Biomechanical Engineering

Accident reconstruction generally focuses on how an event occurred, including vehicle speeds, trajectories, impact configuration, scene evidence, and collision sequence. Biomechanical engineering focuses more specifically on how the resulting motion and forces affected the human body. The disciplines often work together: reconstruction can establish event dynamics, while biomechanical analysis addresses occupant or pedestrian motion, loading, contact, and injury mechanisms. NHTSA's crash-injury research similarly distinguishes detailed vehicle and scene analysis from engineering work that identifies contact locations, applied forces, and injury mechanisms.

A biomechanical expert may assess whether the forces, motions, and loading conditions associated with an accident are mechanically consistent with a proposed injury mechanism. However, determining whether the accident actually caused a specific injury may require appropriately qualified medical expertise. The permissible scope of the opinion depends on the expert's qualifications, the available evidence, and applicable law.

Injury does not depend only on the presence of force. The way a load is applied, its magnitude and direction, the rate and duration of loading, body position, and the properties of the affected tissue can influence the resulting mechanical response. Biomechanical analysis uses those relationships to examine how an event could deform, stretch, compress, or otherwise load anatomical structures.