[1] Department of Orthopaedic Surgery,
[2] Hôpital Cantonal,undefined
[3] CH-1708 Fribourg,undefined
[4] Switzerland e-mail: wachtl@bluewin.ch,undefined
[5] Tel.:+41-26-4267111,undefined
[6] Fax: +41-26-4267225,undefined
[7] Department of Radiology,undefined
[8] Hôpital Cantonal,undefined
[9] Fribourg,undefined
[10] Switzerland,undefined