Symmetrically medial bony gutters for open-door laminoplasty.

Methods: Observational cohort study. Objective: The authors modified open-door laminoplasty in a manner that creates a bony gutter symmetrically and more medially away from the medial border of the lateral mass.

Background: Cervical laminoplasty is becoming popular, but there was no definite position of bony gutter in performing open-door laminoplasty.

Methods: All of the patients underwent our modified open-door laminoplasty with medial bony gutters. The bony gutter on the open side was made 3 mm medially apart from the medial border of the lateral mass, and an opposite gutter on the hinge side was drilled symmetrically to that on the open side while preserving the ventral cortex. The lamina was kept elevated using titanium miniplates bridging the lamina and facet joint on the open side. On the computed tomography, distance of the bony gutters and the cross-sectional area were measured from C4 to C6.

Results: This study included consecutive 61 patients (46 men and 15 women; mean age, 61.6 y old). The average distance of the right bony gutter was 3.43 mm and that of left bony gutter was 3.35 mm. The average cross-sectional area of preoperative and postoperative computed tomography was 189.9 and 281.8 mm in all patients, respectively. In all patients, although bony gutter was placed medially, the spinal canal area was expanded significantly (P < 0.0001). Postoperative C5 palsy developed in one of the 61 patients (1.6%). Compared with patients without C5 palsy, the right bony gutter was placed much closer to the medial border of the lateral mass in a patient with C5 palsy in whom we opened the lamina on the right side.

Conclusions: Our modified open-door laminoplasty with symmetrically and medially placed bony gutters produced low incidence of postoperative C5 palsy with effective expansion of the spinal canal area.