STUDY DESIGN: Prospective, observational study. OBJECTIVE: To evaluate biomechanical changes associated with cervical arthrodesis using a cylindrical titanium cage. SUMMARY OF BACKGROUND DATA: Anterior cervical discectomy and fusion (ACDF) is the "gold standard" for treating cervical disc disease. In an effort to avoid the morbidity associated with autogenous bone graft harvesting, cervical cages are used to achieve fusion. The cages should allow for restoration and maintenance of natural disc height, angulations, and displacements at the operated levels. METHODS: Fifty-four patients underwent standard ACDF using a "stand alone" cylindrical cage implant. Lateral radiographic views of the cervical spine were obtained before surgery, on the first day postoperatively, and at 12 months postoperatively. Disc height, vertebral alignment, angle of lordosis, and range of motion at operated levels were quantified prospectively by distortion compensated Roentgen analysis. RESULTS: At 12 months postoperatively, solid fusion was achieved but the cylindrical cage failed to preserve disc height, prevent kyphosis, and preserve natural intervertebral alignment. We observed significant cage subsidence and malalignment. CONCLUSION: We noticed several unfavorable outcomes when performing an analysis of radiographic parameters after ACDF using a cylindrical titanium cage. Thus, the use of a "stand alone" cylindrical cage in ACDF should be considered with caution.
STUDY DESIGN: Prospective, observational study. OBJECTIVE: To evaluate biomechanical changes associated with cervical arthrodesis using a cylindrical titanium cage. SUMMARY OF BACKGROUND DATA: Anterior cervical discectomy and fusion (ACDF) is the "gold standard" for treating cervical disc disease. In an effort to avoid the morbidity associated with autogenous bone graft harvesting, cervical cages are used to achieve fusion. The cages should allow for restoration and maintenance of natural disc height, angulations, and displacements at the operated levels. METHODS: Fifty-four patients underwent standard ACDF using a "stand alone" cylindrical cage implant. Lateral radiographic views of the cervical spine were obtained before surgery, on the first day postoperatively, and at 12 months postoperatively. Disc height, vertebral alignment, angle of lordosis, and range of motion at operated levels were quantified prospectively by distortion compensated Roentgen analysis. RESULTS: At 12 months postoperatively, solid fusion was achieved but the cylindrical cage failed to preserve disc height, prevent kyphosis, and preserve natural intervertebral alignment. We observed significant cage subsidence and malalignment. CONCLUSION: We noticed several unfavorable outcomes when performing an analysis of radiographic parameters after ACDF using a cylindrical titanium cage. Thus, the use of a "stand alone" cylindrical cage in ACDF should be considered with caution.