Pre-Incision Peripheral Nerve Blocks Versus No Peripheral Nerve Blocks for Lower Extremity Fracture Surgery in Older Adults: A Pilot Feasibility Study

The potential for peripheral nerve blocks to improve clinical outcomes beyond analgesia is based on their ability to interrupt the physiologic stress response to surgical trauma near its origin. Tissue injury triggers nociceptive signals that travel through peripheral nerves to initiate a cascade of neuroendocrine and inflammatory responses, including the release of catecholamines, activation of the hypothalamic-pituitary-adrenal axis, and systemic inflammation. While younger patients can tolerate this stress response, older adults with limited physiologic reserve may experience organ dysfunction when these compensatory mechanisms become overwhelmed. By blocking afferent neural transmission before it reaches the central nervous system, peripheral nerve blocks may attenuate this cascade, potentially reducing sympathetic surge, myocardial oxygen demand, and the release of inflammatory mediators. Additionally, effective peripheral nerve blocks can reduce opioid requirements, avoiding adverse effects including respiratory depression, delirium, and impaired mobilization that particularly affect older adults. These mechanistic advantages may be especially important in older adults with lower extremity fractures, who face both the initial trauma and the additional physiologic burden of surgical repair.

While peripheral nerve blocks are well-established components of multimodal analgesia, emerging evidence suggests their benefits may extend beyond short-term analgesic effects. Recent studies of older adults with hip fractures have found peripheral nerve blocks are associated with additional benefits including reduced mortality, fewer serious adverse events, and increased days alive out of hospital. However, evidence for fractures distal to the hip remains limited. Although current Orthopaedic Trauma Association guidelines recommend peripheral nerve blocks as part of multimodal pain management for hip fractures, time pressures, and uncertainty about benefits beyond short-term analgesia have resulted in variable adoption among anesthesiologists and orthopaedic surgeons. Evidence supporting broader use of peripheral nerve blocks for improving clinical outcomes in lower extremity fractures is still needed.

To address this knowledge gap, a large multicenter randomized controlled trial is needed. However, prior to initiating such a trial, a pilot feasibility study will be conducted comparing pre-incision peripheral nerve blocks to no peripheral nerve blocks. The primary objective is to assess feasibility in terms of patient recruitment, adherence to treatment allocation, data collection methods, protocol compliance, and participant follow-up. This pilot phase will allow for refinement of the primary outcome measure, optimization of data collection procedures, establishment of recruitment rates, and identification of potential barriers to implementation before committing resources to a large-scale definitive trial.