Observational Study
Copyright ©The Author(s) 2024. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Orthop. Mar 18, 2024; 15(3): 247-256
Published online Mar 18, 2024. doi: 10.5312/wjo.v15.i3.247
Single-center experience with Knee+™ augmented reality navigation system in primary total knee arthroplasty
Evangelos Sakellariou, Panagiotis Alevrogiannis, Fani Alevrogianni, Athanasios Galanis, Michail Vavourakis, Panagiotis Karampinas, Panagiotis Gavriil, John Vlamis, Stavros Alevrogiannis
Evangelos Sakellariou, Athanasios Galanis, Michail Vavourakis, Panagiotis Karampinas, John Vlamis, The 3rd Department of Orthopaedic Surgery, National & Kapodistrian University of Athens, KAT General Hospital, Athens 14561, Greece
Panagiotis Alevrogiannis, Panagiotis Gavriil, The 1st Department of Orthopaedic Surgery, National & Kapodistrian University of Athens, Attikon General Hospital, Athens 14561, Greece
Fani Alevrogianni, Department of Anesthesiology, KAT General Hospital, Athens 14561, Greece
Stavros Alevrogiannis, Department of Robotic Hip & Knee Orthopaedic Surgery, Metropolitan General Hospital, Athens 14561, Greece
Author contributions: Sakellariou E contributed to study design, manuscript preparation–original draft presentation; Alevrogiannis P contributed to manuscript preparation–original draft presentation; Alevrogianni F contributed to literature search; Galanis A contributed to data collection, data interpretation; Karampinas P contributed to data collection, data interpretation; Vavourakis M contributed to literature search; Gavriil P contributed to statistical analysis; Vlamis J contributed to study design, manuscript preparation–review and editing; Alevrogiannis S contributed to manuscript preparation–review and editing, supervision.
Institutional review board statement: Our institution’s board committee with the No 29/28-09-2021 decision, approved this research.
Informed consent statement: Informed consent was obtained from all individual participants included in the study.
Conflict-of-interest statement: All the authors report no relevant conflicts of interest for this article.
Data sharing statement: All raw data are available to access should they be requested at michail.vavourakis@outlook.com.
STROBE statement: The authors have read the STROBE Statement—checklist of items, and the manuscript was prepared and revised according to the STROBE Statement—checklist of items.
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: https://creativecommons.org/Licenses/by-nc/4.0/
Corresponding author: Michail Vavourakis, MD, MSc, PhD, Doctor, Surgeon, The 3rd Department of Orthopaedic Surgery, National & Kapodistrian University of Athens, KAT General Hospital, Nikis 2, Athens 14561, Greece. michail.vavourakis@outlook.com
Received: October 29, 2023
Peer-review started: October 29, 2023
First decision: December 19, 2023
Revised: January 15, 2024
Accepted: March 4, 2024
Article in press: March 4, 2024
Published online: March 18, 2024
Processing time: 137 Days and 15.4 Hours
ARTICLE HIGHLIGHTS
Research background

Computer-assisted systems obtained an increased interest in orthopaedic surgery over the last years, as they enhance precision compared to conventional hardware. The expansion of computer assistance is evolving with the employment of augmented reality (AR). With the implementation of navigation systems, orthopaedic surgeons can precisely track and visualize surgical instruments in real-time, conforming to the anatomical structures. Yet, the accuracy of AR navigation systems has not been determined. This case series endeavors to scrutinize the accurateness of component alignment and restoration of the affected limb’s mechanical axis in primary total knee arthroplasty (TKA), employing the Knee+™ system. Additionally, this study aims to evaluate whether such systems are substantively beneficial for a high-experienced knee surgeon.

