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Evaluation of Spin Bias in Systematic Reviews and Meta-analyses of Rotator Cuff Repair With Platelet-Rich Plasma
Moulton, S. G., Hartwell, M. J., Feeley, B. T.
The American journal of sports medicine. 2024;:3635465231213039
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Editor's Choice
Abstract
BACKGROUND The use of platelet-rich plasma (PRP) in orthopaedics continues to increase. One common use of PRP is as an adjunct in rotator cuff repair surgery. Multiple systematic reviews and meta-analyses have summarized the data on PRP use in rotator cuff repair surgery. However, systematic reviews and meta-analyses are subject to spin bias, where authors' interpretations of results influence readers' interpretations. PURPOSE To evaluate spin in the abstracts of systematic reviews and meta-analyses of PRP with rotator cuff repair surgery. STUDY DESIGN Systematic review; Level of evidence, 3. METHODS A PubMed and Embase search was conducted using the terms rotator cuff repair and PRP and systematic review or meta-analysis. After review of 74 initial studies, 25 studies met the inclusion criteria. Study characteristics were documented, and each study was evaluated for the 15 most common forms of spin and using the AMSTAR 2 (A Measurement Tool to Assess Systematic Reviews, Version 2) rating system. Correlations between spin types and study characteristics were evaluated using binary logistic regression for continuous independent variables and a chi-square test or Fisher exact test for categorical variables. RESULTS At least 1 form of spin was found in 56% (14/25) of the included studies. In regard to the 3 different categories of spin, a form of misleading interpretation was found in 56% (14/25) of the studies. A form of misleading reporting was found in 48% (12/25) of the studies. A form of inappropriate extrapolation was found in 16% (4/25) of the studies. A significant association was found between misleading interpretation and publication year (odds ratio [OR], 1.41 per year increase in publication; 95% CI, 1.04-1.92; P = .029) and misleading reporting and publication year (OR, 1.41 per year increase in publication; 95% CI, 1.02-1.95; P = .037). An association was found between inappropriate extrapolation and journal impact factor (OR, 0.21 per unit increase in impact factor; 95% CI, 0.044-0.99; P = .048). CONCLUSION A significant amount of spin was found in the abstracts of systematic reviews and meta-analyses of PRP use in rotator cuff repair surgery. Given the increasing use of PRP by clinicians and interest among patients, spin found in these studies may have a significant effect on clinical practice.
PICO Summary
Population
Patients undergoing arthroscopic rotator cuff repair surgery with platelet-rich plasma (PRP) (25 studies).
Intervention
Systematic review to evaluate the presence of spin bias in the abstracts of systematic reviews and meta-analyses of PRP with rotator cuff repair surgery.
Comparison
Outcome
Each included study was evaluated for the 15 most common forms of spin. Correlations between spin types and study characteristics were evaluated. At least 1 form of spin bias was found in 56% (14/25) of the included studies. In regard to the 3 different categories of spin, a form of misleading interpretation was found in 56% (14/25) of the studies. A form of misleading reporting was found in 48% (12/25) of the studies. A form of inappropriate extrapolation was found in 16% (4/25) of the studies. A significant association was found between misleading interpretation and publication year (odds ratio (OR) 1.41 per year increase in publication; 95% CI [1.04, 1.92]) and misleading reporting and publication year (OR 1.41 per year increase in publication; 95% CI [1.02, 1.95]). An association was found between inappropriate extrapolation and journal impact factor (OR 0.21 per unit increase in impact factor; 95% CI [0.044, 0.99]).
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Cryotherapy following total knee replacement
Aggarwal, A., Adie, S., Harris, I. A., Naylor, J.
