Plate fixation adds stability to two-level anterior fusion in the cervical spine: A randomized study using radiostereometry

This study evaluated whether addition of a cervical spine locking plate (CSLP) in two-level disc fusions improved the postoperative stability and reduced the time to healing. Radiostereometric analysis was used to obtain precise recordings of the three-dimensional motion between the fused vertebrae. Eighteen consecutive patients were operated on with excision of two adjacent cervical discs and anterior horseshoe grafting with autologous bone (Smith Robinson technique). Nine patients were randomized to stabilization with autologous bone grafting and CSLP plate fixation and nine patients to grafting without fixation. Clinical symptoms in terms of pain in the neck and the arm were analysed preoperatively and after 1 year using a visual analogue scale (VAS). The patients operated without a plate displayed increased rotations around the transverse axis, corresponding to the development of a kyphosis [mean value no plate/plate 14.4°/0.8°(repeated measure ANOVA: P < 0.01)]. The mean compression was 3.2 mm larger in patients operated without a plate (repeated measure ANOVA: P < 0.01). Patients operated without a plate had more arm pain at the 1-year follow up (P < 0.05, Mann-Whitney U test). The VAS score for neck pain did not differ significantly between the two groups. Plate fixation could not be demonstrated to increase the healing rate, promote more rapid fusion or influence the frequency of graft complications.