Knee arthroscopy in arthritis: an evidence-practice mismatch

The small inconsequential benefit seen from interventions that include arthroscopy for the degenerative knee is limited in time and absent at one to two years after surgery. Knee arthroscopy is associated with harms. Taken together, these findings do not support the practise of arthroscopic surgery for middle aged or older patients with knee pain with or without signs of osteoarthritis. – Thorlund, Juhl et al.


Andrew Weil, MD. Pinterest

Doctor Skeptic 24 June 2012

Osteoarthritis, where the cartilage lining a joint gets worn down, is common (Australian data, UK data, US data). Most people will get it if they live long enough, and the knee joint is commonly affected. There is little that can be done to repair or reverse this process, and a related paper that covers many osteoarthritis treatments shows that most of the things we do (analgesics, anti-inflammatory medication, injections etc.) only provide temporary relief, and many of them hardly work at all. Treatment, if severe enough, often means a knee replacement.

Knee replacement surgery is major surgery so it is only reserved for those with severe osteoarthritis. So what do surgeons do with patients who have knee pain and mild or moderate arthritis? They often do an arthroscopy: a low risk, day-only procedure that pays well and seems to work some of the time. Hundreds of thousands are done in the US every year, and in my state the rate of arthroscopy is high and is rising.

The trouble is: it doesn’t work. Most patients still have pain, some get worse, and about 20% will end up having a knee replacement within 2 years anyway. Feel free to skip to the last paragraph for the Bottom Line, or read on for the details.

There are many studies that show that some people feel better for a while after an arthroscopy, and this matches the experience and opinion of many surgeons, but that does not constitute evidence that the arthroscopic procedure (cleaning up the knee and removing debris and torn meniscus fragments) actually improves the patient’s condition. In clinical trials comparing arthroscopy with anything else, arthroscopy never wins.

An early study showed that arthroscopy was not as good as just washing the knee out with a needle, but the bombshell article from Moseley came in 2002, in the New England Journal of Medicine. The researchers compared arthroscopic debridement (‘cleaning up’) and lavage (‘washing out’) with a sham procedure. A sham procedure, in which an incision is made and the patients are blinded (unaware of which treatment they received), is a good way of controlling for the placebo effect of surgery.

The researchers measuring the outcomes did not know what group the patients were in, and when they asked the patients which group they thought they were in, they had no clue. So this study was randomly allocated, had a good placebo arm, and involved effective blinding of the patients and the assessors. They measured many outcomes (pain and function) at several time points over a two year period and found that the arthroscopic (active) groups did no better than the placebo group for any outcome at any time point. Criticisms, centred around the ways they measured pain, or on the age or gender of the patients (for example) seem a little desperate.

A later trial from 2008 comparing arthroscopy combined with medical management to medical management alone (without a sham procedure) addressed some of the criticisms of the earlier trial by using validated outcome scores, by including more women and younger patients, and by excluding those with deformity. They showed no difference between the two groups for any of the outcomes, except for a brief improvement in the operative group post-operatively, which was an expected result of the placebo effect of surgery.

Continue reading in Doctor Skeptic

Arthroscopic surgery for degenerative knee: systematic review and meta-analysis of benefits and harms, Thorlund JB, Juhl CB, Roos EM, Lohmander LS. BMJ. 2015 Jun 16;350:h2747. doi: 10.1136/bmj.h2747. Review. Full text

A randomized trial of arthroscopic surgery for osteoarthritis of the knee, Kirkley A, Birmingham TB, Litchfield RB, Giffin JR, Willits KR, Wong CJ, Feagan BG, Donner A, Griffin SH, D’Ascanio LM, Pope JE, Fowler PJ. N Engl J Med. 2008 Sep 11;359(11):1097-107. doi: 10.1056/NEJMoa0708333. Full text

Also see
Should You Get A Lube Job for Your Arthritic Knee? in Pain Science

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