No advantage with navigated versus conventional mechanically aligned total knee arthroplasty-10 year results of a randomised controlled trial

Abstract

Purpose: Computer-assisted surgery (CAS) total knee arthroplasty (TKA) remains a controversial area of surgical practice. The aim of this study is to report the ten-year revision rates and patient-reported outcome measures (PROMS) of a single-blinded, prospective, randomised controlled trial comparing electromagnetically (EM) navigated and conventional TKA.

Methods: 199 patients were randomised to receive either EM navigated or conventional TKA where the aim of implantation was neutral mechanical alignment in all cases. Ten-year revision rates were collated and compared between the two intervention groups. Longitudinal PROMS data was collected prospectively at various time points up to 10 years post-operatively.

Results: Over the ten-year period, there were 23 deaths (22.8%) in the EM navigation cohort and 30 deaths (30.6%) in the conventional cohort. At 10 years post-operatively, there was no statistically significant difference in all cause revision between the EM navigation and conventional cohort (4.0 vs 6.1%, p = 0.429). When analysing causes of revision that might be influenced by utilising EM navigation, there was no statistically significant difference in revisions (3.0% EM navigated vs 4.1% conventional group, p = 0.591). Patients that received navigated TKAs had improved Oxford Knee Society, American Knee Society Score and range of motion at 3 months following surgery compared to conventional TKA (p = 0.002, p = 0.032, and p = 0.05, respectively). However, from 1 to 10 years post-operatively, both interventions had equivalent outcomes.

Conclusion: There is no difference in revision rates or clinical outcomes comparing EM navigated versus conventional TKA at ten-year follow-up. The expected mortality rate makes it unlikely that a difference in revision rates will reach statistical significance in the future. In the setting of an experienced knee arthroplasty surgeon, it is difficult to justify the additional costs of CAS in TKA surgery.

Level of evidence: I.

Keywords: Computer Assisted Surgery; EM Navigation; Knee arthroplasty; Randomised controlled trial.

Fig. 1

CONSORT (Consolidated Standards of Reporting Trials) Flow Diagram demonstrating the flow of patients through the randomised clinical study

Fig. 2

Comparison of post-operative accuracy of component placement in each plane and post-operative mechanical axis alignment as measured from CT scans. Dotted line represents the 3° target window for the mechanical axis

Fig. 3

Mean Oxford Knee Score (A), Range of Motion (B), American Knee Society Scores for Knee Symptoms (C) and Function (D), and SF-36 Physical (E) and Mental (F) patient-reported outcomes over 10 years. *p < 0.05, and **p < 0.01

Fig. 4

Kaplan–Meier survival curve with 95% Confidence Intervals for Total Knee Arthroplasty revision rate at 10 years following surgery comparing navigated (4.0%—4/101 patients) versus conventional surgery (6.1%—6/98 patients)