Comparison of ACDF with stand-alone PEEK cage versus zero-p implant for the treatment of cervical degenerative disease: a systematic review and meta-analysis

Introduction In recent years, stand-alone polyetheretherketone (PEEK) cages (SA) and Zero-P implants (ZP) have been widely adopted clinically in anterior cervical discectomy and fusion (ACDF) for cervical degenerative disease (CDD). However, which is superior between SA and ZP remains highly controversial. This meta-analysis was designed to conduct a head-to-head comparison of the safety, clinical efficacy, and radiological effectiveness of ACDF with ZP and SA. Methods This research was carried out in accordance with the PRISMA Statement. Systematic retrieval of eligible literature was completed covering three core electronic bibliographic databases: PubMed, Web of Science Core Collection, and Embase up to February 19, 2026. For dichotomous outcomes, including the fusion rate and subsidence rate, the effect sizes were calculated as the relative risk (RR) with corresponding 95% confidence intervals (CIs). For continuous outcomes, including surgical time, blood loss, disc height, vertebral height, C2-7 Cobb angle, segmental Cobb angle, VAS score, and NDI score, the effect sizes are expressed as the mean difference (MD) with 95% CIs. Results Eight eligible studies comparing ACDF with SA and ZP for CDD treatment were ultimately included. The pooled patient cohort consisted of 727 participants in total, with 384 patients assigned to the SA group for ACDF and 343 patients allocated to the ZP group. Compared with the ZP, the SA had a significantly shorter operative time and higher NDI score. The segmental Cobb angle, disc height and vertebral height of the SA were significantly lower than those of the ZP. The SA group had a significantly higher subsidence rate than the ZP group, with no remarkable difference observed in the C2-7 Cobb angle, fusion rate, VAS score between the two cohorts. Discussion Current pooled findings suggest that SA may be associated with shorter operative time, while ZP may correlate with lower subsidence rate and better preservation of cervical alignment. As all available evidence is derived exclusively from observational studies and rated as low to very low certainty, the conclusions must be interpreted with caution. Clinical Trial Registration: https://www.crd.york.ac.uk/PROSPERO/view/CRD420261325943 , PROSPERO, CRD420261325943.