The risk of developing serious complications following a knee replacement could be up to 73% higher when a tourniquet is used, compared to surgery without a tourniquet, found a systematic review.
Serious complications during knee replacement surgery are rare. However, researchers at the University of Warwick found that 5.9% of patients whose operations involved a tourniquet had serious complications needing additional health care, compared to 2.9% in those operated on without a tourniquet.
Research from Warwick Clinical Trials Unit has revealed that this common surgery, performed over 100,000 times a year in the UK, is likely to be safer and less painful for patients if surgeons do not use a tourniquet. A tourniquet is typically applied for about an hour during the surgery.
The conclusions are drawn from a new systematic review published in the Cochrane Library and funded by the National Institute for Health Research, drawing on data from 41 previous clinical trials on the use of a tourniquet during knee replacement surgery. The differences became clear when the results from multiple studies around the world were combined.
The researchers conclude that surgeons should now discuss the benefits and risks of using a tourniquet with patients prior to surgery and offer a choice of whether to use a tourniquet or not. The report suggests that a change of surgical practice by not using a tourniquet might avoid up to 1,987 serious complications in the UK each year.
Many people with arthritis are successfully treated with painkillers, exercise and physiotherapy. When arthritis becomes severe, these may be less effective and patients are typically offered knee replacement surgery. This procedure is performed under anaesthetic when the knee joint is opened up, the worn joint surfaces are removed and replaced with artificial surfaces usually constructed from metal and plastic.
Widespread use of tourniquets may relate to surgeons' concerns about blood loss and improving the way that the cement used to hold the knee replacement in place attaches to the bone. However, modern anaesthetic and surgical techniques mean this is unlikely to be a problem. For example, hip and shoulder replacement surgery where the use of a tourniquet is not possible proceed safely, without undue concerns about bleeding or cement fixation of the components. The researchers found no evidence of any problem with the attachment between the cement and the bone when a tourniquet was not used, even in x-ray studies designed to measure this accurately.
The researchers pooled data from 41 previous randomised control trials up to March 2020, involving 2,819 patients, comparing the outcomes when the surgeon used a tourniquet during knee replacement surgery to those who didn't use a tourniquet. Knee function, quality of life, total blood loss and fixation of the components were measured and little difference was found between the two methods. However, where a tourniquet was used 5.9% of patients experienced serious complications such as blood clots, wound infection and the need for further surgery, compared to 2.9% where a tourniquet was not used. Patients who had a knee replacement where a tourniquet was used also reported on average 19% more pain the day after surgery than patients where no tourniquet was used.
Senior author Mr Peter Wall, Consultant Orthopaedic Surgeon from Warwick Clinical Trials Unit and University Hospitals Coventry and Warwickshire NHS Trust, said: "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.
He emphasised that: "Most people do very well after knee replacement, but like any major surgery, there are risks and use of a tourniquet may exacerbate these."
Study details
Tourniquet use for knee replacement surgery
Imran Ahmed, Amit Chawla, Martin Underwood, Andrew J Price, Andrew Metcalfe, Charles Hutchinson, Jane Warwick, Kate Seers, Helen Parsons, Peter DH Wall.
Cochrane Database of Systematic Reviews, 8 December 2020
Abstract
Many surgeons prefer to perform total knee replacement surgery with the aid of a tourniquet. A tourniquet is an occlusive device that restricts distal blood flow to help create a bloodless field during the procedure. A tourniquet may be associated with increased risk of pain and complications.
Objectives
To determine the benefits and harms of tourniquet use in knee replacement surgery.
Search methods
We searched MEDLINE, Embase, and Cochrane Central Register of Controlled Trials (CENTRAL) up to 26 March 2020. We searched clinicaltrials.gov, the World Health Organization trials portal, and several international registries and joint registries up to March 2020.
Selection criteria
We included randomised controlled trials (RCTs) comparing knee replacement with use of a tourniquet versus without use of a tourniquet and non‐randomised studies with more than 1000 participants. Major outcomes included pain, function, global assessment of success, health‐related quality of life, serious adverse events (including venous thromboembolism, infection, re‐operation, and mortality), cognitive function, and survival of the implant. Minor outcomes included blood loss, economic outcomes, implant stability, and adverse events.
Data collection and analysis
Two review authors screened abstracts and full texts, extracted data, performed risk of bias assessments, and assessed the certainty of the evidence using the GRADE approach.
