The purpose of this work was to:​ 1) Identify in vivo failure mechanisms of bone cement;​ 2) Identify parameters Influencing the predominant failure mode;​ and 3) to implement materials science concepts to Improve the bone cement with respect to critical failure modes.

Observations of the fracture morphology of failed specimens retrieved from patients, coupled with known fracture surfaces as a basis for comparison, identified fatigue fracture as a predominant in vivo failure mechanism. Analysis of the fatigue crack damage zone revealed that bone cement does not craze like many polymers;​ the damage zone is characterized by microcracks. Coalescence of microcracks creates the characteristic irregularity of the fatigue fracture surface. An investigation of the Interaction of four microstructural phases of bone cement and the fatigue damage zone revealed that the microcracks formed preferentially in the inter-bead matrix phase. The molecular weight distributions of the two different polymer phases could not be implicated as the causative factor for the preferential inter-bead matrix microcracking. Pores were Indicted as preferential nucleation sites of microcracks In the damage zone, revealing the mechanism associating porosity with fatigue fracture.

A clinically workable, titanium fiber reinforcement scheme was implemented allowing the investigation of fiber reinforcement mechanisms leading to improvements of the fracture characteristics of bone cement. The fracture toughness at 5% volume content was increased more than 50% over a control. The increase in fracture toughness was generally independent of fiber dimensions and the bone cement matrix. Mechanisms that potentially contribute to the increase in fracture toughness were observed.

Fatigue studies were performed on fiber reinforced bone cement, centrifuged bone cement, and centrifuged, fiber reinforced bone cement, compared to a control. Both notched and non-notched specimens were tested to investigate fatigue crack initiation and fatigue crack propagation. The reinforced bone cement showed an outstanding Improvement in fatigue crack propagation resistance. The porosity reduction increased the fatigue crack propagation resistance, but had a more dominant effect on the fatigue crack initiation. The combination of fiber reinforcement and centrifugation produced fatigue lives superior to either treatment alone, over an order of magnitude greater than the control.