46 - Perioperative complications and radiographic outcomes following cervical laminoplasty: a review of 105 cases from a single academic center

Introduction
Cervical laminoplasty was first described in 1973 by Oyama et al. as a motion-preserving, posterior approach to decompress the spinal cord at multiple levels. In contrast to laminectomy, this procedure preserves posterior bone and ligamentous structures and is thought to decrease the destabilizing effects of the decompression, thereby obviating the need for fusion. With the advancement of technology, the safety and efficacy have also increased, resulting in a decrease in commonly associated complications. The change in cervical radiographic parameters has not been well documented, and nor has the prevalence of complications in North American populations.

Objective
This study aims to quantify the prevalence of complications and assess changes in cervical radiographic parameters.

Primary Outcome
Outcomes included intra-operative and post-operative complications.

Secondary outcomes
Change in pre-and post-op C2-7 cobb angle, C2–7 sagittal vertical axis (SVA), and T1 slope.

Materials and Methods
Patient population
After the institutional review board approved the study, we used the Current Procedural Terminology codes for cervical laminoplasty to identify patients who underwent the procedure from January 1, 2011, to December 31, 2022, at a single academic institution in the United States.

Complications
A retrospective chart and radiographic imaging review were conducted for all identified patients. We excluded patients with no accessible medical records documenting the surgeries. We collected demographic data, and documented adverse events that occurred intra-operatively or post-operatively. Post-operative complications were classified into perioperative complications which occurred within 90 days of surgery, and delayed complications that occurred after the said duration. All complications were further divided into minor or major medical and surgical complications.

Radiographic parameters
We analyzed preoperative and postoperative C2-7 cobb angle, C2–7 sagittal vertical axis (SVA), and T1 slopes on upright lateral cervical spine radiographic imaging. Patients without pre-operative or post-operative imaging obtained were excluded from this part of the study. The postoperative measurements were obtained at either the last follow-up visit or at 6 months postoperative visit.

Results:
Patient population
We identified 150 patients who underwent cervical laminoplasty between January 1, 2011, and December 31, 2022 (Figure 1). 105 patients with accessible medical records met the inclusion criteria for assessment of intra-operative and post-operative complications.

Complications
We identified a total of 22 (21.0%) adverse events in 20 patients (Table 1). There were 4 intra-operative (3.8%), 10 peri-operative (9.5%), and 8 delayed post-operative (7.6%) adverse events. Amongst them, 13 (12.4%) were judged to be minor and 9 (8.6%) were judged to be major complications (Table 2).

Radiographic parameters
47 (44.8%) of the 105 patients had pre-and post-operative cervical spine radiographic imaging (Table 3). The average pre-and post-op C2-7 cobb angles were 14.7 degrees and 12.3 degrees (p-value of 0.04). The pre-and post-op SVA was 29.2 mm and 33.3 mm (p-value of 0.07). The pre-op and post-op T1 slopes were 32.3 and 30.2 deg (p-value of 0.07).

Conclusion:
Cervical laminoplasty has a low re-operative rate (5.7%) without significant change in SVA and T1 slope postoperatively. Cervical laminoplasty remains a valuable surgical option for selected patients with cervical myelopathy.