Dynamic Thumb Circumduction Measured With a Wearable Motion Sensor: A Prospective Comparison of Patients With Basal Joint Arthritis to Controls.

Purpose: The purpose of this study was to compare the active range of motion in patients with thumb carpometacarpal (CMC) arthritis to healthy controls. A secondary objective of this study was to examine the feasibility of using wearable motion sensors in a clinical setting. Methods: Asymptomatic controls and patients with radiographic and clinical evidence of thumb CMC joint arthritis were recruited. The experimental setup allowed participants to rest their forearm in neutral pronosupination with immobilization of the second through fifth CMC joints. An electromagnetic motion sensor was embedded into a thumb interphalangeal joint immobilizer, and participants were asked to complete continuous thumb circumduction movements. Data were continuously recorded, and circumduction curves were created based on degrees of motion. Peak thumb abduction and extension angles were also extracted from the data. Results: A total of 29 extremities with thumb CMC arthritis and 18 asymptomatic extremities were analyzed. Bilateral disease was present in 64% of patients. Patient age range was 35-83 years, and the control group age range was 26-83 years. The most affected extremities had Eaton stage 3 disease (38%, N = 11). The average maximum thumb abduction was 53.9° ± 19.6° in affected extremities and 70.8° ± 10.1° for controls. Average maximum thumb extension was 50.0° ± 15.2° in affected extremities and 58.4° ± 9.1° for controls. When comparing patients with Eaton stage 3 and 4 disease to controls, average maximum abduction and extension decreased with increasing disease stage (42.3°, 46.1°, and 70.8° for abduction, respectively, and 58.4°, 43.3°, and 41.3° for extension, respectively). Conclusions: We observed more severe motion limitations with increasing Eaton stage, and statistically significant differences were seen with stage 3 and 4 disease. A wearable motion sensor using a portable experimental setup was used to obtain measurements in a clinical setting. Type of study/level of evidence: Diagnostic II.