Morphometric variability of the gracilis muscle and obturator nerve: A cadaveric study informing reconstructive and surgical innovations

The gracilis muscle is frequently utilized in reconstructive surgery and tendon transfer procedures due to its reliable anatomy and functional versatility. While its general anatomy is well described, detailed morphometric variability related to sex, body weight, and internal scaling relationships remains incompletely characterized. Longitudinal width gradients and their relationship to overall muscle length have not been well defined. Improved understanding of these variations may enhance surgical planning, graft selection, and prosthetic design. Sixty-four formaldehyde-embalmed cadaveric donors were dissected to expose the gracilis muscle and the obturator nerve. A total of 128 gracilis specimens derived from 64 bilateral donors were analyzed. Direct caliper measurements were obtained for total gracilis length with tendon (GMLT), muscle belly length (GML), muscle width at 5-cm intervals (W5 proximal–W25 distal) measured along the muscle belly from its proximal origin, and obturator nerve length. Donor sex and recorded body weight were analyzed for associations with morphometric parameters. Statistical analysis was performed using Spearman correlation and group comparison. Width-level analyses were treated as exploratory, and results are reported with effect sizes rather than formal multiplicity-adjusted significance testing. Minimal side-to-side differences were observed for gracilis length and width (<1% variation). Males demonstrated greater gracilis length with tendon (42.83 ± 3.43 cm vs 40.29 ± 4.38 cm), muscle belly length (28.89 ± 3.17 cm vs 27.47 ± 3.03 cm), distal muscle width, and obturator nerve length (12.68 ± 2.03 cm vs 10.85 ± 1.82 cm) than females. The mean difference in gracilis length with tendon between sexes was 2.54 cm (95% CI: 0.62–4.46 cm). Body weight showed weak correlations with gracilis length (r = 0.14–0.19) but moderate correlations with muscle width, particularly proximally (W5 r = 0.46; W10 r = 0.47). Positive internal scaling relationships were identified between total muscle length and distal width (W25 r = 0.73), indicating a predictable geometric organization of the gracilis muscle. Gracilis muscle morphology demonstrates positive internal scaling patterns and sex variability and moderate weight-related variability while remaining highly conserved with respect to laterality. These findings may be relevant for graft harvest and reconstructive planning. These findings support the importance of patient-specific anatomical considerations during gracilis tendon harvest, transfer length estimation, and reconstructive planning. Incorporating morphometric variability into surgical decision-making may improve procedural accuracy and functional outcomes.