The Cochrane database of systematic reviews. 2023;9(9):Cd007911
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Editor's Choice
Abstract
BACKGROUND Total knee replacement (TKR) is a common intervention for people with end-stage symptomatic knee osteoarthritis, resulting in significant improvements in pain, function and quality of life within three to six months. It is, however, acutely associated with pain, local oedema and blood loss. Post-operative management may include cryotherapy. This is the application of low temperatures to the skin surrounding the surgical site, through ice or cooled water, often delivered using specialised devices. This is an update of a review published in 2012. OBJECTIVES To evaluate the effect of cryotherapy in the acute phase after TKR (within 48 hours after surgery) on blood loss, pain, transfusion rate, range of motion, knee function, adverse events and withdrawals due to adverse events. SEARCH METHODS We searched CENTRAL, MEDLINE, Embase, six other databases and two trials registers, as well as reference lists, related links and conference proceedings on 27 May 2022. SELECTION CRITERIA We included randomised controlled trials or controlled clinical trials comparing cryotherapy with or without other treatments (such as compression, regional nerve block or continuous passive motion) to no treatment, or the other treatment alone, following TKR for osteoarthritis. DATA COLLECTION AND ANALYSIS Two review authors independently selected studies for inclusion, extracted data and assessed risk of bias and certainty of evidence using GRADE. We discussed any disagreements and consulted another review author to resolve them, if required. Major outcomes were blood loss, pain, transfusion rate, knee range of motion, knee function, total adverse events and withdrawals from adverse events. Minor outcomes were analgesia use, knee swelling, length of stay, quality of life, activity level and participant-reported global assessment of success. MAIN RESULTS We included 22 trials (20 randomised trials and two controlled clinical trials), with 1839 total participants. The mean ages reflected the TKR population, ranging from 64 to 74 years. Cryotherapy with compression was compared to no treatment in four studies, and to compression alone in nine studies. Cryotherapy without compression was compared to no treatment in eight studies. One study compared cryotherapy without compression to control with compression alone. We combined all control interventions in the primary analysis. Certainty of evidence was low for blood loss (downgraded for bias and inconsistency), pain (downgraded twice for bias) and range of motion (downgraded for bias and indirectness). It was very low for transfusion rate (downgraded for bias, inconsistency and imprecision), function (downgraded twice for bias and once for inconsistency), total adverse events (downgraded for bias, indirectness and imprecision) and withdrawals from adverse events (downgraded for bias, indirectness and imprecision). The nature of cryotherapy made blinding difficult and most studies had a high risk of performance and detection bias. Low-certainty evidence from 12 trials (956 participants) shows that cryotherapy may reduce blood loss at one to 13 days after surgery. Blood loss was 825 mL with no cryotherapy and 561 mL with cryotherapy: mean difference (MD) 264 mL less (95% confidence interval (CI) 7 mL less to 516 mL less). Low-certainty evidence from six trials (530 participants) shows that cryotherapy may slightly improve pain at 48 hours on a 0- to 10-point visual analogue scale (lower scores indicate less pain). Pain was 4.8 points with no cryotherapy and 3.16 points with cryotherapy: MD 1.6 points lower (95% CI 2.3 lower to 1.0 lower). We are uncertain whether cryotherapy improves transfusion rate at zero to 13 days after surgery. The transfusion rate was 37% with no cryotherapy and 79% with cryotherapy (risk ratio (RR) 2.13, 95% CI 0.04 to 109.63; 2 trials, 91 participants; very low-certainty evidence). Low-certainty evidence from three trials (174 participants) indicates cryotherapy may improve range of motion at discharge: it was 62.9 degrees with no cryotherapy and 71.2 degrees with cryotherapy: MD 8.3 degrees greater (95% CI 3.6 degrees more to 13.1 degrees more). We are uncertain whether cryotherapy improves function two weeks after surgery. Function was 75.4 points on the 0- to 100-point Dutch Western Ontario and McMaster Universities Arthritis Index (WOMAC) scale (lower score indicates worse function) in the control group and 88.6 points with cryotherapy (MD 13.2 points better, 95% CI 0.5 worse to 27.1 improved; 4 trials, 296 participants; very low-certainty evidence). We are uncertain whether cryotherapy reduces total adverse events: the risk ratio was 1.30 (95% CI 0.53 to 3.20; 16 trials, 1199 participants; very low-certainty evidence). Adverse events included discomfort, local skin reactions, superficial infections, cold-induced injuries and thrombolytic events. We are uncertain whether cryotherapy reduces withdrawals from adverse events (RR 2.71, 95% CI 0.42 to 17.38; 19 trials, 1347 participants; very low-certainty evidence). No significant benefit was found for secondary outcomes of analgesia use, length of stay, activity level or quality of life. Evidence from seven studies (403 participants) showed improved mid-patella swelling between two and six days after surgery (MD 7.32 mm less, 95% CI 11.79 to 2.84 lower), though not at six weeks and three months after surgery. The included studies did not assess participant-reported global assessment of success. AUTHORS' CONCLUSIONS The certainty of evidence was low for blood loss, pain and range of motion, and very low for transfusion rate, function, total adverse events and withdrawals from adverse events. We are uncertain whether cryotherapy improves transfusion rate, function, total adverse events or withdrawals from adverse events. We downgraded evidence for bias, indirectness, imprecision and inconsistency. Hence, the potential benefits of cryotherapy on blood loss, pain and range of motion may be too small to justify its use. More well-designed randomised controlled trials focusing especially on clinically meaningful outcomes, such as blood transfusion, and patient-reported outcomes, such as knee function, quality of life, activity level and participant-reported global assessment of success, are required.
