Acknowledgements & Disclosures Analysis of stand-alone anterior lumbar interbody fusion versus transforaminal lumbar interbody fusion and anterior/posterior fusion Anthony E. Bozzio MD, Christopher R. Johnson MS, Jill A. Fattor, PA-C, Vikas V. Patel MA, MD, Evalina L. Burger MD, Andriy Noshchenko MD PhD, Christopher M.J. Cain MD University of Colorado, Anschutz Medical Campus, Department of Orthopaedics, Denver CO INTRODUCTION Degenerative disc disease (DDD) with instability at one or two levels is the leading indication for fusion surgery. A variety of techniques are currently utilized to achieve fusion, including transforaminal lumbar interbody fusion (TLIF), instrumented anterior lumbar interbody fusion (ALIF) and anterior/posterior (A/P fusion). Instrumented anterior fusion devices have been developed, and some have been shown to have similar stability to pedicle screws1. The use of these implants has gained popularity, but it is important to evaluate their effectiveness to determine if the ongoing use of these implants is appropriate. However, data comparing instrumented ALIF other fusion techniques is lacking. The purpose of this study was to compare instrumented ALIF to TLIF and A/P fusion. Analysis focused on radiographic parameters relating to restoration of disk height, lumbar lordosis, pelvic parameters. Additionally, operation time, length of stay in hospital, direct hospital, implant and procedural costs, fusion rates were compared. One Level ALIF TLIF A/P Fusion P(F) - Value No. Patients 38 10 18 Direct Costs – USD (SD) 17288.9A (2800.5) 20305.2B (1870.4) 24248.9C (4388.5) < 0.0001 Medicare Fees - USD 2866.0 4100.0 4586.0 <0.001 Total Costs/Fees USD (SD) 20154.9A (2800.5) 24405.2B (1870.4) 28834.9C (4388.5) Two Level ALIF TLIF A/P Fusion P(F) - Value No. Patients 15 7 17 Direct Costs – USD (SD) 28965.0A (1517.1) 25821.6B (4623.2) 33488.8A (7282.9) 0.0054 Medicare Fees - USD 3658.0.0 5994.0 5803.0 <0.0001 Total Costs/Fees USD (SD) 32623.0B (1517.1) 31815.6B (4623.2) 39291.8A (7282.9) 0.0011 RESULTS A total of 106 patients were reviewed after meeting inclusion and exclusion criteria. All patients were at least 2 years post surgery. Fifty-three patients underwent instrumented ALIF, 36 underwent an A/P fusion and 17 patients underwent a TLIF. The ALIF and A/P fusion groups were demographically similar. The TLIF group varied in age (ALIF=37.8yr; A/P fusion 48.2yr; TLIF 53.1yr F<0.001) and had higher incidence of degenerative spondylolisthesis and canal stenosis requiring direct canal decompression. The A/P fusion group had a higher incidence lytic spondylolisthesis. Otherwise groups were similar in their smoking status and steroid use. There was no significant difference between the groups in relation to patient outcomes as assessed by the ODI and NRS. There was no difference in fusion rates, with one non-union in both the ALIF and TLIF groups that required further surgery. Radiographic parameter restoration was significantly better in the ALIF group compared to the TLIF and A/P fusion groups. Disc angle (p< 0.001), anterior & posterior disc height (p< 0.0001) and pelvic tilt (p< 0.001). Complication rates were similar (one infection in the TLIF group that also resulted in a return to the OR, one malpositioned screw requiring revision and 2 iliac vein injuries in the A/P fusion group). There were no patient deaths, pulmonary emboli, deep vein thromboses, or neurologic injuries. There were statistically significant differences between the three groups in relation to operative time, estimated blood loss, and length of stay with the ALIF group with all these parameters being significantly less than the other two groups (p< 0.0001). Cost data was available for 105 patients and analysis revealed significant savings in the ALIF group compared to both TLIF and A/P fusion (Table 1a & 1b). Cost analysis by surgical technique for one (3a) and two level (3b) procedures. Note: Levels not connected by same letter are significantly different (p<0.05) by Tukey-Kramer multivariate test CONCLUSIONS This study directly compared three different surgical techniques (instrumented ALIF, TLIF and A/P fusion) for one or two level lumbar DDD. Importantly, fusion rates were similar in all groups, despite demographic differences. Secondly, the use of ALIF techniques enabled more effective restoration of segmental anatomy as indicated by disk height, segmental and lumbar lordosis and sagittal alignment as indicted by pelvic parameters. While patient characteristics will influence the decision regarding surgical approach and technique, instrumented ALIF in this series delivered equivalent fusion rates with significant benefits in relation to reduced operating time, hospital stay, blood loss direct costs and surgical fees. Limitations of this study include the retrospective nature, which imparts selection bias. An attempt was made to narrow the indications down to pure degenerative disc disease at one or two levels, accepting only up to a grade II spondylolisthesis. While differences between the groups and the indications for surgery are accepted, the results indicate that where patient pathology and clinical features and surgeon preferences will dictate the best approach in each case, where instrumented ALIF is feasible benefits can be realized in relation to costs and radiographic outcomes compared to TLIF and A/P fusion. Approval for the study was obtained from the Colorado Multiple Institutional Review Board (14-0819) for this was a retrospective review of adult patients with symptomatic DDD localized to one or two levels that underwent elective one or two level instrumented ALIF, TLIF or A/P fusion over a two-year period. Prior lumbar or thoracic fusions, as well as greater than a grade II spondylolisthesis were excluded. Clinical parameters compared included smoking status, diabetes, steroid use, operative time, estimated blood loss, length of hospitalization, use of rhBMP-2, type of anterior implants, stenosis, anterior decompression, Oswestry Disability Index (ODI), Numeric Rating Scale (NRS), and complications. Radiographic parameters included fusion status, local disc angle, lumbar lordosis, disc height, degree of spondylolisthesis, sacral slope, pelvic incidence and pelvic tilt. Fusion was assessed by flexion/extension and plain radiographs, and CT was utilized if the presence of a solid fusion was not evident on plain radiographs. Direct hospital cost were obtained and combined with Medicare allowable fees for each procedure to calculate a total cost for each surgical technique. METHODS REFERENCES 1. Cain CM, Schleicher P, Gerlach R, Pflugmacher R, Scholz M, Kandziora F. A new stand-alone anterior lumbar interbody fusion device: biomechanical comparison with established fixation techniques. Spine. 2005;14(23):2631–2636. doi: 10.1097/01.brs.0000187897.25889.54 Acknowledgements & Disclosures The authors have the following COI’s to disclose: Grants/Research Support: Synthes, Aesculap, Vertiflex, Medtronic, SI Bone, Medicrea, Orthofix, Spinal Kinetics, Integra, Amgen; Consulting Fees: Allosource, Baxter Healthcare, DePuy Synthes, DSM, Paradigm Spine, Signus, X-Spine, Orthofix, Medicrea; Speakers’ Bureau: Stryker, AOSpine; Ownership Interest/Shareholder: N/A; Salary: N/A; Royalty/Patent Holder: Aesculap, Biomet, Springer, SLACK DePuy Synthes.