Evidence based factors influencing outcome of arthroscopy in osteoarthritis of the knee.

Arthroscopy continues to be widely used in the management of knee osteoarthritis despite concerns regarding its effectiveness. The Scottish Arthroplasty Project has demonstrated a three-fold variation in rates of arthroscopy for osteoarthritis of the knee across different regions of Scotland. This has clear ramifications for the utilisation of finite health care resources. In light of such variations in national clinical practice this review identifies the evidence based factors which permit identification of patients who will obtain sustained benefit from arthroscopic treatment of knee osteoarthritis. Such a patient should have symptoms of short duration affecting the medial compartment of the knee, have localised tenderness at the medial joint line, mechanical symptoms and positive findings on meniscal stress testing. There should be neither significant mechanical malalignment nor flexion contracture, there should be preservation of the joint space on radiographs and the patient should not be obese. If these criteria are fulfilled the likelihood for long lasting reduction in symptoms is increased.