Nerve Block for Chronic Pain After Knee Replacement Surgery (the BaCPAKS trial): A multi-centre, randomised, placebo-controlled trial to evaluate the clinical and cost effectiveness of adding an adductor canal block to standard perioperative approaches in primary elective knee joint replacement

RESEARCH QUESTION What is the clinical and cost-effectiveness of adding an adductor canal nerve block (ACB) to spinal or general anaesthesia, with local infiltration analgesia (LIA), for primary elective knee replacement (KR) surgery? BACKGROUND Primary knee replacement (KR) is one of the most painful surgical operations, with up to 60% of patients complaining of moderate-to-severe pain during the hospital stay. Unmanaged acute postoperative pain may lead to chronic postsurgical pain (CPSP), a highly debilitating condition affecting up to 44% of patients after KR. Perioperative nerve blocks may reduce the risk of transition from acute to chronic pain. AIM To conduct a multicentre randomised controlled trial, with an internal pilot and economic evaluation, to compare the clinical and cost-effectiveness of ACB plus LIA, and LIA only, in primary elective KR surgical patients. OBJECTIVES a. To determine if there is a difference in the magnitude of chronic pain at 6-months after KR surgery, between the ACB and usual care with LIA b. To complete a 6-month internal pilot to estimate the feasibility of recruitment c. To estimate the difference between the intervention and control groups with respect to a range of patient-reported and clinical secondary outcomes d. To explore the differential effect of nerve block within pre-specified sub-groups e. To assess the relative cost effectiveness f. To conduct a Study Within A Trial (SWAT) to investigate methods for increasing participants’ understanding of the trial results, by comparing written with animated formats of dissemination METHODS Design Pragmatic, multicentre, randomised sham-controlled trial, with an embedded pilot, a SWAT and an economic evaluation Population Any adult undergoing primary KR surgery for any indication Intervention ACB in addition to general and/or spinal anaesthesia and LIA Comparator Sham ACB in addition to general and/or spinal anaesthesia and LIA Primary outcome Pain magnitude at 6 months post-surgery Secondary outcomes a) Patient reported outcomes (acute and chronic pain; quality of life; pain interference, neuropathic pain) b) Health outcomes (opioid consumption, time to mobilise, complications, secondary procedures) c) Resource utilisation Follow-up Up to 12 months post surgery TIMELINES FOR DELIVERY Months 1-9 (9 months): Trial preparation and start-up Months 10-15 (6 months): Embedded internal pilot period Months 16-33 (18 months): Main trial recruitment Months 34-45 (12 months): Follow-up Month 46-51 (6 months): Data cleaning, analysis, preparation and submission of final report Month 49-57 (9 months): SWAT Total duration: 57 months IMPACT If the trial finds that ACB is superior to usual care in terms of improving pain after KR surgery and being cost-effective, then the adoption of this technique will benefit patients undergoing KR surgery and the health service and will lead to change in care pathways and guidelines. If no benefits are found the trial would provide evidence to stop the use of ineffective treatments within the NHS. DISSEMINATION The results will be shared with stakeholders including patients, doctors, professional societies, trial networks, patient support groups, and NHS policy makers. The findings will be published in major medical journals, presented in national and international scientific meetings and made available on the websites of health professional societies and social media.