Foraminal Access Strategies in Patients with Lumbar Posterolateral Fusions in Transforaminal Endoscopic Spine Surgery: Case Series and Technical Note

Background: The treatment of post-laminectomy lumbar radiculopathy in the setting of a large posterolateral fusion mass presents an anatomic challenge to the spine interventionalist. Objective: To describe outcomes of awake, transforaminal endoscopic surgical treatment for patients presenting with lumbar radiculopathy after instrumented posterolateral lumbar fusions. Study Design: Retrospective chart review. Setting: This study took place in a single-center, academic hospital. Methods: The records of 538 patients who underwent awake transforaminal lumbar endoscopic decompression surgery performed by a single surgeon at a single institution between 2014 and 2019 were retrospectively reviewed. Fifteen consecutive patients who required drilling through their posterolateral fusion masses to access the post-fusion foraminal stenosis were included in this study. All included patients were followed for at least one year after surgery. Results: Fifteen patients (7 male and 8 female) with an average age of 68.1 years (range 38-89, standard deviation 13.4 years) underwent awake transforaminal foraminal decompression surgeries that utilized special techniques to drill through large posterolateral fusion masses to access their foraminal stenosis. One patient (7%) required repeat surgery in the postoperative period due to lack of surgical improvement. For the remaining 14 patients, at one year follow up, the preoperative visual analog scale (VAS) for leg pain and Oswestry disability index (ODI) improved from 7.0 (+/- 1.7) and 40.7% (+/- 12.9) to 1.7 (+/- 1.6) and 12.1% (+/- 11.3). There were no complications such as infection, durotomy, or neurologic injury Limitations: Retrospective case series. Conclusion: Transforaminal endoscopic spine surgery offers a unique approach to post-laminectomy and post-fusion foraminal compression because it avoids scar tissue resulting from previous posterior approaches. Large posterolateral fusion masses associated with some posterior fusions can be a sizeable bony barrier to transforaminal access. The authors share their techniques and success for navigating large posterior, bony fusion masses in transforaminal post-fusion foraminal decompression.