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arthroplasty (TKA). In the other hand, one of its clinical problems was invasion such as largerskin incision and duration of operation. New navigation system was developed to cut the boneminimally invasively for TKA. The purpose of this study was to evaluate the new navigationsystem to cut the bone using reference points in the limited area.(Material and Methods)The accuracy of new developmental navigation system (CT-based) was compared with imagefreeBrainLAB navigation system. This new system was only required the reference points fromunilateral small limited area of femoral condyle and proximal tibia to obtain the optical images.Three-dimensional geometrical bone model was generated from the previously obtained CTimages of cadaveric knee with 3D image analysis software (Mimics, Materialise) and thenconstructed with 3D-CAD software (Imageware1.0, EDS). Bone cutting was achieved by usingthis navigation system (group D) and BrainLAB navigation system (group B) at the same time.The cut surface was measured using 3D surface scanner (Mitsutoyo, JPAPAN). The accuracywas evaluated by comparing the data from 3D surface scanner to these from the two navigationsystems. In clinical situation, we underwent 5 TKA using the two navigation systemsimultaneously. Bone resection was performed in based on group B directions. We evaluatedthe deviation of cutting surface angle and placement in these group D using the group Bmethod.(Results)The deviation in group D / group B data to comparison with 3D scanner measure data was0.8/1.0 degree on coronal plane, 0.9/3.0 degree on sagittal plane, and 1.1/1.0 mm on boneresection at the cutting surface of distal femur. The deviation of anterior femur was 1.6/2.0degree on rotation, 1.7/0.5 degree on sagittal plane and 2.4/0.7 mm on bone resection. Thedeviation of proximal tibia was 0.9/0.3 degree on coronal plane, 0.3/1.5 degree on sagittal planeand 0.8/1.1 mm on bone resection. The accuracy of both group D and group B was sufficientfor the appropriate position in previous reviews. In clinical situation, the deviation of group Dto group B was 1.1 degree on coronal plane, 1.7 degree on sagittal plane and 0.3 mm on boneresection at the cutting surface of distal femur. The deviation of anterior femur was 1.6 degreeon rotation, 1.0 degree on sagittal plane and 1.9 mm on bone resection. The deviation ofproximal tibia was 0.2 degree on coronal plane, 0.1 degree on sagittal plane and 1.4 mm on boneresection. The deviation of group D to group B was less than 2 degree and 2 mm.(Discussion)Although new developmental navigation system had the variability for the rotation and boneresection amount of anterior femur side, this system achieved that the alignment error was lessthan 2 degree and the position error was less than 2 mm. Our navigation system had enoughaccuracy for the bone resection of the knee even in small registration area.Poster: 116Comparison of Three Different Navigation Systems of Accuracy in Revisionfile:///E|/ISTA2010-Abstracts.htm[12/7/2011 3:15:47 PM]