PICO Summary
Population
People undergoing total knee replacement (22 trials, n= 1,839).
Intervention
Cryotherapy alone or with another therapy aiming to reduce pain and swelling.
Comparison
No treatment; other treatments aiming to reduce pain and swelling (e.g., compression bandaging, regional nerve block or continuous passive motion).
Outcome
Blood loss was 264 mL less with cryotherapy at up to 13 days after surgery. 11% more people had a blood transfusion with cryotherapy, or 11 more out of 100, at up to 13 days after surgery. Pain was better by 1.6 points on a 0‐ to 10‐point scale with cryotherapy at 2 days after surgery. For knee range of motion: flexion was 8.3 degrees greater with cryotherapy when people left hospital. Knee function was 13.2 points better on a 0- to 100-point scale with cryotherapy at 2 weeks after surgery. For total adverse events: 2.7 out of 100 people reported adverse events with cryotherapy, and 2.1 out of 100 people reported adverse events without cryotherapy. The certainty of evidence was low for blood loss, pain and range of motion, and very low for transfusion rate, function, total adverse events and withdrawals from adverse events. The authors are uncertain whether cryotherapy improves transfusion rate, function, total adverse events or withdrawals from adverse events. The authors downgraded evidence for bias, indirectness, imprecision and inconsistency.
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3.
Tourniquet use benefits to reduce intraoperative blood loss in patients receiving total knee arthroplasty for osteoarthritis: An updated meta-analysis with trial sequential analysis
Xu, X., Wang, C., Song, Q., Mou, Z., Dong, Y.
Journal of orthopaedic surgery (Hong Kong). 2023;31(2):10225536231191607
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Editor's Choice
Abstract
PURPOSE The efficacy and safety of tourniquets use during total knee arthroplasty (TKA) in patients with osteoarthritis remain debated. This updated systematic review and meta-analysis aimed to further evaluate the role of tourniquets use in patients undergoing TKA for knee osteoarthritis by introducing trial sequential analysis. METHODS PubMed, Embase, and the Cochrane Library were searched. We used the Cochrane risk of bias tool for quality assessment. Statistical heterogeneity across studies was evaluated using Cochran's Q and I(2) statistic. Meta-analysis was performed using Stata/SE 14.0, and trail sequential analysis was performed using TSA software version 0.9.5.10 Beta. In addition, qualitative summary was also used to describe results. RESULTS 15 randomized controlled trials (RCTs) involving 1202 patients were included in the meta-analysis. The pooled results showed that tourniquet use during TKA significantly reduced intraoperative blood loss (mean difference (MD)= -123.84, 95% confidence interval (CI): -163.37 to -84.32, p < .001)and shortened operation time (MD = -4.71, 95% CI: -7.6 to -1.82, p = .001), but there were no significant differences in postoperative blood loss, calculated blood loss, total blood loss, transfusion rate (p = .939), and deep venous thrombosis (DVT) rate between the tourniquet and no-tourniquet groups. TSA confirmed that the result of operation time was false positive, but the results of other outcomes were conclusive. The results of qualitative summary showed conflicting findings in terms of pain, range of motion (RoM) and swelling ratio between the two groups. CONCLUSIONS Tourniquet use in patients receiving TKA for osteoarthritis benefits to reduce intraoperative blood loss but has no effect on postoperative blood loss, calculated blood loss, total blood loss, operation time, transfusion rate, and DVT rate. In addition, it remains unclear the difference between the tourniquet and non-tourniquet groups in terms of pain, RoM and swelling ratio.
PICO Summary
Population
Patients undergoing total knee arthroplasty (TKA) for osteoarthritis (15 randomised controlled trials, n= 1,202).
Intervention
Tourniquet.
Comparison
Non-use of tourniquet.
