The number of individuals who experience lumbar disease or pain is steadily increasing. Interventions of surgery and implantation are also becoming popular remedial measures. However, the rate of failure after lumbar fusion is also a matter of concern. In this study, finite element models of both the natural healthy lumbar spine (L3-L4-L5) and the implanted lumbar spine were developed. Analyses were performed by using varying implant material, as well as with and without a bone graft between L4-L5. The natural lumbar spine with an intervertebral disc complex showed the expected stress contour for different load cases. We observed that implants made of stainless steel with a bone graft at L4-L5 performed better among the all implantation cases. Titanium alloy may also be an acceptable implant, but has not shown satisfactory results. Without placing a bone graft, implantation led to the generation of a very high stress level at all components for all cases, which was totally unsafe.