Comparison of Bicortical versus Unicortical Medial Malleolus Fixation

Ankle fractures continue to increase in incidence and severity in an older, more challenging geriatric population. Medial malleolus fixation with partially threaded cancellous 4.0-mm screws, a common fixation method, has been shown to fail due to pullout strength. Subsequent cadaveric models have shown increased pullout strength with the use of bicortical screws. The literature has also demonstrated fairly good clinical results with the use of bicortical screw fixation in a general population as well as in a complicated patient cohort.

We sought to compare bicortical fully threaded 3.5-mm screw fixation with unicortical partially threaded 4.0-mm fixation in medial malleolus fractures. The aim was to compare postoperative complications such as screw failure/loosening, nonunion, delayed union, painful hardware, time to union, and time to full weightbearing.

Of 292 patients retrospectively reviewed, 126 were included following the inclusion and exclusion criteria. The data included 48 patients in the bicortical group and 78 in the unicortical group, with a mean ± SD combined age of 56.0 ± 18.0 years. Complications occurred in three patients (6%) in the bicortical screw fixation group and in six (8%) in the unicortical group, which did not reach statistical significance.

These results show that medial malleolus fixation has an overall low complication rate of 7% total combined, which is comparable with the current literature. We demonstrated no significant differences in complications, weeks to ambulation, or time to union between bicortical and unicortical fixation.