Abstract
Displaced medial malleolus fractures are considered unstable and typically require
open reduction and internal fixation for anatomic reduction and early joint range
of motion. These fractures are usually fixated with either compression lag screws
or tension band wiring depending on the fracture pattern, size of the distal fragment,
and bone quality. When fracture fixation fails, it is typically in pullout strength.
Failure of primary bone healing can result in nonunion, malunion, and need for revision
surgery. The current study wished to explore a potentially stronger fixation technique
in regard to pullout strength for medial malleolar fractures compared with traditional
cancellous screws. This was a comparative study of the relative pullout strength of
2 fully threaded 3.5-mm bicortical screws versus 2 partially threaded 4.0-mm cancellous
screws for the fixation of medial malleolar fractures. Ten fresh-frozen limbs from
5 cadavers, mean age 79 years (range of 65–97 years), were tested using the Instron
8500 Plus system. The median force recorded at 2 mm of distraction using unicortical
partially threaded cancellous screws was 116.2 N (range 70.2 to 355.5N) compared with
327.6 N (range 117.5 to 804.3 N) in the fully threaded bicortical screw (P = .04). The unicortical screw fixation displayed only 64.53% of the median strength
noted with the bicortical screw fixation at clinical failure. The current study demonstrated
statistically significantly greater pullout strength for 3.5-mm bicortical screws
when compared with 4.0-mm partially threaded cancellous screws used to fixate medial
malleolar fractures in a cadaveric model.
Level of Clinical Evidence
Keywords
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Article info
Publication history
Published online: April 05, 2010
Footnotes
Financial Disclosure: None reported.
Conflict of Interest: None reported.
Identification
Copyright
© 2010 American College of Foot and Ankle Surgeons. Published by Elsevier Inc. All rights reserved.
