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


“Primary goals of interbody fusion include deformity correction and alleviation of pain. Interbody cages serve as spacers to maintain the position of the spine following surgery and often have a central cavity that allows infilling of a graft material.

Certainly, the majority of graft materials used are not approved for load bearing applications. While this may be the case, we considered the immediate post-operative condition and the role that these graft materials may play in load transfer. We found that choosing a graft with mechanical integrity can offload the highest-pressure points at the cage endplate interface, which may reduce the incidence and severity of subsidence. Although some degree of subsidence is common, substantial subsidence reverses two of the key goals of the surgery by causing pain and loss of correction.

The graft material itself is chosen based on a number of considerations but ideally the goal is to achieve a solid bridge of bone between the vertebrae. Bone itself is sensitive to mechanical loading and will eventually be resorbed if it is not loaded. The load transfer between bone and graft particulates may also play a role in encouraging bone formation through direct loading.”

– Study author Matthew Pelletier, PhD