Morphological Analysis of Retrieved Cross- linked UHMWPE and I mproved Microstructures for Enhanced Fatigue and Wear Performance Lisa A. Pruitt, Ph.D. Department of Mechanical Engineering, UC Berkeley, Berkeley, CA Correspondence addresses: Lisa A. Pruitt, Ph.D. Chancellor's Professor Director, Medical Polymers and Biomaterials Group Professor of Mechanical Engineering and Bioengineering Adjunct Professor of Orthopaedic Surgery, UCSF 5134 Etcheverry Hall UC Berkeley Berkeley, CA 94720-1740 Office:510.642.2595 Lab: 510.643.5599 Email:lpruitt@me.berkeley.edu 126