Micro-endoscopy-assisted Extraforaminal Lumbar Interbody Fusion (mELIF) for L5/S1 disorders in 30 cases

<p>Objective: Lumbar interbody fusion is a standard technique for degenerative lumbar disorders with instability. Minimally invasive technique, extraforaminal lumbar interbody fusion (ELIF) was introduced. Approaching from posterolaterally the posterior muscles and the spinal canal was barely invaded. In spite of theoretical advantage, ELIF was technically demanding and has not been popularized. We developed a micro-endoscopy-assisted Extraforaminal Lumbar Interbody Fusion (mELIF), a technique designed as safe and less invasive interbody fusion. We applied mELIF for L5/S1 disorder in 33 cases and here report clinical results.</p><p>Methods: Thirty patients followed over 6 months included, 14 males and 16 females, average age 61.5 underwent the procedure. The index diagnoses were isthmic spondylolisthesis (n=14), foraminal stenosis (n=14), and others. In surgery a patient is put in prone position under general anesthesia. From about 5 cm from midline, as for lateral disc herniation surgery, a 16- or 18-mm diameter tubular retractor was placed at the lateral aspect of the facet joint. The facet joint was partially excised, and the disc space was prepared under micro-endoscopic visual assistance. The spinal canal was not invaded. A cage, local bone and artificial bone graft were inserted into the disc space from unilaterally. Bilateral percutaneous screw-rod constructs were inserted and fixed.</p><p>Results: Clinical symptoms greatly improved in most cases. JOA score (full: 29) increased 11.4 to 24.4. NRS improved 6.4 to 2.1 for lumbar and 5.2 to 1.1 for leg. Twenty cases demonstrated excellent and seven good according to Macnab's criteria. The average surgery time was 192 minutes and blood loss 89 mg. There were neither major clinical adverse effects nor additional surgery. Bone union rate was 14 from 20 cases (70%) at one-year post-surgery.</p><p>Conclusions: The index diagnosis at L5/S1 were isthmic spondylolisthesis and foraminal stenosis in most cases. The spinal canal is usually not involved in these conditions. ELIF is ideal because it does not need to invade the canal. In addition to theoretical advantage of ELIF, mELIF can provide minimally invasiveness and safety by using microendoscope. We experienced 30 cases and the results were favorable. We are certain that mELIF can be comparable with posterior standard interbody fusion techniques for L5/S1 disorders.</p>