1. From the Departments of Radiology (J.G., R.S., C.S., L.F., C.W.A.P.) and Orthopedic Surgery (S.R.), Balgrist University Hospital, University of Zurich, Forchstrasse 340, 8008 Zürich, Switzerland; and Department of Radiology, HFR, University of Fribourg, Fribourg, Switzerland (J.G.).