Peri-articular infiltration in the resource-restrained environment - still a worthwhile adjunct to multimodal analgesia post total knee replacement

Background: Peri-articular infiltrations (PAI) in total knee arthroplasty (TKA) offer effective analgesia, and are cost effective, safe and easy to perform. Currently there is no gold standard technique based on evidence-based medicine; described methods are based on consensus recommendations. The latest literature supports PAI including complex and multiple drug combinations, such as liposomal bupivacaine, ropivacaine and ketorolac, which are not available in all settings. This study aims to prove that a basic PAI technique using widely available and inexpensive agents offers good and effective outcomes in a resource-poor environment. Methods: A double-blind randomised control trial compared the effectiveness of PAI with a simple, widely available anaesthetic solution (bupivacaine and adrenalin) to a normal saline control group. Infiltration volumes were calculated at 1 ml/kg and the infiltration technique followed a specific protocol. Post-operative outcomes included visual analogue scores (VAS), ambulation scores, morphine use, knee range of motion (ROM) and time to discharge. Results: Two comparable groups of 26 patients each were included (intervention: 81% female, mean age 64.8±8.8 years vs control: 65% female, mean age 67.0±7.6 years). All pain-related measures favoured the intervention group but failed to reach statistical significance at 24 and 72 hours. Mean VAS scores at 48 hours were significantly lower in the intervention group. (VAS score 3.0±1.6 vs 4.1±1.2, p=0.013). The other parameters measured strongly favoured the intervention group but did not prove to be significant. Conclusions: A volume per kilogram PAI technique making use of widely available, cost-effective agents provides a statistical reduction in VAS scores at 48 hours post TKA. This suggests that in a resource-poor environment PAI is still a valuable addition to the multimodal analgesia pathway in the post-operative management of TKA. Maximum drug doses may show even more promising results, specifically in the first 24 hours post-operatively. Further studies investigating PAI for TKA in resource-restrained environments are indicated. Level of evidence: Level 2