Arthroscopic knee surgery for osteoarthritis of the knee

This fact box will help you to weigh the benefits and harms of arthroscopic knee surgery for wear and tear (osteoarthritis) of the knee joint. The information and numbers are based on the best scientific evidence currently available.

This fact box was developed by the Harding Center for Risk Literacy.

What is osteoarthritis of the knee?

Osteoarthritis in the knee occurs when the cartilage on the ends of the knee bone wears down over time and causes damage to the knee joint.  Osteoarthritis is the most common joint disease and occurs more often in older people [1].

Many different factors can contribute to osteoarthritis of the knee, such as being overweight or prolonged strain to and overexertion of the knee joint. At advanced stages of the disease, the cartilage can wear down completely (cartilage degeneration) along with other joint tissues. Symptoms of osteoarthritis include stiffness, limited mobility of the joint, and pain while resting or when the joint is under stress [1].

What is arthroscopic knee surgery?

Arthroscopic knee surgery (knee arthroscopy) is performed under local or general anesthesia. Thin tubes are inserted through a small incision into the knee and a liquid solution is injected to wash out loose tissue and pieces of cartilage from the joint. This process is called lavage. If the arthroscopy procedure also involves mechanically smoothing rough cartilage surfaces and removing the loose debris, that process is referred to as debridement [1, 2].

Who might consider arthroscopic knee surgery?

Adults who suffer from severe knee pain and joint problems (e.g. restricted mobility).

What are alternative treatment options?

Non-surgical (conservative) treatments can include lifestyle changes (e.g. exercise, weight loss), physiotherapy, pain medication, and steroid injections. Steroid injections involve injecting a corticosteroid (such as triamcinolone, hydrocortisone, or methylprednisolone) into the affected joint (intra-articular injection). Steroids are active substances with anti-inflammatory properties and thus can relieve pain [3].

Fact box arthroscopic knee surgery for osteoarthritis of the knee
Fact box arthroscopic knee surgery for osteoarthritis of the knee © Harding Center for Risk Literacy
What does the fact box show?

The fact box shows the benefits and harms of knee arthroscopy compared to non-surgical treatment methods (such as lifestyle changes through exercise and/or weight loss, physiotherapy, or steroid injections) or placebo surgeries (sham operations). The patients were observed for up to 24 months. 

The table may be read as follows:

Out of every 100 patients who had arthroscopic knee surgery, 79 experienced at least a slight improvement in pain 3 months later compared to 67 out of every 100 patients who had non-surgical treatment or a placebo surgery (sham operation). Thus, arthroscopic knee surgery was associated with a slight improvement in pain for about 12 out of every 100 patients.

The phrase “at least a slight improvement” relates to a 100-point scale on which patients were asked to rate their pain and mobility of the knee before and after treatment. In order to measure the difference between the treatments, the scores before and after the treatments were averaged and the two values were compared with each other. The smallest average improvement was determined to be 12 points on the 100-point scale and labelled “at least a slight improvement.”

The differences between patients with and without knee arthroscopy for pain and mobility in the first 3 months were no longer evident after 12 months [2].

In both groups, one out of every 100 patients had a knee replacement within 24 months after the treatment [2].

The numbers in the fact box are rounded. The numbers for the pain outcomes are calculated from 9 studies that included a total of 1,102 participants. The numbers for knee mobility outcomes are calculated from 6 studies that included a total of 835 participants. For knee replacement, the numbers are calculated from data from 2 studies with a total of 497 participants [2].

What other aspects should be considered?

As with any surgical intervention, arthroscopy comes with the risk of experiencing surgical complications (e.g. blood clots, joint infections, or nerve damage). The results reported in the studies were not sufficient to provide exact numbers on the risk of complications [2].

Do the results provide proof (evidence) for the benefits and harms of surgery for osteoarthritis of the knee joint?

Overall, the evidence is of moderate to high quality: Where the quality of evidence is moderate, further research is likely to have an important impact on some findings; where the quality of the evidence is high, the findings are very unlikely to be changed over the course of further research [2].

Version history of the fact box
  • July 2019 (update of the accompanying text)
  • October 2018 (creation)

Information within the fact box was obtained from the following sources:

[1] IQWIG. Arthrose 2014. [] 04.07.2019.

[2] Brignardello-Petersen R, Guyatt GH, Buchbinder R et al. Knee arthroscopy versus conservative management in patients with degenerative knee disease: a systematic review. BMJ Open; 2017: 7-e016114.

[3] Jüni P, Hari R, Rutjes AWS, et al. Intra-articular corticosteroid for knee osteoarthritis. Cochrane Database Syst Rev 2015(10).

Documentation on how the numbers in the fact box were determined is available on request.