Placebo Effect in the Treatment of Patellar Tendinopathy and Its Influencing Factors: Systematic Review With Meta-analysis and Meta Regression of Randomized Controlled Trials.

The placebo effect for nonsurgical treatments of patellar tendinopathy is long-lasting (up to 12 months) and statistically and clinically significant. It has a perceived and true component and differs among treatments. The duration of follow-up and the effect size of experimental groups correlate with the magnitude of the placebo component, underlining the importance of RCTs to determine the effectiveness of new treatments of patellar tendinopathy.