1. From the Department of Radiology, Center for Musculoskeletal Care (C.A.A., S.K., G.C.), Department of Orthopedic Surgery, (A.J.R.), and Osteoporosis Center, Hospital for Joint Diseases (S.H.), NYU School of Medicine, NYU Langone Medical Center, 333 E 38th St, New York, NY 10016.