Actigraphy-Based Algorithm for Spinal Range of Motion Assessment for Axial Spondyloarthritis Patients.

Axial spondyloarthritis is a chronic inflammatory disease that primarily affects the axial skeleton. Spinal inflammation, back pain and new bone formation contribute to progressive impairment of spinal mobility. Measuring Spinal Range of Motion (SRoM) is important to assess spinal pathology, monitor disease activity, guide treatment decisions, and determine treatment responses. Standard of care, distance-based and angular-based clinical measurements, have several limitations, including subjectivity, inter-assessor variability, low sensitivity, and an inability to be used for self-assessment. To address these limitations, we have developed a wearable sensor-based algorithm to measure SRoM during a forward flexion bend with a wrist-worn smartwatch. Here, we describe this sensor-based solution for self-administered, angle-based SRoM measurements which correlated with goniometer measurement (r=0.76 similar to 0.89). This accelerometry-based algorithm can be deployed to quantitatively measure changes in spinal mobility with sensitivity to change between consumer and medical-grade devices, as well as across spinal flexion tasks.