Impact of Myelopathy Severity and Degree of Deformity on Postoperative Outcomes in Cervical Spinal Deformity Patients

OBJECTIVE: Malalignment of the cervical spine can result in cord compression, leading to a myelopathy diagnosis. Whether deformity or myelopathy severity is stronger predictors of surgical outcomes is understudied. METHODS: Surgical cervical deformity (CD) patients with baseline (BL) and up to 1-year data were included. Modified Japanese Orthopaedic Association (mJOA) score categorized BL myelopathy (mJOA = 18 excluded), with moderate myelopathy mJOA being 12 to 17 and severe myelopathy being less than 12. BL deformity severity was categorized using the mismatch between T1 slope and cervical lordosis (TS-CL), with CL being the angle between the lower endplates of C2 and C7. Moderate deformity was TS-CL less than or equal to 25° and severe deformity was greater than 25°. Categorizations were combined into 4 groups: group 1 (G1), severe myelopathy and severe deformity; group 2 (G2), severe myelopathy and moderate deformity; group 3 (G3), moderate myelopathy and moderate deformity; group 4 (G4), moderate myelopathy and severe deformity. Univariate analyses determined whether myelopathy or deformity had greater impact on outcomes. RESULTS: One hundred twenty-eight CD patients were included (mean age, 56.5 years; 46% female; body mass index, 30.4 kg/m(2)) with a BL mJOA score of 12.8±2.7 and mean TS-CL of 25.9°±16.1°. G1 consisted of 11.1% of our CD population, with 21% in G2, 34.6% in G3, and 33.3% in G4. At BL, Neck Disability Index (NDI) was greatest in G2 (p=0.011). G4 had the lowest EuroQol-5D (EQ-5D) (p<0.001). Neurologic exam factors were greater in severe myelopathy (p<0.050). At 1-year, severe deformity met minimum clinically important differences (MCIDs) for NDI more than moderate deformity (p=0.002). G2 had significantly worse outcomes compared to G4 by 1-year NDI (p=0.004), EQ-5D (p=0.028), Numerical Rating Scale neck (p=0.046), and MCID for NDI (p=0.001). CONCLUSION: Addressing severe deformity had increased clinical weight in improving patient-reported outcomes compared to addressing severe myelopathy.