314 Minimally Invasive Oblique Lateral Interbody Fusion for L4-5

INTRODUCTION: Minimally invasive oblique lateral interbody fusion (OLIF) has steadily gained popularity as the fusion method of choice in patients with spondylolisthesis or foraminal stenosis. However, the complication rates reported in the literature vary greatly between authors. In this research, the authors report the clinical outcomes and perioperative complications of OLIF at L4-5. METHODS: The authors retrospectively reviewed prospectively acquired records of patients with L4-5 spondylolisthesis or foraminal stenosis who had undergone OLIF between 2013 and 2015. Twenty-nine patients underwent single-level OLIF at L4-5 or 2-level OLIF including L4-5. Among 29 patients, 4 patients transforaminal lumbar interbody fusion or posterior lumbar fusion at other levels with OLIF at L4-5. Outpatient clinic follow-up were scheduled at 1, 3, 6, 12, and 24 months postoperatively. Outcome measures included visual analog scale (VAS), Oswestry Disability Index (ODI), fusion and subsidence rates, and perioperative complications. RESULTS: Twenty-nine patients (9 males, 20 females, and mean age 66.9 years) met the study inclusion criteria. After OLIF procedures, all patients underwent percutaneous pedicle screw fixation in the prone position, with additional posterior laminectomy in 3 patients. The average VAS score for back/leg improved from 6.3/6.5 to 3.1/2.1 at the last follow-up (both P < .001). The average ODI score improved from 50.4 preoperatively to 27.2 at the last follow-up (P < .001). Radiological evidence of fusion on computed tomography scans was noted in 57.0% of the patients in 6 months and 92.9% in 12 months. Subsidence during the follow-up periods occurred in 8 (21.6%) of 37 OLIF levels in 29 patients. Lumbar plexopathy was noted in 4 (13.5%) patients, and consisted of transient motor weakness in 3 (10.3%) patients and numbness in in different 3 (10.3%) patients (Sensory Dermal Zone III in 2, II in 1). All lumbar plexopathy symptoms resolved within 4 weeks postoperatively. Evidence of sympathetic injury on physical examination and digital infrared thermal imaging was noted in 4 (13.5%) patients. CONCLUSION: Minimally invasive OLIF at L4-5 vertebral segment is a safe and effective technique in terms of clinical and radiological outcomes with low risk of perioperative and rare permanent complications.