Relationship between cervical sagittal balance parameters and the clinical outcome after laminoplasty in patients with cervical ossification of the posterior longitudinal ligament

English Keywords:Ossification of posterior longitudinal ligament(OPLL)  Cervical sagittal balance parameter  Sagittal vertical axis(SVA)  Open-door laminoplasty

English Abstract:

  【Abstract】 Objectives: To investigate the relationship between preoperative cervical sagittal balance parameters with postoperative clinical outcome in ossification of posterior longitudinal ligament(OPLL) patients. Methods: Between January 2015 and December 2017, 181 consecutive patients who underwent cervical laminoplasty for OPLL were enrolled. Cervical spine CT, MRI and radiographs were taken before surgery, 2-month after surgery and at 1-year follow-up. The C2-C7 Cobb angle, C2-C7 sagittal vertical axis(SVA), center gravity of head(CGH)-C7 SVA, C1-C7 SVA, T1 slope and the Japanese Orthopedic Association(JOA) scores were also recorded. The patients were divided according to the JOA recovery rate at 1-year followup according to the quantile method. The relationships between postoperative and preoperative variables, including age, JOA score, C2-C7 Cobb angle, T1 slope, CGH-C7 SVA, C1-C7 SVA and C2-C7 SVA were investigated. Results: Mean preoperative of C1-C7 SVA, C2-C7 SVA, CGH-C7 SVA, T1 slope, C2-7 Cobb angle and JOA was 22.5±9.6mm, 25.2±12.5mm, 28.9±17.6mm, 27.3°±9.6°, 11.8°±9.4°, 8.7±2.5 respectively. Further analysis showed that preoperative C1-C7 SVA, T1 slope and CGH-C7 SVA were significantly correlated to the clinical outcome of OPLL patients at 1 year follow-up(P=0.048, P=0.027, P<0.01 respectively). Logistic regression analysis revealed only CGH-C7 SVA had a strong relationship with postoperative clinical outcome(OR=1.654, P<0.01). Conclusions: CGH-C7 SVA is a good predictor of postoperative clinical outcome of the cervical OPLL, and higher preoperative CGH-C7 SVA may increase the risk of bad clinical outcomes in laminoplasty treated OPLL patients.