1. McKay Orthopaedic Research Laboratory; Department of Orthopaedic Surgery; Perelman School of Medicine; University of Pennsylvania; 36th Street and Hamilton Walk Philadelphia 19104 Pennsylvania
2. Translational Musculoskeletal Research Center; Corporal Michael J. Crescenz VA Medical Center; Philadelphia Pennsylvania
3. Department of Bioengineering; School of Engineering and Applied Science; University of Pennsylvania; Philadelphia Pennsylvania