Larger grafts afford neural decompression through anterior column distraction, but may subject the graft and vertebral bodies to excessive loads, increasing graft fracture, and subsidence risk.

Basin subsidence, uplift, fracture are geologic trace formed by stress state with different characters.

It is showed that:(1)the major surface damage patterns due to grinding are microplastic deformation trace, fracture chipping pit, microcracks, and subsidence in the loosen region of material;