Therapeutical concept for injuries of the lower cervical vertebral column

Follow-up of a new titanium cervical plate for fusion of the cervical spine

Cervical plates are in use since the 1990ies for anterior cervical discectomy and fusion (ACDF). The latest step in development was a dynamic plate that allows sliding of the screws facilitating the natural settling of the bone after surgery. We investigated the clinical and radiological results of such a dynamic plate in a patient cohort that underwent single or multi-level ACDF for various cervical degenerative indications, including revision cases, from 2014 to 2019. Clinical and radiological outcome were assessed in 60 eligible patients after a mean of 2.9 years. The assessed neck disability index (NDI), and the visual analogue scale (VAS) of neck and arm pain show comparable results to the literature of ACDF, and specifically other plate designs. Forty-eight Adverse and Serious Adverse Events do not show a link to the product used. Clinical and radiological outcomes of ACDF with dynamic, third generation cervical plates show comparable results to the literature. Careful reporting of all Adverse Events revealed a variety of concomitant diseases, but could not be correlated to the implant used.

Biomechanical analysis of expansion screws and cortical screws used for ventral plate fixation on the cervical spine

Compared to bicortical screws, the surgical risk of injuring intraspinal structures can be minimized with the use of monocortical screws. However, this reduction should not be achieved at the expense of the stability of the fixation. With monocortical stabilization, the expansion screws have the potential of absorbing high loads. Therefore, they are expected to be a suitable alternative to bicortical screws for revision surgeries and in osteoporotic bone. The purpose of this in vitro study was to investigate the stiffness of the two screw-plate systems used for ventral stabilization of the cervical spine, by focusing on the suitability of expansion screws as tools for revision treatments. The study was conducted in ten functional units of human cervical spines. The device sample stiffness was determined for four conditions using a turning moment of 2.25 N m each around one of the three principle axes. The conditions were native, destabilized, primarily stabilized with one of the screw-plate systems, followed by secondary stabilization using the expansion screw implant. The stabilized samples achieved a comparable, in most cases higher stiffness than the native samples. The samples undergoing secondary stabilization using expansion screws tend to display greater stiffness for all three axes compared to the primarily stabilized samples. The achieved tightening moment of the screws was higher than the one achieved with primary fixation. Both plates revealed similar primary stability. Revision surgeries with secondary instrumentation achieve a high stiffness of the screwed up segments. Monocortical expansion screws combined with a trapezoidal plate allow ventral stabilization of the cervical spine that is comparable to the plate fixation using bicortical screws.