Featured Review: Tourniquet in knee replacement surgery

a physician in a white coat points to the replacement joint in a model knee

New Cochrane Systematic Review shows that knee replacement surgery using a tourniquet increases the risk of serious complications, and causes additional pain after surgery

What are the benefits and risks of using a tourniquet in knee replacement surgery?
Senior author Mr Peter Wall, Consultant Orthopaedic Surgeon from Warwick Clinical Trials Unit and University Hospitals Coventry and Warwickshire NHS Trust, summarized:

The evidence indicates that knee replacement surgery performed with a tourniquet increases the risk of serious complications needing additional healthcare, many of which might be avoided if a tourniquet is not used. Most people do very well after knee replacement, but like any major surgery, there are risks and use of a tourniquet may exacerbate these.

Why is this question important?
Knee replacement is a common operation that involves replacing a damaged, worn, or diseased knee with an artificial joint made of metal and plastic. Most surgeons prefer to carry out knee replacement surgery with the aid of a tourniquet ‐ a tight band placed around the thigh that restricts blood flow to the knee. Potential benefits of using a tourniquet include limiting blood loss during surgery and making it easier to conduct the operation. However, a tourniquet may increase the risk of pain and complications for patients after surgery. 

How did the authors identify and evaluate the evidence?
First, they searched for relevant, robust studies in the medical literature. They then compared the results and summarised the evidence from all studies. Finally, they assessed how certain the evidence was. To do this, they considered factors such as the way studies were conducted, study size, and consistency of findings across studies. Based on these assessments, they categorised the evidence as being of very low, low, moderate, or high certainty.

What did they find?
They found 41 studies that involved 2819 people (944 men and 1777 women) who were randomly assigned to have surgery with a tourniquet, or surgery without. This type of study, known as a randomised controlled trial, provides the most robust evidence about the effects of a treatment.

Studies were conducted in hospitals in Australia, Asia, Europe, and the USA. Each study involved between 20 and 166 people who were between 58 and 84 years of age. They were followed for between one day and two years after surgery.

Five studies were publicly funded, and one study received funding from a medical equipment manufacturing company. The other 35 studies did not receive specific funding or did not state who funded them.

The studies provided low to moderate evidence that:

  • Pain on the first day after surgery is probably worse with a tourniquet. On average, on a scale of 0 to 10 (higher scores = worse pain), people operated on with a tourniquet rated their pain as 5.81. People operated on without a tourniquet rated their pain as 4.56 (average difference: 1.25 points);
  • Knee function one year after surgery is probably similar with or without a tourniquet. On average, on a scale of 0 to 100 (higher scores = better functioning), people operated on with a tourniquet rated their knee function as 89.74. People operated on without a tourniquet rated their knee function as 90.03 (average difference: 0.29 points);
  • Satisfaction with treatment may be similar with or without a tourniquet. Six months after the operation, 94% of people operated on with or without a tourniquet were 'extremely' or 'very' satisfied with their treatment;
  • There may be little or no difference in health‐related quality of life with or without a tourniquet. On average, on a scale of 0 to 100 (higher scores = better quality of life), people operated on with a tourniquet rated their quality of life as 54.64. People who had surgery without a tourniquet rated their quality of life as 56.17 (average difference: 1.53 points); and
  • Serious adverse events such as blood clots in the leg or lung, infection, or re‐operation other than to replace the artificial joint are probably more likely to occur with a tourniquet. Five per cent of people operated on with a tourniquet reported serious adverse events compared to 2.9% of people operated on without a tourniquet.

We do not know if using a tourniquet affects chances of needing a second operation to replace an artificial joint because available evidence is of very low certainty.

No studies investigated the effects of surgery with a tourniquet on people’s ability to process thoughts (cognitive function).

What does this mean?
Knee replacement with a tourniquet is probably slightly less beneficial, and is associated with greater risks, than surgery without a tourniquet.

How up‐to‐date is this review?
Evidence in this Cochrane Review is current to March 2020.

Wednesday, December 9, 2020
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