An Explorative Anatomical Study on Inter-Individual Variation of the Tibial Nerve and Landmarks for Perineural Anesthesia in Horses.

The research is about the investigation of the tibial nerve anatomy in horses and determining optimal points for perineural anesthesia injection. No significant variations were observed in the anatomy, but the nerve thickness and amount of perineural tissue could make achieving effective anesthesia difficult.

Objective of the Research

In this study, the researchers examined to understand the anatomy of the tibial nerve in horses. They attempted to track the course of the tibial nerve, record any potential anatomical variations, and identify the best landmarks for injecting perineural anesthesia.

• The procedure of perineural anesthesia in horses can be guided by ultrasound or done blindly. However, the blind method is more commonly used in veterinary practice due to practical constraints.
• The lower accuracy of the blind injection approach could lead to failure to achieve desensitization, and this can be tied to anatomical variations or possibly insufficient landmarks for injection.

Methodology

The research team dissected the medial aspect of the tibia of 10 paired cadaver hindlimbs to investigate the nerve’s course.

• No anatomical variants of the tibial nerve were encountered during the dissections.
• The average thickness of the tibial nerve was measured to be 6 ± 1 mm.
• The junctions of the tibial nerve with the plantar nerves and the medial cutaneous branch were located at maximum distances of 85 mm and 150 mm, respectively, proximal to the proximal edge of the calcaneal tubercle.
• The average distance of the tibial nerve to the cranial border of the superficial digital flexor was calculated to be 11 ± 6 mm.

Conclusions

The study concluded that problems with perineural anesthesia of the tibial nerve may not necessarily be due to anatomical variations.

• The thickness of the nerve and the amount of perineural tissue can pose specific challenges in attaining effective desensitization.
• The results obtained align with the generally recommended site for tibial nerve perineural injection being 100 mm proximal to the calcaneal tubercle and 11 mm cranial to the superficial digital flexor.