Assessing accuracy of sustentaculum screw placement during calcaneal fixation.

BACKGROUND

The aim of this study was to determine the ability of the Harris heel view to confirm placement of the sustentacular screw during calcaneal fixation.

METHODS

A 4.0 cancellous screw was placed in a cadaveric specimen, from lateral to medial in 5 configurations: (1) within the sustentaculum, (2) misdirected inferiorly to sustentaculum, (3) misdirected superiorly to sustentaculum, (4) misdirected anteriorly to sustentaculum, and (5) misdirected posteriorly to sustentaculum. Harris heel views were obtained at 5 angulations and were analyzed to determine screw placement.

RESULTS

A screw placed anatomically was radiographically confirmed by the Harris heel view to be within the sustentaculum in all views. An inferiorly misdirected screw appeared radiographically within the sustentaculum at 30, 40 and 50 degrees but was confirmed misplaced on the 10- and 20-degree views. A posteriorly misdirected screw was confirmed misplaced on all 5 views. An anteriorly misdirected screw appeared radiographically within the sustentaculum on the 10-degree view but was confirmed misplaced on all other views. A superiorly misdirected screw was confirmed misplaced on all views.

CONCLUSIONS

Clinicians should be aware that several specific axial heel views are required to verify placement of the sustentacular screw. An inferiorly misdirected screw will appear to be within the sustentaculum with the standard Harris heel view.

CLINICAL RELEVANCE: Heel views should be obtained from a range of 10 to 50 degrees to confirm accurate placement of the sustentacular screw.