Cryotherapy following total knee replacement

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.