Retrospective Evaluation of Minimally Invasive Lumbar Decompression (mild®) for the Treatment of Neurogenic Claudication: A One-Year Follow-Up Study.

Abstract

Neurogenic claudication can be a chronic, debilitating disorder and is often hard to treat. Lumbar spinal canal stenosis (LSCS) occasioned by hypertrophy of the ligamentum flavum (HLF) is a common cause of neurogenic claudication, especially in the elderly patient population. These patients can be deemed poor surgical candidates due to the multitude of comorbidities with which they present. Minimally invasive lumbar decompression (mild®, Vertos Medical Inc.) is an alternative to surgery for patients who have neurogenic claudication and do not respond to conservative management. The prevailing literature supports the assertion that the mild® procedure is safe and effective. However, larger, high-powered studies are necessary to definitively establish the role of the mild® procedure in interventional pain treatment paradigms, especially when the effectiveness of conventional injections' utility in reducing pain and improving functioning is called into question. This study aims to assess the safety and efficacy of mild® within a one-year follow-up period, using self-reported pain scores, walking distance, and standing time. This project is a retrospective, observational study using data collected from electronic medical records. Procedures were performed between June 11th, 2013, and November 7th, 2024, by a single trained, board-certified anesthesiologist and interventional pain management specialist at the Lahey Hospital and Medical Center, a tertiary academic medical center. Variables measured included pain scores on the visual analog scale (VAS), walking distance (in meters), and standing time (in minutes) at intervals of one month, one-6 months, and 6-12 months. Procedure complications were classified as nonexistent (referred to as "none" by the researchers), minor, or major. A major complication was defined as one that required hospital admission. Statistical analysis was carried out using a paired Wilcoxon signed-rank test with a two-tailed hypothesis. A total of 95 patients underwent mild® in the selected time frame. No patients experienced an intraoperative complication, and 92 (96.8%) experienced no postoperative complications. Postoperative complications were limited to minor issues (e.g., bleeding, nausea, numbness, dizziness). There were significant reductions in VAS pain scores from baseline at one month (7.9 ± 1.2 vs 4.5 ± 2.7, P < 0.00001), one-6 months (7.8 ± 1.3 vs 5.2 ± 2.5, P < 0.00001), and 6-12 months (7.7 ± 1.2 vs 4.4 ± 3.0, P < 0.00001). Significant improvements in walking distance and standing time were also recorded. Limitations include the nature of a single-center, single-provider study. Patient-reported pain scores, walking distance, and standing time are subject to biases in response, recall, and subjectivity. Confounding variables such as epidural steroid injections (ESIs) or changes in enteral medications cannot be taken into consideration. Patients who have HLF-caused LSCS, are unresponsive to conservative treatment, and are poor surgical candidates can undergo mild® safely. This study showed significant improvement in VAS pain scores, walking distance, and standing time at intervals of one month, one-6 months, and 6-12 months.