Center of pressure palindromes reveals a wobbling standing balance in scoliotic girls.

ABSTRACT

BACKGROUND: This study characterized the center of pressure planar displacement by palindromic strings. The objective is to test if the center of pressure pathway of able-bodied girls and those with a moderate and severe scoliosis displayed similar palindromic tendencies. METHODS: The center of pressure excursions of 21 able-bodied girls were compared to 14 girls with a moderate scoliosis and 14 girls with severe one. Each girl was asked to stand upright on a force platform for 64 s. A crisscross grid of nine areas was centered around the mean center of pressure position (G) to define three other zones to use the MATLAB built-in nucleotide sequence analysis function. These were the antero-posterior extremities A, the coronal extremities C and the tilted or the four corners of the crisscross grid, T. The center of pressure positions were associated to any of the 4 zones using the GATC acronym. FINDINGS: For all groups center of pressure pattern in decreasing order was A, G, T and C. Able-bodied girls favored the A zones. Girls with moderate scoliosis displaced their center of pressure mostly in the A zones with shifts in the T sections (P ≤ 0.001). Girls with severe scoliosis, additionally displaced their center of pressure in the C zones (P ≤ 0.001). INTERPRETATION: An ankle modality characterized able-bodied girl's standing balance. Girls with a moderate scoliosis privilege the palindromic zones in the antero-posterior extremities with excursions in the corners of the base of support, girls with severe scoliosis further relied on the medio-lateral zones, suggesting a wobbling standing balance.