Several randomized controlled studies have shown that arthroscopic cleaning has no significant therapeutic effect on osteoarthritis of the knee. However, arthroscopic cleaning of meniscal tears with osteoarthritis and partial meniscectomy is still one of the treatments frequently performed by clinicians in patients with symptomatic osteoarthritis. However, there is also a lack of evidence to support whether this treatment modality has a significant advantage in terms of functional prognosis over nonsurgical conservative management. Recently, a multicenter prospective randomized controlled study was conducted by Jeffrey N. Katz, MD, PhD, of Brigham and Women’s Hospital in Boston, USA, to examine this issue, and was recently published in the New England Journal of Medicine. Symptomatic, imaging-confirmed osteoarthritis of the knee affects approximately 9 million people in the United States. And the prevalence of meniscus tears is also high, with up to 35 percent of people over age 50 suffering from meniscus tears, two-thirds of whom are asymptomatic. Meniscal injuries are particularly prevalent in patients with osteoarthritis, and arthroscopic partial meniscectomy is commonly performed. This surgical procedure focuses on correcting the torn meniscus by stabilizing and flattening its edges. Again, according to data from the United States, approximately 465,000 patients undergo this procedure each year. Because of the high prevalence of meniscal tears combined with osteoarthritis of the knee, and the fact that both can be asymptomatic, it is a challenge to make a clinical decision as to whether a symptomatic patient’s symptoms are from a torn meniscus, from osteoarthritis, or from both. If a physician suspects that symptoms are from a meniscal tear, he or she will usually recommend that the patient undergo arthroscopic surgery. As for osteoarthritis, at least two randomized controlled studies have validated this. One study compared arthroscopic cleaning to sham surgery, and the other compared arthroscopic cleaning to non-surgical procedures, and both concluded that there was no statistically or clinically significant difference between arthroscopically cleaned flushes compared to controls in terms of functional improvement and pain relief over a 24-month period. As a result of these studies, both arthroscopic surgery and physical therapy have the potential to better improve function and relieve pain in patients with osteoarthritis who have clinical symptoms and imaging-confirmed concomitant meniscal tears. In other words, although arthroscopic surgery is not the first or only treatment option for such patients, it is still a viable treatment option, especially for patients for whom non-surgical treatments such as physical therapy are ineffective.