Radiological safety atlas of minimally invasive midfoot fusion: A cadaver study

The popularity of minimally invasive (MIS) foot surgery continues to grow. However, it comes with certain limitations that present notable challenges. One significant hurdle is the absence of direct visualization of neurovascular structures and tendons. The objective of this study is to present fluoroscopic heatmaps that illustrate the trajectories of major structures encountered during MIS midfoot procedures.

Sequential dissection was performed on nine below-knee cadaveric specimens and critical structures were identified and marked, including anterior tibialis tendon (ATT), extensor hallucis longus tendon (EHL), extensor digitorum longus tendon (EDL), superficial peroneal nerve (SPN) and dorsal neurovascular bundle (DNVB) were dissected. Subsequently, flexible wires were positioned and securely placed adjacent to the medial and/or lateral borders of these structures to visualize their trajectories on X-ray imaging. Anteroposterior (AP) and oblique fluoroscopic images of the foot, featuring a calibration marker, were obtained alongside standard photographs. All fluoroscopy images were adjusted to a uniform scale and standardized to a single foot fluoroscopy. The coordinates of the structures were marked on these standardized foot AP and oblique fluoroscopic views. These coordinates were then utilized to generate heatmaps.

Successfully generated heatmaps encompassed the DNVB, ATT, EDL, EHL, and SPN, on AP and oblique fluoroscopic images of the foot. The color gradient used visually represents varying magnitudes, with red indicating the most frequent locations of the structures and blue signifying lower occurrences. These heatmaps also illustrate the highest-risk areas for iatrogenic injury to the structures during MIS procedures.

This study can empower surgical navigation and improve safety in MIS midfoot procedures by providing surgeons with a fluoroscopic heatmap detailing the trajectories of major anatomical structures. The findings from this study present a valuable opportunity to improve surgical accuracy and safety.