[1] Univ Hosp Bern, Inselspital, Dept Diagnost Radiol, CH-3010 Bern, Switzerland
[2] Univ Hosp Bern, Inselspital, Dept Orthoped Surg, CH-3010 Bern, Switzerland
[3] Univ Calif San Francisco, Dept Radiol, San Francisco, CA 94143 USA
[4] Lindenhofspital, Bern, Switzerland