Effect of Lordotic vs. Non-lordotic Cage on Fusion, Sagittal Parameters, and Patient-reported Outcomes in Anterior Cervical Discectomy and Fusion: A Prospective Comparative Cohort Study

Introduction: Anterior cervical discectomy and fusion (ACDF) is a commonly performed procedure. The interbody characteristics for optimal outcomes remain inconclusive. We sought to prospectively compare lordotic and non-lordotic cages regarding fusion rates, subsidence, sagittal parameters, and patient-reported outcomes (PROs)

Methods: We prospectively enrolled patients who underwent 1-2 level ACDF using lordotic or non-lordotic cages for degenerative conditions from 9/2021-8/2022. The follow-up period was 1 year. The primary outcome was fusion as defined by the Song criteria or trabecular bony growth on computed tomography. Secondary outcomes included cage subsidence defined as ≥3 mm loss of fusion segmental height, revision surgery for pseudoarthrosis, time to revision surgery, perioperative outcomes, sagittal parameters, and PROs. PROs [VAS Neck, VAS Arm, Neck Disability Index (NDI), and modified Japanese Orthopedic Association scale (mJOA)] were collected prospectively using a registry. We compared the groups using univariate analysis. We performed logistic regression modeling on fusion, adjusting for age, operative time, and median household income. P< 0.05 was considered significant.

Results: One-hundred-three patients with one-hundred-forty-five cages being placed (57 non-lordotic vs. 63 lordotic) were analyzed. Patients in the lordotic group experienced longer operative time (77 min. vs. 67.5, p=0.003) and had a significantly lower median household income ($72961.96 vs. $84776.59, p=0.050). There was no significant difference in fusion rates, cage subsidence, or need for revision surgery between the lordotic and non-lordotic groups. Patients in the lordotic group demonstrated significant improvements in their VAS Neck (p=0.002), VAS Arm, NDI, and mJOA (p < 0.001) at 1 year postoperatively, whereas non-lordotic patients saw improvement at 1 year in VAS Neck, VAS Arm, and NDI only (p < 0.001). A significantly greater number of patients in the lordotic group had normative T1 slope at 2 weeks postoperatively (89.5% vs. 71.1%), though there was no significant difference preoperatively or at 1 year. There was no significant difference regarding other parameters. Multivariable analysis did not demonstrate any significant independent predictors.

Conclusion : One or two-level ACDF performed using either lordotic or non-lordotic cages resulted in similar fusion rates, cage subsidence, long-term sagittal parameters, and satisfactory PROs.