Anterior cervical discectomy and fusion for cervical myelopathy using standalone tricortical iliac crest autograft: predictive factors for neurological and fusion outcomes

Abstract

Purpose: To investigate the outcomes after anterior cervical discectomy and fusion (ACDF) surgery with standalone tricortical iliac crest autograft and to determine predictive factors for poor neurological recovery, non-union, graft collapse, and loss of C2-7 sagittal alignment. Methods: This was a retrospective study involving patients with cervical myelopathy who underwent ACDF surgery with standalone tricortical iliac autograft between 2006 and 2016, 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 complications such as neurological deterioration, non-union, graft collapse or loss of angle were 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 (standard deviation=2.7). The C2-7 angle gradually became more kyphotic despite an initial lordosis correction intra-operatively. The graft height also gradually collapsed during subsequent follow-up examinations. Multivariate regression model suggested that diabetics (cumulative odds ratio: 7.4) and drinkers (cumulative odds ratio: 8.6) were associated with delayed union. Conclusion: The ACDF using tricortical iliac crest autograft has satisfactory outcomes with low occurrence of complications. Diabetes and regular alcohol consumption were predictors of delayed fusion.