Study of Predisposing Factors of Postoperative Axial Symptom after Unilateral Expansive laminoplasty for Treating Ossification of Cervical Posterior Longitudinal Ligament

Abstract：Objective To investigate features,pathological mechanism and correlated risk factors of postoperative axial symptom (PAS) in multilevel ossification of cervical posterior longitudinal ligament(MOPLL) patients underwent unilateral expansive laminoplasty.Methods 79 patients with no less than 4 segments of MOPLL were treated by unilateral expansive laminoplasty and fixed with continuous miniplate fixation of open side.Preoperative and postoperative corrected value of inter-vertebral range of flexion and extension motion located in over all C2～7,C3～4 and C5～6 segments as well as postoperative alteration amplitude of straight core distance from C2 to C7 vertebrae and maximum gap distance of facet joints within operated domain were recorded.The data were retrospectively analyzed in our department.12 cases had PAS after surgery.The imaging parameters were compared between PAS group and non-PAS group.Results Decrease extent of C2～7 movement in midsagittal plane in PAS group was higher than that in non-PAS group (P ＜ 0.0 5).Preoperative range of C5～6 intervertebral motion in PAS group was larger than that in non-PAS group (P＜0.05).Loss degree of postoperative range of C3～4 sagittal motion in PAS group was more than that in non-PAS group (P＜0.05).Postoperative modification value of vertical core distance from C2 to C7 vertebrae and longest gap distance of lateral mass joints showed no difference between PAS and non-PAS group (P＞0.05).Conclusion The preliminary study suggests that MOPLL patients with preoperative short-segment cervical instability will more likely have imbalance of inter-vertebral motion range and dynamic unsteadiness of stress distribution of soft tissues nearby,which induces PAS.