The report is a product of the VA/HSR Evidence Synthesis Program.

Percutaneous Image-Guided Lumbar Decompression: A Systematic Review of the Minimally Invasive Lumbar Decompression (MILD) Procedure

Takeaway: Lumbar spinal stenosis (LSS) is a common and debilitating condition caused by a narrowing of the spinal canal in the lower back, primarily due to age-related ligamentum flavum hypertrophy (LFH; abnormal thickening of connective tissue in the spine that can put pressure on nerves). Percutaneous image-guided lumbar decompression, also known as minimally invasive lumbar decompression (MILD), is a new, minimally invasive surgical procedure for treating LSS. Among individuals with severely symptomatic LSS due to LFH (>2.5 mm), MILD may modestly reduce pain severity and interference at one year versus conventional medical management or epidural steroid injections and may result in little to no difference versus laminectomy (surgery that removes the arches of vertebrae to alleviate pressure on the spinal cord or nerves) with spinal fusion. Results of this review should be viewed with caution as the quantity and quality of evidence is limited. Additional randomized controlled trials are needed to examine the benefits and harms of MILD compared with laminectomy without fusion, as well as the repeatability of MILD, and outcomes in a broader range of individuals, including those with less severe symptoms and those treated by a wider range of clinicians, including clinicians with less advanced MILD training/experience. Surveillance of patients treated with MILD is needed to develop and assess patient selection and clinician training criteria, long-term effectiveness and harms of MILD, need for subsequent interventions, and cost effectiveness.

Lumbar spinal stenosis (LSS) is a common and debilitating condition caused by a narrowing of the spinal canal in the lower back, primarily due to age-related ligamentum flavum hypertrophy (LFH; abnormal thickening of connective tissue in the spine that can put pressure on nerves). LSS can cause pain, dysfunction, and reduced life quality. There has been a growing need for and interest in minimally invasive LSS treatments. Percutaneous image-guided lumbar decompression, also known as minimally invasive lumbar decompression (MILD), is a new, minimally invasive surgical procedure for treating LSS.

In response to a request from VHA’s Office of Integrated Veteran Care Clinical Determinations Unit and the Pain Management Opioid Safety and Prescription Drug Monitoring Program, HSR’s Evidence Synthesis Program (ESP) Center in Minneapolis reviewed the evidence on the efficacy and safety of the MILD procedure. To identify relevant studies, investigators searched MEDLINE, Embase, and CENTRAL databases through April 21, 2025; hand-searched reference lists and consulted content experts; and searched clinical trial registries for recently completed and ongoing trials.

Summary of Findings

• The ESP investigators identified 27 primary studies evaluating MILD. Most studies were small and short term.
• Among individuals with severely symptomatic LSS due to LFH (>2.5 mm), MILD may modestly improve pain and function at one year versus conventional medical management (CMM). Adverse events did not differ between groups.
• MILD may reduce pain severity and interference at 6 months and 1 year compared with epidural steroid injections (ESI).
• Compared with laminectomy (surgery that removes the arches of vertebrae to alleviate pressure on the spinal cord or nerves) with spinal fusion, MILD may have similar effects on pain and function, but the effects on harms and subsequent surgeries are very uncertain.
• Compared with interspinous spacers (small devices implanted between vertebrae), evidence regarding subsequent surgeries is very uncertain, but MILD may be associated with fewer adverse events.
• Uncontrolled observational studies suggest wide-ranging rates of subsequent surgery but few adverse events following MILD.
• Data on procedural complications and subsequent procedures/surgeries are limited. Long-term results are not known.
• There is no MILD evidence from VHA medical centers regarding individuals with less severe or shorter symptom duration, those undergoing repeat MILD, or whether effects vary by patient and spine characteristics or clinicians’ training, experience, and volume.

Implications

Results of this review should be viewed with caution as the quantity and quality of evidence is limited. What information does exist suggests that MILD may provide similar or greater improvement in pain and function compared with other widely used options including CMM, ESI, and lumbar decompression surgery. All of these options appear to be associated with improvement in symptoms from baseline, though the reason for this and clinical/policy implications are not fully clear, especially given that two of the comparator groups (ESI and CMM) either have been shown not to have long-term effectiveness or are typically not considered incrementally effective after 3–6 months.

Limitations

The evidence for MILD is sparse and includes only four randomized controlled trials (RCTs), none of which were large or provided adequate data beyond one year. All studies reported improvements from baseline in both the intervention and control groups, making it challenging to interpret findings. Only one trial (MILD versus ESI) was rated as low risk for bias, and its reporting did not extend beyond six weeks.

Future Research

Additional RCTs are needed to examine the benefits and harms of MILD compared with laminectomy without fusion, as well as the repeatability of MILD, and outcomes in a broader range of individuals, including those with less severe symptoms and those treated by a wider range of clinicians, including clinicians with less advanced MILD training/experience. Surveillance of patients treated with MILD is needed to develop and assess patient selection and clinician training criteria, long-term effectiveness and harms of MILD, need for subsequent interventions, and cost effectiveness.

Citation:

Ullman K, Landsteiner A, Zerzan N, et al. Percutaneous Image-Guided Lumbar Decompression: A Systematic Review of the Minimally Invasive Lumbar Decompression (MILD) Procedure. Washington, DC: Evidence Synthesis Program, Health Systems Research, Office of Research and Development, Department of Veterans Affairs. VA ESP Project #09-009; 2026.

To view the full report, go to vaww.hsrd.research.va.gov/publications/esp/lumbar-decompression.cfm (This report is available via intranet only.)

How can VA leadership work with the ESP? Nominations for systematic review topics may be submitted to the program at any time. When you submit a topic nomination form, ESP Coordinating Center staff will work with you to determine the appropriate research approach and ESP product to address your questions of interest. Topics are selected and assigned to an ESP Center based on program capacity and alignment with VA national goals.

This Management Brief is provided to inform you about recent HSR findings that may be of interest. The views expressed in this article are those of the authors and do not necessarily reflect the position or policy of the Department of Veterans Affairs. If you have any questions or comments about this Brief, please email CIDER. The Center for Information Dissemination and Education Resources (CIDER) is a VA HSR Resource Center charged with disseminating important HSR findings and information to policy makers, managers, clinicians, and researchers working to improve the health and care of Veterans.

This report is a product of VA/HSR's Evidence Synthesis Program (ESP), which was established to provide timely and accurate synthesis of targeted healthcare topics of particular importance to VA managers and policymakers, and to disseminate these reports throughout VA.

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