Morphometric analysis of the axillary nerve in relation to the deltopectoral and deltoid-splitting approaches: implications for surgical safe zones

Abstract Purpose The deltopectoral splitting approach is commonly used in shoulder surgery; however, injury to the axillary nerve remains a major concern due to potential motor and sensory deficits. This study aimed to define the anatomical relationships of the axillary nerve to surrounding structures in order to optimize surgical access and minimize the risk of iatrogenic injury. Methods Thirty formalin-fixed cadavers (15 males, 15 females) were dissected. Quantitative measurements were obtained to determine the position of the axillary nerve relative to the deltopectoral interval and deltoid muscle. Descriptive statistics, reported as means ± standard deviations (SD), were calculated, and independent t-tests were used to evaluate differences based on sex and laterality. Results Sex-specific differences were observed in axillary nerve positioning. The superior safe zone, measured from the acromion to the anterior branch of the axillary nerve, averaged 65.31 ± 10.82 mm in females and 71.18 ± 9.72 mm in males. The distance from the anterior border to the anterior branch was 48.72 ± 10.89 mm in both sexes. In contrast, the posterior branch measured 21.45 ± 9.25 mm in females and 33.03 ± 22.74 mm in males. No significant differences were observed between left and right shoulders ( p ≥ 0.11). Conclusion The deltopectoral approach provides reliable access to the glenohumeral joint while minimizing axillary nerve injury when anatomical variations are considered. These findings underscore the importance of sex-specific morphometric considerations and support the integration of population-specific anatomical data into surgical planning to enhance safety and optimize clinical outcomes.