Monitoring daily shoulder activity before and after reverse total shoulder arthroplasty using inertial measurement units

Van de Kleut, Madeleine L.; Bloomfield, Riley A.; Teeter, Matthew G.; Athwal, George S.

Abstract Background The purpose of this study was to use at-home, portable, continuous monitoring technologies to record arm motion and activity preoperatively and postoperatively after reverse total shoulder arthroplasty (RTSA). Methods Thirty-three patients indicated for RTSA were monitored preoperatively, three, and 12 months postoperatively. Inertial measurement units were placed on the sternum and upper arm of the operative limb, recording humeral motion relative to the torso for the duration of a waking day. Elevation events (EE)/hour, EE/hour greater than 90°, time spent above 90°, and activity intensity were calculated and compared between time points. Patient-reported outcome measures were also collected at all time points. Results At three (P=0.040) and 12 (P=0.010) months after RTSA, patients demonstrated a significantly greater number of EE/hour greater than 90° compared to preoperatively. There were no significant differences (P≥0.242) in the amount of time spent at different elevation angles at any time point, or in arm activity intensity. Overall, 95% of the day was spent at elevation angles less than 60° and 90% of the day in a low or moderate intensity state. Pearson correlations demonstrated relationships between forward elevation and the number of EE/hour (r=0.395, P=0.001) and the number of EE/hour greater than 90° (r=0.493, P<0.001). Conclusion After RTSA, patients significantly increase the frequency of arm elevation to higher angles. However, no differences were found in the amount of time spent at different elevation angles. Overall, after RTSA, greater than 95% of the day was spent at elevation angles less than 60° and less than 1% of the day was spent above 90° of elevation. Level of Evidence Level IV; Case Series; Treatment Study;