1. From the Departments of Radiology (L.F., A.B.R., R.S., C.W.A.P.) and Orthopedics (S.F.F.), Balgrist University Hospital, Forchstrasse 340, CH-8008 Zurich, Switzerland; and Faculty of Medicine, University of Zurich, Zurich, Switzerland (L.F., A.B.R., R.S., S.F.F., C.W.A.P.).