[Analysis of reason for postoperative axial pain caused by unilaterally open-door cervical laminoplasty]

To explore the reason of postoperative axial pain (PAP) complication caused by unilaterally open-door cervical laminoplasty with Centerpiece mini-plate fixations for the treatment of multilevel cervical spondylotic myelopathy(CSM).

The clinical data of 79 patients with CSM who underwent unilaterally open-door cervical laminoplasty from January 2010 to December 2013 were retrospectively analyzed. There were 45 males and 34 females, aged from 48 to 75 years old with an average of (58.7±4.4) years, complicated with ossified posterior longitudinal ligament(OPLL) of 42 cases. Courses of disease were from 2.1 to 3.9 years with an average of (3.0±0.4) years. Decompression segment occurred in C₃-C₆ of 31 cases, C₃-C₇ of 9 cases, C₄-C₇ of 39 cases. The condition of PAP was record. Cervical curvature index, cervical lordosis angle, the rate of cervical instability, the motion of flexion and extension between PAP group and non-PAP group were compared preoperatively. Multivariate non-linear regression analysis was used to verify relationship between aforementioned parameters and incidence of PAP. JOA score of preoperative, postoperative 6 months and initial onset of PAP, the improvement rate of JOA score and Odom criteria at final follow-up were used to evaluate curative efficacy.

All the patients were followed up from 26 to 44 months with an average of (36±9) months. Among them, 12 patients occurred PAP who receive the conservative treatment. The rate of preoperative cervical instablility of PAP group were higher than that of non-PAP group(P<0.05). Preoperative cervical instability was the only independent risk factor in predicting occurrence of PAP. There were no significant differences in cervical curvature, cervical lordosis index, the motion of flexion and extension between PAP and non-PAP group before operation. There were no significant differences in the improvement of nerve function and clinical effect between PAP and non-PAP group after operation(P>0.05).

Preoperative cervical instability is prone to inducing the respectively intervertebral motion disorder and imbalance of stress redistribution, which results in PAP after cervical unilateral laminoplasty. Correct treatment of preoperative cervical instability is a key factor to prevent the occurrence of PAP after cervical laminoplasty, which would not affect long-term nerve functional recovery pronouncedly.