Outcome
The pooled results showed that tourniquet use during TKA significantly reduced intraoperative blood loss (mean difference (MD)= -123.84; 95% confidence interval (CI) [-163.37, -84.32]) and shortened operation time (MD= -4.71; 95% CI [-7.6 to, -1.82]), but there were no significant differences in postoperative blood loss, calculated blood loss, total blood loss, transfusion rate, and deep venous thrombosis rate between the tourniquet and no-tourniquet groups. Trial sequential analyses confirmed that the result of operation time was false positive, but the results of other outcomes were conclusive. The results of qualitative summary showed conflicting findings in terms of pain, range of motion and swelling ratio between the two groups.
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Interventions for reducing red blood cell transfusion in adults undergoing hip fracture surgery: an overview of systematic reviews
Lewis, S. R., Pritchard, M. W., Estcourt, L. J., Stanworth, S. J., Griffin, X. L.
The Cochrane database of systematic reviews. 2023;6(6):Cd013737
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Editor's Choice
Abstract
BACKGROUND Following hip fracture, people sustain an acute blood loss caused by the injury and subsequent surgery. Because the majority of hip fractures occur in older adults, blood loss may be compounded by pre-existing anaemia. Allogenic blood transfusions (ABT) may be given before, during, and after surgery to correct chronic anaemia or acute blood loss. However, there is uncertainty about the benefit-risk ratio for ABT. This is a potentially scarce resource, with availability of blood products sometimes uncertain. Other strategies from Patient Blood Management may prevent or minimise blood loss and avoid administration of ABT. OBJECTIVES To summarise the evidence from Cochrane Reviews and other systematic reviews of randomised or quasi-randomised trials evaluating the effects of pharmacological and non-pharmacological interventions, administered perioperatively, on reducing blood loss, anaemia, and the need for ABT in adults undergoing hip fracture surgery. METHODS In January 2022, we searched the Cochrane Library, MEDLINE, Embase, and five other databases for systematic reviews of randomised controlled trials (RCTs) of interventions given to prevent or minimise blood loss, treat the effects of anaemia, and reduce the need for ABT, in adults undergoing hip fracture surgery. We searched for pharmacological interventions (fibrinogen, factor VIIa and factor XIII, desmopressin, antifibrinolytics, fibrin and non-fibrin sealants and glue, agents to reverse the effects of anticoagulants, erythropoiesis agents, iron, vitamin B12, and folate replacement therapy) and non-pharmacological interventions (surgical approaches to reduce or manage blood loss, intraoperative cell salvage and autologous blood transfusion, temperature management, and oxygen therapy). We used Cochrane methodology, and assessed the methodological quality of included reviews using AMSTAR 2. We assessed the degree of overlap of RCTs between reviews. Because overlap was very high, we used a hierarchical approach to select reviews from which to report data; we compared the findings of selected reviews with findings from the other reviews. Outcomes were: number of people requiring ABT, volume of transfused blood (measured as units of packed red blood cells (PRC)), postoperative delirium, adverse events, activities of daily living (ADL), health-related quality of life (HRQoL), and mortality. MAIN RESULTS We found 26 systematic reviews including 36 RCTs (3923 participants), which only evaluated tranexamic acid and iron. We found no reviews of other pharmacological interventions or any non-pharmacological interventions. Tranexamic acid (17 reviews, 29 eligible RCTs) We selected reviews with the most recent search date, and which included data for the most outcomes. The methodological quality of these reviews was low. However, the findings were largely consistent across reviews. One review included 24 RCTs, with participants who had internal fixation or arthroplasty for different types of hip fracture. Tranexamic acid was given intravenously or topically during the perioperative period. In this review, based on a control group risk of 451 people per 1000, 194 fewer people per 1000 probably require ABT after receiving tranexamic acid (risk ratio (RR) 0.56, 95% confidence interval (CI) 0.46 to 0.68; 21 studies, 2148 participants; moderate-certainty evidence). We downgraded the certainty for possible publication bias. Review authors found that there was probably little or no difference in the risks of adverse events, reported as deep vein thrombosis (RR 1.16, 95% CI 0.74 to 1.81; 22 studies), pulmonary embolism (RR 1.01, 95% CI 0.36 to 2.86; 9 studies), myocardial infarction (RR 1.00, 95% CI 0.23 to 4.33; 8 studies), cerebrovascular accident (RR 1.45, 95% CI 0.56 to 3.70; 8 studies), or death (RR 1.01, 95% CI 0.70 to 1.46; 