Foraminal Stenosis Grade and Oswestry Disability Index Improvement After Single-Level Lumbar Decompression: A...

To evaluate, in a single-institution cohort, whether foraminal stenosis grade is associated with Oswestry Disability Index (ODI) improvement after single-level lumbar decompression.

We retrospectively reviewed 178 consecutive single-level lumbar decompressions (CPT 63047) at Twin Cities Spine Center (Minneapolis, Minnesota, USA), 2018 to 2023. Foraminal stenosis was graded by the Lee system; a second blinded rater regraded all foramina and graded central canal (Lee) and lateral recess (Bartynski) stenosis. The primary outcome was absolute three-month ODI improvement. Regression adjusted for imaging, surgical, and biopsychosocial covariates.

Interobserver agreement for foraminal grade was 90% (kappa 0.83). We did not detect an association between foraminal grade and ODI improvement, unadjusted (p=0.76) or adjusted, using either rater's grades. Central canal stenosis was absent in 71% of patients, whereas lateral recess stenosis was severe in 59%. In post hoc analysis, lateral recess grade was associated with greater improvement in a reduced model (β=5.51 per grade; p=0.022) but not in the full model (p=0.067). Depression (β=-9.39; p=0.005) and preoperative opioid use (β=-6.64; p=0.044) were associated with less improvement; opioid use was associated with higher unadjusted 90-day readmission (15% vs 4.0%; p=0.023). The ODI minimum clinically important difference was met by 66%; 90-day surgical complications occurred in 6.2%.

In our experience, foraminal stenosis grade was not detectably associated with ODI improvement after single-level decompression, in a cohort with frequent coexisting lateral recess compression. Depression and opioid use were associated with less improvement.