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

Lateral lumbar interbody fusion (LLIF) has biomechanical advantages due to the preservation of ligamentous structures (ALL/PLL), and optimal cage height afforded by the strength of the apophyseal ring. We compare the biomechanical motion stability of multiple levels LLIF (4 segments) utilising PEEK interbody 26mm cages to stand-alone cage placement and with supplemental posterior fixation with pedicle screw and rods. Six lumbar human cadaver specimens were stripped of the paraspinal musculature while preserving the discs, facet joints, and osteoligamentous structures and potted. Specimens were tested under 5 conditions: intact, posterior bilateral fixation (L1-L5) only, LLIF-only, LLIF with unilateral fixation and LLIF with bilateral fixation. Non-destructive testing was performed on a universal testing machine (MTS Systems Corp) to produce flexion-extension, lateral-bending, and axial rotation using customized jigs and a pulley system to define a non-constraining load follower. Three-dimensional spine motion was recorded using a motion device (Optotrak). Results are reported for the L3-L4 motion segment within the construct to allow comparison with previously published works of shorter constructs (1-2 segments). In all conditions, there was an observed decrease in ROM from intact in flexion/extension (31%-89% decrease), lateral bending (19%-78%), and axial rotation (37%-60%). At flexion/extension, the decreases were statistically significant (p<0.007) except for stand-alone LLIF. LLIF+unilateral had similar decreases in all planes as the LLIF+bilateral condition. The observed ROM within the 4-level construct was similar to previously reported results in 1-2 levels for stand-alone LLIF and LLIF+bilateral. Surgeons may be concerned about the biomechanical stability of an approach utilizing stand-alone multilevel LLIF. Our results show that 4-level multilevel LLIF utilizing 26 mm cages demonstrated ROM comparable to short-segment LLIF. Stand-alone LLIF showed a decrease in ROM from the intact condition. The addition of posterior supplemental fixation resulted in an additional decrease in ROM. The results suggest that unilateral posterior fixation may be sufficient

Introduction. The placement of a large interbody implant allows for a larger surface area for fusion, vis a vis, via retroperitoneal direct anterior, antero-lateral and lateral approaches. At the same time, spinal navigation facilitates a minimally invasive fixation for inserting posterior pedicle screws. We report on the first procedures in the United Kingdom performed by a single-surgeon at a single- centre using navigated robot-assisted spine surgery without the need for guide-wires. Materials and Methods. Whilst positioned in the supine or lateral position, a routine supine anterior lumbar interbody fusion (ALIF), and/or antero-lateral ALIF (AL-ALIF) and/or lateral lateral interbody fusion (LLIF) is performed. The patient is then turned prone or kept in the single lateral position (SPL) for insertion of the posterior screws performed under robotic guidance. Intraoperative CT scan 3D images captured then are sent to the Robotic software platform for planning of the screw trajectories and finally use again at the end of the procedure to confirm screw accuracy. We identified 34 consecutive patients from October 2019 to January 2020 who underwent robotic assisted spine surgery. The demographic, intraoperative, and perioperative data of all these patients were reviewed and presented. Results. Of the 34 patients, 65 levels were treated in total using 204 screws. Of the 21 patients (60%) who underwent single-level fixation, 14 of them (67%) were treated at the L5/S1 level, 3 at L3/L4, 3 at L4/L5 and 1 at L2/L3 level. The remaining 13 patients (40%) underwent multi-level fixation, of which 4 were adult scoliosis. 15 underwent a supine ALIF approach, 1 underwent AL-ALIF, 8 patients underwent combined LLIF and AL-ALIF approach in a lateral decubitus, whilst 9 underwent pure LLIF approach (of which 3 patients were in the single position lateral) and one patient had previous TLIF surgery. The average estimated blood loss was 60 cc. The average planning time was 10 min and the average duration of surgery was 50 min. The average patient age was 54 years and 64% (22/34) were male. The average BMI was 28.1 kg/m. 2. There were no re-interventions due to complications or mal positioned screws. Conclusion. Minimally invasive spine surgery using robot-assisted navigation yields an improved level of accuracy, decreased radiation exposure, minimal muscle disruption, decreased blood loss, shorter operating theatre time, length of stay, and lower complication rates. Further follow-up of the patients treated will help compare the clinical outcomes with other techniques