Evaluating the Efficacy of the Sub-psoas Fascial Plane Block for Post-operative Analgesia Following Hemiarthroplasty

Background:

Hip fracture surgery is one of the commonest orthopaedic operations performed in the Republic of Ireland, and is associated with significant patient morbidity, mortality and health care costs. The National Irish Hip Fracture Report recorded 1,950 hip fractures in 2013, 71% were female and the highest proportions were in the 80-89 age group. It has been estimated that the overall prevalence of hip fractures is projected to increase in line with increasing elderly population and projected demographic changes.

Early remobilization has become a key integral component of the optimal post-surgical management of hip fractures. Based on the National Institute for Health and Care Excellence (NICE) guidance, the National Hip Fracture UK Database has adopted patient remobilisation on the day of or day after surgery as a key performance indicator. Early mobilisation has been shown to reduce the risk of in-hospital mortality following hip fracture and to increase the likelihood of discharge from hospital. In 2018, 20% of patients failed to achieve the early remobilisation target, due to pain and/or hypotension, factors which might have been anticipated by clear perioperative protocols and closer working between surgery and anaesthetic colleagues.

Current AAGBI guidelines describe core principles of the peri-operative management of people with hip fracture, with one of their aims recommending a peripheral nerve block immediately prior to operative fixation of a hip fracture (in the Emergency Department and at the time of surgery, provided six hours have passed between blocks). There are two peripheral nerve blocks commonly used in the perioperative setting of hip fracture repair, namely femoral or fascia iliaca block. Both techniques have been proven to be safe and efficacious, however, these peripheral nerve blocks have been associated with some residual muscle weakness and increased falls risk which further hampens the ability of a patient to remobilize post-operatively. There is a clinical need to establish a safe, reliable regional anaesthetic technique that will still offer long-acting opioid sparing analgesia, yet minimise the associated motor blockade in order to improve and facilitate remobilization. By also potentially interrupting the sympathetically mediated pain in the lower limb following hip surgery through the blockade of this lumbar sympathetic plexus, it may provide an avenue to produce significant analgesia without causing somatic sensory deficits (e.g. residual motor weakness), thereby facilitating early remobilisation and enhanced recovery. This is not a new technique, rather it is a new approach to a very well established and utilized technique (the psoas compartment block) which has been shown to be very effective, this approach is expected to be as efficacious and potentially safer than previous approaches as it avoids the nerve roots. In terms of the side effect profile of this novel approach to the PCB - there are no new expected side effects above the standard previously explained effects that can occur with any regional technique (for example, haematoma/ LAST / Neuropraxia). This approach would theoretically be associated with a lower side effect profile than previous landmark or current ultrasound-guided PCB technique as it avoids the risk profile of traversing the psoas muscle body and near the exit of the lumbar plexus nerve roots.

This study aims to follow up on the inital case series discussed above to evaluate the efficacy of the SPF block for post op analgesia in patients undergoing hemiarthroplasty surgery.