Radiographic Fusion Rates Following a Stand-alone Interbody Cage Versus an Anterior Plate Construct for Adjacent Segment Disease After Anterior Cervical Discectomy and Fusion

Study Design. Case-control. Objectives. The aim of this study was to evaluate fusion rates and compare a stand-alone cage construct with an anterior-plate construct in the setting revision anterior cervical discectomy and fusion (ACDF) for adjacent segment disease. Summary of Background Data. Anterior cervical discectomy and fusion are considered the criterion standard of surgical treatment for cervical myelopathy and radiculopathy. One common consequence is adjacent segment disease. Treatment of adjacent segment disease is complicated by the previous surgical implants, which may make application of an additional anterior cervical plate difficult. Stand-alone cage constructs obviate the need for removal or revision of prior implants in the setting of adjacent segment disease. Methods. All patients undergoing surgery for adjacent segment disease in a 2-year period were identified and separated into groups based on implant construct. A control group of patients undergoing primary, single-level ACDF were selected from during the same 2-year period. Demographic variables, fusion rate, and reoperation rate were compared between groups. Continuous variables were compared using Studentttest, fusion, and revision rates were compared using Pearson chi(2)test. Results. Patients undergoing primary ACDF had lower age and American Society of Anesthesia score as well as shorter operative time. Fusion rate was higher for primary ACDF compared to all patients who underwent ACDF for adjacent segment disease (95%vs.74%). When compared to primary ACDF, patients with a stand-alone cage construct had significantly lower fusion rate (69%vs.95%) and higher reoperation rate (14%vs.0%). There were no significant differences in anterior plate construct versus stand-alone cage construct in terms of fusion and reoperation. Conclusion. Symptomatic adjacent segment disease can be managed surgically with either revision anterior plating or a stand-alone cage constructs, although our results raise questions regarding a difference in fusion rates that requires further investigation.