The relationship between spino-pelvic parameters with coronal lower extremity alignment in patients with low back pain: a prospective radiographic study.

Abstract

Spine-pelvic parameters and lower limb alignment serve as key clinical indicators in orthopedics. It remains unclear whether these measures are interrelated. This study examines the relationship between spine-pelvic parameters and coronal lower extremity alignment in individuals with low back pain (LBP). We prospectively enrolled LBP patients aged over 50 years from April 1, 2023 to September 30, 2025. Radiographic evaluation included standing full-spine lateral and posteroanterior views, along with lower extremity posteroanterior radiographs. Spine-pelvic parameters assessed were pelvic incidence (PI), lumbar lordosis, pelvic tilt, sacral slope, sagittal vertical axis, and coronal balance distance. Lower extremity parameters included the hip-knee-ankle angle (HKA) and Kellgren-Lawrence grade. Parameters were compared across groups, and correlation analyses were conducted. The study included 264 patients (mean age 64.1±7.3 years; 63.6% female). Mean PI was 49.8±10.5°, and mean HKA was 177.2±4.1°. Significant differences in HKA were observed among PI groups (P=0.002), and PI differed significantly across HKA groups (P=0.026). A weak negative correlation was found between PI and HKA (r=-0.183, P=0.003). Sacral height showed significant correlations with PI (P<0.001) and HKA (P=0.010). A weak inverse association exists between PI and HKA in LBP patients, and sacral height was found to have significant influences on PI and HKA.