In Vivo Ultrasound Characterization of the Tibial Nerve at the Supramalleolar Region

BACKGROUND: Accurate knowledge of the supramalleolar anatomy of the tibial nerve is essential for safe ultrasound-guided procedures and proximal nerve interventions in the foot and ankle. However, quantitative in vivo ultrasound reference data describing its positional anatomy at this level remain scarce. METHODS: An in vivo ultrasound anatomical study was conducted in 100 healthy volunteers to evaluate the supramalleolar position of the tibial nerve. Measurements included the distance from the medial border of the tibial cortex to the center of the nerve, nerve depth from the skin surface, nerve perimeter, and the anatomical relationship between the tibial nerve and the posterior tibial artery. Associations with sex and anthropometric variables were analyzed using appropriate inferential statistical tests. RESULTS: Ultrasound imaging demonstrated a stable and predictable anatomical configuration of the tibial nerve at the supramalleolar level, with bifurcation observed in only 1% of cases. Men showed a greater distance between the tibial nerve and the medial tibial cortex compared with women (p = 0.009), whereas women exhibited greater nerve depth (p = 0.003). The tibial nerve-tibial cortex distance was positively correlated with body weight (p < 0.001), body mass index (p = 0.001), and malleolar circumference (p = 0.004). No significant associations were observed between anthropometric variables and the anatomical relationship between the tibial nerve and the posterior tibial artery (p > 0.05). CONCLUSIONS: The tibial nerve at the supramalleolar level exhibits a stable in vivo anatomical arrangement with minimal branching variability. These ultrasound-based reference values provide clinically relevant information that may enhance diagnostic assessment and support ultrasound-guided procedural planning in the foot and ankle.