Evaluation of plantar pressures and center of pressure trajectories in Adolescent Idiopathic Scoliosis

Adolescent idiopathic scoliosis (AIS) has been postulated to affect gait patterns and postural stability due to its effect on center of body mass. 1) Determine the correlation between Cobb angle and COP in the anterior-posterior (AP) direction, COP in the medial-lateral (ML) direction, COP oscillation (COP-O) from midline walking, peak pressures, and pressure-time integrals (loading) at 10 anatomic foot segments; 2) Determine the differences in COP-AP, COP-ML, COP-O, and peak plantar pressures at 10 anatomic foot segments between the normal group and the AIS group. All patients wore a gown to expose the posterior trunk and underwent evaluation with Formetric 4D (DIERS International GmbH, Schlangenbad, Germany) while walking on the treadmill at 2 km/hour for 15 seconds. A total of 24 pressure metrics at 10 anatomic foot segments were evaluated. We then analyzed the data using t-test and linear regression analyses.16 patients were assigned to a normal group (Cobb angle 10° or less, n=4) or AIS group (Cobb greater than 10°, n=12). Of note, AIS patients had statistically significant lower max. pressures at the hallux and the 2nd, 4th, 5th metatarsal head compared to the normal group. Additionally, there was a statistically significant linear association between Cobb angle and both hallux max. pressure and hallux pressure-time integral (P<0.05). Reduced peak plantar pressures before the toe-off phase of gait cycle indicate that AIS patients may lean backwards and have posterior postural sway, which may be associated with hypokyphosis during walking.