Poster Presentation 50th International Society for the Study of the Lumbar Spine Annual Meeting 2024

Introduction

The assessment of global spinal alignment using full-spine standing radiographs is commonly used when considering a surgical strategy for patients with adult spinal deformity (ASD). However, these patients often experience worsening of low back pain when walking, suggesting that the pathological mechanism of ASD involves dynamic factors. This study aimed to evaluate dynamic changes in spinopelvic alignment and muscle activity during gait in patients with ASD using three-dimensional (3D) gait analysis synchronized with electromyography.

Methods

We retrospectively reviewed data from patients with ASD who underwent 3D gait analysis at our institution. Static spino-pelvic alignment was assessed using full-spine standing radiographs before 3D gait analysis. The static spino-pelvic parameters measured were C7 sagittal vertical axis (C7SVA), thoracic kyphosis (TK), lumbar lordosis (LL), pelvic tilt (PT), pelvic incidence (PI), and T1 pelvic angle (TPA).

A 3D gait analysis synchronized with electromyography was performed during continuous gait according to each patient’s limit. Dynamic kinematic parameters were divided into the following spinal segments: thoracic (T-), upper thoracic (UT-), lower thoracic (LT-), lumbar (L-), and pelvic (P-). The sagittal angle of each spinal segment to the pelvic angle (T-P SA, UT-P SA, LT-P SA, L-P SA) and the pelvic sagittal angle to the horizontal axis (P-SA) were assessed as dynamic spino-pelvic kinematic parameters (Fig. 1). Trunk and hip muscle activity during gait was assessed using wireless surface electromyography. Dynamic spino-pelvic kinematic variables and electromyographic muscular activity were compared between the first and final laps during gait analysis. We also evaluated whether changes in dynamic kinematic parameters correlated with static radiological alignment. Paired t-test and Pearson correlation were used for statistical analysis. P values < 0.05 were considered significant.

Results

The present study included 50 patients with ASD (13 males, 37 females). The mean values for each radiological spinal parameter were as follows: C7SVA, 127 mm; TK, 19°; LL, 8.5°; PT, 32°; PI, 48°; TPA, 38°. Thoracic and pelvic anterior tilt (T-P SA, UT-P SA, LT-P SA, and P-SA) increased significantly after continuous walking (Table 1). Lumbar tilt did not change significantly. Muscle activity in the gluteus maximus increased significantly after walking. Furthermore, an increase in thoracic anterior tilt during walking (ΔT-P SA, ΔUT-P SA, and ΔLT-P SA) was significantly correlated with PT and TPA.

Discussion

The present 3D gait analysis in patients with ASD showed that thoracic and pelvic anterior tilt significantly increased after continuous walking, resulting in worsening of sagittal balance. The increased activity of gluteus maximus muscles during gait may indicate compensation for deterioration in sagittal balance. A more significant increase in thoracic anterior tilt during gait was observed in patients with ASD who had larger PT and TPA, suggesting that the failure of greater compensation by pelvic posterior tilt for sagittal spino-pelvic malalignment is associated with a severe deterioration in sagittal balance during gait. Our 3D gait analysis synchronized with electromyography shows potential utility in assessing differences in individual compensatory endurance in patients with ASD. This may allow us to plan more appropriate corrective surgical procedures for each patient.