Statistical analysis
pain
Descriptive statistical analysis included means and SD for continuous variables, and numbers and percentages for categorical variables. As the distribution of the results was non-normal, non-parametric comparison tests were used. Pre-intervention comparisons of baseline characteristics were performed using the Chi-square test for sex, KL grade, and involved side. The Wilcoxon two-sample test was used to analyze age, BMI, and pain onset. Changes in treatment effectiveness are presented as the difference between the post-intervention and baseline values (termed delta). The time effect of the PEMFT and LLLT groups was analyzed separately using Friedman’s Chi-square test along with analysis of the effect size by using the Friedman test effect size. The magnitude of the effect size was defined by Kendall’s W value as 0.1–0.3, small effect; 0.3–0.5, moderate effect; and ≥ 0.5, large effect. The group effect was analyzed using the Wilcoxon two-sample t test along with the Wilcoxon effect size test (r). The magnitude of the effect was defined as 0.10–< 0.3 for a small effect, 0.30–< 0.5 for a moderate effect, and ≥ 0.5 for a large effect. The group × time effect was analyzed using Wilcoxon two-sample T to explore whether the time effect was different between the two groups. The Wilcoxon effect size test (r) was used to assess the effect size. Statistical significance was set at 