Function-Specific Profiles of Chronic Low Back Pain in Middle- Aged and Older Patients and Their Association with Standing Sagittal Spinopelvic Alignment: A Cross-Sectional Study

Abstract

Background/Objectives: Chronic low back pain (LBP) in older adults is usually quantified as a single global score, which may not reflect the activities in which pain actually limits the patient. This study described function-specific LBP profiles in middle-aged and older patients and examined their cross-sectional association with standing sagittal spinopelvic alignment. Methods: This cross-sectional, retrospective observational study evaluated 102 patients with chronic LBP, categorized into Group M (under 75 years; n = 51) and Group O (75 years or older; n = 51). Visual Analog Scale (VAS) scores were assessed during rest, getting up, rolling over, and walking (gait). An exploratory index, the proportional pain contribution (VAS%), was derived by expressing each phase as a percentage of the sum of the four scores; because the four values sum to 100% by definition, VAS% was interpreted only as a descriptor of the within-patient distribution of pain and always alongside the absolute scores. Lumbar lordosis (LL), pelvic incidence (PI), pelvic tilt (PT), sacral slope and PI minus LL (PI–LL) were measured on standing radiographs. Results: Group M reported higher absolute pain than Group O at rest, on getting up and on rolling over (all p < 0.001), whereas absolute gait pain did not differ between the groups (p = 0.730). As a consequence of this pattern, Gait VAS% was higher in Group O (median 59.8% vs. 27.3%, p < 0.001). Group O had lower LL (p = 0.001) and a larger PI–LL (p = 0.005); PI and PT did not differ significantly. Gait VAS% correlated with age (τ = 0.33) and PI–LL (τ = 0.29). In exploratory multivariable models, age and PI–LL were retained in the final model for Gait VAS% and were independently associated with it (β = 0.37 and 0.30 respectively; R2 = 0.29). Conclusions: In this sample, the older patients reported less pain at rest and during postural transitions but similar pain during walking, so that walking accounted for a larger share of their total reported pain burden. This proportional pattern was associated with a larger standing PI–LL mismatch, although the association was modest. The findings are descriptive and hypothesis-generating, and suggest that asking separately about pain during walking may add information that a single global score does not capture.