle fatigue were investigated using bootstrapped mixed-effect models. Patients and older controls had greater spine inclination than young controls. Spinal alignment did not differ between patients and older controls. Dynamic activity increased spine inclination, thoracic kyphosis, and pelvic tilt across all groups. Compared to non-fatigued conditions, significant spine inclination increases and lumbar lordosis decreases occurred with fatigue. A significant interaction effect for group and activity was found between patients and young controls. Our findings suggest that age and activity, rather than lumbar spinal stenosis and muscle fatigue, play a critical role in spinal alignment. Further studies are warranted to investigate the underlying mechanisms. gov ID NCT05309447.