1Department of Medicine, University of Cambridge, Cambridge, United Kingdom
2Present address: Department of Nuclear Medicine, Queen Elizabeth Hospital, Birmingham, United Kingdom
3Department of Orthopedics, Peterborough District Hospital, Peterborough, United Kingdom
4Orthopedic Research Unit, University of Cambridge, Cambridge, United Kingdom
5Present address: Ayr & Arran National Health Service Trust, Ayr, United Kingdom
6Department of Radiology, Johns Hopkins Outpatient Center, Baltimore, Maryland, USA