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Report From a Quality Assurance Program on Patients Undergoing the MILD Procedure


  • Name of the department(s) and institution(s) to which the work should be attributed: Department of Anesthesiology, Stony Brook University.
  • Financial sources that supported the work: Department of Anesthesiology, Stony Brook University.
  • The authors declare no conflict of interest, and none of the authors are consulting for Vertos Medical. Brian Durkin has received research support from Vertos Medical, but none of the patients included in the database presented here were part of the Vertos study. Brian Durkin is a mild procedure proctor for Vertos Medical.

Reprint requests to: Brian Durkin, DO, Department of Anesthesiology, Health Science Center, Level 4, Stony Brook University, Stony Brook, NY 11794, USA. Tel: 631-444-2358; Fax: 631-444 2907; E-mail:



To characterize trends in pain and functional outcomes and identify risk factors in patients with lumbar spinal stenosis (LSS) and neurogenic claudication undergoing the “Minimally Invasive Lumbar Decompression” (MILD) procedure.


Retrospective observational cohort study.


Academic multidisciplinary pain center at Stony Brook Medicine.


Patients undergoing the MILD procedure from October 2010 to November 2012.


De-identified perioperative, pain and function related data for 50 patients undergoing MILD were extracted from the Center for Pain Management's quality assessment database. Data included numerical rating scale (NRS), symptom severity and physical function (Zurich Claudication Questionnaire), functional status (Oswestry Disability Index [ODI]), pain interference scores (National Institutes of Health Patient-Reported Outcomes Measurement Information System [PROMIS]), and patients' self-reported low back and lower extremity pain distribution.


No MILD patient incurred procedure-related complications. Average NRS scores decreased postoperatively and 64.3% of patients reported less pain at 3 months. Clinically meaningful functional ODI improvements of at least 20% from baseline were present in 25% of the patients at 6 months. Preliminary analysis of changes in PROMIS scores at 3 months revealed that pre-MILD “severe” lumbar canal stenosis may be associated with high risk of “no improvement.” No such impact was observed for NRS or ODI outcomes.


Overall, pain is reduced and functional status improved in LSS patients following the MILD procedure at 3 and 6 months. Given the small sample size, it is not yet possible to identify patient subgroups at risk for “no improvement.” Continued follow-up of longer-term outcomes appears warranted to develop evidence-based patient selection criteria.