VARIABILITY OF REFERENCE AXES FOR FEMORAL COMPONENT ROTATION MEASURED INTRA-OPERATIVELY IN NAVIGATION ASSISTED TOTAL KNEE ARTHROPLASTY USING GAP TECHNIQUE

Abstract

Achieving the correct amount of femoral component rotation has become the basic objective of surgical techniques in total knee arthroplasty and this can be done either with a measured resection technique or indirectly by flexion/extension gap equalization technique. We demonstrated the variabilities of the reference axes (PCA, WSL, TEA) when soft tissue tension was managed intraoperatively by navigation system. The mean angle of transepicondylar line, Whiteside’s line, posterior condylar line from the proximal tibia resection plane were 1.29 ± 3.67 (mean ± SD; range 7 to 10.5), 3.90 ± 4.17 (mean ± SD; range 3 to 15.5), −4.03 ± 2.71 (mean ± SD; range 9.5 to 1.0) respectively. Coefficient of variation(CV(%); std/mean × 100) were 283, 106, 67 respectively. Out of the 3 reference axes widely used for femoral component rotation, angles from proximal tibia resection plane to posterior condylar line showed the least range of variance.