The effect of opioid-free anesthesia on postoperative pain in orthopedic surgery: a systematic review and meta-analysis of randomized controlled trial

Background: Opioid-free anaesthesia (OFA) is increasingly recognized as a perioperative approach that may offer effective pain control with reduced risk of adverse effects. Considering that orthopaedic surgeries often lead to at least moderate postoperative pain, we assessed the effectiveness and safety of OFA in orthopaedic procedures. Methods: We searched PubMed, ScienceDirect, ProQuest, and EuropePMC for relevant randomised controlled trials (RCT) and supplemented the data with citation tracking. Data were analysed using RevMan version 5.4. The risk of bias and the certainty of evidence were evaluated using the Cochrane Risk of Bias 2.0 tool and the GRADE approach. The study was registered on PROSPERO (CRD420251048348). Results: Seven RCTs involving 408 patients were included. The intensity of postoperative pain measured in the post-anaesthesia care unit (mean difference [MD]: −0.08), at 24 hours (MD: −0.06), and at 48 hours (MD: −0.26) was not statistically significant. OFA reduced the risk of postoperative nausea and vomiting (PONV) (RR: 0.37; P = .00001) and prolonged the time to first request for analgesia (MD: 25.60 minutes; P = .00001). Twenty-four-hour morphine consumption was comparable across groups (MD: −0.28; P = .76). OFA reduced the incidence of intraoperative hypotension (risk ratio [RR]: 0.56; P = .02) but increased the risk of intraoperative bradycardia (RR: 1.86; P = .04). Conclusions: In orthopaedic surgery, OFA provides comparable pain control to opioid-based anaesthesia. It also reduced the incidence of postoperative nausea and vomiting and intraoperative hypotension, and prolonged the time to the first request for analgesia (statistically, but not clinically). However, the potential risk of bradycardia should be considered when using dexmedetomidine-based analgesics.