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Three-dimensional assessment of the intervertebral kinematics after Mobi-C total disc replacement at the cervical spine in vivo using the EOS stereoradiography system

 Marc-Antoine Rousseau, MD, PhD,1,2 Sébastien Laporte, PhD,1 Thierry Dufour, MD,3 Jean-Paul Steib, MD, PhD,4 Jean-Yves Lazennec, MD, PhD,2 Wafa Skalli, PhD1

1Biomechanics Lab, Arts et Métiers ParisTech, Centre national de la recherche scientifique (CNRS), unités mixtes de recherche (UMR) 8005, Paris, France 2Department of Orthopaedic Surgery, Hôpital Pitié Salpétrière Assistance Publique - Hôpitaux de Paris (AP-HP), Paris, France 3Department of Neurosurgery, Hôpital La Source, Orléans, France 4Department of Orthopaedic Surgery, Hopitaux Universitaires de Strasbourg, Strasbourg, Franc



Because 3-dimensional computed tomography and magnetic resonance imaging analysis of the spinal architecture is done with the patient in the supine position, stereoradiography may be more clinically relevant for the measurement of the relative displacements of the cervical vertebrae in vivo in the upright position. The innovative EOS stereoradiography system was used for measuring the relative angular displacements of the cervical vertebrae in a limited population to determine its feasibility. The precision and accuracy of the method were investigated.


In 9 patients with 16 Mobi-C prostheses (LDR Medical, Troyes, France) and 12 healthy subjects, EOS stereoradiography of the lower cervical spine (C3-7) was performed in the neutral upright position of the neck, flexion, extension, left and right lateral bending, and left and right axial rotation. The angular displacements were measured from the neutral position to every other posture. The random error was studied in terms of reproducibility. In addition, an in vitro protocol was performed in 6 specimens to investigate accuracy.


The reproducibility and the accuracy variables varied similarly between 1.2° and 3.2° depending on the axis and direction of rotation under consideration. The Mobi-C group showed less mobility than the control group, whereas the pattern of coupling was similar.


Overall, the feasibility of dynamic EOS stereoradiography was shown. The prosthesis replicates the pattern of motion of the normal cervical spine.

Cervical Spine, Disc prosthesis, EOS system, kinematics, In vivo, Stereoradiography
Volume 5 Issue 3