• Emily J Osborn, Christine L Farnsworth, Joshua D Doan, and Eric W Edmonds.
• Department of Orthopaedic Surgery, University of California San Diego, San Diego, CA, USA. Electronic address: ejosborn@ucsd.edu.
• Clin Biomech (Bristol, Avon). 2018 Jun 1; 55: 94-99.

BackgroundClassic implants for operative intervention of mid-shaft clavicle fractures in adolescents can become symptomatic, requiring removal. This study compares 1) biomechanical properties and 2) clinical outcomes in adolescents of mid-shaft clavicle fracture fixation with bioabsorbable versus metal implants.MethodsSix synthetic clavicles with mid-shaft fractures underwent bioabsorbable plating. A testing frame applied 10 non-destructive torsion and 10 axial compression cycles, followed by cantilever bending to failure. Stiffness was calculated; maximum failure load and failure mode were recorded. Results were compared to previous data for locked metal constructs. Retrospective review of surgically treated clavicle fractures over three years included functional and radiographic outcomes.FindingsBioabsorbable plates had lower torsional stiffness (P < 0.001) and maximum cantilever load (P < 0.0001) than locked metal plates. There was no significant difference in compression stiffness (P = 0.2) or cantilever bending stiffness (P = 0.4). Primary failure of metal plates was screw pull-out compared to plate bending in bioabsorbable constructs. Seven patients with bioabsorbable implants were included. All patients with bioabsorbable constructs achieved radiographic union, but 71% lost reduction. Despite fracture angulation, all achieved normal shoulder function after one year determined by QuickDASH evaluation. None required a second surgery.InterpretationBioabsorbable implants had lower torsional stiffness and cantilever failure load, but comparable compression stiffness to metal implants. Bioabsorbable implants failed via gradual bending versus the catastrophic failure seen in metal implants. The clinical review allows understanding of the sequelae of this lower failure load of bioabsorbable plates where their use allowed in fracture displacement, yet achievement of ultimate radiographic union and acceptable functional outcomes.Copyright © 2018 Elsevier Ltd. All rights reserved.

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