Short plate with screw angle over 20 degrees improves the radiologic outcome in acdf: Clinical study

Background: Anterior cervical discectomy and fusion surgery is a common procedure for degenerative cervical spine. This describes allospacer and implant-related outcomes, comparing medium plate–low screw angle and short plate–high screw angle techniques. Methods: From January 2016 to June 2019, 79 patients who underwent ACDF were prospectively enrolled. Patients were divided, depending on the plate–screw system used: medium plate–low screw angle (12.3 ± 2.5 to 13.2 ± 3.2 degrees), and short plate–high screw angle (22.8 ± 5.3 to 23.3 ± 4.7 degrees). Subsidence, ALOD, and sagittal cervical balance were analyzed using lateral cervical X-rays. NDI and VAS scores were also evaluated. Results: Age for medium plate–low-angled screw group is 58.0 ± 11.3 years, and 55.3 ± 12.0 in the short plate–high-angled screw group (p-value = 0.313). Groups were comparable in mean NDI (p-value = 0.347), VAS (p-value = 0.156), C2–C7 SVA, (p-value = 0.981), and lordosis angle (p-value = 0.836) at 1-year post-surgery. Subsidence was higher in the medium plate–low-angled screw than in the short plate–high-angled screw (25% and 8.5%, respectively, p-value = 0.045). ALOD is also more common in the medium plate group (p-value = 0.045). Conclusion: Use of a short plate and insertion of high-angled screws (more than 20 degrees) has less chance of subsidence and occurrence of ALOD than the traditional technique of using medium plate and low angle.