[1] Department of Orthopedics,
[2] Westfälische Wilhelms-Universität,undefined
[3] Albert-Schweitzer-Str. 33,undefined
[4] 48149 Münster,undefined
[5] Germany e-mail: hillmaa@uni-muenster.de,undefined
[6] Tel.: +49-251-8347963,undefined
[7] Fax: +49-251-8347989,undefined