[Effect of the proximal level on post-laminoplasty loss of lordosis]

To analyze the effect whether or not retaining muscle ligament complex of C2 attachment on cervical spine kyphotic deformity after single open-door laminoplasty.

A total 40 patients with cervical spondylotic myelopathy underwent single open-door laminoplasty from February 2011 to June 2014 were retrospectively analyzed. Of them, single open-door for C₃-C₆ was 40 cases (group A), including 28 males and 12 females, with an average age of (68.4±9.3) years old;and single open-door for C₄-C₆ plus C₃ laminectomy decompression (in order to protect the muscle ligament complex of C₂ attachment) was 40 cases (group B), including 26 males and 14 females, with an average age of (66.8±8.4) years old. Japanese Orthopaedic Association (JOA) score, visual analogue scale (VAS), Cobb angle of sagittal plane from C₂-C₇, cervical range of motion were used to evaluate effects before operation and at the latest follow-up.

All the patients were followed up from 24 to 31 months with an average of(26.5±3.4) months. There was no significant differences in VAS, JOA scores and cervical range of motion before surgery between two groups (P>0.05) and all above items were significantly improved at the latest follow-up (P<0.05), but there was no significant difference between two groups(P>0.05). There was no significant difference in cervical Cobb angle before surgery between two groups(P>0.05), and postoperative Cobb angle had obviously improved in two groups(P<0.05), but the improvement of group B was better than that of group A.

Starting the laminoplasy on C₄ level and retainning the muscle ligament complex of C₂ attachment can obviouly decrease cervical spine syphotic deformity.