# Comparing Movement Patterns and Physical Function Between Chronic Low Back Pain Patients With Nociplastic and Nociceptive Pain Categories

## TL;DR

This study compares movement and physical function in chronic low back pain patients with different pain types, finding that perceived disability is worse in one group but not reflected in actual movement.

## Contribution

The study reveals that nociplastic pain is linked to worse perceived function but not worse biomechanical performance compared to nociceptive pain.

## Key findings

- Nociplastic patients reported worse physical function and had higher anxiety and depression.
- Nociplastic patients had slower sit-to-stand times but biomechanical scores closer to healthy controls.
- Pain category was a significant predictor of perceived function but not objective movement metrics.

## Abstract

Individuals with chronic low back pain (LBP) often present with significant physical dysfunction. The underlying cause is difficult to diagnose due to the heterogeneous nature of LBP categories.

Two hundred and fifty‐six patients were assessed as having either nociceptive (NC) or nociplastic (NP) chronic low back pain using validated surveys, including the PainDETECT Questionnaire and a chronic overlapping pain condition screener. Additional covariates of anxiety, depression, and fear avoidance were evaluated using standard surveys. Physical function was judged objectively using a sit‐to‐stand test (STS; quantified using marker‐less motion capture calculated kinematic scores and movement metrics) and subjectively (PROMIS‐physical function survey). Demographics (age, sex, BMI), psychological factors, and biomechanical outcomes were compared across pain categories using nonparametric statistics and regression modeling.

Compared to the NC group, the NP group was significantly older (NP: 61.0 ± 21.0, NC: 53.5 ± 29.3, p = 0.03) and reported higher levels of anxiety (NP: 51.2 ± 17.4, NC: 48.0 ± 13.4, p = 0.002) and depression (NP: 49.0 ± 14.7, NC: 41.0 ± 10.8, p = 0.009). NP also had worse perceived physical function (PROMIS‐PF) (NP: 39.3 ± 6.9, NC: 42.1 ± 7.3, p < 0.001) and slower STS times (NP: 12.5 ± 6.1 s, NC: 12.0 ± 5.8, p = 0.03). Despite these differences, the NP group exhibited biomechanical function closer to the healthy control average motion trajectory (K‐score; NP: 77.6 ± 8.1, NC: 75.6 ± 8.1, p = 0.03) during the STS task. Regression models evaluating the association between biomechanical variables and pain categories, while adjusting for age, sex, and BMI, identified significant differences between pain categories only for PROMIS‐physical function.

While individuals with nociplastic pain reported lower perceived physical function and exhibited differences in demographic and psychological factors, pain categories were not significant predictors of objective biomechanical measures after adjusting for age, sex, and BMI. However, pain category was a significant predictor of PROMIS‐PF, suggesting that it is more closely associated with perceived functional limitations than with quantitative biomechanical performance.

Are differences in perceived disability between nociceptive and nociplastic cLBP patients reflected in actual movement patterns or in patients' perceived functional ability? Despite worse patient‐reported disability, primarily nociplastic patients did not exhibit worse biomechanical function when compared to primarily nociceptive patients.