Load-sharing through elastic micro-motion accelerates bone formation and interbody fusion

Eric H Ledet,Glenn P Sanders,Darryl J Dirisio,Joseph C Glennon

doi:10.1016/j.spinee.2018.02.004

Abstract

Background ContextAchieving a successful spinal fusion requires the proper biological and biomechanical environment. Optimizing load-sharing in the interbody space can enhance bone formation. For anterior cervical discectomy and fusion (ACDF), loading and motion are largely dictated by the stiffness of the plate, which can facilitate a balance between stability and load-sharing. The advantages of load-sharing may be substantial for patients with comorbidities and in multilevel procedures where pseudarthrosis rates are significant. PurposeWe aimed to evaluate the efficacy of a novel elastically deformable, continuously load-sharing anterior cervical spinal plate for promotion of bone formation and interbody fusion relative to a translationally dynamic plate. Study Design/SettingAn in vivo animal model was used to evaluate the effects of an elastically deformable spinal plate on bone formation and spine fusion. MethodsFourteen goats underwent an ACDF and received either a translationally dynamic or elastically deformable plate. Animals were followed up until 18 weeks and were evaluated by plain x-ray, computed tomography scan, and undecalcified histology to evaluate the rate and quality of bone formation and interbody fusion. ResultsAnimals treated with the elastically deformable plate demonstrated statistically significantly superior early bone formation relative to the translationally dynamic plate. Trends in the data from 8 to 18 weeks postoperatively suggest that the elastically deformable implant enhanced bony bridging and fusion, but these enhancements were not statistically significant. ConclusionsLoad-sharing through elastic micro-motion accelerates bone formation in the challenging goat ACDF model. The elastically deformable implant used in this study may promote early bony bridging and increased rates of fusion, but future studies will be necessary to comprehensively characterize the advantages of load-sharing through micro-motion.

Highlights

BACKGROUND CONTEXTAchieving a successful spinal fusion requires the proper biological and biomechanical environment
In patients where three or more motion segments must be included in the fusion construct, most surgeons choose to do a combined anterior and posterior reconstruction, as fusion rates are reduced in these situations and construct failure is high with an anterior alone approach [6,7]
To facilitate controlled continuous load-sharing with the interbody space, we evaluated an elastically deformable anterior cervical plate which promotes load-sharing through controlled micromotion (ReVeal Anterior Cervical Plating System, ReVivo Medical, Loudonville, NY, USA) (Fig. 1)

Summary

Introduction

BACKGROUND CONTEXTAchieving a successful spinal fusion requires the proper biological and biomechanical environment. For anterior cervical discectomy and fusion (ACDF), loading and motion are largely dictated by the stiffness of the plate, which can facilitate a balance between stability and load-sharing. PURPOSE: We aimed to evaluate the efficacy of a novel elastically deformable, continuously loadsharing anterior cervical spinal plate for promotion of bone formation and interbody fusion relative to a translationally dynamic plate. RESULTS: Animals treated with the elastically deformable plate demonstrated statistically significantly superior early bone formation relative to the translationally dynamic plate. CONCLUSIONS: Load-sharing through elastic micro-motion accelerates bone formation in the challenging goat ACDF model. The elastically deformable implant used in this study may promote early bony bridging and increased rates of fusion, but future studies will be necessary to comprehensively characterize the advantages of load-sharing through micro-motion. The current designs of fracture fixation plates, intramedullary rods, and external fixation systems are based on these guiding biomechanical principles

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