Cervical curvature after double-door laminoplasty and autologous spinous process graft

English Keywords:Cervical Spondylosis, Spinal Stenosis, Autologous Spinous, Double-door Laminoplasty, Sagittal Morphology

English Abstract:

  【Abstract】 Objectives: To explore the sagittal morphology of cervical spine after double-door laminoplasty and autologous spinous process graft in cervical myelopathy. Methods: A total of 57 patients were recruited in this study, who underwent double-door laminoplasty and autologous spinous process graft from January 2006 to June 2014, including 24 patients with ossified posterior longitudinal ligament and 33 patients with multilevel cervical spondylotic myelopathy. All the parameters measured on the lateral radiographs of cervical spine were recorded before operation and at the final follow-up . The occipitocervical parameters and cervical spine sagittal parameters were as follows: occipital incidence(OI), occipital slope(OS), occipital tilt(OT), C0-C2 angle, C2-C7 angle, C0-C7 angle, C2-C7 sagittal vertical axis(SVA), range of motion(ROM) and thoracic 1 slope(T1-slope). Pre- and postoperative neurological status was evaluated by using the Japanese Orthopaedic Association(JOA) scoring system for cervical myelopathy. All the parameters were compared between preoperation and the final follow-up by independent sample t test and Pearson correlation analysis. Results: There was no complication found intraoperatively or postoperatively. The average follow-up time was 13.6±9.3 months. JOA score was 10.9±2.7 at preoperation, which was significantly lower than that at final follow-up(14.1±2.1, P<0.01). After operation, the JOA score had improved 40.0%-83.3%(average 53.1%). Occipitocervical parameters between the two time points were not significantly different(P>0.05). However, significant correlation was observed between OI and C0-C2 angle in the two time points(r=0.542, P=0.014 vs r=0.479, P=0.027). C0-C2 angle, C2-C7 angle, C0-C7 angle, C2-C7 SVA and T1 slope were significantly higher at final follow-up than those at preoperation(P<0.05), while ROM was significantly lower postoperatively. Conclusions: There is no significant difference in occipitocervical parameters between preoperation and final follow-up after double-door laminoplasty and autologous spinous process graft. However, the occipitocervical parameters are correlated with the upper cervical sagittal alignment. The sagittal cervical curvature changes postoperatively: leaning forward of cervical spine, higher cervical lordosis, lower cervical sagittal vertical axis, and higher T1 slope.