Radiographic monitoring of the distal insertion of the calcaneofibular ligament in anatomical reconstructions of ankle instabilities: A preliminary cadaveric study

•No radiographic localization of the distal calcaneofibular ligament insertion exists.•Dissected and marked CFL insertions were visualized fluoroscopically.•Two virtual tangents on a standardized lateral radiograph support CFL positioning.•The tangents intersection replicates CFL insertion within a 6 mm zone.•Intraoperatively this might help to improve graft or ligament positioning.

BackgroundThe purpose of the study therefore was to determine radiographic landmarks that support the identification of the insertion site of the distal calcaneofibular ligament (CFL) in anatomic ankle ligament reconstructions.MethodsIn 10 lower limb cadaver specimens the midpoint of the distal CFL insertion was dissected and marked with a nail inserted orthogonally. On a standardized lateral radiograph in neutral ankle position a horizontal tangent was aligned to the deepest visible concavity of the tarsal sinus and one vertical tangent to the farthest posterior convexity of the talus. Additionally, a line was drawn from the radiographically marked distal CFL to the fibular insertion of the CFL to determine the CFL-fibular angle.ResultsIn relation to the radiographic tangents intersection the mean deviation of the depicted CFL nails was 2.2 mm [SD ±1.1 mm] leading to an angular, circular to slightly oval 6 mm insertion. The scatter-plot of the marked positions convened along a line from the supposed fibular CFL insertion to the intersection in all cases. The mean CFL-fibular angle was 131.7° [SD ±3.16°].ConclusionsDetermining a virtual intersection between a horizontal tangent aligned to the deepest visible concavity of the tarsal sinus and one vertical tangent aligned to the farthest posterior convexity of the talus on a standardized lateral radiograph in neutral ankle position supports an anatomic insertion of the distal calcaneofibular ligament most probably.