Load Sharing and Endplate Pressure Distribution in Anterior Interbody Fusion Influenced by Graft Choice

Background: Cage subsidence is a known complication of spinal fusion. Various aspects of cage design have been investigated for their influence on cage subsidence, whereas the potential contribution of graft material to load sharing is often overlooked. We aimed to determine whether graft in the aperture affects endplate pressure distribution.

Methods: The pressure distributions of a polyetheretherketone interbody cage with 3 different aperture graft conditions were evaluated: empty, demineralized bone matrix, and supercritical CO2-treated allograft bone crunch (SCCO2).

Results: Graft materials contributed as much as half the load transmission for SCCO2, whereas demineralized bone matrix contributed one third. Endplate areas in contact with the cage demonstrated decreased areas within the highest-pressure spectrum with SCCO2 graft materials compared with empty cages.

Conclusions: Graft choice plays a role in reducing peak endplate pressures. This finding is relevant to implant subsidence, as well as graft loading and remodeling.

Keywords: Endplate; Fusion; Graft; Interbody; Pressure; Subsidence.