Adductor canal block in total knee arthroplasty: a scoping review of the literature.

Background: An adductor canal block is commonly used to reduce pain after total knee arthroplasty. Practice varies in terms of site of injection, local anaesthetic, and adjuncts used, with poor consensus in relation to the best approach. The aim of this scoping review was to assess the evidence for efficacy and safety of adductor canal block, determine variation in the technique used, type and dose of medication, and compare the efficacy of adductor canal block with other nerve block techniques. Methods: Four databases were searched to identify relevant studies (Medline, Embase, Cochrane, and ClinicalTrials.gov). A total of 285 articles were found, and data was extracted from 130 randomised controlled trials. Results: Adductor canal block is a safe and potentially effective peripheral nerve block for reducing postoperative pain after total knee arthroplasty while preserving motor function. Of all adjuncts to adductor canal block assessed, either dexamethasone or dexmedetomidine provide additional analgesic benefit. Adductor canal block combined with peri-articular local anaesthetic injection provides the best outcomes. Continuous infusion of local anaesthetic through a catheter placed in the adductor canal provides no additional benefit over a single injection. The site of injection used for adductor canal block does not seem to affect efficacy. There was no evidence to support the superiority of any single local anaesthetic agent. Conclusion: This scoping review has identified variation in the use of medications, doses, techniques, and adjuncts for adductor canal block. As such, definitive conclusions regarding the most effective practice for adductor canal block cannot be made.