Abstract
AIMS AND OBJECTIVES: In the past years, further development in knee replacement still continues. Computer-assisted surgery techniques in total knee arthroplasty (TKA) are on the rise. One point of criticism is the prolonged time of surgery and associated cost as known from old techniques like navigation. The primary objective of this study was to determine the learning curve for the time of surgery and accuracy in implant positioning for an imageless robotic system for TKA. MATERIALS AND METHODS: In this prospective study, the first 30 robotic-assisted TKA from a single senior surgeon were analyzed with regard to time of surgery and accuracy of implant position on the basis of the intraoperative plan and the postoperative x-rays. This data was compared to the last 30 manual TKAs of the same surgeon with the same prosthesis. Evaluation of the learning curve was performed with CUSUM analysis. The time of surgery after finishing the learning curve in the robotic group was compared to the manual group. RESULTS: The learning curve in the robotic group for surgery time was finished after 11 cases. The robotic experience did not affect the accuracy of implant positioning, such as limb alignment and restoration of the joint line. The mean absolute deviation of the postoperative limb alignment to the intraoperative plan was 2° (+/- 1,1). The mean absolute deviation of the medial proximal tibial (mPTA) and distal lateral femoral angle (dLFA) was 1° (+/- 0,9) for both. The mean surgery time in the robotic group after finishing the learning curve was 66 minutes (+/- 4,2) and in the total manual group 67 minutes (+/- 3,5) (n.s.). CONCLUSION: After finishing the initial learning curve of 11 cases for robotic-assisted TKA the time of surgery is equal to the manual conventional technique. However, there is no learning curve for implant positioning with the imageless robotic system. The implementation of the intraoperative plan is accurate to 1° with the robotic system.