Background. Carbon fibre (CF) instrumentation is known to be radiolucent and has a tensile strength similar to metal. A specific use could be primary or oligometastatic cancer where regular surveillance imaging and Stereotactic Radiotherapy are required. CT images are inherently more prone to artefacts which affect Hounsfield unit (HU) measurements. Titanium (Ti) screws scatter more artefacts. Until now it has been difficult to quantify how advantageous the radiolucency of carbon fibre pedicle screws compared to titanium or metallic screws actually is. Methodology. In this retrospective study, conducted on patients from 2018 to 2020 in SGH, we measured the HU to compare the artifact produced by CF versus Ti pedicle screws and rods implanted in age and sex matched group of patients with oligometastatic spinal disease. Results. Eleven patients were included in each group. We compared the change of HU between preoperative and postoperative cases of both CF & Ti screws, which clearly shows Ti screws scatter lot more artefacts than CF screws. We are proposing a CT artefact grading system from grade 0 to grade 4 based on the percentage change of HU for unequivocal understanding of the CT artefacts. Conclusion. This study clearly shows the artefacts produced by the metallic implants are significantly higher than the carbon fibre implants. Considering the efficacy of the RT and the increased life expectancy as a consequence, carbon instrumentation MAY BE superior to titanium or metallic instrumentation. The artefact grading system will help the clinicians in describing and planning where the artefacts need to be factorized

Introduction. Tomita En-bloc spondylectomy (TES) of L5 is one of the most challenging spinal surgical techniques. A 42-year-old female was referred with low back pain and L5 radiculopathy with background of right shoulder excision of liposarcoma. CT-PET confirmed a solitary L5 oligometastasis. MRI showed thecal sac indentation and therefore was not suitable for stereotactic ablative radiotherapy (SABR) alone. Planning Methodology. First Stage: Carbon fibre pedicle screws were planned from L2 to S2AI-Pelvis, aligned to her patient-specific rods. Custom 3D-printed navigation guides were used to overcome challenging limitations of carbon instruments. Radiofrequency ablation (RFA) of L5 pedicles prior to osteotomy was performed to prevent sarcoma cell seeding. Microscope-assisted thecal sac-tumour separation and L5 nerve root dissection was performed. Novel surgical navigation of the ultrasonic bone cutter assisted inferior L4 and superior S1 endplate osteotomies. Second stage: We performed a vascular-assisted retroperitoneal approach to L4-S1 with protection of the great vessels. Completion of osteotomies at L4 and S1 to en-bloc L5: (L4 inferior endplate, L4/5 disc, L5 body, L5/S1 disc and S1 superior endplate). Anterior reconstruction used an expandable PEEK cage obviating the need for a third posterior stage. Reinforced with a patient-specific carbon plate L4-S1 promontory. Sacrifice of left L5 nerve root undertaken. Results. Patient rehabilitated well and was discharged after 42 days. Patient underwent SABR two months post-operatively. Despite left foot drop, she was walking independently 9 months post-operatively. Conclusion. These challenging cases require a truly multi-disciplinary team approach. We share this technique for a dual stage TES and metal-free construct with post adjuvant SABR for maximum local control

Study Design. Single surgeon prospective cohort with radiological follow-up. Background. Anjarwalla et al. have shown that the addition of posterior pedicle supplementation without posterolateral fusion during an ALIF procedure significantly increases the rate of interbody fusion when using a carbon fibre / PEEK cage packed with autogenous iliac crest graft. Stand alone ALIF cages which utilise screws passing through the interbody cage and into the vertebral bodies were designed to obviate the need for a posterior procedure by increasing the anterior construct stability and fusion rate. Objective. To assess the effect of posterior pedicle screw supplementation without posterolateral fusion on the fusion rate of ALIF when using anterior cage and screw constructs. Method. Between 2003 and 2008 91 patients underwent ALIF procedure under a single surgeon for low back pain associated with degenerative disc disease or lytic spondylolisthesis. Routine CT was performed at around 1 to 2 years follow up to ensure union prior to discharge. It was noted that there was a significant number of locked pseudathroses, especially in 2 level cases, and in 2006 the surgeon started to perform simultaneous supplementary posterior pedicle screw stabilisation without posterolateral fusion in the majority of cases. Results. Of the 91 patients, 77 (85%) had CT follow up at mean 21 months. 45 patients had anterior surgery alone (26 single level and 19 two level) and 32 had front back surgery (15 single level and 17 two level). Pseudarthrosis was seen in 16 patients (36%) of the anterior alone group and 2 (6%) of the front back group. In the anterior alone group, pseudarthosis occurred in 6 / 26 (23%) patients with single level surgery and 10 /19 (53%) of those with two level surgery. In this last group, the pseudarthosis occurred in the upper fusion level in five patients and at both fusion levels in other five. Conclusion. Posterior pedicle screw supplementation without posterolateral fusion improves the fusion rate of ALIF when using anterior cage and screw constructs. We would recommend supplementary posterior fixation especially in cases where more than one level is being operated