Evaluation of a Monocoritcal Screw for Anterior Cervical Fusion and Plating

As documented by earlier studies, monocortical screw fixation in anterior cervical fusion and plating failed to achieve the stability of bicortical fixation. The purpose of this study was to evaluate the stability and safety of a new monocortical screw–plate–system for anterior cervical fusion and plating according to Caspar in comparison to bicortical fixation. In the biomechanical part of the study two groups comprising of six fresh human cadaveric spines(C4–C7), matched for bone mineral density were used. Range of motion and neutral zone were analysed in flexion–extension, axial rotation and lateral bending in a custom spine tester using pure moments of 2.5 Nm for each specimen in the intact state, after discectomy at C5/6 followed by bone grafting plus plating with either monocortical or bicortical screws. The clinical part of the study was performed as a prospective study (mean follow–up 26 months)on 30 patients, suffering from cervical disc disease, who underwent anterior cervical fusion and plating with monocortical screws. No significant difference could be found in all motion planes between monocortical and bicortical fixation techniques. At the latest follow–up, no hardware or graft related complications were seen in any of the patients. Thus, monocortical screw fixation is recommended for anterior cervical fusion and plating in degenerative disease, making the procedure quicker, easier and safer.