Ground reaction force complexity in hallux valgus

Investigating the complexity of movement systems can be insightful in clinical decision making. The study conducted to evaluate whether complexity of ground reaction force is affected by hallux valgus grades and footwear or foot side conditions.

A sample of 120 females including 30 participants in each group of healthy and mild, moderate, and severe hallux valgus were recruited in this case-control study. Hallux valgus grades were assessed using Manchester scale. Ground reaction force were measured in bare foot and shod conditions for both feet and weighted permutation entropy was used to calculate the complexity. Nonparametric tests were employed for statistical inference.

The first important result was that hallux valgus caused loss of complexity of ground reaction force with a medium to large effect size. However, we did not find any difference between three grades of hallux valgus entropy. The second finding was that entropy of healthy group decreased from barefoot to shod condition with a large effect size and the third finding was that ground reaction force entropy were similar in both feet.

The findings are aligned with the theory that loss of complexity appears when the biological systems become functionally impaired. As soon as hallux valgus initiates, all potential risks related to the reduction of complexity appear. So, we suggest to administer conservative treatments in the early stages of hallux valgus. The study outcomes can be used for evaluation of foot function, classification of the foot types, or footwear selection.