This study presents common rib fracture patterns and influential variables and provides probabilistic statements to guide rib fracture interpretations.
Forensic anthropologists receive more requests for trauma analysis than any other aspect of the biological profile. Blunt force trauma to the ribs is some of the most common trauma recorded in a medical examiner’s setting, however the structural complexity of ribs makes it difficult to move beyond descriptive documentation of injuries. A sample of 1,415 deceased individuals with known blunt force trauma to the torso were collected from four geographically diverse medical examiner offices. Demographic data and fracture variables were recorded per individual. Frequency distributions, chi-squared tests, Kruskal-Wallis tests of independence, Dunn’s tests, and multiple correspondence analysis were employed to understand variable relationships. Conditional probabilities were calculated to provide probabilistic statements. Additionally, random forest analysis was conducted to classify location and type of fracture based on covariates. A total of 24, 853 fractures were recorded. The most common fractures were displaced and simple fractures on ribs three through seven in the anterolateral and posterolateral locations. The less common fracture patterns revealed significant relationships with demographic data and provided empirical evidence for previously untested statements. BMI had a significant relationship with location, such that fractures were more frequently recorded in lower ribs in individuals with a BMI category of obese. Age had a significant relationship with fracture type and fracture location in all analyses; younger individuals were more likely to have incomplete fractures and incur fractures anteriorly, and older individuals were more likely to have multi-fragmentary fractures. The current study indicates that rib fracture types and location are dependent on the demographics of the individual. Demographics, such as age and health of the individual inform the material properties and structural geometry of bone, which is how bone biomechanics are recommended to be incorporated into trauma analysis. Furthermore, the results from this research can be applied to motor vehicle safety research, experimental research avenues, and bioarcheological trauma analysis. Future rib fracture research should focus on including a more holistic view of an individual during the interpretation of fracture patterns. (Published abstract provided)