MLIF - Minimally Invasive Lumbar Interbody Fusion MTLIF - Minimally Transforaminal Lumbar Interbody Fusion ODI - Oswestry Disability Index PLIF - Posterior Lumbar Interbody Fusion TLIF - Transforaminal Lumbar Interbody Fusion VAS - Visual Analog Scale

A prospective multicentral observational study of minimally invasive fusion to treat degenerative lumbar disorders, and to report outcomes of one or two level minimally invasive posterior lumbar interbody fusion (MLIF) for degenerative lumbar disorders in a multi-center 1-year prospective study. We prospectively studied a group of 32 patients, mostly female 24 (75% female), and 8 males (25%). They underwent minimally invasive transforaminal lumbar interbody fusion (mTLIF), 21 of them monosegmental and 11 bisegmental. Patients demographics, intra-operative data and complications were recorded. Time to first ambulation, time to study-defined recovery, surgical duration, blood loss, fluoroscopy time and adverse events were recorded. Visual analogue scale (VAS) of back and legs pain, Oswestry disability index (ODI) and health-related questionnaire (EQ-5D) were assessed preoperatively and at defined time points through 12 months postoperatively. Mean surgical duration, blood loss and intraoperative fluoroscopy time were 125 vs. 175 minutes, 150 vs. 170 ml, and 105 vs. 145 seconds in oneand two-level segments, respectively. Mean preoperative VAS back (6.5) and VAS leg (7.9) scores dropped significantly (p<0.0001) to 3.5 (2.6) and 2.6 (2.0) at discharge (6 weeks). At the end, this is the largest prospective multi-center observational study of MLIF to date, following routine local standard of practice and, MLIF demonstrated favourable clinical results with early and sustained improvement in patient reported outcomes and low major perioperative morbidity.