Development of a lumbar facet joint replacement

A majority of the American population will experience low-back pain during their lifetime. With this debilitating condition affecting more people every day, a solution is required to help the population. One of the causes of low-back pain is facet degeneration. Currently, there are no replacement devices on the market that solves this issue.

This thesis presents a design of a facet joint replacement to reduce low-back pain due to facet degeneration. A finite element model of the lumbar spine (L3-L5) was developed to evaluate the implant. Range of motion (ROM), facet contact forces and intervertebral disc stresses were compared for the instrumented and intact model. Futhermore, two additional surgical cases, a laminectomy and facetectomy, were also considered. It was found that the implant followed intact ROM and disc stresses better than a laminectomy and facetectomy. However, there was a large increase in facet contact forces at the adjacent non-operated level, which may ultimately lead to facet degeneration at the adjacent level. Further mechanical testing of the implant is required.