Main results
We included 41 RCTs with 2819 participants. Trials included from 20 to 199 participants. Mean age ranged between 58 and 84 years. More than half of the RCTs had unclear risk of selection bias and unclear risk of performance and detection bias due to absence of blinding of participants and surgeons.
Major outcomes
Pain: at postoperative day 1, pain (on a scale from zero to 10, with higher scores indicating worse pain) was ranked at 4.56 points after surgery without a tourniquet and at 1.25 points (MD) higher (95% CI 0.32 higher to 2.19 higher) with a tourniquet (8 studies; 577 participants), for an absolute difference of 12.5% higher pain scores (95% CI 3.2% higher to 21.9% higher) and a relative difference of 19% higher pain scores (95% CI 3.4% higher to 49% higher) with a tourniquet. Evidence for these findings was of moderate certainty, downgraded due to risk of bias. Knee replacement with a tourniquet probably led to higher postoperative pain scores at day 1, although this difference may or may not be noticeable to patients (based on a minimal clinically important difference (MCID) of 1.0).
Function: at 12 months, tourniquet use probably makes little or no difference to function, based on an MCID of 5.3 for Knee Society Score (KSS) and 5.0 for Oxford Knee Score (OKS). Mean function (on a scale from 0 to 100, with higher scores indicating better outcomes) was 90.03 points after surgery without a tourniquet and was 0.29 points worse (95% CI 1.06 worse to 0.48 better) on a 0 to 100 scale, absolute difference was 0.29% worse (1.06% worse to 0.48% better), with a tourniquet (5 studies; 611 participants). This evidence was downgraded to moderate certainty due to risk of bias.
Global assessment of success: low‐certainty evidence (downgraded due to bias and imprecision) indicates that tourniquet use may have little or no effect on success. At six months, 47 of 50 (or 940 per 1000) reported overall successful treatment after surgery without a tourniquet and 47 of 50 (or 940 per 1000) with a tourniquet (risk ratio (RR) 1.0, 95% CI 0.91 to 1.10) based on one study with 100 participants.
Health‐related quality of life: at six months, tourniquet may have little or no effect on quality of life. The 12‐Item Short Form Survey (SF‐12) score (mental component from zero to 100 (100 is best)) was 54.64 after surgery without a tourniquet and 1.53 (MD) better (95% CI 0.85 worse to 3.91 better) with a tourniquet (1 study; 199 participants); absolute difference was 1.53% better (0.85% worse to 3.91% better). Evidence was of low certainty, downgraded due to risk of bias and small number of participants.
Serious adverse events: the risk of serious adverse events was probably higher with tourniquet; 26 of 898 (29 per 1000) reported events following surgery without a tourniquet compared to 53 of 901 (59 per 1000) with a tourniquet (RR 1.73, 95% CI 1.10 to 2.73) in 21 studies (1799 participants). Twenty‐nine more per 1000 patients (95% CI 3 to 50 more per 1000 patients) had a serious adverse event with a tourniquet. Forty‐eight (95% CI 20 to 345) participants would need to have surgery without a tourniquet to avoid one serious adverse event. This evidence was downgraded to moderate certainty due to risk of bias.
Cognitive function: one study reported cognitive function as an outcome; however the data were incompletely reported and could not be extracted for analysis.
Survival of implant: it is uncertain if tourniquet has an effect on implant survival due to very low certainty evidence (downgraded for bias, and twice due to very low event rates); 2 of 107 (19 per 1000) required revision surgery in the surgery with a tourniquet group compared to 1 of 107 (9 per 1000) without a tourniquet group at up to two years' follow‐up (RR 1.44, 95% CI 0.23 to 8.92). This equates to a 0.4% (0.7% lower to 7% more) increased absolute risk in surgery with a tourniquet.
Authors' conclusions
Moderate certainty evidence shows that knee replacement surgery with a tourniquet is probably associated with an increased risk of serious adverse events. Surgery with a tourniquet is also probably associated with higher postoperative pain, although this difference may or may not be noticeable to patients. Surgery with a tourniquet does not appear to confer any clinically meaningful benefit on function, treatment success or quality of life. Further research is required to explore the effects of tourniquet use on cognitive function and implant survival, to identify any additional harms or benefits.
If a tourniquet continues to be used in knee replacement surgery, patients should be informed about the potential increased risk of serious adverse events and postoperative pain.
[link url="https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD012874.pub2/full"]Full text in Cochrane Review Library (open access) [/link]
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