Subsidence Following Anterior-Only Anterior Cervical Corpectomy Fusion For Cervical Spondylotic Myelopathy: Systematic Review and Meta-Analysis.

Study design: Systematic review and meta-analysis.

Objective: To examine the occurrence and potential contributing factors of interbody subsidence following anterior-only ACCF performed for CSM.

Summary of background data: Surgical interventions for cervical spondylotic myelopathy (CSM) frequently involve anterior approaches, such as anterior cervical discectomy/fusion (ACDF) or anterior cervical corpectomy/fusion (ACCF). Although graft subsidence is a well-established and described complication in ACDF procedures, much less has been published regarding factors related to subsidence in patients undergoing anterior-only ACCF for CSM.

Methods: A systematic literature search was conducted using PubMed, Embase, and COCHRANE. The study's inclusion criteria encompassed anterior-only anterior cervical corpectomy and fusion (ACCF), surgery for the primary diagnosis of cervical spondylotic myelopathy (CSM). Qualitative analysis was performed for complications and revision rates. The data were subjected to meta-analysis to evaluate subsidence incidence rates, and meta-regression analysis was used to assess variations between different graft types.

Results: Two hundred forty-five abstracts were evaluated and 34 papers met the inclusion criteria. Two thousand five patients were evaluated over a mean of 31 months (range: 6-56 mo). Pooled subsidence rates expressed as incidence per person-years based on graft type were as follows: 2% (carbon fiber), 27% (fibular strut allograft), 2% (nHAPA composite strut), 5% (PEEK), 10% (static titanium), and 2% (expandable titanium cages). The combined subsidence rate for all grafts was 7%. Notably, the expandable titanium cohort demonstrated a lower subsidence rate (2%) compared with the overall pooled cohort (7%), while other graft types showed no significant difference.

Conclusion: Subsidence occurred in ∼7% of patients undergoing anterior-only ACCF procedures for CSM. Notably, the use of expandable metal cages resulted in a lower rate of subsidence compared with the broader cohort. This finding suggests that these implant options may be preferable to reduce the risk of subsidence when corpectomy is necessary without posterior fixation.