Changes in Dynamic Plantar Pressure and Asymmetry in AIS Following PSSE

Adolescent idiopathic scoliosis (AIS) may manifest with instability and abnormal plantar pressure during gait. However, there is limited objective evidence to support efficacy of short-term physiotherapeutic scoliosis specific exercises (PSSE) with or without bracing on the improvement of plantar pressure. Thus, this study aimed to (1) compare various plantar pressure parameters and their symmetry indexes during gait before and after PSSE; (2) assess those differences during gait between braced and non-braced groups.

Our study included AIS patients with surface topography analysis before and after 6-16 weeks of PSSE treatment. Plantar pressure data was compared pre- vs. post-PSSE regardless of bracing status as well as grouped by bracing status. The Robinson symmetry index (RSI) was calculated to assess foot pressure symmetry.

Forty-two patient encounters were analyzed (81% female, age 13.4±1.9 years, initial Cobb angle 35.3±9.7°; and 71% braced). Regardless of bracing status, bilateral step length, bilateral peak hallux and medial hindfoot pressures, and convex lateral hindfoot pressure all increased after PSSE treatment (P<0.05). After treatment, concave center of pressure (CoP) oscillation decreased in the braced group and increased in the non-braced group (P=0.004); braced RSI for CoP oscillation decreased vs. increased in the non-braced group (P=0.04). Conversely, braced concave CoP trajectory in the anterior-posterior direction (CoP AP) increased but decreased in the non-braced group (p=0.01). Braced concave peak pressure at the 5th metatarsal head also increased but decreased in the non-braced group (P=0.027).

Increased bilateral hallux peak pressure and step length with PSSE suggest stronger push-off at terminal stance and improved walking capability. Reduced CoP oscillation and longer CoP AP trajectory on concave side suggest PSSE and bracing improve balance. Short-term PSSE treatment redistributes abnormal plantar pressure while concomitant bracing provides further improvements in balance and ambulatory efficiency.