Impact of different laminae open angles on axial symptoms after expansive open-door laminoplasty

The present study is a retrospective study. Axial symptoms are frequently encountered complication after laminoplasty. Some studies have reported the influencing factors and preventive measures of axial symptoms after laminoplasty. However, impact of different laminae open angles on the postoperative axial symptoms remains unclear. The objective of the present study was to explore the effect of different laminae open angles on postoperative axial symptoms and to discuss the possible mechanisms of the impact of different open angles on axial symptoms. We retrospectively analyzed 124 patients with multilevel cervical compression myelopathy who were treated with expansive open-door laminoplasty from February 2012 to January 2015. The operational level ranged from C3-C7 in all patients. The laminae open angles at the C4, C5, and C6 levels were measured 1 week postoperative. The mean value was taken for statistical analysis. The patients were divided into 2 groups, group A (open angles < 40°, 71 patients including 44 males and 27 females) and group B (open angles ≥ 40°, 53 patients including 32 males and 21 females). C2-C7 Cobb angle, range of cervical motion (ROM), Japanese Orthopedic Association (JOA) score, and visual analog scale (VAS) score for axial pain were compared between the 2 groups. All patients completed at least 2-year follow-up. Both groups gained significant JOA improvement postoperatively (P < .05). Preoperative and postoperative C2-C7 Cobb angle and ROM comparisons were significantly different (P < .05) in both groups. There were no significant difference for other clinical and radiography parameters between the groups (P > .05). At 2 weeks and 6 months after surgery, there was significant difference in axial symptoms between the 2 groups (P < .05). At final follow-up, the difference between the 2 groups was not statistically significant (P > .05). In different angles of the lamina open-door, incidence of axial symptoms has statistically difference between the 2 groups. When the lamina open-door angles are <40°, there are not only ensure adequate spinal cord decompression but reduces the incidence of early and midterm postoperative axial pain.