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Using a tourniquet in knee replacement surgery raises the risk of serious complications such as blood clots and infection. A new analysis of thousands of knee replacements also confirms that patients had more pain the day after surgery if a tourniquet was used.

Tying a tight band (tourniquet) around an injured arm or leg has been used for thousands of years to stem severe bleeding. Tourniquets are still routinely used in knee replacement surgery, but some experts argue that restricting blood flow in this way can cause clinical problems.

Serious complications are rare, with or without a tourniquet. But knee replacement surgery is a common procedure, performed more than 100,000 times each year in the UK. The study suggests that encouraging surgeons not to use tourniquets could avoid nearly 2,000 serious complications in the UK per year. 

Surgeons should discuss the risks of using a tourniquet with patients before the surgery and offer a choice of using one or not, the researchers recommend.

What’s the issue?

People with severe arthritis of the knee may be offered knee replacement surgery, in which worn joints are replaced with versions made of metal and plastic. Most surgeons use a tourniquet during surgery. It inflates around the thigh to squeeze blood vessels closed; it reduces blood loss and keeps the surgical area drier. 

Knee surgery usually takes about an hour. Some surgeons are concerned that restricting blood flow to the lower leg for that length of time may increase the risk of dangerous blood clots forming. These can travel around the body and block blood vessels beyond the leg, including in the lung.

Blood clots and other serious adverse effects following knee replacement surgery are rare. This means many surgeons who use a tourniquet will not see any problems, and may therefore not appreciate the risk. Before this study, there was little reliable evidence that pooled the results of multiple studies exploring this complication. 

What’s new?

This review pooled the results of 41 high quality trials around the world. They all compared results of patients who were randomly chosen either to have a tourniquet or no tourniquet during knee replacement surgery. In all, 2,819 patients were included. 

People who had a knee replacement with a tourniquet applied:

    • had an increased risk of serious complications - from one in 34 (2.9%) without, to one in 17 (5.9%) with a tourniquet 
    • had a slight increase in pain on the day after surgery recorded by researchers (patients may not have noticed the difference)
    • stayed in hospital eight hours longer on average
    • had the same overall blood loss, knee function and health-related quality of life as when no tourniquet was used
    • spent slightly less time in surgery (3.7 minutes on average), which was the only benefit of the tourniquet.

Overall, the study concluded that it is difficult to justify the use of a tourniquet in knee replacement surgery.

Why is this important?

Currently approximately nine in ten surgeons use a tourniquet during knee replacement surgery. This study shows that tourniquets increase the risk of blood clots, infections and other complications when used in knee surgery.

The risk is still low; the vast majority of knee replacement operations do not lead to serious complications. But because the procedure is common, the researchers estimate that  changing surgical practice to avoid using tourniquets could avoid nearly 2,000 serious complications in the UK each year.

What’s next?

These results will raise awareness among surgeons of the possible negative effects of using a tourniquet. They could change practice and lead to more surgeons offering surgery without a tourniquet.

The study will also raise awareness among patients of the risks of using tourniquets. Patients will be able to discuss the issue with their surgeon.

You may be interested to read

The full paper: Ahmed I, and others. Tourniquet use for knee replacement surgery. Cochrane Database of Systematic Reviews 2020;2:CD012874 

Abridged summary of the paper: Ahmed I, and others. Time to reconsider the routine use of tourniquets in total knee arthroplasty surgery. The Bone and Joint Journal 2021;103-B:5 


Funding: This project was funded by a NIHR Post-Doctoral Fellowship Award. 

Conflicts of Interest: The study authors declare no conflicts of interest.

Disclaimer: NIHR Alerts are not a substitute for professional medical advice. They provide information about research which is funded or supported by the NIHR. Please note that views expressed in NIHR Alerts are those of the author(s) and reviewer(s) and not necessarily those of the NHS, the NIHR or the Department of Health and Social Care.

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Study author

A tourniquet which stops blood flow to a patient’s leg might be expected to cause a problem, but I am surprised that the increase in risk of complications is so pronounced.

I think it is important that patients are made aware of the risks of using a tourniquet during knee replacement surgery and allowed the option to choose surgery without a tourniquet if they wish.

A widespread change in practice amongst surgeons in the UK alone could avoid a substantial number of complications.

Peter Wall, Associate Clinical Professor in Trauma and Orthopaedic Surgery, University of Warwick

Versus Arthritis

With hundreds of thousands currently waiting for joint operations due to the NHS backlog, knee replacement surgery is a lifeline that can cure the severe pain and disability caused by arthritis, which all too often robs people of their ability to work or enjoy life.

To have the best possible treatment, people with arthritis need their surgeons and other health professionals to clearly explain the procedure in a way they can understand, outline the hoped-for benefits and potential risks, and ensure that they are fully informed and involved in decisions about the care they will receive. 

Instinctively, it might seem that a tourniquet is a good idea. What this study shows though is that using a tourniquet increases complications for patients, leading to more pain after the operation, and a greater risk of blood clots and infections, which can be debilitating and even fatal – and that’s before even thinking about the increased treatment costs to health services too. So while there may be times when a tourniquet is still a good idea, it would seem they should not be used routinely. And where there may be a valid clinical reason to consider using one, then the health-care professionals must always discuss the options with the patient, and ensure they have been able to make a collaborative, shared decision.

Benjamin Ellis, Clinical Policy Lead, Versus Arthritis 

Member of the Public 

I have supported friends and family through joint related surgery, although not a total knee replacement. Knowing this kind of research exists would enable me to point someone to it should the need arise.

The research suggests that using a tourniquet may not confer any particular benefits but may pose a limited number of post-operative risks. This may discourage the general use of tourniquets during surgery. People need to have informed discussions with medical professionals ahead of surgery about the operative approach being proposed.” 

Gavin Edwards, Public contributor, London 

Orthopaedic Surgeon

The recent Cochrane review indicated that tourniquet use for knee replacement surgery both increases the risk of serious complications and is associated with higher pain scores in the days after surgery, while no differences in knee function, satisfaction or quality of life were found with or without tourniquet use. Although the evidence is not compelling, it should be enough to make us question why tourniquets are used. 

Many surgeons were trained to perform knee replacement surgery using tourniquets, and as such to move away from this technique is a significant change of practice. Tourniquet use no doubt provides a more bloodless field, and advocates claim this may lead to more accurate or faster surgery. However, with modern anaesthetic techniques and tranexamic acid, bleeding intra-operatively can be much better managed, and dry surgical fields can be obtained to facilitate the surgery and cementation of the implants. 

Tourniquet-free knee replacement surgery has been performed routinely in our unit in Exeter for over 15 years, with excellent outcomes and low revision rates when evaluated through the National Joint Registry. Surgeons wishing to go tourniquet-free therefore should have the confidence that equivalent outcomes can be achieved should they wish to do so.

Jonathan Phillips, Consultant Orthopaedic Surgeon, Princess Elizabeth Orthopaedic Centre, Exeter 


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