Treatment of postoperative pain should rely on results from randomized controlled trials and meta-analyses of high scientific quality. The efficacy of a particular intervention may depend on the type of surgical procedure, which supports the reporting of "procedure-specific" interventions. The aim of this systematic review was to document the procedure-specific evidence for analgesic interventions after total hip arthroplasty (THA). This PRISMA-compliant and PROSPERO-registered review includes randomized placebo-controlled trials (RCTs) of medication-based analgesic interventions after THA. Endpoints were postoperative opioid consumption, pain scores (rest and during mobilization), adverse events, and length of hospital stay. Fifty-eight trials with 19 different interventions were retrieved. High risk of bias, substantial differences in assessment-tools and criteria for pain, irregular reporting of adverse events, considerable differences in supplemental analgesic consumption, and basic analgesic regimens generally characterized trials. Meta-analyses of non-steroidal anti-inflammatory drugs, local infiltration analgesia, intrathecal opioids, and lumbar plexus block provided a 24-hour intravenous morphine-sparing effect of 14.1 (95 % confidence interval: 8.0-20.2) mg, 7.5 (3.7-11.3) mg, 19.8 (14.9-24.7) mg, and 11.9 (6.4-17.3) mg, respectively. Non-steroidal anti-inflammatory drugs and lumbar plexus block were demonstrated to provide reductions in postoperative pain scores. Intrathecal opioids increased pruritus, and lumbar plexus block reduced nausea and pruritus. The GRADE-rated quality of evidence ranged from low to very low throughout the analyses. This review demonstrated, that some analgesic interventions may have the capacity to reduce mean opioid requirements and/or mean pain intensity compared with controls, but the available randomized placebo-controlled trials does not allow a designation of a "best proven intervention" for THA.

Pregabalin has demonstrated anti-hyperalgesic properties and was introduced into acute pain treatment in 2001. Our aim was to evaluate the beneficial and harmful effects of pregabalin in postoperative pain management. We included randomized clinical trials investigating perioperative pregabalin treatment in adult surgical patients. The review followed Cochrane methodology, including Grading of Recommendations Assessment, Development, and Evaluation (GRADE), and used trial sequential analyses (TSAs). The primary outcomes were 24 h morphine i.v. consumption and the incidence of serious adverse events (SAEs) defined by International Conference of Harmonisation Good Clinical Practice guidelines. Conclusions were based primarily on trials with low risk of bias. Ninety-seven randomized clinical trials with 7201 patients were included. The 24 h morphine i.v. consumption was reported in 11 trials with overall low risk of bias, finding a reduction of 5.8 mg (3.2, 8.5; TSA adjusted confidence interval: 3.2, 8.5). Incidence of SAEs was reported in 21 trials, with 55 SAEs reported in 12 of these trials, and 22 SAEs reported in 10 trials with overall low risk of bias. In trials with overall low risk of bias, Peto’s odds ratio was 2.9 (1.2, 6.8; TSA adjusted confidence interval: 0.1, 97.1). Based on trials with low risk of bias, pregabalin may have a minimal opioid-sparing effect, but the risk of SAEs seems increased. However, the GRADE-rated evaluations showed only moderate to very low quality of evidence. Consequently, a routine use of pregabalin for postoperative pain treatment cannot be recommended.

Background: Morphine‐sparing effects are often used to evaluate non‐opioid analgesic interventions. The exact effect that would warrant the implementation of these interventions in clinical practice (a minimally important difference) remains unclear. We aimed to determine this with anchor‐based methods.Methods: This was a post hoc analysis of three studies investigating pain management after hip or knee arthroplasty (PANSAID [NCT02571361], DEX‐2‐TKA [NCT03506789] and Pain Map [NCT02340052]). The overall population was median aged 70, median ASA 2, 54% female. We examined the correlation between 0 and 24 h postoperative iv morphine equivalent consumption and the severity of nausea, vomiting, sedation and dizziness. The anchor was different severity degrees of these opioid‐related adverse events. The primary outcome was the difference in morphine consumption between patients experiencing no versus only mild events. Secondary outcomes included the difference in morphine consumption between patients with mild versus moderate and moderate versus severe events. We used Hodges–Lehmann median differences, exact Wilcoxon–Mann–Whitney tests and quantile regression.Results: The difference in iv morphine consumption was 6 mg (95% confidence interval: 4–8) between patients with no versus only mild events, 5 mg (2–8) between patients with mild versus moderate events and 0 mg (−4 to 4) between patients with moderate versus severe events.Conclusions: In populations comparable to this post‐hoc analysis (orthopaedic surgery, median age 70 and ASA 2), we suggest a minimally important difference of 5 mg for 0–24 h postoperative iv morphine consumption.

Patients undergoing spinal surgery are at high risk of acute and persistent postoperative pain. Therefore, adequate pain relief is crucial. This systematic review aimed to provide answers about best-proven postoperative analgesic treatment for patients undergoing lumbar 1- or 2-level fusions for degenerative spine diseases. We performed a search in PubMed, Embase, and The Cochrane Library for randomized controlled trials. The primary outcome was opioid consumption after 24 hours postoperatively. We performed meta-analyses, trial sequential analyses, and Grading of Recommendations assessment to accommodate systematic errors. Forty-four randomized controlled trials were included with 2983 participants. Five subgroups emerged: nonsteroidal anti-inflammatory drugs (NSAIDs), epidural, ketamine, local infiltration analgesia, and intrathecal morphine. The results showed a significant reduction in opioid consumption for treatment with NSAID (P < 0.0008) and epidural (P < 0.0006) (predefined minimal clinical relevance of 10 mg). Concerning secondary outcomes, significant reductions in pain scores were detected after 6 hours at rest (NSAID [P < 0.0001] and intrathecal morphine [P < 0.0001]), 6 hours during mobilization (intrathecal morphine [P = 0.003]), 24 hours at rest (epidural [P < 0.00001] and ketamine [P < 0.00001]), and 24 hours during mobilization (intrathecal morphine [P = 0.03]). The effect of wound infiltration was nonsignificant. The quality of evidence was low to very low for most trials. The results from this systematic review showed that some analgesic interventions have the capability to reduce opioid consumption compared with control groups. However, because of the high risk of bias and low evidence, it was impossible to recommend a “gold standard” for the analgesic treatment after 1- or 2-level spinal fusion surgery.