Spinal fusion is an effective surgical treatment for intervertebral disc degeneration. However, the consequences of implantation with interbody cages on load transfer and bone remodelling in the vertebral bodies has scarcely been investigated. Using detailed 3D models of an intact and implanted lumbar spine and the strain energy density based bone remodelling algorithm, this study investigated the evolutionary changes in bone density distributions around porous and solid interbody cages. Follower load technique and submodelling approach were employed to simulate applied loading conditions on the lumbar spine models. The study determined the relationship between mechanical properties and parametrical characteristics of porous Body-centered-cubic (BCC) models, which corroborated well with Gibson-Ashby and exponential regression models. Variations in porosity affected the peri-prosthetic stress distributions and bone remodelling around the cages. In comparison to the solid cage, stresses and strains in the cancellous bone decreased with an increase in cage porosity; whereas the range of motion increased. For the solid cage, increase in bone density of 20-28% was predicted in the L4 inferior and L5 superior regions; whereas the model with 78% porosity exhibited a small 3-5% change in bone density. An overall increase of 9-14% bone density was predicted in the L4 and L5 vertebrae after remodelling for solid interbody cages, which may influence disc degeneration in the adjacent segment. In comparison to the solid cage, an interbody cage with 65-78% porosity could be a viable and promising alternative, provided sufficient mechanical strength is offered.