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

Background: An adductor canal block (ACB) is commonly used in anaesthetic practice to reduce pain after total knee arthroplasty (TKA). Practice varies in terms of anatomical location, local anaesthetic and adjuncts used, with poor consensus in relation to the best approach. The aim of this scoping review was to 1) assess the evidence for efficacy of ACB, 2) assess the safety of ACB, 3) determine the variation in type of medication, dose of medication, anatomical site, and technique for ACB, 4) compare the efficacy of ACB to other nerve block techniques.
Methods: Four databases were searched to identify all 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: ACB is a safe and potentially effective peripheral nerve block for reducing postoperative pain after TKA and preserves motor function. Of all adjuncts to ACB assessed, either dexamethasone or dexmedetomidine provide the additional analgesic benefit. ACB combined with peri-articular local anaesthetic injection provides the best outcomes. Continuous infusion of an ACB gives no additional benefit over a single injection. Anatomical location of ACB does not seem to affect efficacy. There was no evidence to support the use of a single local anaesthetic agent.
Conclusion: This scoping review has identified a huge variation in the use of medications, doses, techniques and adjuncts for ACB. As such definitive conclusions regarding the most effective practice for ACB cannot be concluded. Standardisation across all aspects of ACB are required to allow for accurate comparison between future studies before any recommendations regarding merit can be made.