Safety and effectiveness of PEEK cages for fusion after anterior cervical corpectomy in patients with degenerative spinal stenosis: a narrative review

Abstract Background Observational studies on the safety and clinical outcomes of PEEK vertebral body replacement cages have not yet been reviewed in a structured manner. Methods A structured literature review was conducted of observational studies dealing exclusively with ACCF treated with PEEK cages according to the PRISMA protocol using the search terms: ‘anterior cervical corpectomy + PEEK cage’. A modified NHLBI Quality Assessment Tool for case series studies was used to objectify the risk of bias. The evidence from the summarised data was classified according to the GRADE criteria. Results A total of 5 retrospective studies involving 279 patients were identified. The pooled stable fusion rate was 0.88 (95% CI [0.75, 1.02]) with moderate heterogeneity ( I 2 = 48.75%). Loosening or breakage of screws is rare (weighted average 0.05 (95% CI [− 0.02, 0.12]) with substantial heterogeneity [ I 2 = 98.31%]). No fractures of the ventral plates or PEEK cages were reported. Severe subsidence (> 3 mm) was found in 25/209 cases and the weighted average was 0.11 (95% CI [0.06, 0.18]) with substantial heterogeneity ( I 2 = 64.42%). In 10/247 cases, revision surgery was necessary due to a fusion complication with a weighted average revision rate of 0.04 (95% CI [0.00, 0.08]) and substantial heterogeneity ( I 2 = 88.69%). The most common reason for revision was the fracture of a screw-bearing vertebral body with subsequent ventral dislocation of the cage-screw-plate complex in osteoporotic patients following multilevel corpectomy. All dislocations requiring revision occurred within the first 4 months post-operatively. Conclusions ACCF with PEEK cages has similar good neurological and radiological results as ACCF with other fusion materials. The complication and revision rates are not higher than those reported in the literature for other ACCF fusion devices. Osteoporosis patients who undergo multisegmental ACCF may have a greater risk of implant dislocation, especially if they are prone to falls within the first 4 months after surgery. The review of the included studies revealed a low GRADE level of evidence. The clinical and radiological outcome parameters of the studies were heterogeneous, and the follow-up intervals were inconsistent.