The Relationship Between the Anatomy of the Nuchal Ligament and Postoperative Axial Pain After Cervical Laminoplasty Cadaver and Clinical Study

Study Design. A cadaver and clinical study investigated the attachment of the nuchal ligament to the cervical spinous process. Objective. To investigate the anatomical details of the attachment of the nuchal ligament to the spinous process and the relationship between the morphology of the nuchal ligament and postoperative axial pain after laminoplasty. Summary of Background Data. The relationship between the length of the C6 spinous process and the morphology of the nuchal ligament and occurrence of postoperative axial pain has not been elucidated. Methods. The morphology of the nuchal ligament was investigated in 35 cadavers and 60 patients on preoperative computed tomography and magnetic resonance imaging. The lengths of the C6 and C7 spinous processes were measured, and the C6: C7 ratio (C6 spinous process length/C7 spinous process length) was calculated. The relationship between the morphology of the attachment of nuchal ligament to the C6 spinous process and the C6: C7 ratio were investigated. In addition, the effects of the anatomy of the nuchal ligament around the C6 spinous process and different procedures of surgical invasion to C6 or C7 on postoperative axial pain were investigated for 113 patients who underwent laminoplasty. Results. The nuchal ligament was attached to not only the C7 spinous process, but also the C6 spinous process when the C6: C7 ratio was more than 0.8. When the nuchal ligament was attached to the C6 spinous process and to C7, postoperative axial pain after C3-C7 laminoplasty occurred more often compared with C3-C6 laminoplasty for patients without the nuchal ligament attached to the C6 spinous process. Conclusion. This study shows that there is an association between the individual anatomical differences of the nuchal ligament and the occurrence of postoperative axial pain after laminoplasty. Careful attention should be paid to the morphology of the attachment of the nuchal ligament to the C6 spinous process to reduce postoperative axial pain.