Failure Analysis of a Humeral Shaft Locking Compression Plate-Surface Investigation and Simulation by Finite Element Method

A case study of a failed humeral shaft locking compression plate is presented, starting with a clinical case where failure occurred and an implant replacement was required. This study uses finite element method (FEM) in order to determine the failure modes for the clinical case. Four loading scenarios that simulate daily life activities were considered for determining the stress distribution in a humeral shaft locking compression plate (LCP). Referring to the simulation results, the failure analysis was performed on the explant. Using fracture surface investigation methods, stereomicroscopy and scanning electron microscopy (SEM), a mixed mode failure was determined. An initial fatigue failure occurred followed by a sudden failure of the plate implant as a consequence of patient's fall. The fracture morphology was mostly masked by galling; the fractured components were in a sliding contact. Using information from simulations, the loading was inferred and correlated with fracture site and surface features.