• PURPOSE
    • Sagittal alignment restoration is considered crucial for successful lumbar fusion outcomes, yet the specific relationships between spino-pelvic parameters and patient-reported outcomes remain incompletely understood. This prospective cohort study investigated associations between sagittal alignment parameters and pain/disability outcomes following lumbar fusion surgery.
  • METHODS
    • Fifty-nine patients with lumbar spondylolisthesis undergoing short-segment transforaminal lumbar interbody fusion (TLIF) were prospectively enrolled. Radiographic parameters including pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), lumbar lordosis (LL), thoracic kyphosis (TK), and sagittal vertical axis (SVA) were measured pre- and post-operatively. Visual analog scale (VAS) and Oswestry Disability Index (ODI) were assessed pre-operatively and at final follow-up (median 99.5 days). Correlational analyses correlated sagittal parameters, parameter changes, and clinical outcomes.
  • RESULTS
    • Despite substantial clinical improvement (median ODI: 72 to 15, p < 0.001; mean VAS: 8.95 to 2.55, p < 0.001), average lumbar lordosis decreased by 4.1°, and SVA increased by 18.5 mm postoperatively. Of all radiographic parameters analyzed, only the change in lumbar lordosis (ΔLL) was significantly associated with pain improvement (ΔVAS, r = - 0.288, p = 0.027). Changes in other parameters, including SVA, and absolute postoperative alignment values, were not significantly associated with clinical outcomes.
  • CONCLUSIONS
    • In this cohort, revealed a clinical-radiographic paradox where patients experienced substantial symptom relief after fusion despite a lack of overall sagittal alignment correction. Early pain improvement correlated only with the magnitude of individualized lordosis restoration, not with achieving normative targets. These findings suggest surgical strategy should prioritize patient-specific realignment over the pursuit of universal radiographic goals.