Two authors (K.-V.C., C.-Y.H.) independently evaluated all articles eligible for inclusion. The data extracted from the selected studies included patient characteristics, information on PRP administration, and details of outcome measurements. The Jadad scale was used to assess the quality of the randomized controlled trials. The aggregate scores ranged from 0 to 5 points. Trials with scores <3 were assumed to have a lower methodological quality.15 Prospective follow-up and quasi-experimental GSK126 studies were evaluated by using the Newcastle-Ottawa Scale to assess the quality of selection, comparability, exposure, and outcome. The maximum scores observed

were 9 points, and total scores <4 points were considered low in quality.16 Discrepancies between the 2 independent evaluations for potential articles were resolved through discussion and consensus. Data were extracted from 3 points at or closest to the 2nd, 6th, and 12th months

after the interventions. Effect sizes were estimated from functional knee joint scales and applied to compare the results across studies or between different therapeutic approaches. Ku0059436 If more than 1 functional scale was available for a study, we selected only 1 measurement according to the order of IKDC, KOOS, and then WOMAC. Since some studies had multiple treatment arms, we treated each arm as a separate data set for analysis. To evaluate the effectiveness of PRP treatment, compared with the pretreatment condition, tetracosactide we used the standardized mean difference between the

baseline and status after therapy. Data were derived from the ratio of the difference between baseline and posttreatment functional scores to the SD of the pooled results. Positive and negative values of the effect sizes indicated a functional improvement and decline, respectively. For cases in which the functional score SD was deficient, the value was computed from the P value of the corresponding hypothesis testing. The pooled SD resulted from the square root [(participant numbers in baseline − 1)*(SD of scores in baseline)2 + (participant numbers after treatment − 1)*(SD of scores after treatment)2]/[(participant numbers in baseline − 1) + (participant numbers after treatment − 1)]. 16 and 17 Because the pooled SD was calculated based on the rule of intention to treat, the dropout rate was not considered, and the participant numbers remained unchanged between the baseline and posttreatment data sets. The effect sizes were pooled by using a random-effect model and were represented by a point estimate with a 95% confidence interval (CI). Regarding the comparison with the baseline condition, an advantage of PRP referred to a positive summed effect size with a 95% CI above a zero value.