INTRODUCTION
Unlike central stenosis, there is a higher likelihood of instability after decompressive surgery for foraminal stenosis, so fusion is often performed in conjunction. Recently, minimally invasive surgery techniques have enabled extended endoscopic lumbar foraminotomy (EELF), which consists of simultaneous lumbar foraminotomy and lateral recess decompression surgery using a uniportal endoscopic technique while minimizing facet removal. The objective of this study was to compare early postoperative outcomes between between EELF and transforamianl lumbar interbody fusion (TLIF)
METHODS
This study was a prospective observational study and was approved by an institutional review board (2106-203-1231). The study inclusion criteria were 1) dominant unilateral radicular pain (NRS >=5), 2) intractable to previous non-surgical treatment for more than 3 months, 3) foraminal stenosis at or above L4-5 and 4) no severe central stenosis and instability. All patients were given a choice between conventional fusion surgery and EELF and a final surgical decision was made through a shared discussion. The EELFs were performed under a general anesthesia and intraoperative neuromonitoring. Neural foramen including superior articular process was enlarged with a reamer to the lateral recess. Remaining bone and soft tissues were removed with endoscopic forceps, scissors and drill under a direct vision. Patients were scheduled to visit at postoperative 1, 3, 6 and 12 months, and clinical outcomes (numeric rating scale of back pain [NRS-B, /10], and leg pain [NRS-L, /10], Korean-version Oswestry disability index [K-ODI, /45], Euro-Quality of Life-5 Dimension [EQ-5D]) were assessed at each clinic visit. The areas of neural foramen were measured before and after EELF at sagittal magnetic resonance imaging (MRI).
RESULTS
From Jan. 2021 to Oct. 2022, 26 patients (M:F= 10:16, mean age: 72.3±7.5) underwent EELF and 26 patients (M:F= 7:19, mean age: 69.9±7.0) underwent TLIF. The mean area of neural foramen in EELF group was 48±20 (mm2), and it was significantly increased to 114±34 (mm2) (p < 0.05) after surgery. The postoperative mean NRS-L, ODI and EQ-5D of EELF were significantly improved compared with those before the operations (p < 0.05). There were no significant diffrences in NRS-L, ODI, EQ5D between the two groups. However, EELF group showed unfavorable NRS-B compared to TLIF group (4.9±0.5 in EELF group vs. 3.6±0.6 in TLIF group, p < 0.05). EELF group showed significant shorter operating time (75 min vs. 189 min, p < 0.05) and less estimated blood loss (63 ml vs. 444 ml, p < 0.05) than those of TLIF group. Intraoperative neuromonitoring showed that spontaneous electromyography(EMG) occured in 9/26 patients with EELF and and working tube was adjusted accordingly. Motor eveked potential (MEP) decreased more than 50% in 2 patients without neurologic complication. A dural injury occurred in 2 patients of EELF and 1 patient of TLIF group, but those were minimal and did not cause a sequel.
DISCUSSION
EELF may be a good alternative for patients presenting mainly with leg pain due to foraminal and lateral recess stenosis.