Exploring Humerus Bone’s Fracture Patterns and Fixation Systems Via Laser Vibrometry

Abstract Background The mechanical performance assessment of orthopedic fixation systems is computationally and experimentally challenging due to the complex geometrical and mechanical features of bones. Non-contact experimental techniques, widely adopted in several engineering fields, is shown to overcome these issues. Objective This work discusses a comparative experimental investigation into specimens mimicking healthy humerus bones and fractured bones subject to an innovative surgery procedure and to a classical technique referred to as the gold standard surgery. The new surgery consists in the installation of an external fixation mechanism that constrains, according to different spatial patterns, a certain number of titanium slender bars inserted and clamped into the fractured bones. Methods The mechanical properties of artificial bones are characterized through compressive tests, while the morphology of the fracture surface is analyzed using a scanning electron microscope. A three-dimensional laser vibrometer is used to measure the resonance frequencies, mode shapes, damping ratios, and mechanical waves propagating from the actuators across the surface of the bones. Results The results provide insights into which configuration of the fixator performs better for a fast recovery. Based on the observed dynamic behaviors, the optimal configuration of the fixator offers performance that is comparable to, or potentially better than, the gold standard surgical procedure. Conclusions The novelty and feasibility of the adopted experimental approach paves the way towards the adoption of advanced non-contact techniques for the mechanical characterization of complex, non-homegenous and anisotropic materials and structures in biomedical applications enabling also data-driven models of the systems.