Three-Dimensional Computed Tomography Image Reformation for Comparison of Foraminal Cross-Sectional Dimension in Patients Who Have Undergone Laminoplasty and Laminectomy with Fusion.

Purpose of the study: Laminectomy with fusion (LF) is commonly performed with laminoplasty (LP) for cervical myelopathy. Foraminal stenosis is important in the surgical treatment of cervical myelopathy. LF and LP can affect foraminal size in different ways. This study aimed to compare foraminal dimensions after LF and LP using a medical computer-assisted design (CAD) program.

Material and methods: Computed tomography (CT) scans of the cervical vertebrae of 16 patients with cervical myelopathy were retrospectively viewed in the Digital Imaging and Communications in Medicine format on a CAD program. CT images were reformatted in an oblique plane perpendicular to the long axis of each foramen from C2-C3 to C6-C7. The narrowest foraminal crosssectional dimension (FCD) was measured and compared between the LF and LP groups at the operated, non-operated, and C4-C5 levels. The difference between the preoperative and postoperative FCDs was also calculated and compared between the operated and C4-C5 levels. Intra- and interobserver reliabilities for FCD measurements were evaluated using intraclass correlation coefficients.

Results and discussion: At the operated spinal levels, the LF and LP groups showed decreased and increased mean FCDs, respectively. At the adjacent non-operated levels, the mean FCD slightly increased in both the groups. In the LF group, the difference between the preoperative and postoperative FCDs in the C4-C5 levels was larger than that in the other operated levels, but this difference was insignificant.

Conclusions: LF and LP showed contrary results for FCD. Therefore, FCD and kyphosis should be considered for LF and LP.

Key words: three-dimensional, foraminal cross-sectional dimension, laminoplasty, laminectomy fusion, computer-aided design, drafting system, preoperative-postoperative comparison.