Monaz: Hello, I'm Monaz Mehta, editor in the Cochrane Editorial and Methods department. The Cochrane Musculoskeletal Group has produced more than 200 reviews of a very wide range of interventions for patients with musculoskeletal problems. In this podcast, senior author Peter Wall, talks with Imran Ahmed, Trainee Orthopaedic Surgeon and NIHR Doctoral Researcher at Warwick Clinical Trials Unit and University Hospitals Coventry and Warwickshire NHS Trust in the UK about their December 2020 review of the effects of using a tourniquet in knee replacement surgery.

Peter: Hello Imran, perhaps you could begin by telling us a little about tourniquets and knee replacement surgery?

Imran: Thanks Peter. A tourniquet is a device which is wrapped around a part of the body and squeezes it to stop blood flow. In knee replacement surgery, it would be put on the thigh to stop blood flowing to the rest of the leg and its use is well established amongst surgeons who do this type of surgery.

Peter: If it's already well established, why was it important to do this review?

Imran: Even though it is widely used, it's still important to know whether it is actually worthwhile. Knee replacement is a common operation in which a damaged or worn knee is replaced with an artificial joint made of metal and plastic and we need to be sure that the various things we do during the surgery are genuinely helpful. For the tourniquet, surgeons use it to reduce bleeding, which might improve their field of view and allow the cement used to bond the knee replacement components to the bone more strongly. However, when we do similar surgery to replace a hip or shoulder, a tourniquet is not possible and these operations proceed safely, without undue concerns about bleeding or the strength of the cement. There is also some evidence that using a tourniquet can increase the risk of surgical complications. 

Peter: That sets the scene nicely. It sounds like the tourniquet might be an intervention that could do more harm than good. Did you find the evidence you needed, and what did it say about using a tourniquet in knee replacement surgery?

Imran: We found 41 clinical trials which had included just over 2800 patients that met our criteria. These provided moderate quality evidence that the risk of serious complications was 73% higher when a tourniquet is used, compared to surgery without a tourniquet. These complications included blood clots, wound infection and the need for further surgery. However, serious complications during knee replacement surgery are rare, with 5.9% of patients whose operations involved a tourniquet having serious complications needing additional health care, compared to 2.9% in those operated on without a tourniquet. We also found that patients who had a knee replacement with a tourniquet reported on average 19% more pain the day after surgery than patients where no tourniquet was used.

Peter: Alongside this evidence on possible problems from using a tourniquet, did you find evidence of any benefit for its use in knee replacement surgery?

Imran: The short answer is no. When we looked at knee function, quality of life or total blood loss there was little or no difference between patients having surgery with or without a tourniquet. We're also uncertain if surgery with a tourniquet had any impact on survival or fixation of an implant because only limited, low quality evidence is available for these outcomes. 

Peter: Overall, then, what are your take-home messages about tourniquets for knee replacement surgery?

Imran: Firstly, our review has shown that there is moderate quality evidence that the use of a tourniquet in total knee replacement surgery is probably associated with an increased risk of serious complications and higher postoperative pain, while there is currently no evidence to suggest any major benefits. This means that patients should probably be informed about the potential risks of surgeons using a tourniquet during knee replacement surgery and surgeons might want to think about questioning their use of tourniquets in knee replacement surgery.

Peter: Thanks Imran. If people would like to read the review, how can they get hold of it?

Imran: It's available online - just go to Cochrane Library dot com and type "tourniquet for knee replacement surgery".