Does Preoperative T1 Slope and Cervical Lordosis Mismatching Affect Surgical Outcomes After Laminoplasty in Patients with Cervical Spondylotic Myelopathy?

OBJECTIVE:To assess whether preoperative T1 slope and cervical lordosis mismatching affect the surgical outcomes of patients with cervical spondylotic myelopathy (CSM) after laminoplasty. METHODS:A total of 85 patients with CSM who underwent unilateral open-door laminoplasty between January 2013 and May 2017 were retrospectively reviewed. Based on preoperative T1 slope and C2-C7 lordosis matching, the patients were divided into 2 groups: the match group and the mismatch group. The T1 slope minus C2-C7 lordosis (T1S-CL) <20° was defined as matching. Radiographic parameters included T1 slope, C2-C7 lordosis, C2-C7 sagittal vertical axis (SVA), and T1S-CL. Clinical outcomes were based on the Neck Disability Index (NDI) and Japanese Orthopedic Association (JOA) scores. RESULTS:The preoperative T1S-CL had significant correlation with T1 slope (r = 0.283), C2-C7 lordosis (r = -0.611), and C2-C7 SVA (r = 0.331). At the final follow-up, patients in the mismatch group had a higher incidence of postoperative cervical kyphosis (P = 0.007) and C2-C7 SVA >40 mm (P = 0.043). The mismatch group also had greater △C2-C7 lordosis (P = 0.028), △C2-C7 SVA (P = 0.042), and △T1S-CL (P = 0.044). Comparison of clinical outcomes revealed that patients in the match group had better NDI and JOA recovery (P < 0.05). CONCLUSIONS:T1S-CL is a clinically relevant parameter for surgical decision making because patients with T1S-CL mismatching are more likely to have postoperative kyphotic alignment changes and cervical sagittal imbalance. Laminoplasty might not be a suitable option for patients with T1S-CL mismatching.