Anterior cervical discectomy and fusion for cervical myelopathy using stand-alone tricortical iliac crest autograft: Predictive factors for neurological and fusion outcomes

Purpose: The purpose of this article is to investigate the outcomes after anterior cervical discectomy and fusion (ACDF) surgery with stand-alone tricortical iliac crest autograft and to determine predictive factors for poor neurological recovery, non-union, graft collapse and loss of C2-C7 sagittal alignment. Methods: This was a retrospective study involving patients with cervical myelopathy who underwent ACDF surgery with stand-alone tricortical iliac autograft between 2006 and 2016, with a minimum 2-year postoperative follow-up. Outcomes included the change in Japanese Orthopaedic Association (JOA) scores clinically and timing of fusion, graft height and C2-7 angle measured on lateral radiographs. Any complication such as neurological deterioration, non-union, graft collapse or loss of angle was recorded. Delayed union was considered as radiological union identified only beyond postoperative 6 months. Risk factors including age, smoking, drinking, comorbidities and operative levels were analysed through a multivariate regression for their respective influences on the various outcomes. Results: Of the 69 patients studied, none of the patients had non-union, while 33 (47.1%) achieved fusion in 6 months. The most common complications were anterior protrusion of graft (5.8%) and hoarseness (2.9%). The 1-year mean change in JOA score was 3.9 +/- 2.7. The C2-7 angle gradually became more kyphotic, despite an initial lordosis correction intraoperatively. The graft height also gradually collapsed during subsequent follow-ups. Multivariate regression model suggested that diabetics (cumulative odds ratio 7.4) and drinkers (cumulative odds ratio 8.6) were associated with delayed union. Conclusion: ACDF using tricortical iliac crest autograft has satisfactory outcomes with low occurrence of complications. Diabetics and drinkers were predictors of delayed union.