Anterior cervical fusion: a biomechanical comparison of 4 techniques

Laboratory investigation

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Cervical instrumented fusion is currently performed using several fixation methods. In the present paper, the authors compare the following 4 implantation methods: a stand-alone cage, a cage supplemented by an anterior locking plate, a cage supplemented by an anterior dynamic plate, and a dynamic combined plate–cage device.


Four finite element models of the C4–7 segments were built, each including a different instrumented fixation type at the C5–6 level. A compressive preload of 100 N combined with a pure moment of 2.5 Nm in flexion, extension, right lateral bending, and right axial rotation was applied to the 4 models. The segmental principal ranges of motion and the load shared by the interbody cage were obtained for each simulation.


The stand-alone cage showed the lowest stabilization capability among the 4 configurations investigated, but it was still significant. The cage supplemented by the locking plate was very stiff in all directions. The 2 dynamic plate configurations reduced flexibility in all directions compared with the intact case, but they left significant mobility in the implanted segment. These configurations were able to share a significant part of the load (up to 40% for the combined plate–cage) through the posterior cage. The highest risk of subsidence was obtained with the model of the stand-alone cage.


Noticeable differences in the results were detected for the 4 configurations. The actual clinical relevance of these differences, currently considered not of critical importance, should be investigated by randomized clinical trials.

Abbreviation used in this paper: ROM = range of motion.

Article Information

Address correspondence to: Fabio Galbusera, M.S.Eng., IRCCS Istituto Ortopedico Galeazzi, via R. Galeazzi 4, 20161 Milan, Italy. email:

© AANS, except where prohibited by US copyright law.



  • View in gallery

    Finite element models of the C4–7 segment implanted with a stand-alone cage (a), a cage supplemented by an anterior plate (locking or dynamic; b), and a combined plate–cage device (c).

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    Illustration demonstrating the geometry of the screw– plate interface in the models including the dynamic plate and the combined plate–cage device. The inclination of the screw head was assumed to be 45°. The clearance between the head and the plate was 0.1 mm.

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    Graph showing the ROMs calculated with the finite element models in flexion, extension, right lateral bending, and right axial rotation.

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    Graph showing the fraction of load shared by the cage calculated with the models including the cage supplemented with the anterior locking or dynamic plate and the model including the combined plate–cage device.

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    Images showing the contact pressures in extension at the cage–C6 endplate interface calculated with the models including a stand-alone cage (a), a cage supplemented by an anterior locking plate (b), cage supplemented by an anterior dynamic plate (c), and a combined plate–cage device (d).



Adams MSCrawford NRChamberlain RHSonntag VKDickman CA: Biomechanical comparison of anterior cervical plating and combined anterior/lateral mass plating. Spine J 1:1661702001


Brodke DSKlimo P JrBachus KNBraun JTDailey AT: Anterior cervical fixation: analysis of load-sharing and stability with use of static and dynamic plates. J Bone Joint Surg Am 88:156615732006


Cauthen JCTheis RPAllen AT: Anterior cervical fusion: a comparison of cage, dowel and dowel-plate constructs. Spine J 3:1061172003


Espinoza-Larios AAmes CPChamberlain RHSonntag VKDickman CACrawford NR: Biomechanical comparison of two-level cervical locking posterior screw/rod and hook/rod techniques. Spine J 7:1942042007


Fraser JFHärtl R: Anterior approaches to fusion of the cervical spine: a metaanalysis of fusion rates. J Neurosurg Spine 6:2983032007


Galbusera FBellini CMRaimondi MTFornari MAssietti R: Cervical spine biomechanics following implantation of a disc prosthesis. Med Eng Phys [epub ahead of print]2008


Greene DLCrawford NRChamberlain RHPark SCCrandall D: Biomechanical comparison of cervical interbody cage versus structural bone graft. Spine J 3:2622692003


Hakalo JPezowicz CWronski JBedzinski RKasprowicz M: Comparative biomechanical study of cervical spine stabilisation by cage alone, cage with plate, or plate-cage: a porcine model. J Orthop Surg 16:9132008


Nunley PDJawahar AKerr EJ IIICavanaugh DAHoward CBrandao SM: Choice of plate may affect outcomes for single versus multilevel ACDF: results of a prospective randomized single-blind trial. Spine J [epub ahead of print]2008


Pflugmacher RSchleicher PGumnior STuran OScholz MEindorf T: Biomechanical comparison of bioabsorbable cervical spine interbody fusion cages. Spine 29:171717222004


Rancourt DShirazi-Adl ADrouin GPaiement G: Friction properties of the interface between porous-surfaced metals and tibial cancellous bone. J Biomed Mater Res 24:1503 15191990


Rapoff AJConrad BPJohnson WMCordista ARechtine GR: Load sharing in Premier and Zephir anterior cervical plates. Spine 28:264826502003


Samartzis DShen FHLyon CPhillips MGoldberg EJAn HS: Does rigid instrumentation increase the fusion rate in one-level anterior cervical discectomy and fusion?. Spine J 4:6366432004


Shimamoto NCunningham BWDmitriev AEMinami AMcAfee PC: Biomechanical evaluation of stand-alone interbody fusion cages in the cervical spine. Spine 26:E432E4362001


Wang JCMcDonough PWEndow KKanim LEDelamarter RB: The effect of cervical plating on single-level anterior cervical discectomy and fusion. J Spinal Disord 12:4674711999


Wang MGourab KMcGrady LMRao RD: Alteration of load sharing of anterior cervical implants with change in cervical sagittal alignment. Med Eng Phys 30:7687732008


Wilke HJKettler AClaes L: Primary stabilizing effect of interbody fusion devices for the cervical spine: an in vitro comparison between three different cage types and bone cement. Eur Spine J 9:4104162000


Yang SWang LW: Biomechanical comparison of the stable efficacy of two anterior plating systems. Clin Biomech (Bristol Avon) 18:S59S662003




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