Regional anaesthesia for knee arthroplasty in the <scp>UK</scp> : survey of practice

Abstract

Analgesia that facilitates early mobilisation is crucial for achieving the best possible outcome after knee arthroplasty and may reduce chronic post-surgical pain [1]. Peri-articular local infiltration anaesthesia offers effective analgesia and is recommended by the National Institute for Health and Care Excellence [2]. Regional anaesthesia techniques such as adductor canal block offer a desirable combination of sensory nerve blockade with minimal risk of quadriceps weakness but have unproven overall benefit [3]. Reflecting this, national guidelines do not recommend routine use of adductor canal block, and the National Institute for Healthcare Research (NIHR) has commissioned a trial to establish whether regional analgesia improves outcomes [4]. We conducted an online survey of practice to understand variation in the practice of anaesthesia for knee arthroplasty in the UK using https://www.onlinesurveys.ac.uk and to explore equipoise for a trial of adductor canal block in this population. The survey was distributed to the mailing list of the National Research Scotland Anaesthesia, Anaesthesia and Peri-operative Medicine Subspecialty Group, contacts in the Peri-operative Medicine Clinical Trials Network and professional contacts of the REALISE trial group. The survey asked about primary anaesthetic; regional anaesthesia (including type, drug, concentration and volume); local infiltration (including approach, technique and additives); adjustments for partial or robotic knee arthroplasty; and trial equipoise. Of the 161 responses, three were excluded as the respondent did not regularly provide anaesthesia for knee arthroplasty. Of the remainder, most came from anaesthetists in Scotland or Northern England (n = 116, 73%). In total, 128 (81%) respondents thought the NIHR-commissioned call asked an important research question. The majority of responders (n = 147, 93%) worked in centres where < 25% of all cases were undertaken as day-case procedures. Spinal anaesthesia was the primary technique of choice (n = 150, 95%). Adductor canal block was employed routinely by 85% (n = 134); one responder used femoral nerve blocks instead of adductor canal blocks. Additional nerve blocks were used rarely (n = 4, 2.5%) and always combined with an adductor canal block. Twenty-three (15%) responders stated they performed no peripheral nerve blocks. Surgical local anaesthetic infiltration was usually performed (n = 146, 92%) and mostly combined with adductor canal block (n = 122, 77%). Focused infiltration of the posterior capsule was more common (n = 55, 58%) than peri-articular infiltration (n = 40, 42%). In addition, 54 (34%) responders reported that adrenaline, tranexamic acid, ketorolac or diclofenac were added to the local infiltration mixture. Most responders used levobupivacaine for adductor canal block (n = 119/134, 89%), but there were variations in the drug, concentration and volume (Table 1). Most common was 20 ml 0.25% levobupivacaine. The volume varied between 10 and 60 ml. Although there is no consensus ‘ideal’ volume, an excessive volume of local anaesthetic may migrate proximally into the femoral triangle or distally into the popliteal fossa resulting in inadvertent motor block [3]. Conversely, it is important that local anaesthetic reaches distally within the adductor canal to block various nerves that lie within it at that level, including the articular branch of the obturator nerve [5]. Fifteen responders adjusted their technique for partial knee arthroplasty including low-dose spinal (n = 3); no block (n = 5); general anaesthesia (n = 2); low dose adductor canal block (n = 3); and low-dose spinal plus general anaesthesia (n = 2). Most responders had no experience with robotic knee arthroplasty or did not change management. Some responders did propose adjustments for robotic knee arthroplasty including general anaesthesia (n = 7); higher dose spinal (n = 7); lower dose ACB (n = 1); and lower dose spinal plus general anaesthesia