A Feasibility Study to Evaluate the TURRIS Facet Fusion System in Lumbar Spinal Surgery

Inclusion Criteria: * one-level fusion at L4/L5 with dorsal instrumentation and, if required, with monolateral decompression and/or intervertebral disc removal and implantation of an intervertebral implant Exclusion Criteria: Patient * had previous surgical stabilizations at the involved or adjacent levels * has lytic spondylolisthesis * has degenerative spondylolisthesis grade II or higher * has radiographic signs of significant instability and/or hypermobility of the segment (\>3mm translation, \>11° rotation difference from adjacent level) * has scoliosis \> 10° at the involved segment * has osteoporosis to a degree that spinal instrumentation would be contraindicated. * has presence of active malignancy. * has overt or active infection, either local or systemic * is less than 18 years old * is pregnant or plan a pregnancy during the study duration * has a BMI \> 35 * has a progressive neuromuscular disease * has a condition which requires postoperative medications that may interfere with bone metabolism * has a history of autoimmune disease * has a history of endocrine or metabolic disorders known to affect osteogenesis * is mentally ill or incompetent * is an alcohol and/or drug abuser * is not available for follow up visits