ESRA Newsletter journal Club

ESRA Newsletter journal Club

I am writing this brief letter after receiving the invitation from the ESRA Newsletter Journal Club to present articles that have recently influenced my clinical practice. After an initial moment of hesitation, a few key publications quickly and clearly came to mind, which I will share below. They focus on two main aspects: the pathophysiology of peripheral nerve injury associated with regional anaesthesia and regional analgesia techniques for hip surgery.

Pathophysiology of Peripheral Nerve Injury Associated with Regional Anaesthesia

Several papers published over the last decade by Miguel Ángel Reina have completely revolutionized the understanding of nerve injury pathophysiology related to peripheral nerve blocks, challenging long-established axioms, beliefs, and myths upheld for over three to four decades. Although it is difficult to choose just one, I would highlight the editorial titled: “Redefining needle placement and pressure monitoring in regional anesthesia: insights from advanced imaging and innovative technologies”.¹

As an editorial, and thus an article of opinion and reflection, it may inherently carry a significant bias. Despite this, the authors masterfully compile the evidence generated in the past decade regarding the anatomy of peripheral nerves. They describe the internal epineurium, a circumfascicular membrane that encloses multiple fascicles and essentially defines “nerves within a nerve”; the circumneurium, a novel connective tissue structure outside the nerve that interacts with the epineurium; and the fact that human peripheral nerves are polyfascicular (except for brachial plexus roots, which are mono- or oligofascicular). The fascicles themselves are much smaller than the needles commonly used in clinical practice, making intrafascicular needle placement nearly impossible. Additionally, they emphasize the robust, protective fibrous layer that constitutes the endoneurium, a tight and resilient barrier that hinders the penetration of injected solutions.

The paper also highlights the limitations of classic studies on opening injection pressure monitoring, as these were conducted on mono- or oligofascicular animal models and are therefore not directly extrapolable to humans. Furthermore, the authors discuss the physical constraints of current pressure monitoring systems and their inability to determine whether a pressure increase results from needle-nerve or needle-fascia contact.

Hip Analgesia Techniques

My clinical experience has led me to delve into the innervation of the hip joint. One particular paper has reshaped my understanding of hip innervation, prompting me to explore additional research and ultimately revise my approach to analgesia for hip surgery—particularly for arthroscopic procedures but also in my regional technique for total hip arthroplasty. This paper is a systematic review and meta-analysis on hip capsule innervation: “A systematic review and meta-analysis of the hip capsule innervation and its clinical implications” ², authored by Joanna Tomlinson, an anatomist from the University of Otago, New Zealand, who is arguably the foremost expert in this field.

In this paper, the authors highlight the significant variability in reported hip capsule innervation among different studies, with numerous nerves involved. They establish the prevalence of each nerve’s contribution and underscore the potential importance of the posterior capsule, which may play a more significant role than previously thought. Specifically, they document systematic innervation from sacral plexus nerves such as the nerve to quadratus femoris (99% prevalence), the superior gluteal nerve (57%), and branches of the sciatic nerve (51%).

This insight led me to explore and eventually incorporate recently published posterior capsular block techniques into my practice, such as the Posterior Hip Pericapsular Neurolysis³ and the Deep Posterior Gluteal Compartment Block,⁴ which I now use systematically in combination with anterior capsular-focused techniques—especially the IlioPsoas Plane Block⁵ or (less frequently) the PENG Block⁶ for primary total hip arthroplasty or hip arthroscopic surgery.

Although no randomized controlled trials (RCTs) have yet been published on the combination of anterior and posterior capsular blocks, my admittedly questionable clinical impression is that this approach enhances analgesic quality for the aforementioned surgeries.

1. McLeod GA, Sala-Blanch X, van Niekerk D, Reina MA. Redefining needle placement and pressure monitoring in regional anesthesia: insights from advanced imaging and innovative technologies.Reg Anesth Pain Med 2025; rapm-2024-106356.
2. Tomlinson J, Ondruschka B, Prietzel T, Zwirner J, Hammer N. A systematic review and meta-analysis of the hip capsule innervation and its clinical implications.Sci Rep 2021; 11: 1–15.
3. Ng TK, Peng P, Chan W. Posterior hip pericapsular neurolysis (PHPN) for inoperable hip fracture: an adjunct to anterior hip pericapsular neurolysis.Reg Anesth Pain Med 2021; rapm-2021-103023.
4. Vermeylen K, Aken D Van, Versyck B, Casaer S, Bleys R, Bracke P, Groen G. Deep posterior gluteal compartment block for regional anaesthesia of the posterior hip: a proof-of-concept pilot study.BJA Open 2023; 5: 100127.
5. Nielsen ND, Greher M, Moriggl B, Hoermann R, Nielsen TD, Børglum J, Bendtsen TF. Spread of injectate around hip articular sensory branches of the femoral nerve in cadavers.Acta Anaesthesiol Scand 2018; 62: 1001–6.
6. Short AJ, Barnett JJG, Gofeld M, Baig E, Lam K, Agur AMR, Peng PWH. Anatomic Study of Innervation of the Anterior Hip Capsule: Implication for Image-Guided Intervention.Reg Anesth Pain Med 2018; 43: 186–92.