Postoperative Outcomes and Complications after Anterior Cervical Discectomy and Interbody Fusion with a Self-locking Stand-alone Cage

Abstract

Purpose: A self-locking stand-alone cage have been used for anterior cervical discectomy and fusion (ACDF). The purpose of this study was to evaluate the clinical and radiographic results in patients who underwent ACDF using this cage and to identify the risk factors for postoperative cage subsidence of this cage.

Methods: This retrospective study included 15 patients who underwent ACDF (total 22 levels: 9 at 1 level, 5 at 2 levels, and 1 at 3 levels) with a self-locking stand-alone cage from July 2017 to February 2019. In the preoperative radiographical analysis, the C2-7 sagittal vertical axis (SVA), the C2-7 Cobb angle, and the segmental lordotic angle (SLA) were evaluated. Postoperative cage subsidence was considered to be significant when subsidence over 2 mm occurred at the midpoint interbody height (IBH) at each level. The clinical outcomes were evaluated by Japanese Orthopaedics Association (JOA) scoring system.

Results: Posteoperative JOA score improved significantly after surgery (p< 0.01). Eighteen (82%) of 22 cages achieved bony fusion. Postoperative cage subsidence over 2 mm occurred in 9 (41%) of 22 cages. There was no significant difference in age, sex, BMI, follow-up period, C2-7 SVA, C2-7 Cobb angle, JOA score, and fusion rate between the patients with subsidence under 2 mm (Group I) and the patients with subsidence over 2 mm (Group S). The preoperative SLA was significantly lower in Group S (p=0.04). When differences were compared in SLAs between before and just after the operation, Group S showed significantly higher differences (p=0.03). As a major complication, 1 patient developed aspiration pneumonia due to dysphagia, and 1 patient underwent posterior decompression and fusion due to neurological deterioration caused by cage subsidence.

Conclusion: ACDF with this cage achieved satisfactory clinical and radiographical outcomes with a low incidence of postoperative complications. However, this study indicated that postoperative subsidence of this cage system might be caused by overcorrection of preoperative segmental kyphosis in patients with lower SLA.