AB0867 ANALYSIS OF SPINAL MOVEMENT USING 3D MOTION CAPTURE: NEW INSIGHTS TO IMPROVE PATIENT-SPECIFIC SPINAL MOBILITY ASSESSMENT IN AXIAL SPONDYLOARTHRITIS
Authors: L. Wade, D. Cazzola, J. Bilzon, R. Sengupta
Journal: Annals of the Rheumatic Diseases (2024)

<h3>Background:</h3> Within axial spondyloarthritis (axSpA), the Bath Ankylosing Spondylitis Metrology Index (BASMI) is widely used to assess spinal mobility. However, this measure does not correlate well with radiographic disease progression [1], can produce inconsistent results between clinicians and only assesses lumbar and cervical mobility. Thus, restricted mobility at other areas are ignored, despite axSpA patients presenting with highly variable locations of disease activity, limiting the potential to develop patient-specific interventions to maintain lifetime mobility. <h3>Objectives:</h3> Compare forward flexion, lateral bending and cervical rotation BASMI measures to range of motion (RoM) of a 3D multi-segment spine, and examine how lumbar, thoracic, and cervical spine mobility differs between patients. <h3>Methods:</h3> Thirty-one (21M, 10F, 50 ± 8 years, 82 ± 18 kg, 173 ± 8.5 cm) radiographic axSpA patients were assessed using the BASMI, and then performed standing spine forward flexion, lateral bending and axial rotation, while recorded with 3D marker-based motion capture. Motion capture used markers placed on five body segments (head/neck, upper thoracic, lower thoracic, lumbar and pelvis), to examine segment-segment RoM using inverse kinematics in OpenSim [2]. Three maximal RoM values were recorded for each patient and then averaged, with whole spine RoM calculated as the sum of all segments, excluding the pelvis. Pearson r correlations were calculated between composite BASMI measures (lumbar forward flexion, lumbar lateral bending and cervical rotation) and full spine RoM or individual segment-segment RoM obtained from 3D motion capture. <h3>Results:</h3> Despite assessing lumbar and cervical RoM, composite BASMI measures correlated better with whole spine RoM obtained from 3D motion capture (Table 1). This result is consistent with BASMI lateral lumbar bending, a measures which records the distance between the fingers and the ground, capturing whole spine lateral bending. In general, composite BASMI measures were not very strongly correlated (r = &lt;0.8) to whole or region-specific spinal RoM from 3D motion capture, possibly due to composite BASMI measures being converted to a 10-point scale, potentially limiting their utility to monitor disease progression. Forward flexion measures likely need to account for the substantial lower thoracic flexion observed when using 3D motion capture, in addition to lumbar flexion (Figure 1A). Figure 1 demonstrates substantial mobility variations between patients, illustrating the potential of measuring and monitoring spinal movement with a multi-spine segment measure, both within spinal regions and between different movements. Patients may have very limited spinal RoM in one region which may be accommodated for at another region, or through pelvis rotation, to achieve functional mobility. Therefore, these results indicate that segment-segment RoM in radiographic axSpA patients is not indicative of mobility at neighbouring regions, limiting the use of the BASMI and its composite measures. These results may also provide quantitative measures of patient-specific movement at individual spinal regions, which could be targeted through personalised treatments to regain spinal mobility, or even just functional mobility. <h3>Conclusion:</h3> To improve monitoring of spinal mobility and disease progression in axSpA, focussing on regional differences within each patient's spine, as well as across different spinal movements, will be vital. A more in-depth and targeted assessment, harnessing future markerless motion capture methods [3], could potentially enable patient-specific interventions to maximise their mobility, and could also have improved correlation with radiographic disease progression. <h3>REFERENCES:</h3> [1] Rezvani A et al. Spine, 37(19). 2012 [2] Bruno A et al. J Biomech Eng, 137(8). 2015 [3] Wade, L et al. Peer J, 10. 2022 <h3>REFERENCES:</h3> NIL. <h3>Acknowledgements:</h3> This research was funded by the UKRI Centre for Analysis of Motion, Entertainment Research and Applications (EP/M023281/1 and EP/T014865). <h3>Disclosure of Interests:</h3> <b>None declared.</b>