Data Analysis
Data were analyzed with SPSS, version 13.0.† Descriptive statistics for demographic data and all outcome measures were expressed as means and standard deviations. Comparisons among groups were performed,
using one-way analyses of variance (ANOVAs), for age, body mass, height, and body mass index to show homogeneity of the sample at baseline. The data for the KOOS and the NPRS were analyzed using a mixed model (group _ time) ANOVA. The factor “group” had 4 levels (control, placebo, low-dose PSW, and high-dose PSW), and the repeated factor “time” had 3 levels (preintervention, postintervention, and 12-month follow-up, except for the control group). We also compared the proportion of participants who met or exceeded the MCID in the posttreatment evaluation compared with baseline for the pain and functional scales in the studied groups.