In femoral head osteonecrosis, the processes of subchondral fracture and head collapse are mechanical events, and therefore are amenable to study using techniques of biomechanics, especially finite element analysis. Also, most interventions undertaken to forestall collapse attempt to do so by providing a mechanically more favorable environment for weakened areas of the head, and in many instances their structural efficacy can be quantified. This article reviews the literature on the biomechanics of osteonecrosis, focusing on how the lesion morphology influences collapse risk, and the degree to which surgical interventions serve to reduce that risk. Interventions considered include osteotomy, core drilling, and structural bone grafting.