Cervical unilateral open-door laminoplasty with titanium miniplates through newly designed hydroxyapatite spacers.

A newly designed hydroxyapatite (HA) spacer for cervical laminoplasty is provided with a hole through which the titanium miniplate is passed. A new method of unilateral open-door laminoplasty with titanium miniscrew and miniplate through this HA spacer is described. Twenty-two patients with cervical stenotic disorders were treated by this procedure. Only the predominantly affected side of the laminae is exposed. The supraspinous and interspinous ligaments and the deep muscle layer in the contralateral side are left intact. A 4-mm wide gutter near the intervertebral joint is made and contralateral hinges are made under the deep muscle layer with minimum detachment of these muscles. The opened lamina is fixed with the titanium miniplate passed through the hole in the newly designed HA spacer. Mean operative time for the 22 operations was 193.5 minutes. Mean enlargement of the minimum spinal canal diameter was 50.9%. Neurological outcomes after 3 months were evaluated according to the Japanese Orthopaedic Association (JOA) scoring. Mean recovery rate of JOA score by Hirabayashi's method was 49.5%. Only 2 patients reported postoperative axial neck pain. Our method for unilateral open-door laminoplasty provides adequate decompression and tight fixation of laminae, and is less invasive to the posterior supporting elements of cervical spine.