Research progress on sagittal balance and minimal clinically important difference after two-level lumbar...

Sagittal alignment influences functional recovery after surgery for two-level lumbar spondylolisthesis, yet evidence specific to this population remains limited. This review synthesizes current findings on postoperative changes in lumbar lordosis (LL), sagittal vertical axis (SVA), pelvic tilt, and pelvic incidence-lumbar lordosis mismatch (PI-LL), and examines their associations with patient-reported outcomes. Available studies indicate that two-level fusion generally produces greater LL correction than single-level fusion, although restoration of global sagittal balance and ideal PI-LL matching is less consistent. Improvements in LL and PI-LL are associated with better Oswestry Disability Index (ODI) and pain outcomes, and reported thresholds such as LL improvement of at least 8° and postoperative PI-LL of 10° or less may help predict achievement of the ODI minimal clinically important difference (MCID). These values should be interpreted as radiographic predictors of clinically meaningful improvement rather than MCID thresholds for the radiographic parameters themselves. Current evidence is constrained by heterogeneous study designs, small retrospective cohorts, inconsistent definitions, and limited two-level subgroup analyses. Prospective multicentre studies using standardized radiographic assessment, validated patient-reported anchors, and stratification by age, fusion level, and pelvic morphology are needed to define reliable surgical correction targets.