Knee arthroscopy has in many cases replaced the classic arthrotomy that was performed in the past. Today knee arthroscopy is commonly performed for treating meniscus injury, reconstruction of the anterior cruciate ligament and for cartilage microfracturing. Arthroscopy can also be performed just for diagnosing and checking of the knee; however, the latter use has been mainly replaced by magnetic resonance imaging.
During an average knee arthroscopy, a small fiberoptic camera (the arthroscope) is inserted into the joint through a small incision, about 4 mm (1/8 inch) long. A special fluid is used to visualize the joint parts. More incisions might be performed in order to check other parts of the knee. Then other miniature instruments are used and the surgery is performed.
Arthroscopic surgeries of the knee are done for many reasons, but the usefulness of surgery for treating osteoarthritis is questionable. A double-blind placebo-controlled study on arthroscopic surgery for osteoarthritis of the knee was published in the New England Journal of Medicine in 2002. In this three-group study, 180 military veterans with osteoarthritis of the knee were randomly assigned to receive arthroscopic débridement with lavage, or arthroscopic lavage alone without debridement (a procedure only imitating the surgical debridement, where superficial incisions to the skin were made to give the appearance that the debridement procedure had been performed). For two years after the surgeries, patients reported their pain levels and were evaluated for joint motion. Neither the patients nor the independent evaluators knew which patients had received which surgery (thus the “double blind” notation). The study reported, “At no point did either of the intervention groups report less pain or better function than the placebo group. Because there is no confirmed benefit for these surgeries in cases of osteoarthritis of the knee, many payors are reluctant to reimburse surgeons and hospitals for what can be considered a procedure which seems to create the risks of surgery with questionable or no demonstrable benefit.
A 2008 study confirmed that there was no long-term benefit for chronic pain, above medication and physical therapy. Since one of the main reasons for arthroscopy is to repair or trim a painful and torn or damaged meniscus, a recent study in the New England Journal of Medicine which shows that about 60% of these tears cause no pain and are found in asymptomatic subjects, further calls the rationale for this procedure into question
After having a knee arthroscopy, there will be swelling around the knee. Swelling can take anywhere from 7–15 days to completely settle. It is important to wait until there is no swelling left around the knee before doing any serious exercise or extensive walking, because the knee will not be fully stable; extensive exercise may cause pain and in some cases cause the knee to swell more.