Special Poster Session 51st International Society for the Study of the Lumbar Spine Annual Meeting 2025

INTRODUCTION

The heterogenous biopsychosocial nature of low back pain (LBP) results in high variation in treatment responses where some patients benefit while other don’t. To better understand this heterogeneity, this study focused on the utility of standardized in-clinic sensor-based functional assessments as a phenotyping tool to determine variations in pain-related functional profiles of LBP and identify unique homogenous clusters or subgroups that are associated with treatment response.

METHODS

This approach integrated novel biomechanical measures that capture intrinsic variations in pain-related function. LBP participants (n = 671) completed a series of patient-reported outcome questionnaires that target critical biopsychosocial domains and underwent a 10-minute standardized functional motion assessment of the lumbothoracic (trunk) spine. Patients were assessed using an in-clinic spine-specific functional assessment to benchmark the extent of their functional impairment. Participants were recruited based on eligibility criteria and medical history.  All study assessments were conducted at baseline and at 3-month follow-up. Clustering analyses were then performed on extracted spinal motion signatures to identify and characterize potential subgroups.

RESULTS

Clustering identified 3 patient subgroups (defined by baseline motion signatures) with varying pain and functional impairment profiles. We observed significant associations between cluster membership and treatment response assessed at the 3-month follow-up (Figure1). These clusters showed significant (p < 0.0001) phenotypic variations in motion-based function (low motion values for Cluster 1; moderate motion for Cluster 2; and high motion for Cluster 3) between clusters. Longitudinal analysis of PGIC responses at 3-months found that approximately 47% of patients in Cluster 1 reported a positive response at follow-up, compared to 51% and 60% of patients in Clusters 2 and 3, respectively, who indicated improvement in their condition. Additionally, about 25% of patients in Cluster 1 reported a negative response, while only 17.6% of patients in Cluster 2 and 9.0% in Cluster 3 indicated a worsening of their condition. We also found that cluster membership was significantly associated (p < 0.03) with PGIC responses.

DISCUSSION

While PROs are widely used in clinical practice to evaluate key biopsychosocial domains of spine health, they are inherently subjective, can be influenced by psychological factors leading to an incomplete picture of LBP progression. By incorporating objective, sensor-based assessments alongside PROs, there is potential to enhance patient phenotyping and inform more tailored treatment strategies, thus improving outcomes. Our results demonstrate the ability of these sensor-based functional assessments to identify distinct functional phenotypes, showing significant variability across most biopsychosocial domains (e.g. pain interference, physical function, and social role), except for anxiety.

These results support the novel use of sensor-based functional assessments for phenotyping of LBP and highlights between cluster differences at baseline across many biopsychosocial measures as well as variation in longitudinal responses between clusters. Our study showed that sensor-based functional assessments can provide a means of objectively evaluating the extent of functional impairment and indirectly capture intrinsic biopsychosocial factors related to LBP to better inform clinical decision-making.

Figure 1. Trunk motion (motion index) and biopsychosocial characteristics as a function of motion clusters. All differences among clusters were significant except for anxiety.