Lumbar Spinal Stenosis Represents a Distinct Sagittal Alignment Phenotype Beyond Normal Aging.

STUDY

DESIGN

Retrospective cohort study comparing sagittal spinopelvic alignment in patients with lumbar spinal stenosis (LSS) to age- and sex-matched normative data and evaluating postoperative changes following decompression surgery.

OBJECTIVE

To determine whether LSS represents a distinct sagittal alignment phenotype beyond normal aging and to assess alignment changes up to two years after decompression surgery.

SUMMARY OF BACKGROUND DATA: Sagittal alignment in healthy populations and adult spinal deformity is has been widely studied. However, the sagittal alignment specific to LSS remains poorly researched.

METHODS

Patients undergoing decompression without fusion for LSS between 2014 and 2022 at a single institution were included. Exclusion criteria were prior surgery, infection, tumor, scoliosis, or lack of radiographic data. Sagittal parameters were measured preoperatively and at two-year follow-up. We calculated normative value using a large population-based Japanese cohort. Comparison between LSS and controls were performed using one-sample t-tests.

RESULTS

448 patients were included for analysis. Compared to controls, LSS patients had significantly higher SVA and PT, and lower LL, SS, and TK. Postoperative alignment improved but did not normalize. Residual malalignment persisted across all age groups, indicating a distinct alignment phenotype in LSS.

CONCLUSION

LSS is associated with a unique sagittal alignment profile that exaggerates age-related changes. Decompression surgery partially improves sagittal alignment. These findings suggest intrinsic structural differences in LSS and highlight the need for individualized treatment and long-term follow-up.

LEVEL OF EVIDENCE: 3.