Optimal rotational positioning of tibial component in total knee arthroplasty: determined by linker surgical technique using a high definition CT.

Introduction: The rotational alignment of femoral and tibial components is an important determinant of the success of Total Knee Arthroplasty (TKA). The optimal rotational position of the tibial component is still unclear. The purpose of this study was (1) to determine the pre-operative S-TEA (surgical-transepicondylar axis) derived tibialanteroposterior (AP) axis angle and postoperative tibial component axis angle using a "Bird's eye" high-definition CT image in TKA performed by Linker surgical technique; (2) to determine the femorotibial mismatch angle; and (3) to determine the optimal tibial component rotation in a well-aligned femoral and tibial components.
Materials and Methods: 55 knees in 49 osteoarthritis patients who underwent primary TKA by Linker surgical technique were evaluated. Preoperative tibial AP axis angle, and the postoperative tibial component axis angle were measured. Rotational mismatch between femoral and tibial components was also measured.
Results: The mean angle of the pre-operative tibial AP axis was 17.8° ± 4.0°, ranging from 4.3° to 25.4°. The mean angle of the post-operative tibial component axis was 16.2° ± 4.9°, ranging from 3.8° to 25.2°. The mean postoperative tibial component axis line was at 14.2% ± 11.9%.
Conclusion: Because of the variability of pre-operative S-TEA derived tibial AP axis angle, the tibial component axis angle was also variable among the knees, but the two angles bore a strong correlation to each other. Based on our results, the optimal axis of the tibial component passes about halfway through the medial edge and medial one-third of the tibial tuberosity.
Level of Evidence: Level II.