Geometric results of anterior cervical plate stabilization in degenerative disease

Study Design. Consecutive case retrospective computerized analysis of lateral radiographs. Objectives. To investigate the time evolution of the geometry of anterior cervical discectomy and fusion using a new computer-aided measurement technique. Summary of Background Data. Prior clinical studies have reported benefits and complications of anterior cervical plate stabilization, but have not comprehensively described changes in sagittal geometry following arthrodesis and plating. High fusion success rates have been reported for single-level discectomy and fusion, whereas multilevel procedures have demonstrated lower clinical success rates with increased hardware failure and pseudarthrosis rates. Methods. Sagittal alignment data were collected from lateral radiographs of 51 patients with 52 operations for single- or multiple-level anterior cervical discectomy and fusion, both with and without anterior cervical plate stabilization. Intervertebral angulation and separation at the operated segments before surgery, immediately after surgery, and at long-term follow-up were compared using a computer-aided technique. Results. Single-level anterior cervical discectomy and fusion with plate stabilization lost 0.9degrees of the operatively obtained lordosis after surgery compared to 7.5degrees for single-level fusions with bone alone (P = 0.0001). In multilevel anterior cervical discectomy and fusion, the bottommost level of the anterior cervical discectomy and fusion construct was much more prone to collapse than the remaining levels (mean bottom-level loss of 4.0degrees vs. mean 0.2degrees increase at the remaining levels, P < 0.0001). Conclusions. Anterior cervical plate stabilization helps maintain operatively obtained segmental distraction and lordosis following anterior cervical discectomy and fusion. In multilevel procedures, this study found that postoperative collapse is largely localized to the bottommost level, where hardware failure and pseudarthrosis have been observed most often by others.