Biomechanical Evaluation of Titanium, Biodegradable Plate and Screw, and Cyanoacrylate Glue Fixation Systems in Craniofacial Surgery

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Abstract
Choice of appropriate fixation after reduction of displaced bone fragments or advancement of osteotomized segments requires knowledge of the maximal force to which these segments can be subjected. The present study was performed to obtain a biomechanical comparison of a variety of resorbable fixation systems as an alternative to metal plates and screws. Sheep cadaver parietal bone segments were osteotomized and fixed with one of six methods of fixation: (A) titanium plates and screws consisting of (1) miniplates and 2.0-mm-diameter screws; (2) midface plates and 1.5-mm screws; (3) microplates and 1.0-mm screws; (B) resorbable systems consisting of combinations of butyl-2cyanoacrylate glue and biodegradable polylactic acid/polyglycolic acid copolymer plates and 2.0-mm screws as follows: (1) direct glue fixation of segments; (2) resorbable plates fixed to bone segments with cyanoacrylate glue; (3) resorbable plates fixed with resorbable screws. Compression testing was performed upon bone segments advanced and fixed across a central gap, and distraction testing was performed on bone segments fixed in direct contact. Force to failure in both distraction and compression was significantly greater in bone segments fixed with titanium miniplates than with any other method of fixation. Segments fixed with plates and screws, either nonresorbable or resorbable, achieved stronger fixation in distraction than in compression for all plate sizes tested. Resorbable plate and screw fixation was as strong as standard titanium midface and microplating systems in distraction, and stronger than the latter techniques in compression. With compressive forces of relapse, fixation with glue and resorbable plates was as strong as standard titanium midface and microplating systems. However, with distractive forces of relapse, glue fixation of either the bone segments or resorbable plates was weaker than both titanium and resorbable alternatives in which plates and screws were used. These findings may have direct impact on the choice of fixation devices used to support osteotomized or fractured bone segments, which are subjected to persistent muscular and soft-tissue pull.