Adjacent Segment Disease after Cervical Spine Fusion

Study Design. A retrospective study of 70 patients undergoing surgical treatment for adjacent segment disease (ASD) after anterior cervical decompression and fusion (ACDF). Objective. To analyze the risk factors for the development of ASD in patients who underwent ACDF. Summary of Background Data. ACDF has provided a high rate of clinical success for the cervical degenerative disc disease; nevertheless, adjacent segment degeneration has been reported as a complication at the adjacent level secondary to the rigid fixation. Methods. Between January 2005 and December 2012, 70 consecutive patients underwent surgery for ASD after ACDF in our institution. In all patients thorough clinical and radiological examination was performed preoperatively, postoperatively, and at the final follow-up. The clinical data included the Neck Disability Index (NDI) and the Visual Analogue Scale (VAS). The radiological evaluation included x-rays and magnetic resonance imaging (MRI) for all patients. The duration of follow up after the adjacent segment operation ranged from 3 to 10 years. Results. Surgery for ASD was performed after a mean period of 32 months from the primary ACDF. ASD occurred after single level ACDF in 54% of cases, most commonly after C5/6 fusion (28%). Risk factors for ASD were found to be preexisting radiological signs of degeneration at the primary surgery (74%) and bad sagittal profile after the primary ACDF (90%). Conclusion. ASD occurred predominantly in the middle cervical region (C4-6); especially in patients with preexisting evidence of radiological degeneration in the adjacent segment at the time of primary cervical fusion, notably when this surgery failed to restore or maintain the cervical lordosis.