Below is an example of a clinical study that is pure “propaganda”. It was put together by well-meaning KOLs and well-meaning professionals in a device company. (Note: not to pick on ZB or Rosa, because there are thousands of examples like this in orthopedics.)

Where are the controls? Why isn’t there a significant sample size? Where is the scientific method?

Study confirms high accuracy of a new robotically assisted technique for total knee arthroplasty (ZB landing page)

Robotic Total Knee Arthroplasty (TKA) has gained popularity over the last few years for improving the accuracy of implant positioning and reducing issues with limb alignment when compared with a conventional jig-based TKA. Pain, instability and limitation of the range of motion are the most commonly reported symptoms among unsatisfied patients. The major causes of unsuccessful TKA are inadequate alignment and errors in balancing.

The aim of the study was to evaluate the accuracy of the robotically assisted method to see if outcomes for patients could be improved. 75 patients underwent total knee arthroplasty using a new, robotic system (ROSA® Knee System; Zimmer Biomet, Warsaw, IN) with a Posterior Stabilized Total Knee Arthroplasty (Persona® Knee System). The planned, validated and measured angles and cuts for the distal and posterior femur, for the proximal tibia and for the final coronal alignment on long standing X-rays were compared to determine whether there was a variation in the accuracy of the robot or the jig procedures.

A significant difference was found only between the average planned and the average validated angle for femoral flexion, tibial coronal axis, medial and lateral cuts. The average difference was below 1 mm or under 1 degree and no statistical difference was found between planned validated and measured cuts. The average difference between planned HKA and measured was 1.2 ± 1.1. Simply put, no statistically significant difference was found.

This study demonstrates that when using this new surgical robot in total knee arthroplasty, surgeons can perform accurate bone cuts and achieve the planned angles and resections necessary, possibly within hybrid techniques that include new and conventional technology. The study suggests that using this new surgical robot in total knee arthroplasty will reduce the number of patients affected by alignment and balancing issues to improve patient satisfaction after TKA procedures.

Rossi S M P, Sangaletti R, Perticarini L, Terragnoli F, Benazzo F. Read more: https://pubmed.ncbi.nlm.nih.gov/34981162/

Stefano Marco Paolo Rossi 1, Rudy Sangaletti 2 3, Loris Perticarini 2, Flavio Terragnoli 4, Francesco Benazzo 2 3

Abstract

Purpose: Over the last decade, robotic TKA gained popularity for improving the accuracy of implant positioning and reducing outliers in limb alignment comparing to conventional jig-based TKA. Hypothesis of this study was that this newly designed robotically assisted system will achieve a high level of accuracy for bone resection. Purpose of the study was to evaluate the accuracy of the system.

Methods: For this study, 75 knees in 75 patients were operated using a new, robotic system (ROSA® Knee System; Zimmer Biomet, Warsaw, IN) with a Posterior Stabilized Total Knee Arthroplasty (Persona® Knee System). The planned, validated and measured angles and cuts for the distal and posterior femur, for the proximal tibia and for the final coronal alignment on long standing x-rays were compared.

Results: A statistically significant difference was found only between the average planned and the average validated angle for femoral flexion, tibial coronal axis, medial and lateral cuts; the average difference was in any case below 1 mm or under 1 degree with SD < 1. No statistical difference was found between planned validated and measured cuts. Average difference between planned HKA and measured was 1.2 ± 1.1. No statistically significant difference was found.

Conclusions: The results of this study demonstrated that using this new surgical robot in total knee arthroplasty it is possible to perform accurate bone cuts and to achieve the planned angles and resections.

Keywords: Accuracy; Computer assisted surgery; In vivo; Navigation; Robotic surgery; Total knee arthroplasty.

Conflict of interest statement

Prof Francesco Benazzo declares a teaching contract with the manufacturer (Zimmer Biomet); all other authors declare no conflict of interest related to the present study.