Impact of Nonlordotic Sagittal Alignment on Short-term Outcomes of Cervical Disc Replacement.

Objective: To evaluate outcomes of cervical disc replacement (CDR) in patients with nonlordotic alignment.

Methods: Patients who underwent CDR were retrospectively reviewed and divided into 3 cohorts: (1) neutral/lordotic segmental and C2-7 Cobb angle (L), (2) nonlordotic segmental Cobb angle, lordotic C2-7 Cobb angle (NL-S), and (3) nonlordotic segmental and C2-7 Cobb angle (NL-SC). Radiographic and patient-reported outcomes (PROMs) were compared.

Results: One-hundred five patients were included (L: 37, NL-S: 30, NL-SC: 38). A significant gain in segmental lordosis was seen in all cohorts at < 6 months (L: -1.90° [p = 0.007]; NL-S: -5.16° [p < 0.0001]; NL-SC: -6.00° [p < 0.0001]) and ≥ 6 months (L: -2.07° [p = 0.031; NL-S: -6.04° [p < 0.0001]; NL-SC: -6.74° [p < 0.0001]), with greater lordosis generated in preoperatively nonlordotic cohorts (p < 0.0001). C2-7 lordosis improved in the preoperatively nonlordotic cohort (NL-SC: 8.04°) at follow-up of < 6 months (-4.15°, p = 0.003) and ≥ 6 months (-6.40°, p = 0.003), but not enough to create lordotic alignment (< 6 months: 3.89°; ≥ 6 months: 4.06°). All cohorts showed improvement in Neck Disability Index, visual analogue scale (VAS) neck, and VAS arm, without significant difference among groups in the amount of improvement ( ≥ 6-month PROMs follow-up = 69%).

Conclusion: In patients without major kyphotic deformity, CDR has the potential to generate and maintain lordosis and improve PROMs in the short-term, and can be an effective treatment option for patients with nonlordotic alignment.