Introduction: Anterior plate constructs for cervical discectomy and fusion have been linked to post-operative dysphagia, increased operative times, and wider surgical exposures. Several “low profile” integrated stand-alone spacers (SAS) have been developed. While these spacers have demonstrated successful clinical outcomes and similar biomechanical stability to anterior plate constructs in single-level fusions, their biomechanical stability in multi-level constructs has not yet been established.
Methods: Twelve human cadaveric cervical spines (C2-T2) were non-destructively tested with a six-degree-of-freedom simulator under axial rotation (AR), flexion-extension (FE) and lateral bending (LB) loading. After intact analysis, each specimen underwent sequential instrumentation and testing: A) C5-6 spacer/plate with C6-7 SAS, B) C5-7 SAS, C) C5-7 spacer/plate (Figure 1). Range of motion (ROM) data was obtained and analyzed with paired t-tests and Bonferroni correction.
Results: The 2-level plate construct significantly reduced flexion-extension ROM compared to the 2-level SAS (p <0.05). There was no difference noted in lateral bending or axial rotation between the 2-level SAS and the 2-level plate constructs (p >0.05) (Figure 2).
Conclusions: Stand-alone cervical spacers with integrated screws for hybrid and 2-level SAS constructs are reasonable alternatives to two level plate fixation; however, clinical trials are necessary to determine if the increased ROM in flexion-extension noted in the SAS constructs translates to clinical outcome.
Patient Care: Improve biomechanical understanding of cervical integrated spacer constructs
Learning Objectives: By the conclusion of this session, participants should be able to describe the biomechanical stability of a stand-alone spacer in multi-level and hybrid fusion constructs.