Convened under the auspicious of esteemed endorsers - ISTA

ResultCup geometries with screws had been prepared and cup position with screws direction werevery useful. The edge of acetabulum and cup edge are well compared then could obtain a bettercup alignment. Screws are said to be safe if they were inserted in upper posterior quadrant.However so long as the cluster cup was used, when the cup was given 30 degrees anteriorrotation, 25 mm screw was still acceptable using CAT angiography.ConclusionThree dimensional display without goggle was a useful tool to observe preoperative planninginside the operation theater.Saturday, October 9, 2010, 16:00-16:50Session B22: Arthroplasty- Getting it Right!Accuracy of Cup Center Position, Leg Length, and Offset in Image-FreeHip Navigation System*Fumiaki Inori - Saisekai Nakatsu Hospital - Osaka city, JapanHirotsugu Ohashi - Department of Orthopaedic Surgery, Saiseikai Nakatsu Hospital - Osaka,JapanHirotake You - Saiseikai Nakatsu Hospital - Osaka, JapanYoshiaki Okajima - Osaka Saiseikai Nakatsu Hospital - Osaka, JapanKenji Fukunaga - Dept. of Orthopaedic Surgery, Osaka City University Graduate School ofMedicine - Osaka, JapanHideyuki Tashima - Saiseikai Nakatsu Hospital - Osaka, Japan*Email: inorin@flute.ocn.ne.jpIn previous congress of ISTA in Hawaii, we reported the results about accuracy of the cupcenter position in our image-free navigation system. In the new version of our navigationsystem, leg elongation and offset change as well as cup center position can be navigated. In thisstudy, we therefore investigated the accuracy of cup center position, leg elongation and offsetchange.Twenty four THA operations were performed with using the image-free OrthoPilot THA3.1dysplasia navigation system (B. Braun Aesculap, Tuttlingen, Germany) between August 2009and December 2009 by three experienced surgeons. In this system, cup center height was shownas the distance from tear drop, and cup medialization was shown as horizontal distance frominner wall of acetabulum. Leg elongation and offset change were navigated by comparing thetwo reference points in femur between registration before neck resection and that after insertingthe trial implant. After operation, the cup angles were measured on CT image, and cup centerposition, leg elongation and offset change were measured on plain radiography. We comparedthese values that indicated by the navigation system to those measured on the CT image and theplain radiography.The average cup inclination was 37.5 ± 7.0 degree and anteversion was 22.2 ± 4.7 degree. Thefile:///E|/ISTA2010-Abstracts.htm[12/7/2011 3:15:47 PM]