Zero-profile implant system versus novel plate systems after ACDF for comparison of sagittal balance parameters and clinical efficacy analysis

Abstract

Background: The zero-profile implant system (Zero-P) and conventional plates have been widely used in anterior cervical discectomy and fusion (ACDF) to treat cervical spondylosis. The purpose of this study was to compare the effects of the application of Zero-P and new conventional plates (ZEVO, Skyline) in ACDF on the sagittal imaging parameters of cervical spondylosis patients and to analyze their clinical efficacy.

Methods: We conducted a retrospective study on 119 cervical spondylosis patients from January 2018 to December 2021, comparing outcomes between those receiving the Zero-P device (n = 63) and those receiving a novel conventional plate (n = 56, including 46 ZEVO and 10 Skyline plates) through ACDF. Cervical sagittal alignment was assessed pre- and postoperatively via lateral radiographs. The Japanese Orthopedic Association (JOA), Neck Disability Index (NDI), and visual analog scale (VAS) scores were recorded at baseline, after surgery, and at the 2-year follow-up to evaluate patient recovery and intervention success.

Results: There were significant differences in the postoperative C0-C2 Cobb angle and postoperative sagittal segmental angle (SSA) between patients in the novel conventional plate group and those in the Zero-P group (P < 0.05). Postoperatively, there were significant changes in the C2‒C7 Cobb angle, C0‒C2 Cobb angle, SSA, and average surgical disc height (ASDH) compared to the preoperative values in both patient groups (P < 0.05). Dysphagia in the immediate postoperative period was lower in the Zero-P group than in the new conventional plate group (0% in the Zero-P group, 7.14% in the novel conventional plate group, P = 0.046), and the symptoms disappeared within 2 years in both groups. There was no statistically significant difference between the two groups in terms of complications of adjacent spondylolisthesis (ASD) at 2 years postoperatively (3.17% in the Zero-P group, 8.93% in the novel conventional plate group; P = 0.252). According to the subgroup analysis, there were significant differences in the postoperative C2‒C7 Cobb angle, C0‒C2 Cobb angle, T1 slope, and ASDH between the ZEVO group and the Skyline group (P < 0.05). Compared with the preoperative scores, the JOA, NDI, and VAS scores of all groups significantly improved at the 2-year follow-up (P < 0.01). According to the subgroup analysis, the immediate postoperative NDI and VAS scores of the ZEVO group were significantly better than those of the Skyline group (P < 0.05).

Conclusion: In ACDF, both novel conventional plates and Zero-P can improve sagittal parameters and related scale scores. Compared to the Zero-P plate, the novel conventional plate has a greater advantage in correcting the curvature of the surgical segment, but the Zero-P plate is less likely to produce postoperative dysphagia.

Keywords: ACDF; Sagittal balance parameters; Skyline; ZEVO; Zero-P.

Fig. 1

Schematic of the Zero-P® (a), ZEVO® (b), and Skyline® (c) implants and related postoperative X-ray images

Fig. 2

a–f: Pre- and postoperative radiographs of a 58-year-old woman following C4–C6 ACDF with the Zero-P system showing significant spinal improvement and decompression. g–l Post-C5-7 ACDF with the ZEVO System. Imaging of a 51-year-old man revealed resolved herniation and the absence of significant stenosis postsurgery. m–r: The efficacy of the Skyline System was demonstrated in a 71-year-old man, with pre- and postoperative images showing corrected alignment and decompression at C5–C7

Fig. 3

Radiographic measurements. A C2‒C7 Cobb angle. B C0‒C2 Cobb angle. C C2–C7 Sagittal Vertical Axis (SVA). D T1 slope. E C2 slope

Fig. 4

Comparisons of the NDI, VAS score and JOA score between the Zero-P group and the plate (Skyline & ZEVO) group at different time points. **Significantly different, P < 0.01. *Significantly different, P < 0.05

Fig. 5

Subgroup comparisons of the NDI, VAS score and JOA score between the Skyline group and ZEVO group at different time points. ** Significantly different, P < 0.01. * Significantly different, P < 0.05