OTA 2013 Posters

Scientific Poster #127 Basic Science OTA 2013

Are Hook Plates Advantageous to Antiglide Plates for Vertical Shear Malleolar Fractures?

Daniel A. Jones, MD; J. Gary Bledsoe, PhD; Lisa K. Cannada, MD;
Saint Louis University Department of Orthopaedic Surgery, St. Louis, Missouri, USA

Purpose: The purpose of this project is to evaluate the biomechanical properties of the hook plate versus the antiglide plate in the treatment of the supination-adduction (SAD) ankle fracture.

Methods: Fourth generation polyurethane models of the left tibia were obtained and subjected to pretesting stiffness. Identical vertical fractures of the medial malleolus were created. The fractures were stabilized with one of the following constructs: a one-third tubular plate in an antiglide fashion with two screws proximal to the fracture (TwS), the one-third tubular plate with two screws proximal to the fracture and with an additional screw perpendicular through the vertical shear fragment (ThS), or a hook plate (HP). Ten models were randomly assigned to each of the three groups. The constructs were tested in offset axial loading to simulate loading in supination. The constructs were evaluated for construct stiffness and load to failure.

Results: The ThS construct yielded higher stiffness versus the TwS (P <0.05) and the HP (P <0.05). The plate stiffness of the HP construct compared to the TwS was not significant (P = 0.350). When analyzing absolute load to failure, the difference between ThS and TwS was 638 N and between ThS and HP was 530 N (P <0.05). The HP had a load to failure that was on average 108 N more than the TwS, but this was not significant (P = 0.063).

Conclusion: This study examined the biomechanical properties of a traditional fixation (TwS group), a commonly used fixation (ThS group), and a newer construct (HP group). The HP group is unique to this study and to our knowledge there is no literature on this type of fixation for this fracture. Antiglide plating technique with an additional screw placement (ThS) is biomechanically superior to the other two constructs investigated in terms of stiffness and absolute load to failure for fixation of vertical shear medial malleolus fractures. This construct represents strong, stable support for this fracture.

Alphabetical Disclosure Listing

• The FDA has not cleared this drug and/or medical device for the use described in this presentation   (i.e., the drug or medical device is being discussed for an “off label” use).  ◆FDA information not available at time of printing. Δ OTA Grant.