Imageless Navigation for TKA Increases Implantation Accuracy

Abstract

Because we are performing TKAs on heavier, younger patients, greater stress is being put on the implants and is increasing the importance of implantation accuracy. We performed a prospective randomized study to compare the radiographic results and the 3-month clinical outcomes in 100 patients who had TKAs using an imageless navigation system with 100 patients treated using conventional implantation instruments. We measured component alignment by standard radiographs. Clinical outcomes were based on the Insall score, anterior knee pain, feeling of instability, and the step test. The mechanical axis of the limb was within 3 degrees varus/valgus in 92% of the patients who had navigated procedures versus 76% of patients who had conventional surgery. The tibial slope showed a rate of inaccuracy of 3 degrees or less for 98% of the patients in the navigated TKA group versus 80% of the patients in the conventional group. The surgical time was longer for navigated TKA than for the conventional procedure (88 +/- 16 versus 68 +/- 18 minutes, respectively). Clinical outcomes and postoperative blood loss were similar in both groups. The navigation system increased implantation accuracy but did not prevent outliers and did not solve the problems associated with identifying and obtaining accurate component rotation.

Which Factors Increase Risk of Malalignment of the Hip-Knee-Ankle Axis in TKA?

“…Outlier rates were 5% to 21% for postoperative limb mechanical axis, 4% to 11% for femoral component alignment, and 3% to 11% for tibial component alignment. A higher outlier rate in some of these studies when compared to our results could be due to the fact that some of these studies involved multiple surgeons where individual experience with navigation could have played a role [8,10] (in contrast to our single-surgeon study), had relatively smaller number of knees (maximum of 100-500 TKAs) [2,8,10,11,14,17,26], and were performed early during the evolution of navigation software and tools (1999)(2000)(2001)(2002)(2003) [2,8,10,11] (Table 5).…”

Imageless computer assisted versus conventional total knee replacement. A Bayesian meta-analysis of 23 comparative studies

“…There were 4,063 patients with 4,163 TKRs. Ten trials were prospective and randomised [22][23][24][25][26][27][28][29][30][31]. Table 1 is a descriptive table that summarises the various trial characteristics and participant demographics.…”

Correlation between preoperative and postoperative knee kinematics in total knee arthroplasty using cruciate retaining designs

“…A few kinematic studies have been undertaken to investigate the kinematics of osteoarthritic knee preoperatively [2,3,11,15,20], but we are unaware of any kinematic studies that addressed the relationship between the kinematic variables of knees before and after TKA. Initially, navigation systems were used to improve implant alignment during TKA [10,13,14], but more recently a number of kinematic studies have used navigation systems to investigate passive knee kinematics in patients with osteoarthritis during TKA [3,5,11,20,21]. However, it still remains unclear how the preoperative knee kinematics affect the knee kinematics after TKA.…”

“…Despite favourable long-term survival and patient satisfaction after total knee arthroplasty (TKA), some patients complain of unsatisfactory subjective function [6,8,10]. This dissatisfaction may be explained partly by abnormal kinematics following TKA [1], and thus, knee kinematics following TKA have been studied extensively [4,6,7,12,17,[22][23][24][25]27].…”