title: Biomechanical Evaluation of Plate Versus Lag Screw Only Fixation of Distal Fibula Fractures.
abstract: Traditional fixation of unstable Orthopaedic Trauma Association type B/C ankle fractures consists of a lag screw and a lateral or posterolateral neutralization plate. Several studies have demonstrated the clinical success of lag screw only fixation; however, to date no biomechanical comparison of the different constructs has been performed. The purpose of the present study was to evaluate the biomechanical strength of these different constructs. Osteotomies were created in 40 Sawbones(®) distal fibulas and reduced using 1 bicortical 3.5-mm stainless steel lag screw, 2 bicortical 3.5-mm lag screws, 3 bicortical 3.5-mm lag screws, or a single 3.5-mm lag screw coupled with a stainless steel neutralization plate with 3 proximal cortical and 3 distal cancellous screws. The constructs were tested to determine the stiffness in lateral bending and rotation and failure torque. No significant differences in lateral bending or rotational stiffness were detected between the osteotomies fixed with 3 lag screws and a plate. Constructs fixed with 1 lag screw were weaker for both lateral bending and rotational stiffness. Osteotomies fixed with 2 lag screws were weaker in lateral bending only. No significant differences were found in the failure torque. Compared with lag screw only fixation, plate fixation requires larger incisions and increased costs and is more likely to require follow-up surgery. Despite the published clinical success of treating simple Orthopaedic Trauma Association B/C fractures with lag screw only fixation, many surgeons still have concerns about stability. For noncomminuted, long oblique distal fibula fractures, lag screw only fixation techniques offer construct stiffness similar to that of traditional plate and lag screw fixation.
authors.affiliation: Orthopedic Resident, Department of Orthopaedic Surgery, University of California, San Diego, CA.
authors.forename: Amirhossein
authors.initials: A
authors.lastname: Misaghi
authors.affiliation: Biomechanical Engineer, Orthopedic Biomechanics Research Center, San Diego, CA.
authors.forename: Josh
authors.initials: J
authors.lastname: Doan
authors.affiliation: Program Manager, Division of Orthopedics, Rady Children's Hospital, San Diego, CA.
authors.forename: Tracey
authors.initials: T
authors.lastname: Bastrom
authors.affiliation: Orthopedic Surgeon, Rady Children's Hospital and University of California, San Diego, CA. Electronic address: apennock@rchsd.org.
authors.forename: Andrew T
authors.initials: AT
authors.lastname: Pennock
mesh_terms: D064386:Ankle Fractures / Q000601:surgery; D001696:Biomechanical Phenomena; D001860:Bone Plates; D001863:Bone Screws; D005360:Fibula / Q000293:injuries*; D005593:Fracture Fixation, Internal / Q000295:instrumentation* / Q000379:methods; D050723:Fractures, Bone / Q000601:surgery*; D006801:Humans; D017145:Models, Educational; D013718:Tensile Strength
keywords: ankle; interfragmental compression; neutralization plate; tibia; trauma