Predictive Model of Tibial Nerve Depth for Needle-Based Interventions With Broader Applications: An Observational Study in a Spanish Cohort

Objective: To develop a predictive model for estimating the depth of the tibial nerve using anthropometric and demographic data to improve the safety and accuracy of needle-based interventions.

Design: Cross-sectional observational study.

Setting: European University of Madrid, Spain.

Methods: Fifty volunteers aged 18–45 years, without any conditions affecting muscle tone, significant lower limb asymmetries, or history of lower limb surgeries. Demographic and anthropometric data, including sex, age, height, weight, BMI, and measurements of leg length and circumference at specific points, were collected. Ultrasound imaging was used to measure the depth of the tibial nerve at the popliteal fossa and mid-third of the leg.

Results: The predictive model identified leg girth at the mid-third as a significant predictor of tibial nerve depth, explaining 22.3% of the variance (R² = 0.223, p < 0.05). Gender and leg girth together explained up to 17.8% of the variance for proximal tibial nerve depth (R² = 0.178, p < 0.05). Additionally, males exhibited greater leg length (mean = 95.9 cm) compared to females (mean = 90.8 cm, p = 0.01), with no significant difference in tibial nerve depth between genders (p > 0.05). Strong correlations were observed between tibial nerve depth and BMI at both the proximal and mid-third levels (r = 0.4–0.5, p < 0.001).

Conclusion: This predictive model shows that leg girth and gender are significant predictors of tibial nerve depth in a healthy cohort. However, its clinical utility remains preliminary and requires external validation in larger, diverse, and pathology-specific populations to confirm broader applicability in clinical settings.