Relationship between hinge fracture and postoperative axial symptoms after cervical laminoplasty

Objective To identify the clinical characteristics of fractured hinges after open-door cervical laminoplasty for cervical canal stenosis and explore the relationship between hinge fractures and axial symptoms. Methods This was a retrospective study of patients with cervical myelopathy who underwent open-door laminoplasty between November 2014 and November 2016 at the Affiliated Hospital of Qingdao University. Cervical CT scans were performed after surgery and the Takeuchi criteria were applied to evaluate the postoperative axial symptoms. Results Of 223 opened laminae in 67 patients, 67 laminae (30.0%) in 30 patients (44.8%) showed fracture. The frequency of hinge fractures was higher at C6 (53.7%). Forty-nine fractured laminae (73.13%) were non-displaced and 18 were displaced. At 3 months, 33 fractured laminae (49.3%) showed bony union on CT, and union rates were 86.6% and 91.0% at 6 and 12 months, respectively, indicating that the union rate was lower for displaced fractures than for non-displaced fractures. Among the 67 patients, 14 had axial symptoms: three of 37 (8.1%) patients without hinge fractures and 11 of 30 (36.7%) patients with hinge fractures. One year later, the hinge fractures were healed in 24/30 patients. Among the six unhealed patients, five still suffered from axial symptoms. The frequency of axial symptoms was higher in the patients with three or more hinge fractures (66.7%) than in the patients with only one (16.7%) or two (46.7%) hinge fractures. Conclusions Patients with hinge fractures may have an increased risk for axial symptoms after open-door cervical laminoplasty. The frequency of axial symptoms decreases with fracture healing.