Medical practice

Knee surgery 'waste of time', researchers argue

"Knee surgery is 'pointless and potentially harmful' for thousands of patients," the Daily Mirror reports.

Researchers have looked at previous studies that had compared arthroscopic (keyhole) knee surgery with exercise or sham surgery (placebo) for middle-aged people with knee pain – specifically, knee pain caused by osteoarthritis or a tear in the cartilage, but not those with a ligament condition.

They found that both exercise and arthroscopy improved knee pain. Arthroscopy was slightly better, improving pain by a small amount, which was described as the equivalent to using a painkiller such as paracetamol or ibuprofen. There was no difference between the interventions for function of the knee.

Current UK guidelines recommend arthroscopy for people with knee osteoarthritis and a clear history of "mechanical locking", where a person is unable to bend or straighten the knee. People with this symptom were not analysed separately in this research, so it remains unclear whether this recommendation would change on the basis of this study.

Patient satisfaction reported after surgery appears to be positive.

Whether surgery is an option for you or not, UK guidelines recommend that all people with osteoarthritis should do exercise for local muscle strengthening and general aerobic fitness purposes.

Where did the story come from?

The study was carried out by researchers from the University of Southern Denmark, Copenhagen University Hospital, Odense University Hospital in Denmark and the University of Lund in Sweden. It was funded by the Swedish Research Council.

The study was published in the peer-reviewed British Medical Journal on an open-access basis, so the study is free to read online or download as a PDF.

The UK media’s reporting of the story was possibly a little over-dramatic and gave the impression that these results would lead to a change in clinical guidelines. The Daily Telegraph said keyhole knee surgery "does little good and could kill patients". The Mail Online reported that experts were saying: "Surgeons should stop carrying out keyhole knee operations on middle-aged and elderly people."

The review concluded that the evidence did not support keyhole knee surgery for middle-aged or older patients with knee pain, with or without signs of arthritis, but this is not official advice.

This study is new, and while it may stimulate discussion about whether current advice is appropriate, it will not change it overnight. This research needs to be considered in light of all other evidence.

What kind of research was this?

This was a systematic review of randomised controlled trials (RCTs) on the benefits of arthroscopy for knee pain in middle-aged and older people. It included a meta-analysis, which pooled the results of the studies. This type of study can provide a clearer picture of clinical effectiveness than individual studies. It involves systematically identifying all the available evidence, assessing the quality and summarising the findings.

Arthroscopy is a type of keyhole surgery for the knee. It can be used to remove a damaged section of the cartilage (partial meniscectomy) or for removing any dead tissue that might be floating in the fluid of the knee joint and causing the knee to lock (debridement).

What did the research involve?

The researchers searched five medical databases, including Medline and Embase, for RCTs on the benefits of arthroscopy for people with or without osteoarthritis. The reference list of any relevant study was also reviewed, in an attempt to capture all available trials. They looked for any studies published up to 2014.

When looking at the potential harm of arthroscopy, they limited the time period to after the year 2000, due to surgical and anaesthetic advances in technique. They also opened up the search criteria to include adverse events reported in observational studies, as well as RCTs.

Two researchers independently sifted all of the results, which is important for reducing any potential bias.

Studies were excluded if the person had a ligament injury.

What were the basic results?

Nine trials were identified in which arthroscopy was compared to sham surgery or exercise. Sham surgery, sometimes called "placebo surgery", is the surgical equivalent of using a placebo pill to test a new drug. Sham surgery is thought to offer no benefit to the patient, but typically contains the same pre- and post-surgery elements of real surgery. These included a total of 1,270 people aged 49.7 to 62.8 years.

Both arthroscopy and exercise were shown to substantially improve symptoms. Arthroscopy was slightly better than control conditions for pain 3 to 24 months post-op. This difference was 2.4mm on a 0 to 100mm visual analogue scale for pain – essentially, a sliding scale of reported pain ranging from entirely pain-free to intolerable pain (95% confidence interval (CI) 0.4 to 4.3). There was no difference in physical function between arthroscopy or control conditions.

Arthroscopy was associated with side effects that included:

  • deep vein thrombosis (4.13 occurrences per 1,000 procedures) – a blood clot that usually develops in the blood vessels of the legs
  • pulmonary embolism (1.45 occurrences per 1,000 procedures) – a blood clot that develops inside the lungs
  • infection (2.11 occurrences per 1,000 procedures)
  • death (0.96 occurrences per 1,000 procedures)

How did the researchers interpret the results?

The researchers concluded that: "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."


This systematic review has found there is little difference between arthroscopy and exercise in the treatment of knee pain, excluding people with damage to their ligaments. Both arthroscopy and exercise improved symptoms for people with and without osteoarthritis. However, there were rare but serious risks associated with the arthroscopy procedure.

In 2008, the National Institute for Health and Care Excellence (NICE) produced a guideline on the treatment of osteoarthritis and recommended that "referral for arthroscopic lavage and debridement should not be offered as part of treatment for osteoarthritis, unless the person has knee osteoarthritis with a clear history of mechanical locking". This systematic review did not separately analyse results for people with a history of mechanical locking – where a person is unable to bend or straighten the knee, which can occur when the cartilage is torn. Therefore, it is unclear whether this recommendation would change following this piece of research.

Before consenting to any type of surgery, it is recommended that you ask your surgeon or clinical in charge of your care for an explanation of both the potential benefits and risks of surgery, so you can make an informed decision.

The NHS Choices Health A-Z section contains details of the most widely used types of surgery. 

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