Objectives: To develop a model for investigating mechanisms of injury and mathematical method for determining the degree of force necessary to result in the types of fractures seen in child abuse. Methods: An animal model was chosen to establish the methodology due to low availability of infant human specimens. Mechanical testing was performed on 25 infant porcine femurs using an MTS Bionix machine. Radiographs and bone mineral densitometry scans were obtained on each bone to generate geometric and content parameters. Failure load (force applied for fracture) and energy to failure (work required to overcome bone stiffness) were mechanically measured. Two types of force were applied to evaluate bone strength. For transverse fractures, force was applied in three-point bending, simulating direct injury through impact. Spiral fractures were created by torsional load application, simulating indirect injury through rotation. Geometric and bone mineral data were incorporated to compute parameters related to bone strength and then correlated to failure loads. Linear regressions relating computed parameters to the experimentally determined mechanical data were calculated. Results: Three-point bending consistently resulted in transverse fractures. Torsional loading resulted in spiral fractures or growth plate failures. There was a highly reproducible relationship between the computed strength parameter and the measured failure strength. The correlation coefficients (r squared) for failure loads and energy to failure in 3 point bending were 0.92 and 0.88. The difference between predicted and actual force, and predicted and measured energy to failure was (4.74±3.72)% and(12.19±4.28)% respectively. For torsion the correlation coefficients (r squared) for failure load and energy were 0.89 and 0.62 with predictability errors of (11.02±7.93)% and (39.55±33.54)% respectively. Conclusion: This in-vitro study establishes a methodology for predicting with a high degree of certainty the amount of force necessary to fracture a specific bone and introduces an innovative, promising method for future establishment of objective data to evaluate history and mechanism of injury in children with long bone fractures.