Assessing the efficacy of Fibergraft Bioactive Glass in patients undergoing posterolateral lumbar fusion surgery

This is a single-arm, prospective study that aims to assess the radiological and clinical efficacy of Fibergraft Bioactive Glass in patients undergoing posterolateral lumbar fusion surgery for degenerative disc disease. It is important to note that Fibergraft Bioactive Glass is commercially available within Australia, and has therefore been adopted into clinical practice as the primary bone graft substitute for this surgery. As such, if a patient chooses not to participate in the study, then neither their surgery or post-operative treatment will be effected in any way. If a patient does choose to participate, then they will be required to attend one non-standard follow up appointment at the 2-year (primary timepoint) post-operative timepoint. The Procedure: The surgery is performed whilst the patient is under general anaesthetic, and positioned lying prone on the operating bed. An incision (6-8cm) is made on the midline of the lower back, and the posterior musculature is dissected and retracted. Pedicle screws are inserted, and rods are placed. The transverse processes and facet joints of the vertebrae to be fused are decorticated and the shavings of local bone are left in place to act as autologous graft. Synthetic bone graft substitute is then overlayed in the posterolateral gutters. This may be performed in conjunction with a decompression via a laminectomy. This involves the removal of the lamina and decompression of the spinal nerves. Fibergraft Bioactive Glass: Fibergraft is a synthetic bone graft substitute designed to mimic the body's natural bone healing process and augment the use of autologous bone graft material. It is comprised of 45S5 bioactive glass and features a porous outer shell which allows for the uninterrupted growth of new bone through the cell. The Follow-Up: As a part of standard clinical practice, participants will be required to attend follow-up appointments at the 6-month, and 1-year post-operative timepoints. In addition to these appointments, participants will be required to attend one non-standard follow-up appointment at the 2-year post-operative timepoint, which represents the final timepoint within the observational period. The Observations - radiological: Participants will be required to undergo flexion/extension x-rays at the 6-month and 1-year post-operative timepoints. These images will be used to assess for screw breakage, rod breakage, and for angulation of greater than 5 degrees at the fused segment. At the 1- and 2-year post-operative timepoints, participants will be required to undergo a Computed Tomography (CT) scan which will be used to grade the degree of fusion at each segment, and assess for screw loosening, screw breakage, and rod breakage. The Observations - patient reported outcomes: At each of the post-operative appointments, participants will be asked to complete subjective questionnaires pertaining to their level of self reported pain and disability. These questionnaires include: the Oswestry Disability Index (ODI), and the Back and Leg Visual Analogue Scores (Back VAS and Leg VAS).