From Block to Cryoneurolysis: Ultrasound-Guided Interventions for the Infrapatellar Branch of the Saphenous Nerve in Knee Surgery: A Narrative Review.

Background: The infrapatellar branch of the saphenous nerve (IPBSN) is a key contributor to perioperative pain after knee surgery. Although ultrasound-guided blocks are well established, related interventions are moving toward longer-acting methods such as cryoneurolysis. Objective: This narrative review evaluated the role of ultrasound-guided IPBSN interventions in perioperative knee analgesia, distinguishing current nerve blocks from emerging technologies. Methods: We conducted a narrative review of the literature on preoperative and postoperative IPBSN interventions, focusing on a qualitative synthesis of the findings. Results: Current high-level evidence (primarily randomized controlled trials) supports targeted IPBSN blocks as an effective component of multimodal analgesia, substantially reducing acute postoperative pain. In contrast, evidence for cryoneurolysis is currently limited to case series and early feasibility studies; however, it shows promising potential for prolonged analgesia, reduced opioid consumption, and shortened hospital stays. Conclusion: The available evidence supports ultrasound-guided IPBSN nerve blocks as a useful component of multimodal analgesia for acute postoperative pain after knee surgery, particularly when administered preoperatively. However, the evidence base for cryoneurolysis remains preliminary and is limited by small sample sizes, variable protocols, and a lack of fully powered randomized trials. Although single-injection nerve blocks represent a relatively well-established technique, cryoneurolysis should still be regarded as an emerging intervention that requires further validation. High-quality, multicenter randomized controlled trials with standardized protocols are urgently needed to clarify the comparative effectiveness, optimal timing, and patient-selection criteria for these interventions.