Relationship between sagittal parameters and clinical efficacy of modified laminoplasty in the treatment of ossification of the posterior longitudinal ligament of cervical spine

English Keywords:Ossification of the posterior longitudinal ligament  Laminoplasty  C3 laminectomy  Sagittal alignment

English Abstract:

  【Abstract】 Objectives: To investigate the effect of modified laminoplasty with C3 laminectomy and C7 U type laminectomy in maintaining the sagittal balance of cervical spine and its effect on the clinical outcome. Methods: 99 cases with ossification of the posterior longitudinal ligament(OPLL) were included in a case-control study. There were 42 patients in C3 laminectomy group, included 22 males and 20 females, with an average age of 61.4±9.2 years(39-78 years). C3 laminectomy, C4-6 laminectomy and C7 laminectomy were performed. At the same time, 57 patients (31 males and 26 females, mean age 59.3±8.65 years, 41-79 years) were treated with standard laminoplasty (C3 open group). The mean follow-up was 45.9±8.8 months. The JOA and NDI scores of the two groups were observed pre- and post- operation. The changes of cervical physiological curvature and C2-7 SVA pre-and post-operation were observed in the two groups. The patients with cervical spondylosis in each group were divided into subgroups, and the differences of JOA and NDI scores between the subgroups were compared. Comparison of sagittal parameters between C3-6 and C3-7 laminoplasty in C3 open group were performed. Results: There was no significant difference in preoperative indexes between the two groups, and the JOA and NDI scores of the two groups were significantly improved at final follow-up. There was no difference in JOA score between the two groups at final follow-up, but the NDI scores in C3 laminectomy group was better(6.06±4.49 vs 8.25±7.53). At final follow-up, the cervical curve of the two groups decreased in varying degrees. Compared with the preoperative cervical curve, there was no significant difference in C3 laminectomy(the variation of cervical curvature was 6.25°±10.22°), but there was difference in the C3 laminoplasty group(the variation of cervical curvature was 6.25°±10.22°). There were significant differences in cervical curve between the two groups(P＜0.05). At final follow-up, the C2-7 SVA of the two groups increased in varying degrees, there was no significant difference in C3 laminectomy group compared with the preoperation, but there was significant difference in C3 laminoplasty group, and there was significant difference in C2-7 SVA between the two groups. There were 30 cases of C3-6 laminoplasty and 27 cases of C3-7 laminoplasty, and there was no significant difference in cervical curve and C2-7 SVA between the two subgroups. There was no significant difference in JOA, NDI scores between cervical lordosis and kyphosis groups at final follow-up(P＞0.05). Conclusions: The modified laminoplasty with C3 laminectomy can effectively maintain the postoperative cervical curve and slow down the progress of cervical kyphosis after posterior cervical surgery. There was no significant correlation between the changes of cervical sagittal participation and the clinical effect post-operation.