Daily shoulder activity in patients with anterior shoulder instability before and after shoulder stabilizing surgery...

Anterior shoulder instability may impact daily physical activities, particularly those requiring movements above shoulder level, and is typically treated with stabilizing surgery. However, quantification of the shoulder function during activities of daily living, both before and after a shoulder stabilizing surgery, is unknown. The aim was to evaluate daily shoulder activity in patients with anterior shoulder instability before and after stabilizing surgery using inertial measurement units.

Thirty-two patients with unilateral anterior shoulder instability scheduled for shoulder stabilizing surgery were enrolled. Bilateral shoulder activity and patient-reported outcomes were obtained preoperatively and one year postoperatively using inertial measurement unit sensors over one or two days. Inertial measurement unit outcomes, including position, motion frequency, velocity, and acceleration, were compared using mixed model analysis.

No significant differences in daily shoulder activity from pre- to postoperatively were found between the injured and healthy shoulders for any outcome measure. However, one year postoperatively, patients achieving improvements above the minimally clinically important difference in Disabilities of Arm, Shoulder and Hand questionnaire tended to spend 1.7 percentage points more time at velocities above 30 deg./s (95%CI 1.0; 3.6) than those below the minimally clinically important difference.

Daily shoulder activity was generally low, with limited use above shoulder level. No differences were found in daily shoulder activity between the healthy and injured shoulders in patients with anterior shoulder instability from pre- to postoperative. Future studies should incorporate velocity measures and longer monitoring periods or focus on disease-specific activities to detect subtle changes in shoulder activity.