Authors describe their first experience with a computerized navigation system for cup insertion in THR (Medivision). Computer navigation systems started first at the Müller Institute (Bern) in 1991 when prof. Nolte inserted his first pedicle screw in a spine specimen.

In January 1997 a CT-based cup module for hip pros-thesis was developed in laboratory by prof. Nolte. At the end of 1998 a first clinical trial on a CT-based cup navigation started in Maastrict by Prof. Geesink. A new CT-free cup navigation module appeared on the scene at the end of 2000. The first clinical successful CT-free cup navigation was performed in Ludwigshafen by Dr. Grützner in January 2001.

More then 3000 hip implants have been done with good results in Europe. A postoperative CT accuracy study of cup orientation shows mean error of about 5° (to be published by Bernsmann et al. in summer 2001). Medivision uses in orthopedic surgery are multiple. Spine surgery, Pelvic Osteotomy, C-arm Navigator, C-arm Nailing, CT-based Cup, CT-free Cup, ACL-reconstruction, Total Knee Replacement. We used Medivision first in THA to asses cup orientation and lower limb length. First results confirm system reliability. The feeling with this computer-guided surgery is good and grew up every new case. Learning curve is not so long and deep if few principles are used.