Continuous Activity Tracking Using a Wrist-Mounted Device in Adult Spinal Deformity: A Proof of Concept Study.

BACKGROUND: Sagittal imbalance in adult spinal deformity (ASD) likely influences balance and ambulatory capacity because of muscular demand, pain, and disability. Disability measures for ASD rely heavily on ambulatory function; however, current metrics may fail to fully capture its contribution. We sought 1) to determine the utility of continuous remote step count monitoring and activity tracking in ASD using a consumer-friendly accelerometer, and 2) to investigate trends and patterns both before and after surgical intervention.

CASE DESCRIPTION: One patient with progressive ASD was enrolled. Daily step count (SC), distance traveled (DT), and levels of activity were measured using a wrist-mounted device for 17 months. Spinopelvic parameters were measured from standing radiographs. The patient underwent T4-ilium long-segment fusion for correction of progressive deformity (coronal cobb angle: 8°; sagittal vertical axis: 4 cm; coronal vertical axis: 2 cm); recovery was uneventful. The device was worn for 216 of 520 (41%) recorded days during waking hours, with an average SC of 5254 ± 2696 per day. SC (P < 0.001), DT (P < 0.001), and minutes of light activity (LA) (P < 0.001) declined over the 9-month preoperative course, whereas sedentary activity increased (P < 0.001). After surgery, SC, DT, and LA decreased in the early postoperative period, with a significant increase at 7-8 months compared with the preoperative period (P < 0.001).

CONCLUSIONS: Wrist-mounted devices are a noninvasive and effective measure to track daily activity and ambulatory capacity of patients with spinal deformity. In a single case, progressive deformity correlated with worsening activity levels, whereas deformity correction improved SC and activity level. These results support remote activity monitoring as an exploratory outcome for future studies.