MiDAS I (mild® Decompression Alternative to Open Surgery): A Preliminary Report of a Prospective, Multi-Center Clinical Study

ackground: Neurogenic claudication due to lumbar spinal stenosis is a common problem that can becaused by many factors including hypertrophic ligamentum flavum, facet hypertrophy, and disc protrusion.When standard medical therapies such as pain medication, epidural steroid injections, and physical therapyfail, or when the patient is unwilling, unable, or not severe enough to advance to more invasive surgicalprocedures, both physicians and patients are often left with a treatment dilemma. Patients in this studywere treated with mild®, an ultra-minimally invasive lumbar decompression procedure using a dorsalapproach. The mild procedure is performed under fluoroscopic imaging to resect bone adjacent to, andachieve partial resection of, the hypertrophic ligamentum flavum with minimal disruption of surroundingmuscular and skeletal structure.Objective: To assess the clinical application and patient safety and functional outcomes of the mildlumbar decompression procedure in the treatment of symptomatic central canal spinal stenosis.Study Design: Multi-center, non-blinded, prospective clinical study.Setting: Fourteen US spine specialist practices.Methods: Between July 2008 and January 2010, 78 patients were enrolled in the MiDAS I Study andtreated with the mild procedure for lumbar decompression. Of these patients, 6-week follow-up wasavailable for 75 patients.Outcome Assessment: Visual Analog Score (VAS), Oswestry Disability Index (ODI), ZurichClaudication Questionnaire (ZCQ), and SF-12v2® Health Survey. Outcomes were assessed at baselineand 6 weeks post-treatment.Results: There were no major device or procedure-related complications reported in this patient cohort.At 6 weeks, the MiDAS I Study showed statistically and clinically significant reduction of pain as measuredby VAS, ZCQ, and SF-12v2. In addition, improvement in physical function and mobility as measured by ODI,ZCQ, and SF-12v2 was statistically and clinically significant in this study.Limitations: This is a preliminary report encompassing 6-week follow-up. There was no controlgroup.Conclusions: In this 75-patient series, and in keeping with a previously published 90-patient safetycohort, the mild procedure proved to be safe. Further, based on near-term follow-up, the mild proceduredemonstrated efficacy in improving mobility and reducing pain associated with lumbar spinal canalstenosis.Key words: Spine, lumbar, decompression, fluoroscopy, mild, stenosis, ligamentum flavum, minimallyinvasive