*2.4. Statistical Analysis*

Statistical analysis was performed with SPSS Statistics 27.0 (IBM Corp., New York, NY, USA). When comparing the affected side to the non-affected side of the same subject, a test of normality, the Shapiro–Wilk test (α = 0.05), was completed. For the variables that were not normally distributed, a Wilcoxon signed-rank test (α = 0.05) was used to compare the samples. The other variables were statistically compared using a paired *t*-test t (α = 0.05). A univariate analysis of variance (ANOVA) was used to compare the control group with the affected group. The same analysis was performed with the inclusion of the BMI as

a covariate, since the BMIs of the patients were found to be significantly higher than those in the control group.

To guard against the inflation of a type I error but maintain statistical power across the multiple comparisons, an adjusted alpha level was applied by dividing the alpha level by the number of parameters (*p* = 0.05/4 = 0.0125). Additionally, the effect size was determined for each difference (Cohen's d for the *t*-tests, r for the Wilcoxon tests, and partial <sup>η</sup><sup>2</sup> for the ANOVA tests). A large effect size can be interpreted when d ≥ 0.8, r ≥ 0.5, and <sup>η</sup><sup>2</sup> ≥ 0.25 [19,20].

To evaluate the level of joint coupling between a number of inter-segment angles, cross-correlation coefficients were calculated based on the 1D waveforms associated with the normalized stance phases [21]. The following four joint couplings were analyzed: ankle inversion–eversion with ankle adduction–abduction, ankle inversion–eversion with forefoot dorsal flexion–plantar flexion, ankle inversion–eversion with forefoot inversion– eversion, and ankle inversion–eversion with forefoot adduction–abduction. This selection was based on a previous publication, which showed the high correlation between these four inter-segment rotations [22]. When assessing the cross-correlation, the following benchmarks were used: a large joint coupling >0.7 or <−0.7, a medium joint coupling between (−) 0.3 and (−) 0.69, and a small joint coupling between −0.3 and 0.3 [22].
