Automated Contralateral Ankle Joint Comparison Using Flat Panel C-Arm Imaging

Overview

This study introduces a novel pipeline for automatic alignment and visualization of bilateral ankle joints from a single 3D C-arm scan using flat panel technology. The method enables direct side-by-side comparison of anatomical landmarks, potentially improving intra-operative assessment of fibular reduction without additional radiation exposure.

Background

Ankle fractures are common and often involve syndesmotic injury, requiring precise anatomical reduction to prevent joint instability and early osteoarthritis. Intra-operative imaging with fluoroscopy or 3D C-arm scans is standard for verifying reduction and implant positioning. However, manual adjustment of standard anatomical planes is time-consuming and subjective, and current contralateral comparisons require additional scans, increasing radiation dose and procedure time. Computer-assisted methods have been proposed but remain complex or require extra imaging.

Data Highlights

The proposed workflow localizes both ankles within a single 3D image volume, estimates standard anatomical planes automatically for each ankle, and aligns them for direct comparison. This approach leverages the improved field of view and image quality of flat panel detectors to capture both ankles simultaneously, reducing radiation exposure and acquisition time compared to previous methods requiring multiple scans or projections.

Key Findings

• Automatic localization and segmentation of bilateral ankle regions of interest (ROIs) from a single 3D C-arm volume is feasible.
• Standard anatomical planes for each ankle can be estimated automatically, overcoming the need for manual adjustment.
• Alignment of the two ankles based on these planes enables direct side-by-side visualization of relevant anatomical landmarks.
• Using flat panel detector technology allows imaging of both ankles in one scan, reducing radiation dose and intervention time.
• The pipeline addresses variability in fibula and tibia positioning by incorporating multi-bone shape models rather than relying on rigid registration.

Clinical Implications

This automated contralateral comparison tool can assist surgeons intra-operatively by providing an objective, standardized visualization of both ankles without additional imaging. It may improve detection of malreduction and implant positioning, potentially reducing the risk of joint instability and premature osteoarthritis. Adoption of this technology could streamline workflow and decrease radiation exposure during ankle fracture surgeries.

Conclusion

The study demonstrates the feasibility of an automated pipeline for contralateral ankle joint comparison using a single flat panel C-arm volume. This approach offers a promising advancement toward improved intra-operative assessment and surgical outcomes in ankle fracture management.

References

1. Thomas et al. 2023 -- Computer-assisted contralateral side comparison of ankle joints
2. Mukhopadhyay et al. 2019 -- Importance of contralateral ankle comparison
3. Fürnstrahl et al. 2018 -- Pre-operative assistance system for contralateral comparison
4. Brehler et al. 2020 -- Standard plane calculation using SURF features
5. Lu et al. 2021 -- 2D standard plane detection in echocardiography