Biomechanical Comparison of Four Different Lateral Plate Constructs for Distal Fibula Fractures

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1 Biomechanical Comparison of Four Different Lateral Plate Constructs for Distal Fibula Fractures Tobin Eckel, MD Richard Glisson, BS Prashanth Anand, MD Selene Parekh, MD

2 Biomechanical Comparison of Four Different Lateral Plate Constructs for Distal Fibula Fractures Tobin Eckel, MD My disclosure is in the Final AOFAS Program Book. I have no potential conflicts with this presentation.

3 Displaced lateral malleolar fractures are often treated with lateral plate fixation Introduction We subjected a range of contemporary lateral fibula plates to a series of controlled mechanical tests designed to reveal performance differences

4 Methods Forty fresh frozen lower extremities were divided into four groups A Weber B distal fibula fracture was simulated with an osteotomy and stabilized using one of four plate systems: Synthes one-third tubular plate with interfragmentary lag screw Synthes LCP locking plate with lag screw Orthohelix MaxLock Extreme lowprofile locking plate with lag screw TriMed Sidewinder non-locking plate Sagittal plane bending test setup. Controlled bending load is applied 150 mm from center of fracture. Clinometer measures fibula shaft angulation relative to immobile distal fragment.

5 Controlled monotonic bending and cyclic torsional loading were applied to quantify: Methods Bending stiffness Torsional stiffness Fracture site motion Torsion testing apparatus. Rotation was applied to distal fibula fragment. Both distal fragment and fibula shaft rotation were monitored to accurately calculate motion at level of fracture.

6 Results Mean (n=10 per group) bending stiffness calculated between 1 Nm and 1.5 Nm of bending moment. Bending direction refers to distal fragment motion relative to the fibula shaft

7 Results Mean initial torsional stiffness calculated between 1.5 Nm and 2.0 Nm of torque. Rotation direction refers to distal fragment motion relative to the fibula shaft.

8 Results Mean (n=10 per experimental group) fracture site angulation under 1.5 Nm bending moment. Bending direction refers to distal fragment moton relative to the fibula shaft. Mean initial fracture site rotation under 2.0 Nm torsional moment. Rotational direction refers to distal fragment motion relative to the fibula shaft.

9 Conclusions Significant differences in plate performance were not demonstrated The effects of bone quality variability and differences in interfragmentary screw trajectory resulted in data dispersion that confounded absolute ranking of plate performance.

10 References 1. Hess F, Sommer C. Minimally invasive plate osteosynthesis of the distal fibula with the locking compression plate: first experience of 20 cases. J Orthop Trauma;25: Hewitt J HC, Tennant J, May R, Parekh SG. Cost Effectiveness of the Trimed Sidewinder Plate for the Treatment of Weber B Ankle Fractures. Current Orthopaedic Practice 2011;22: Kim T, Ayturk UM, Haskell A, et al. Fixation of osteoporotic distal fibula fractures: A biomechanical comparison of locking versus conventional plates. J Foot Ankle Surg 2007;46: Klos K, Sauer S, Hoffmeier K, et al. Biomechanical evaluation of plate osteosynthesis of distal fibula fractures with biodegradable devices. Foot Ankle Int 2009;30: Lamontagne J, Blachut PA, Broekhuyse HM, et al. Surgical treatment of a displaced lateral malleolus fracture: the antiglide technique versus lateral plate fixation. J Orthop Trauma 2002;16: McKenna PB, O'Shea K, Burke T. Less is more: lag screw only fixation of lateral malleolar fractures. Int Orthop 2007;31: Milner BF, Mercer D, Firoozbakhsh K, et al. Bicortical screw fixation of distal fibula fractures with a lateral plate: an anatomic and biomechanical study of a new technique. J Foot Ankle Surg 2007;46: Minihane KP, Lee C, Ahn C, et al. Comparison of lateral locking plate and antiglide plate for fixation of distal fibular fractures in osteoporotic bone: a biomechanical study. J Orthop Trauma 2006;20: Panchbhavi VK, Vallurupalli S, Morris R. Comparison of augmentation methods for internal fixation of osteoporotic ankle fractures. Foot Ankle Int 2009;30: Schaffer JJ, Manoli A, 2nd. The antiglide plate for distal fibular fixation. A biomechanical comparison with fixation with a lateral plate. J Bone Joint Surg Am 1987;69: Tornetta P, 3rd, Creevy W. Lag screw only fixation of the lateral malleolus. J Orthop Trauma 2001;15: