Fracture healing and bone remodeling with human standard-sized magnesium versus polylactide-co-glycolide (PLGA) plate and screw systems using a mini-swine craniomaxillofacial osteotomy fixation model

Publication date: Available online 31 March 2018
Source:Journal of Oral and Maxillofacial Surgery
Author(s): Benoît Schaller, John Patrik Matthias Burkhard, Madeleine Chagnon, Stefan Beck, Thomas Imwinkelried, Michel Assad
PurposeThis study compared the degradation profile, safety and efficacy of a bioresorbable magnesium (Mg) alloy and polylactide-co-glycolide (PLGA) polymer osteosynthesis systems for the treatment of fractures in a load-sharing maxillofacial environment using a new mini-swine fracture fixation model.MethodsTwo types of clinically relevant situations were evaluated in five Yucatan miniature pigs. Defined porcine midface osteotomies of the supra-orbital rim and zygoma were created and fixed with either coated Mg (test animals) or PLGA plate and screw osteosynthesis systems (control animals). Following surgery, mini-pigs were able to recover for either one or nine months with continuous in vivo post-implantation monitoring. Standardized computed tomography (CT) imaging was taken immediately post-operatively and at termination for all animals. The nine-month cohort additionally underwent CT at 2, 4, and 6 months post-surgery. At necropsy, osteotomy sites and bone-implant units were harvested and the healing was evaluated under micro-CT, histopathology and histomorphometry.ResultsFollowing clinical and radiological follow-up examination, all fracture sites healed well for both magnesium and polymer groups regardless of time. Complete bone union and gradually disappearing osteotomy lines were observed across all implantation sites, with no major consistency change in periprosthetic soft tissue nor soft tissue calcification. Macroscopic and microscopic examination showed no negative influence of gas formation observed with Mg during the healing process. Histopathology demonstrated similar fracture healing outcomes for both plating systems with good biocompatibility as evidenced by a minimal or mild tissue reaction.ConclusionThe present study confirms that WE43-Mg alloy exhibited excellent fracture healing properties before its full degradation and without causing any significant inflammatory reactions in a long-term porcine model. Compared to PLGA implants, magnesium represent a promising new biomaterial with reduced sizes and improved mechanical properties in order to support fracture healing in a load-sharing environment.



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