Effects of intraoperative hinge fracture on postoperative cervical spine alignment in double door cervical laminoplasty

Introduction Hinge fracture and cervical kyphosis are known complications of cervical laminoplasty. Prior literatures on hinge fracture focused mainly on laminoplasty performed using the open-door technique. In this study we aim to assess the effect of intraoperative hinge fracture on postoperative cervical spine alignment in cervical laminoplasty performed using the double door technique.Methods This study recruited patients who received double door cervical laminoplasty from January 2014 to December 2022. The diagnosis, demographic data, preoperation and postoperation cervical spine alignment of the patients with intraoperative hinge fracture were compared with patients withouintraoperative hinge fracture. Cervical spine alignment was measured using C2-7 Cobb's angle on neutral lateral cervical spine X ray.Results Nine patients with intraoperative hinge fracture and 51 patients without intraoperative hinge fracture were recruited into the study. There was no statistically significant difference in age, sex, diagnosis and preoperative cervical spine alignment between the patients with and without intraoperative hinge fracture. Significant difference was found in the postoperation cervical spine alignment (1.9 +/- 15.5 degrees vs 9.7 +/- 13.6 degrees, p = .044) and change in cervical spine alignment (-12.9 +/- 12.1 degrees vs -4.0 +/- 10.0, p = .02) between patients with and without intraoperative hinge fracture.Conclusions In double door cervical laminoplasty, intraoperative hinge fracture is associated with development of postoperative cervical kyphosis.