Delayed hinge fracture after plate-augmented, cervical open-door laminoplasty and its clinical significance.

BACKGROUND CONTEXT: Among the various forms of laminoplasty fixation, plate augmentation provides a semirigid arch reconstruction and is gaining popularity as the result of its safety and effectiveness. However, the effects of this procedure on hinge status and subsequent bony healing remain unclear.

PURPOSE: We sought to evaluate the status and time course of bony healing of the hinge gutter and to determine the effect on postoperative clinical course of plate-only, open-door cervical laminoplasty.

STUDY DESIGN: This was a retrospective clinical series.

PATIENT SAMPLE: A total of 79 adult men and women undergoing cervical laminoplasty in a university hospital setting were studied.

OUTCOME MEASURES: Time-dependent changes in hinges observed on computed tomography (CT) were used to measure the radiological outcome. A numerical rating scale of axial neck pain and arm pain was used to evaluate the clinical outcome.

METHODS: Patients who underwent plate-only, open-door laminoplasty for cervical myelopathy and had available postoperative CT scans were enrolled in this study. Neck pain intensity before and 1 year after surgery was assessed with questionnaires. CT scans (n=125) obtained after surgery were assessed in terms of bony healing of the hinge.

RESULTS: Most of the hinges were initially well-bent. Only 9% were found to be "fractured" or "in danger of fracture" at 1 week. Primary healing without callus formation, which is the next step of bony healing of well-bent hinges, was observed in 62% of cases at month 4. The remaining 38% were classified as "fractured" or in the process of "secondary healing." A similar number of hinges was classified as "secondarily healed" after 1 or 2 years of follow-up. All except one hinge were well united and incorporated at the final follow-up, and the number of hinges classified as "fractured or secondarily healed" related to postoperative axial neck pain with respect to the 1-year visual analog scale for the neck and the Neck Disability Index.

CONCLUSIONS: Although plate-only, open-door laminoplasty is a safe and reliable surgery for decompression of multilevel cervical disease, the fixation that it provides on the open side may not be sufficiently stable to allow successful primary healing. Additional attention should be paid to the hinged side to prevent delayed fracture in the early postoperative period and to reduce postoperative axial pain.