Biomechanical effects of spinal orthoses on the trunk during a sit-to-stand-to-sit task

Abstract

Background: Spinal orthoses can be used to limit active Range of Motion (RoM) in different directions and to support trunk extension, however their effect on movement and muscle activity remains uncertain.

Objective: This study explored the effects of two semi-rigid spinal orthoses on trunk kinematics and muscle activity compared to no brace. Study Design: A pre-clinical, feasibility study.

Methods: Markerless motion capture and surface electromyography was collected from twenty healthy participants each performing 5 repetitions of a sit-to-stand-to-sit task under three conditions: No Brace (NB), Brace A (Medi Spinomed®, Bayreuth, Germany) and Brace B (DonJoy® Osteostrap, Enovis, UK). Repeated measures analysis of variance (ANOVA) was used to evaluate trunk kinematics and muscle activity between conditions.

Results: During sit-to-stand, average muscle activity of the dominant latissimus dorsi was significantly reduced in Brace A compared to NB (MD=0.13, p=0.019), but there were no differences between Brace A and Brace B (MD=-0.08, p=0.097). During both standing and sitting, participants were significantly more flexed forward in Brace A compared to NB (MD=1.65 - 2.23, p<0.015) and Brace B (MD=1.46 - 1.55, p=0.040). During stand-to-sit, peak extension angular velocity significantly increased in Brace A and Brace B compared to NB (MD=5.74, p=0.011, MD=6.68, p=0.046 respectively). Central tendencies for perceived comfort were ‘comfortable’ for both Braces, and perceived ease of task performance was ‘very easy’ for Brace A and ‘easy’ for Brace B, with brace preference split equally.

Conclusions: Active RoM was not limited using either brace, however these did assist movement into extension, which may offer a clinical benefit, with small changes also seen in latissimus dorsi muscle activity. Further work including clinical populations is warranted using intervention periods that reflects clinical practice.