Predicting post-laminoplasty kyphosis in cervical spondylotic myelopathy patients without preoperative kyphosis: a retrospective study

BACKGROUND: This study aimed to determine potential risk factors for post-laminoplasty kyphosis and the effect of postoperative kyphosis on neurologic function recovery. METHODS: A total of 266 patients with cervical spondylotic myelopathy (CSM) underwent traditional cervical laminoplasty with a minimum of a 12-month follow-up period. The patients were divided into non-kyphosis (NK group) and kyphosis (K group) groups based on the postoperative C2-7 Cobb angle. Clinical and radiological measurements were collected preoperatively and at the final follow-up. RESULTS: Of the 266 patients, 26 (9.77%) developed postoperative kyphosis at the final follow-up. The postoperative Japanese Orthopedic Association score did not differ significantly between the NK and K groups (P > 0.05). The postoperative numeric rating scale (NRS) also showed no significant difference between the NK and K groups; however, postoperative NRS improved better than the preoperative values in the NK group (P < 0.001). Multivariate analysis revealed that the preoperative C2-7 extension Cobb angle and C2-7 Cobb angle were independent predictors of post-laminoplasty kyphosis. Cut-off values for predicting postoperative kyphosis were a C2-7 extension Cobb angle of 18.00° and a C2-7 Cobb angle of 9.30°. CONCLUSIONS: Low preoperative C2-7 extension Cobb angle and C2-7 Cobb angle may be associated with post-laminoplasty kyphosis in CSM patients without preoperative kyphosis. The cut-off value of the C2-7 extension Cobb angle and C2-7 Cobb angle were 18.00° and 9.30°, respectively.