In vitro validation of a novel inertial-based cutting guide for tibial resection in total knee arthroplasty.

Background: Correct component alignment in total knee arthroplasty (TKA) is crucial for implant functionality and longevity. Several devices have been developed to help surgeons to achieve optimal component positioning. The purpose of our study was to evaluate the accuracy and reliability of a novel inertial-based cutting guide used to perform tibial resection in TKA taking into account users with different levels of experience.

Methods: Seven operators (raters) with different levels of experience participated in the study. To evaluate the accuracy, the varus/valgus (VV) and slope (SL) angles obtained with this novel device were compared with the reference angles obtained with the navigation system. To calculate intra-(rater) reliability repeated measurements of VV and SL angles by the same operator were used. To calculate inter-(rater) reliability repeated measurements of VV and SL by different operators were used.

Results: A total of 140 acquisitions were performed. In this study both for the VV and for the SL the maximum mean absolute error (MAE) that the inertial system registered was <1°. Intra-inter reliability was evaluated by calculating the Fleiss' Kappa coefficient, which recorded values close to 0.75 (75%) with regard to the VV and the SL for intra-reliability, while values were recorded around 0.9 (90%) for the inter subject reliability.

Conclusions: The Perseus system is accurate, reliable and surgeon-friendly and could be very useful in improving results in low-volume centers.