180 patients with knee osteoarthritis were randomized to undergo arthroscopic lavage, arthroscopic debridement, or placebo arthroscopy to determine the efficacy of arthroscopy in alleviating pain. Participants were followed-up for 2 years after intervention for outcomes in pain and function. The results throughout the trial indicated that there were no significant differences in pain between arthroscopic lavage and placebo surgery, or arthroscopic debridement and placebo surgery. Moreover, functional assessment indicated a significantly worse outcome with debridement compared to placebo arthroscopy and 2-week and 1-year follow-up.