Anterior cervical fusion: a biomechanical comparison of 4 techniques. Laboratory investigation

J Neurosurg Spine. 2008 Nov;9(5):444-9. doi: 10.3171/SPI.2008.9.11.444.


Object: 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. METHODS 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.

Results: 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.

Conclusions: 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.

Publication types

  • Comparative Study

MeSH terms

  • Biomechanical Phenomena
  • Bone Plates*
  • Cervical Vertebrae*
  • Finite Element Analysis
  • Humans
  • Internal Fixators*
  • Joint Instability / surgery*
  • Models, Biological
  • Range of Motion, Articular
  • Spinal Diseases / surgery*
  • Spinal Fusion / instrumentation*
  • Spinal Fusion / methods
  • Weight-Bearing