Impact of nonlordotic sagittal alignment on short-term outcomes of cervical disc replacement

Abstract

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.