This prospective longitudinal study will compare incidence rates of Medicare beneficiary surgical and minimally invasive intervention post index procedure, as well as harms associated with the MILD procedure, at 24 months post-treatment with MILD, tested against a control group of similar patients that have had a comparable procedure. This study will start with patients treated with a study procedure having an index date on or after January 1, 2017, and enrollment will continue until stopped by the sponsor.

In this study the treatment group will include all patients receiving MILD, and the control group will include all patients receiving IPD for the treatment of LSS during the enrollment period. Reoperation and harms data will be studied for the MILD and IPD procedures for a 24-month follow-up period after the index procedure using Medicare claims data. This study is exempt from IRB oversight (Department of Health and Human Services regulations 45 CFR 46) and does not require prior enrollment nor patient consent. The inclusion of the study's NCT number on MILD Medicare claims is required and results in enrollment.

Inclusion Criteria:

• Medicare beneficiaries receiving MILD or interspinous process decompression
• Diagnosis of LSS with NC

Exclusion Criteria:

• Patients that have received a laminectomy, laminotomy, fusion, interspinous process decompression, or MILD in the lumbar region during the 12 months prior to the index date

Study participants will include Medicare beneficiaries for whom claims have been submitted to the Medicare Claims database and who have been enrolled in Medicare fee-for-service or Medicare Advantage for one year prior to their index procedure and two years post index procedure.