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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.

Anterior Cervical Discectomy and Fusion

Anterior cervical discectomy and fusion can be performed for a variety of pathologies but is most commonly used for the treatment of cervical radiculopathy or myelopathy. The procedure involves an anterior decompression of the disc space followed by interbody grafting and fusion. Supplemental anterior plating is commonly performed, and in certain circumstances, posterior instrumentation may provide additional fixation. The procedure includes the following steps: (1) The use of an anterior approach to the cervical spine, most commonly the Smith-Robinson approach medial to the sternocleidomastoid muscle and the carotid sheath. (2) Confirmation of the proper spinal level. (3) Elevation of the longus colli muscle, which acts as a cuff for the placement of retractors. (4) Removal of the involved disc and decompression of the spinal cord and nerve roots. This is facilitated by disc space distraction, most commonly via distraction pins. Osteophytes along the floor of the spinal canal impinging on the spinal cord are removed with a burr. Soft disc and anular material are also removed, usually with curets and rongeurs. Uncovertebral osteophyte resection and foraminotomies are completed to decompress the exiting nerve roots. (5) Carpentry and decortication of the end plates in preparation for fusion. (6) Sizing of the disc space followed by insertion of an interbody graft. (7) Anterior fixation, most commonly via application of a plate-and-screw construct. (8) Hemostasis and closure.