Can We Tell if the Syndesmosis Is Reduced Using Fluoroscopy?

Area of Science:

• Orthopaedic Surgery
• Radiology
• Biomechanical Analysis

Background:

• Accurate reduction of the fibula in relation to the tibia is crucial for ankle syndesmosis stability.
• Fluoroscopic imaging is commonly used intraoperatively to assess reduction.
• Determining subtle sagittal plane displacement can be challenging.

Purpose of the Study:

• To evaluate orthopedic surgeons' ability to detect fibular malreduction in the sagittal plane using fluoroscopic images.
• To assess the utility of comparing fluoroscopic images with the contralateral (uninjured) ankle.
• To determine interobserver reliability in identifying fibular displacement.

Main Methods:

• Lateral radiographs of cadaveric ankles with simulated 2.5 mm and 5 mm anterior/posterior fibular translations were created.
• Four orthopedic trauma surgeons assessed randomly selected images, distinguishing between reduced and displaced fibulae.
• Sensitivity, negative predictive value (NPV), and interobserver reliability (kappa statistic) were calculated.

Main Results:

• Surgeons demonstrated higher accuracy in identifying malreduction (NPV 95% ipsilateral, 85% contralateral) than reduction.
• Sensitivity for detecting reduction was 94% for the ipsilateral ankle and 68% for the contralateral ankle.
• Anterior displacement and larger displacements (5 mm) were diagnosed more easily; 2.5 mm posterior displacement was most difficult. Intraobserver agreement was excellent for anterior displacement and 5 mm displacements.

Conclusions:

• Experienced surgeons can achieve and assess fibular reduction within 2.5 mm of translation.
• Fluoroscopic comparison with the contralateral normal ankle aids significantly in identifying syndesmotic malreduction.
• While the acceptable degree of syndesmotic displacement remains undefined, these findings suggest a high level of diagnostic capability for experienced surgeons.