Development of an ultrasound-guided radiofrequency ablation technique in the equine cadaveric distal limb: histological findings and potential for treating chronic lameness.
Authors: Amari Martina, Rabbogliatti Vanessa, Ravasio Giuliano, Auletta Luigi, Brioschi Federica Alessandra, Riccaboni Pietro, Dell'Aere Silvia, Roccabianca Paola
Journal: Frontiers in veterinary science
Summary
Radiofrequency ablation (RFA), a well-established pain management technique in human medicine, has never been systematically evaluated for treating chronic equine lameness until now. Researchers developed an ultrasound-guided technique to ablate the palmar digital nerves at the fetlock and pastern in ten cadaveric equine forelimbs, testing four temperature and duration protocols (ranging from 60°C for 6 minutes to 90°C for 2 minutes) and examining the resulting histological changes across 40 total treatments. The procedure successfully reached the target nerve in 31 of 40 cases, with significantly more failures at the fetlock than the pastern; histological analysis revealed that successful ablations produced axonal degeneration, collagen homogenation, and thermal coagulation of nerve tissue, effects that increased with treatment intensity and proper needle positioning. The findings demonstrate that consistent ultrasound visualisation and accurate needle placement are critical for effective nerve damage, with the higher-intensity protocols showing the most reliable coagulation. For practitioners managing horses with chronic distal forelimb lameness unresponsive to conventional therapies, these results suggest that in-vivo clinical trials of RFA merit serious consideration, potentially offering a new interventional option for pain relief when other treatments have failed.
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Practical Takeaways
- •Ultrasound-guided radiofrequency ablation of palmar digital nerves is technically feasible in horses and produces reproducible thermal damage to target nerves, offering a potential new pain management tool for chronic forelimb lameness.
- •Accurate needle positioning very close to the target nerve is critical for treatment success; the pastern location appears more accessible than the fetlock using this technique.
- •This cadaveric proof-of-concept supports progressing to clinical trials, but practitioners should await in vivo safety and efficacy data before considering this technique for chronic lameness cases.
Key Findings
- •Palmar digital nerves were consistently visualized on ultrasound in transverse palmaro-lateral and palmaro-medial views at fetlock and pastern, positioned close to the palmar digital artery.
- •Ultrasound-guided radiofrequency ablation successfully targeted the nerves in 31/40 cases (77.5%), with significantly higher failure rates at the fetlock (p=0.008) compared to pastern.
- •Radiofrequency ablation produced thermal injury with axonal degeneration and collagen homogenation, with nerve coagulation significantly associated with treatment intensity (p=0.03) and needle-to-nerve proximity (p=0.009).
- •HIGH (90°C, 2 min) and VERY HIGH (80°C, 8 min) radiofrequency settings demonstrated the most effective nerve coagulation and warrant in vivo clinical testing for chronic distal forelimb lameness in horses.