Research motivation

This study aims to examine the accuracy of component alignment and restoration of the affected limb’s mechanical axis in primary TKA, utilizing an AR navigation system and to assess whether such systems are conspicuously fruitful for an accomplished knee surgeon. Our study denotes the reproducible accuracy of an AR system (Knee+™, Pixee Medical) in 30 TKA patients compared to their intraoperative measurements, which is one of the largest clinical studies of this size to examine the accuracy and efficacy of this system. AR solutions can potentially decrease the outcome dependence on the surgeon’s parameters by providing preoperative planning in the surgeon’s field of view or even indicating impeccable trajectories for placing implants with overlays. In particular, the Knee+™ AR system equips the surgeon with a thorough preoperative plan projected in real-time concerning the alignment of bone components and mechanical axis restoration.

Research objectives

The results indicate satisfactory postoperative coronal alignment without outliers across all three implants. The procedure was performed comfortably and repeatedly by the same team. AR navigation systems can bolster orthopaedic surgeons’ accuracy in achieving precise axial alignment. With regard to the rigorous limits and standards employed for the goals of our study, it is vitally important to emphasize that a difference of 1˚ in final implants’ position is unlikely to be clinically significant, as numerous studies have demonstrated that differences in coronal alignment after TKA of up to 3˚ (or even up to roughly 6˚) result in good clinical outcomes

Research methods

From May 2021 to December 2021, 30 patients, 25 women and 5 men, underwent a primary unilateral TKA. Revision cases were excluded. A preoperative radiographic procedure was performed to evaluate the limb’s axial alignment. All patients were operated on by the same team, without a tourniquet, utilizing three distinct prostheses with the assistance of the Knee+™ AR navigation system in every operation. Postoperatively, the same radiographic exam protocol was executed to evaluate the implants’ position, orientation and coronal plane alignment. We recorded measurements in 3 stages regarding femoral varus and flexion, tibial varus and posterior slope. Firstly, the expected values from the AR system were documented. Then we calculated the same values after each cut and finally, the same measurements were recorded radiologically after the operations. Concerning statistical analysis, Lin’s concordance correlation coefficient was estimated, while Wilcoxon Signed Rank Test was performed when needed.

Research results

A Wilcoxon Signed Rank Test was performed to determine whether there was a statistically significant difference regarding the expected values and radiographic calculations. A statistically significant difference was observed regarding mean expected values and radiographic measurements for femoral flexion measurements only (Z score = 2.67, P value = 0.01). Nonetheless, this difference was statistically significantly lower than 1 degree (Z score = -4.21, P value < 0.01). In terms of discrepancies in the calculations of expected values and controlled measurements, a statistically significant difference between tibial varus values was detected (Z score = -2.33, P value = 0.02), which was also statistically significantly lower than 1 degree (Z score = -4.99, P value < 0.01). There was no difference between the different implants used.

Research conclusions

Our study aimed to denote the reproducible accuracy of an AR system (Knee+™, Pixee Medical) in 30 TKA patients compared to their intraoperative measurements. At this time, to the best of our knowledge, this is one of the largest clinical studies of this size to examine the accuracy and efficacy of this system, but the first to include implants with different characteristics. The results indicate that good varus/valgus alignment was accomplished without outliers, whilst sagittal alignment was generally featured satisfactory, while the procedure was performed comfortably and repeatedly by the same team. AR solutions can potentially decrease the outcome dependence on the surgeon’s parameters by providing preoperative planning in the surgeon’s field of view or even indicating impeccable trajectories for placing implants with overlays. Diminishing cutting errors is the challenge of every AR system assisting TKA. The Knee+™ AR system equips the surgeon with a thorough preoperative plan projected in real-time concerning the alignment of bone components and mechanical axis restoration. It is a user-friendly system with an effortless intraoperative setup that guides the surgeon throughout the surgery and is versatile in amending operative plans if necessary. Further research is required to evaluate their efficacy and potential.

Research perspectives

In the future, it will distinctly possibly serve as a transcendent human-computer interface, enabling dexterous surgeons to attain superior results. Nonetheless, further technological and medical research is requisite to achieve AR technologies' maximum potential and cost-effectiveness. Until then, it is vitally important for the orthopaedic surgeon to rely on their training and adroitness for decision-making and opting wisely to employ an AR system.