Effect of lamina open angles in expansion of unilateral open-door laminoplasty on the clinical results in treating cervical myelopathy

English Keywords:Cervical myelopathy  Expansion of unilateral open-door laminoplasty  Lamina angle opened  Complication  Close of the opened laminae

English Abstract:

  【Abstract】 Objective：To evaluate and compare the relation between the efficacy and clinical results of expansion of open-door laminoplasty with different angles in lamina open-door.Method：198 cases were select from July 2006 to January 2009 who underwent posterior cervical unilateral open-door laminoplasty and received treatment for more than 24 months follow-up of patients with cervical myelopathy.There were 115 male cases and 83 female case with the mean age of 49±5 years（range，29-72 years）.There were 39 double-segment cases，including 11 C3-C5 cases and 28 C4-C6 cases；97 three-segment（C4-C7） cases and 62 four segment（C3-C7） cases.All of these cases had cervical spine anterior-posterior and lateral，oblique and double-bit excessive flexion and extension cervical spine X-ray，CT and MRI.Preoperative JOA scores were 4 to 9，an average of 6.3±2.9.By CT scan after 1 week in accordance with the measurement on the angle of the lamina to 30° for the open boundaries，the cases were divided into two groups，to compare operation time，blood loss，postoperative complications，C2-C7 Cobb angle，index of cervical lordosis，cervical movement and to values after the shift，and evaluate the neurological function at final follow-up and calculate improvement rate of nerve function.Result：Group A：a total of 76 cases had an opening angle change＞30°.Group B：a total 122 cases had an opening angle change 15°-30°.In preoperative JOA scores，C2-C7 Cobb angle，index of cervical lordosis，cervical movement between the two groups showed no statistically significant difference（P>0.05）.The surgical time and blood loss in group A were 110±13min and 250±80ml，and in group B respectively 120±30min and 230±100ml，the difference was not statistically significant（P>0.05）.In group A，51 patients after surgery（67.1%） had axial symptoms，8 patients（10.4%） with C5 nerve root palsy，1 patient（1.32%） with mild cervical kyphosis.In group B，37 cases（10.5%） had axial symptoms，3 patients（2.4%） with C5 nerve root palsy，4 patients（3.28%） with open door closed.The incidence of axial symptoms and C5 nerve palsy of group A was higher than that of group B，the incidence of postoperative complications between the two group wae more significant different（P<0.05）.The improve rate of JOA scores in final follow-up was （72.1±11.7）% in group A and（69.0±12.3）% in group B，with no significant difference.The value of spinal cord after shift at 1 month follow-up is 0-7.95mm，average 2.41±0.46mm.C2-C7 Cobb angle，index of cervical lordosis，cervical movement between the two groups showed no statistically significant difference（P>0.05）.Conclusion：Different lamina open angles in improve rate of neurological function after surgery are not significantly different.The changes of the opening angle controlled between 15°-30° will lower the incidence of C5 nerve root palsy and axial symptoms，but reclose should be prevent.