[Feasibility study of a novel preoperative planning method for predicting the increment of spinal canal cross-sectional area and opening angle in single open-door laminoplasty].

Abstract

Objective: To investigate the clinical feasibility of a paper-cutting method to simulate posterior cervical single open-door laminoplasty for predicting postoperative increases in central sagittal canal diameter and cross-sectional area of the spinal canal.

Methods: Between January 2021 and February 2022, 21 patients underwent posterior cervical single open-door laminoplasty, including 12 males and 9 females, aged from 42 to 73 years with a mean of (59.7±9.9) years. There were 18 cases of ossification of the posterior longitudinal ligament, 3 cases of ligamentum flavum hypertrophy, 11 cases of multilevel cervical disc herniation, and 2 cases of developmental spinal stenosis. Cervical CT data were imported into Mimics software to measure preoperative and postoperative spinal canal parameters. Preoperative C₃-C₇ vertebrae were 3D-printed to simulate open-door laminoplasty, and corresponding spinal canal parameters were recorded. The increase in cross-sectional area of the spinal canal was calculated using the sector area formula ( S=nπr²/360). Comparative statistical analysis was performed among preoperative measurements, postoperative outcomes, simulated open-door parameters, and to verify the clinical feasibility of the paper-cutting method and the formula for calculating the increase in spinal canal cross-sectional area.

Results: Imaging data were obtained in all 21 patients. Preoperative VAS and JOA scores in the 21 patients were (6.80±1.93) and(10.52±3.80), respectively, which significantly improved to (2.42±1.20) and (12.90±4.18) at 12 months postoperatively (P<0.05). Additionally, significant differences were observed in the C₃-C₇ spinal canal parameters between pre-and post-operation(P<0.05). At 3 days postoperatively, the C₃ opening angle (22.94±5.00)° was significantly smaller than those at the C₄ (28.67±5.99)°, C₅ (30.78±5.94)°, C₆(29.18±6.55)°, and C₇(27.32±6.18)° segments (P<0.05). Furthermore, the opening width at C₃(7.09±0.28) mm and C₇(7.47±0.36) mm, as well as the increase in spinal canal cross-sectional area at C₃(68.54±17.39) mm² and C₇(63.64±15.82) mm², were significantly smaller than those at C₄(9.17±0.32) mm and (86.84±18.12) mm², C₅(9.31±0.34) mm and (92.80±18.94) mm², and C₆(8.60±0.35) mm and (79.53±17.06) mm², respectively(P<0.05). There were no statistically significant differences among the spinal canal parameters measured by the paper-cutting method, the increment of spinal canal cross-sectional area calculated by the formula, and the actual postoperative CT measurements(P>0.05).

Conclusion: The extent of laminar opening varies among different cervical levels in posterior cervical single-open door laminoplasty. In clinical practice, the paper-cutting method can be used to plan relevant surgical parameters and may help reduce the incidence of intraoperative and postoperative complications.