Risk Factors for Hinge Fracture Associated with Surgery Following Cervical Open-Door Laminoplasty.

Objective: The purpose of this study was to analyze the risk factors for hinge fracture (HF) and non-union during cervical open-door laminoplasty (CODL).

Methods: We included 25 patients who underwent CODL with available serial computed tomography scans acquired at 2 days and 1 year postoperatively. Patients' medical records and radiographic data were reviewed. Risk factors related to the surgical procedures were evaluated including the lamina angle, spinous angle, difference in the lamina angle, outer cortex location (OCL), and inner cortex location.

Results: There were a total of 76 hinges. Of these, 44 laminae were classified as deformed hinges, and 32 were classified as fragmented hinges. Additionally, 66 laminae were healed completely, and 10 laminae were not healed by 12 months postoperatively. The OCL (odds ratio, 70.45; 95% confidence interval, 7.73-641.76) was identified as a predictor of HFs immediately following CODL. However, none of the factors we evaluated was related to hinge non-union.

Conclusion: A medially located hinge gutter ( >1.9 mm from the pedicle on the outer cortex) seems to be an important risk factor for HFs following CODL. However, the hinge healing status was not related to the surgical technique.