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In people with degenerative knee disease, arthroscopic knee surgery improves pain by a very small amount but does not improve physical function

Thorlund JB, Juhl CB, Roos EM, et al. Arthroscopic surgery for degenerative knee: systematic review and meta-analysis of benefits and harms. BMJ. 2015;350:h2747.

Review question

In people with knee pain and degenerative knee disease, does arthroscopic knee surgery improve pain or physical function?


Degenerative knee disease, which may develop into osteoarthritis, is a breakdown of knee cartilage and underlying bone that causes knee pain, swelling, stiffness, and reduced mobility. It often results from repetitive stress on the knee and is more common in older people, heavier people, women, and athletes.

Degenerative knee disease can be treated with pain medications, anti-inflammatory drugs, corticosteroid injections, weight loss, and physical therapy and exercise. Arthroscopic knee surgery uses small instruments inserted through small incisions in the knee and may include meniscectomy (removal of the meniscus, the cartilage of the knee) and/or debridement (smoothing rough surfaces).

How the review was done

The researchers did a systematic review based on studies available up to August 2014.

They found 9 randomized controlled trials with 1270 people (average age 50 to 63 years).

Key features of the trials were:

  • people had knee pain and degenerative knee disease and may have had osteoarthritis, but did not have cruciate ligament injuries;
  • treatment was arthroscopic surgery with partial meniscectomy and/or debridement;
  • treatment was compared with controls, which included lavage (washing out of the inside of the knee), sham surgery, supervised exercise, unsupervised/home exercise, physical and medical therapy, and physiotherapy; and
  • outcomes were measured 3 months to 24 months after treatment.

What the researchers found

The quality of evidence was high for pain and physical function outcomes.


Compared with nonsurgical treatments, arthroscopic surgery reduced pain by a very small amount overall.

Pain was improved by a small amount at 3 months and a very small amount at 6 months, but not at 12 , 18 , or 24 months after surgery.

Physical function

Compared with nonsurgical treatments, arthroscopic surgery did not reduce or improve physical function overall or at any time point between 3 and 24 months after surgery.

Adverse effects

Rates of complications from surgery varied across 9 studies, averaging about 5.7 per 1000 procedures for clots in veins, 1.5 per 1000 for clots to the lung, 2 per 1000 for infection, and 1 per 1000 for death.


In people with knee pain and degenerative knee disease, arthroscopic knee surgery improves pain by a very small amount immediately after surgery but does not improve physical function.

Effects of arthroscopic surgery for degenerative knee disease


Number of trials (people)

Effects of surgery compared with control at 3 to 24 months*


9 (1270)

Very small improvement†: 2.4 mm on a 100 mm scale (but could be as few as 0.4 mm or as many as 4.3 mm). About 16 people (as few as 9 or as many as 91) would have to have surgery for 1 extra person to have a small improvement, compared with not having surgery.

Physical function

6 (999)

No improvement.

*Controls were lavage, sham surgery, supervised exercise, unsupervised/home exercise, physical and medical therapy, and physiotherapy.

†Based on standardized mean differences (SMD); very small = less than 0.2 SMD, small = 0.2 to 0.49 SMD, medium = 0.5 to 0.79 SMD, large = 0.8 or more SMD.


Randomized controlled trials
Studies where people are assigned to one of the treatments purely by chance.
Systematic review
A comprehensive evaluation of the available research evidence on a particular topic.

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