Introduction. Intraoperative navigation systems for lumbar spine surgery allow to perform preoperative planning and visualize the real-time trajectory of pedicle screws. The aim of this study was to evaluate the deviation from preoperative planning and the correlations between screw deviation and accuracy. Method. Patients affected by degenerative spondylolisthesis who underwent posterior lumbar interbody fusion using intraoperative 3D navigation since April 2022 were included. Intraoperative cone-beam computed tomography (CBCT) was performed before screw planning and following implantation. The deviation from planning was calculated as linear, angular, and 3D discrepancies between planned and implanted screws. Accuracy and facet joint violation (FJV) were evaluated using Gertzbein-Robbins system (GRS) and Yson classification, respectively. Statistical analysis was performed using SPSS version28. One-way ANOVA followed by Bonferroni post-hoc tests were performed to evaluate the association between GRS, screw deviation and vertebral level. Statistical significance was set at p<0.05. Result. This study involved 34 patients, for a total of 154 pedicle screws. Mean age was 62.6±8.9 years. The mean two-dimensional screw tip deviation in mediolateral (ML), craniocaudal (CC), and anteroposterior (AP) was 2.6±2.45mm, 1.6±1.7mm, and 3.07±2.9mm, respectively. The mean screw tip 3D deviation was 5±3.3mm. The mean two-dimensional screw head deviation in ML, CC and AP was 1.83±1.8mm, 1.7±1.67mm and 3.6±3.1mm, respectively. The mean screw head 3D deviation was 4.94±3.2mm. 98% of screws were clinically acceptable (grade A+B), and grade 0 for FJV. Significant results were found between GRS and ML (p=0.005), AP (p=0.01) and 3D (p=0.003) tip deviations, and between GRS and AP and 3D head deviations (both p=0). Moreover, a significant correlation was found between GRS and vertebral level (p=0). Conclusion. Our results showed a reasonable rate of discrepancy between planned and positioned screws. However, accuracy was clinically acceptable in almost all cases. Therefore, pedicle screw fixation using intraoperative CBCT, 3D navigation and screw planning is safe and accurate

Aim. To investigate the role of websites in enhancing patients' understanding of reason and risk of surgery as a part of informed consent for elective un-instrumented lumbar spine surgery (EULSS). Methodology. This was a National Research Ethical Committee approved RCT study. 63 patients underwent EULSS, out of which 14(29%) declined participation and 14(29%) were excluded. One did not have surgery therefore 34 were randomised to Standard (S) and intervention group (I) using sealed envelope. Standard group were given verbal information & leaflet while the Intervention group were given information on relevant section of . www.eurospine.org. and . www.spinesurgeons.ac.uk. websites. A 13 item Informed Consent Questionnaire (ICQ) was used to collect data. The primary outcomes were patients' perceived understanding of reason and risk of EULSS. Results. Average age was 54 (21–82) years, with similar demographics in both groups. Complete data was available for 20 (13 Standard and 7 Intervention group). No difference (χ. 2. = 0.42, df=1, p= 0.52) was observed on perception of reason and risk of surgery between two groups. Website usage increased from 30% to 50% in intervention group who continued to use the website. Conclusion. Website use appears to be useful to participants. Although support has not been found to accept the experimental hypothesis, valuable information has been gained that will serve to facilitate larger study to further explore the effectiveness of websites in enhancing of EULSS. No Conflict of interest. No funding obtained. This abstract has not been previously published in whole or substantial part nor has it been presented previously at a national meeting

Summary. In this study, OsteoAMP® bone graft showed superior fusion rates as compared to rhBMP-2 at all timepoints (p<0.004). Additionally, OsteoAMP® bone graft had >80% few adverse events as compared to rhBMP-2. Introduction. Adverse events and complications related to use of rhBMP-2 have raised many ethical, legal, and reimbursement concerns for surgeons. OsteoAMP® bone graft is an allograft derived growth factor, rich in osteoinductive, angiogenic, and mitogenic proteins. The following data displays a blinded, multi -center study evaluating and comparing fusion outcomes between rhBMP-2 and OsteoAMP® bone graft. Patients & Methods. A total of 254 consecutive patients (383 total levels) were treated with TLIF or LLIF spine fusion procedures. A group of 70 patients (53.3 ± 11.1 y/o) were treated with rhBMP-2 (Infuse®/Inductos®, Medtronic) and local bone inside of a PEEK interbody cage with an average of 1.44 levels per surgery. A group of 184 patients (60.5 ± 13.1 y/o) were treated with OsteoAMP® (Advanced Biologics) and local bone inside of a PEEK interbody cage with an average of 1.53 levels per surgery. Fusion assessments were made by a blinded independent radiologist based on radiograph and CT images at 6w, 3m, 6m, 12m, and 18m follow up. Radiographically evident adverse events were also assessed in a blinded manner by an independent radiologist. Results. Overall fusion analysis showed superiority in efficacy of OsteoAMP® over rhBMP-2 at all time points (p<0.004). Use of rhBMP-2 produced limited early fusions at 6 months (22.7%) yet improved at 1 year (71.4%). OsteoAMP® facilitated fusion for the majority of patients by 6 months (54.1%) and nearly all patients within 1 year (93.9%). At 18 months, 99.3% of OsteoAMP® patients had fused while the rhBMP-2 arm had an 86.7% fusion rate. Total time for fusion for OsteoAMP® was approximately half that of rhBMP-2 at 211.4 days and 407.1 days respectively. A subset cohort of 47 patients in the rhBMP-2 arm had OsteoAMP® packed anterior to the PEEK cage. When OsteoAMP® was used as an extender to rhBMP-2 in this manner, fusion rates increased at all timepoints (p=0.05 at 18 months) over patients that only had rhBMP-2 and local bone within the disc space. Though, the fusion rates of OsteoAMP® without rhBMP-2 remained higher than the rhBMP-2/local bone/OsteoAMP® extender cohort at all timepoints (p<0.05). To further isolate the effect of OsteoAMP, a subset cohort of 52 patients within the OsteoAMP® treatment arm in the absence of rhBMP-2 did not utilise bone marrow aspirate. The fusion rates of patients within this cohort was statistically higher at 6 months but did not show statistically higher fusion rates at 3 months, 12 months, or 18 months (p>0.12). When compared to the rhBMP-2 study arm, patients within the OsteoAMP® arm that did not receive bone marrow aspirate demonstrated higher fusion rates at all time points (p<0.04 at 12 and 18 months). The rhBMP-2 arm had more than 5 times the incidence of radiologically evident adverse events (osteolysis and ectopic bone formation) compared to the OsteoAMP® arm (43.3% vs. 8.2%, respectively). Discussion. Despite its use with an older patient population and a higher number of levels per surgery, OsteoAMP® has shown great promise as a faster and safer alternative to rhBMP-2 in lumbar spine surgery