Human variation and its influence on fracture outcomes in experimental tibial blunt trauma

Interpreting skeletal trauma requires understanding how fracture outcomes reflect both extrinsic loading conditions and intrinsic biological variation. However, the contribution of biological variability to fracture behavior remains poorly defined, even under controlled loading conditions. This study examines how intrinsic factors influence fracture outcomes in human tibiae subjected to blunt impacts. Sixty human tibiae were experimentally loaded under consistent dynamic four-point bending conditions. Fracture count and morphology were evaluated in relation to age, sex, body composition, and tibial geometry using descriptive, bivariate, and multivariate statistical approaches. Fracture outcomes ranged from simple to complex despite identical loading conditions. Fracture count showed limited association with biological or skeletal variables and was a limited standalone indicator of trauma severity under controlled conditions. Fracture morphology varied across sex and showed significant differences with BMI, weight, and age. Multivariate statistics identified clustering patterns not apparent in univariate analyses. These findings indicate that intrinsic biological variability contributes to fracture outcomes and that fracture morphology reflects the interaction of biological and mechanical factors and extrinsic loading. Together, these results show that both the individual and the event contribute to fracture morphology, limiting its use as a standalone indicator of force or injury mechanism in forensic interpretation.