This article reviews a series of biomechanical studies performed in the author's laboratory, evaluating the instabilities produced by the more common and problematic pelvic ring fracture patterns and the increasingly popular and newly developed modes of internal fixation. Topics that are discussed include the following: anteroposterior compression injuries and the disrupted sacroiliac joint; sacral fractures; anteroposterior compression injuries and symphyseal fixation; new symphyseal plate designs; unstable pubic rami fractures; unstable fractures of the iliac wing; and resuscitation fixator biomechanics.