High-Resolution Ultrasonographic Morphometry of the Superficial and Deep Peroneal Nerves in Healthy Young Adults: Reference Values From an Indian Cohort.

Introduction Peripheral nerve ultrasonography is an important diagnostic modality for evaluating nerve pathologies. Cross-sectional area (CSA) and perimeter measurements are key parameters for diagnosis and clinical management. The deep peroneal nerve (DPN) and superficial peroneal nerve (SPN) are prone to entrapment and traumatic injuries, yet normative morphometric data for these nerves in healthy individuals are limited. Understanding their relationship with anthropometric parameters such as body mass index (BMI) may help refine diagnostic criteria and guide procedures, including nerve blocks and surgical interventions. Aim The study aimed to assess the morphometric characteristics of the DPNs and SPNs using high-resolution ultrasonography (HRUS) in healthy young adults and to evaluate their association with BMI. Materials and methods This cross-sectional observational study was conducted in the Department of Anatomy, King George's Medical University, Lucknow, India, from September 2018 to August 2019. One hundred first-year medical students (50 males, 50 females; age 17-25 years) were included after informed consent. HRUS was performed using a linear array transducer (6-13 MHz) to measure CSA, perimeter, and depth from skin (DFS) of bilateral DPN and SPN at predetermined anatomical sites. The DPN was examined at the fibular neck and 3 cm proximal to the superior extensor retinaculum. The SPN was evaluated at the fibular neck, at the distal one-third of the lateral leg before piercing the deep fascia, and 5 cm above the lateral malleolus. Statistical analysis was performed using SPSS version 21.0 (IBM Corp., Armonk, NY). Paired t-tests assessed bilateral differences, independent t-tests evaluated gender differences, and one-way analysis of variance (ANOVA) compared BMI categories. Significance was set at p<0.05. Results The mean CSA of DPN was 7.90±1.70 mm² at site 1 (fibular neck) and 6.30±1.60 mm² at site 2 (3 cm proximal to the superior extensor retinaculum), with perimeter values of 8.88±1.44 mm and 7.61±1.56 mm, respectively. For SPN, mean CSA values were 8.40±1.80 mm² at site 1 (fibular neck), 6.30±1.60 mm² at site 2 (distal one-third of the lateral leg before piercing the deep fascia), and 5.90±1.40 mm² at site 3 (5 cm above the lateral malleolus), with perimeter measurements of 9.29±1.61 mm, 7.60±1.64 mm, and 7.28±1.53 mm, respectively. Significant bilateral differences were observed, with right-sided nerves larger than left-sided nerves (p<0.001). DPN CSA and perimeter were significantly greater in males than females (p<0.05), whereas SPN showed variable gender differences across sites. DFS measurements indicated both nerves were significantly deeper in females (p<0.001). No statistically significant association was found between nerve dimensions and BMI categories (p>0.05). Conclusion This study provides reference values for DPN and SPN morphometry in healthy young Indian adults. The observed bilateral asymmetry and gender differences highlight the need to consider these factors during ultrasound evaluation. The absence of significant BMI correlation suggests that nerve dimensions in healthy individuals are largely independent of BMI. These findings contribute normative data useful for diagnosing peroneal neuropathies and improving ultrasound-guided interventions.