Analysis of Spino-Pelvic Parameters and Segmental Lordosis with L5-S1 Oblique Lateral Interbody Fusion (OLIF 5-1) at the Bottom of a Long Construct in CMIS Correction of ASD

Abstract Background Lateral interbody fusion (LIF) is an effective adjuvant for CMIS treatment of ASD. Accessing L5-S1 with an oblique lateral approach (OLIF 5-1) allows for an ALIF at the lumbosacral junction without repositioning the patient. We review the early outcomes and complication of OLIF 5-1 at the bottom of the long construct for MIS treatment of ASD. Methods We queried prospectively collected registry of 111 consecutive ASD (Cobb>20, or SVA>50, or PI/LL mismatch>10) patients who underwent CMIS correction from January 2015-January 2019. Sixty patients were identified with 4+ levels fused and OLIF at L5-S1. Multilevel pre-psoas LIF+L5-S1 oblique lateral ALIF were done in the first stage. Three days later, stage 2 included MIS pedicle screws with aggressive rod contouring and derotation/translation. Results Mean age was 66.8yrs (48-79), mean FU was 24months (3-60). Mean level fused was 7 levels (4-9). Significant improvement in L5-S1 SL, LL, SVA, PI/LL mismatch and PT following the first stage (p Conclusion The single position MIS L5-S1 OLIF at the bottom of a long construct in conjunction with multilevel pre-psoas LIF seems to be a safe and effective technique in improving SL, global LL and SVA with low risk of perioperative and postoperative complications.