ORIGINAL ARTICLE Biomechanical Analysis of Bicondylar Tibial Plateau Fixation: How Does Lateral Locking Plate Fixation Compare to Dual Plate Fixation? Thomas F. Higgins, MD, Joshua Klatt, MD, and Kent N. Bachus, PhD Objectives: This study is designed to test the comparative strength of lateral-only locked plating to medial and lateral nonlocked plat- ing in a cadaveric model of a bicondylar proximal tibial plateau fracture. Methods: Ten matched pairs of human cadaveric proximal tibia specimens were used for biomechanical testing. Cyclic loading using a materials testing device simulated initial range of motion and load bearing following surgical repair. Subsidence of the medial and the lateral condyles was measured following 10,000 cycles from 100N to 1,000N; the maximum load to failure on the medial condyle for both plate constructs was also measured. Results: On the lateral side, dual plating (DP) allowed an average of 0.68 6 0.14 mm of subsidence, compared with 1.03 6 0.27 mm for the fixed-angle plate (FAP) (P = 0.077). On the medial side, DP allowed an average of 0.78 6 0.15 mm of subsidence, compared with 1.51 6 0.32 mm for the FAP (P = 0.045). No significant difference was found in the maximal load to medial condyle fixation failure between either plating construct (P = 0.204). Conclusions: The results of this study demonstrate that dual-plate fixation allows less subsidence in this bicondylar tibial plateau cadaveric model when compared to isolated locked lateral plates. This may raise concerns about the widespread use of isolated lateral locked plate constructs in bicondylar tibial plateau fractures. Key Words: tibial plateau fracture, biomechanics, locked plating, bicondylar fracture (J Orthop Trauma 2007;21:301–306) INTRODUCTION Bicondylar fractures of the tibial plateau present a unique surgical challenge, given the necessity of restoring articular congruity and correcting axial alignment of the lower extremity. Open reduction internal fixation has been the standard of care for most displaced intraarticular tibial plateau fractures, but this has been a particularly troublesome procedure in bicondylar fractures. 1–10 With articular involvement mainly on the lateral plateau, a lateral approach and plating are mandated. When both condyles are involved, buttressing or fixation of both the medial and the lateral cortices with dual plates has been indicated to prevent medial collapse and subsequent varus deformity. However, osteosynthesis is dependent on the balance between achieving rigid fixation and preservation of the local biological environment, and this balance may be compromised with dual plating. The biologic implications of medial and lateral soft tissue stripping are concerning, and this has been associated with a high complication rate. 1,3,5,8,9,11 The evolution of locking plates has given surgeons the ability to achieve more rigid constructs without enlarging the plate footprint on bone. The wide commercial availability of fixed-angle plates (FAPs) specifically designed to accommo- date the proximal tibia laterally has made it possible to achieve fixation of some displaced bicondylar injuries without directly plating the medial side. If rigid fixation of the medial condyle and medial cortex may be achieved with a locking interface in these laterally based plates, this may provide sufficient fixation to obviate any further soft tissue insult to the medial metaphysis. With a deep infection rate of more than 8% reported with a dual incision technique in experienced hands, there is certainly an incentive to try to fix the entire bicondylar injury from the lateral side only. 1 However, if isolated lateral locked plating does not provide sufficient fixation to resist subsidence of the medial condyle, axial alignment of the limb may be lost, producing varus deformity and jeopardizing the long-term outcome. 3,7,12–18 There are clinical data to suggest that unilateral locked plating of bicondylar tibial plateau frac- tures may lead to significant malreduction and loss of reduction. 19 The purpose of our study was to compare the stability of FAP and dual plating (DP) techniques in complex bicondylar tibial plateau fractures in a cadaveric cyclic loading model. Our hypotheses were that fixed-angle plate constructs would show no significant difference in (1) subsidence when compared with the dual plate constructs, and/or would not have (2) the capacity to carry more ultimate compressive loads than the dual plate constructs. Accepted for publication February 21, 2007. From the University of Utah Department of Orthopaedics, Orthopaedic Bioengineering Research Laboratory, Salt Lake City, Utah. The University of Utah Orthopedic Bioengineering Laboratory and this project have been supported with unrestricted scientific research grants from The Educational Research Development Council of Salt Lake City, Utah; Synthes Corporation; and the Musculoskeletal Transplant Foundation. Reprints: Thomas F. Higgins, MD, University of Utah Department of Orthopaedics, 590 Wakara Way, Salt Lake City, Utah 84108 (e-mail: thomas.higgins@hsc.utah.edu). Copyright Ó 2007 by Lippincott Williams & Wilkins J Orthop Trauma  Volume 21, Number 5, May 2007 301