ORIGINAL ARTICLE Stabilization of the Syndesmosis in the Maisonneuve Fracture—A Biomechanical Study Comparing 2-Hole Locking Plate and Quadricortical Screw Fixation Richard Gardner, FRCS(Orth), Taher Yousri, MRCS, Fiona Holmes, MEng, Damian Clark, MRCS, Phil Pollintine, PhD, Anthony W. Miles, MSc(Eng), and Mark Jackson, FRCS(Orth) Objective: The aim of this study is to determine whether a 2-hole locking plate has biomechanical advantages over conventional screw stabilization of the syndesmosis in this injury pattern. Methods: Six pairs of fresh-frozen human cadaver lower legs were prepared to simulate an unstable Maisonneuve fracture. Each limb was compared with its pair; the syndesmosis in one being stabilized with two 4.5-mm quadricortical cortical screws, the other a 2-hole locking plate with 3.2-mm locking screws. The limbs were then mounted on a servohydraulic testing rig and axially loaded to a peak load of 800N for 12000 cycles. Fibula shortening and diastasis were measured. Each limb was then externally rotated until failure occurred. Failure was defined as fracture of bone or metalwork, syndesmotic widening, or axial migration .2 mm. Results: Both constructs effectively stabilized the syndesmosis during the cyclical loading within 0.1 mm of movement. However, the locking plate group demonstrated greater resistance to torque compared with quadricortical screw fixation (40.6 Nm vs. 21.2 Nm, respectively, P value , 0.03). Conclusion: A 2-hole locking plate (with 3.2-mm screws) provides significantly greater stability of the syndesmosis to torque when compared with 4.5-mm quadricortical fixation. Key Words: maisonneuve fracture, syndesmosis, locking plate, diastasis (J Orthop Trauma 2013;27:212–216) INTRODUCTION The Maisonneuve ankle fracture was first described in 1840. 1 The mechanism involves foot pronation with external rotation resulting in rupture of the deltoid ligament or fracture of the medial malleolus with subsequent injury to the anterior tibiofibular ligament, interosseous membrane, and a spiral fracture of the proximal third of the fibula. 2 There is a resultant diastasis of the distal tibiofibular articulation. The treatment of syndesmotic injuries is a subject of ongoing controversy with disagreement over the most appropriate method of stabilization. 2 Biomechanical studies have investigated the importance of reducing the diastasis and correcting fibula length and external rotation. Widening of the syndesmosis with 1 mm of lateral displacement of the talus is associated with a 42% reduction in tibiotalar contact area. 3 Thordarson et al 4 dem- onstrated the highest peak contact pressures were associated with shortening of the fibula, when compared with lateral shift and external rotation. A significant increase in pressures was noted with only 2 mm of shortening. Standard surgical treatment for unstable syndesmotic injuries involving a fracture of the proximal fibula involves placement of 1 or 2 screws at a location just proximal to the syndesmosis. Numerous studies have compared the use of tricortical and quadricortical stabilization of the syndesmo- sis, 5 the use of 3.5-mm or 4.5-mm screws, 6 and the benefits in using stainless steel, titanium or bioabsorbable screws, 7,8 and more recently a suture endobutton. 9 Thompson and Gesink 5 suggested that there is no bio- mechanical advantage of a 4.5-mm tricortical screw when compared with a 3.5-mm screw when tested to failure in external rotation. In a further cadaveric study, Hansen et al 6 suggested a larger diameter screw (4.5-mm quadricortical cortical screw) provides greater resistance to applied shear stress at the syndesmosis. The control of shear stress at the syndesmosis is an essential part of the treatment of Maisonneuve fractures. Low Weber C fractures are frequently stabilized with a plate, before insertion of a screw(s) to reduce the diastasis. The consideration of shear stress across the diastasis screw is therefore less of a factor as the fibula is a complete strut. In the Maisonneuve fracture, the screw(s) must resist both tensile and shear forces to avoid a late diastasis or fibula shortening. Locking plates have been a major advance in fracture management. The fixed angle device has been shown to provide both angular and axial stability by eliminating the risk of the screw toggling in the plate. 10,11 This has attractions in the management of the Maisonneuve fracture by theoretically Accepted for publication April 20, 2012. From the Orthopaedic Department, Bristol Royal Infirmary and Centre for Orthopaedic Biomechanics, University of Bath, Bristol, United Kingdom. No funds were received in support of this work. No benefits in any form have been or will be received from a commercial party related directly or indirectly to the subject of this article. The authors have no financial disclosures or conflicts of interest to declare. This research study and the use of cadaveric material were approved by the Research Ethics Committee. Reprints: Richard O. E. Gardner, FRCS(Orth), Orthopaedic Library, Bristol Royal Infirmary, Upper Maudlin Street, Bristol BS2 8HW, United Kingdom (e-mail: richardgardner@doctors.org.uk). Copyright © 2013 by Lippincott Williams & Wilkins 212 | www.jorthotrauma.com J Orthop Trauma  Volume 27, Number 4, April 2013