The primary goal of the proposed research is to gather data on the clinical efficacy of the Trabecular Metal™ Posterior Lumbar Interbody Fusion (PLIF) cage with pedicle screw instrumentation for the treatment of one-level lumbar spine fusions. Based on this pilot data, we hope to establish a level of acceptable clinical performance for the Trabecular Metal™ cage, a benchmark against which subsequent investigations can be compared.