# Implant Navigation During TMJ Reconstruction: A Proof-of-Concept Study

## TL;DR

This study introduces new methods to improve the accuracy of temporomandibular joint implant placement during surgery.

## Contribution

The paper presents a marker-based navigation workflow and orientation screws to enhance TMJ replacement precision.

## Key findings

- Marker-based navigation offers a more intuitive way to assess 3D implant orientation compared to conventional methods.
- Guiding screws improve the accuracy of guide placement during TMJ surgery.
- Precise guide positioning is critical to avoid negative clinical outcomes from implant misalignment.

## Abstract

Background/Objectives: One key objective in temporomandibular joint replacement is to precisely position the implant according to the virtual surgical plan, utilizing drilling and osteotomy guides for accuracy. However, implementing this process can be challenging, as—even though the drilling and osteotomy guides should only fit in one position—there often are still multiple potential positions for both guides and implants on smooth bony surfaces. Even minor deviations in the implant’s placement can affect wear, influence biomechanical behavior, and lead to adverse outcomes. Intraoperative navigation has emerged to verify the alignment of implants with the preoperatively planned ideal position. While the use of navigation systems in TMJ surgery is well documented for certain procedures, its application in TMJ replacement cases has been limited. Methods: In this study, two methods to improve the accuracy of TMJ replacement are introduced: a new marker-based navigation workflow and the use of orientation screws in two patients. Results: Unlike conventional navigation methods, the marker-based system provides a more intuitive method for assessing the 3D orientation of the TMJ implant concerning the planned position, enhancing surgical accuracy. The addition of a guiding screw provides a reference point to enhance the accuracy of guide placement. Conclusions: The accurate placement of the prosthesis largely relies on the precise positioning of the guides. Even slight inaccuracies in the position of the TMJ prosthesis, resulting from suboptimal guide placement, can lead to significant negative clinical outcomes. Marker-based navigation and the use of guiding screws may potentially improve the precision of TMJ replacement procedures.