10 studies). We judged evidence from these outcomes to be moderate certainty, downgraded for imprecision. Another review, with a similarly broad inclusion criteria, included 10 studies, and found that tranexamic acid probably reduces the volume of transfused PRC (0.53 fewer units, 95% CI 0.27 to 0.80; 7 studies, 813 participants; moderate-certainty evidence). We downgraded the certainty because of unexplained high levels of statistical heterogeneity. No reviews reported outcomes of postoperative delirium, ADL, or HRQoL. Iron (9 reviews, 7 eligible RCTs) Whilst all reviews included studies in hip fracture populations, most also included other surgical populations. The most current, direct evidence was reported in two RCTs, with 403 participants with hip fracture; iron was given intravenously, starting preoperatively. This review did not include evidence for iron with erythropoietin. The methodological quality of this review was low. In this review, there was low-certainty evidence from two studies (403 participants) that there may be little or no difference according to whether intravenous iron was given in: the number of people who required ABT (RR 0.90, 95% CI 0.73 to 1.11), the volume of transfused blood (MD -0.07 units of PRC, 95% CI -0.31 to 0.17), infection (RR 0.99, 95% CI 0.55 to 1.80), or mortality within 30 days (RR 1.06, 95% CI 0.53 to 2.13). There may be little or no difference in delirium (25 events in the iron group compared to 26 events in control group; 1 study, 303 participants; low-certainty evidence). We are very unsure whether there was any difference in HRQoL, since it was reported without an effect estimate. The findings were largely consistent across reviews. We downgraded the evidence for imprecision, because studies included few participants, and the wide CIs indicated possible benefit and harm. No reviews reported outcomes of cognitive dysfunction, ADL, or HRQoL. AUTHORS' CONCLUSIONS Tranexamic acid probably reduces the need for ABT in adults undergoing hip fracture surgery, and there is probably little or no difference in adverse events. For iron, there may be little or no difference in overall clinical effects, but this finding is limited by evidence from only a few small studies. Reviews of these treatments did not adequately include patient-reported outcome measures (PROMS), and evidence for their effectiveness remains incomplete. We were unable to effectively explore the impact of timing and route of administration between reviews. A lack of systematic reviews for other types of pharmacological or any non-pharmacological interventions to reduce the need for ABT indicates a need for further evidence syntheses to explore this. Methodologically sound evidence syntheses should include PROMS within four months of surgery.
PICO Summary
Population
Adults undergoing hip fracture surgery (26 systematic reviews, n= 3,923).
Intervention
Pharmacological and non-pharmacological interventions to prevent or minimise blood loss, treat the effects of anaemia, and reduce the need for allogenic blood transfusions (ABT).
Comparison
Between and within categories of intervention, standard of care or placebo.
Outcome
17 reviews were found about tranexamic acid, 9 reviews about iron, and none for any other types of treatment. The three reviews providing the most relevant information were: A review about tranexamic acid including 24 studies with 2,148 people with a broken hip; a review about tranexamic acid including 10 studies with 1,123 people; and a review about iron including 2 studies with 403 people. The authors concluded that tranexamic acid probably reduces the need for ABT in adults undergoing hip fracture surgery, and there is probably little or no difference in adverse events. For iron, there may be little or no difference in overall clinical effects, but this finding is limited by evidence from only a few small studies. Reviews of these treatments did not adequately include patient-reported outcome measures, and evidence for their effectiveness remains incomplete.
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5.
Tourniquet use for knee replacement surgery
Ahmed I, Chawla A, Underwood M, Price AJ, Metcalfe A, Hutchinson C, Warwick J, Seers K, Parsons H, Wall PD
The Cochrane database of systematic reviews. 2020;12:Cd012874
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Editor's Choice
Abstract
BACKGROUND 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.
PICO Summary
Population
Patients undergoing knee replacement surgery (41 studies, n= 2,819).
Intervention
Tourniquet use.
Comparison
No tourniquet use.
Outcome
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 with a tourniquet. Function at 12 months: 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, absolute difference was 0.29% worse.26 of 898 reported events following surgery without a tourniquet compared to 53 of 901 with a tourniquet. Twenty-nine more per 1000 patients had a serious adverse event with a tourniquet.