Radiographic evaluation of talonavicular joint after talar screw placement: a cadaver study

Twelve cadaver feet were used for a radiographic assessment of the talonavicular joint. A 4.0- or a 6.5-mm screw was inserted through the posterior tubercle of the talus, directed anteriorly into four quadrants of the talar head. Lateral, dorsoplantar, lateral oblique, and medial oblique radiographic views were obtained for each specimen, to assess the position of the screw tip in relation to the talonavicular joint. The lateral view consistently demonstrated the screw tip violation when the screw was directed through the center of the talar head, but it failed when screws were passed into the medial or lateral quadrants of the talar head. The dorsoplantar view consistently demonstrated a screw tip violation of the superior two quadrants of the talar head when other views failed. Each screw tip violation of the inferior quadrants (medial and lateral) required a different view. A screw tip violation of the inferior medial quadrant required the lateral oblique view, whereas the inferior lateral quadrant required the medial oblique view for full appreciation. Here again, other views failed to demonstrate minor screw tip violations consistently. Using these views to assess screw placement could decrease the risk of developing posttraumatic arthritis caused by screw tip violation of the talonavicular joint.