Arthroscopic treatment is possible for certain knee osteoarthritis, especially in elderly patients who have undergone conservative treatment with poor results and who do not have enough indications for arthroplasty. In particular, arthroscopic treatment is helpful for patients with 1) mild internal or external knee deformity, 2) no or only minor x-ray changes, and 3) significant motor deficits or pain and joint exudates that are inconsistent with the clinical presentation and x-ray. In such cases, careful excision of unstable meniscal cartilage fragments and loose articular cartilage surface tissue, removal of intercondylar fossa, and drilling of exposed subchondral bone less than 1 cm in diameter can result in a 5-year symptom relief rate of 60% to 80%.