Outcome of instrumented lumbar fusion for low grade spondylolisthesis; Evaluation of interbody fusion with & without cages.

Object: The aim is to evalute the outcome of posterior lumbar interbody fusion with autologous bone graft versus titanium Cages, BAK system (Bagby - Kuslich, Spine Tech, Inc. Minneapolis, MN) for low grade spondyloisthesis (Grade1,11). Interbody cages have been developed to replace tricortical Interbody grafts in posterior lumbar interbody fusion (PLIF) procedures.