Comparison of the Degree of Expanded Spinal Canal Area between the Hinge-Side Area and the Open-Side Area in Cervical Open-Door Laminoplasty

Background: There have been reports on the significant canal cross-sectional area (CSA) expansion difference between pre- and post-operation, but no comparison of CSA expansion between the hinge-side area (Area H) and the open-side area (Area O) has been reported. This study aimed to measure the spinal CSA expansion between Area H and Area O retrospectively after open-door laminoplasty using new titanium spacers and evaluated this common decompression procedure's effectiveness. Materials and Methods: This study included 27 patients diagnosed with cervical spondylotic radiculopathy or myelopathy, ossification of the posterior longitudinal ligament, and developmental canal stenosis from February 2021 to October 2022. The CSA difference between pre- and post-cervical laminoplasty (C4–C6 levels) was measured with cervical transverse computed tomography scan images. The CSA difference in Area H and Area O between pre- and post-laminoplasty was similarly calculated. Results: The spinal canal areas of each segment after open-door laminoplasty were significantly enlarged (P < 0.05). Area O was also significantly enlarged compared to that of Area H (P < 0.05). Conclusion: Area O was more enlarged than Area H, and both sides were statistically enlarged after open-door laminoplasty.