Rotator cuff tears impair shoulder function and induce pain, thereby decreasing the ability to perform activities of daily living (ADL) and, therefore, quality of life [1]. Arthroscopic rotator cuff repair (ARCR) is an effective treatment for rotator cuff tears, with favorable postoperative outcomes [2,3]. Following ARCR, to prevent retears, it is recommended to gradually increase exercise intensity from 3 months postoperatively and remove upper-limb use restrictions at approximately 6 months postoperatively [4,5]. Additionally, a significantly improved range of motion (ROM) and muscle strength are achieved within 6 months postoperatively, restoring ADL [6,7]. However, subjective activity levels may decrease postoperatively despite improved functional outcomes [8]. Therefore, understanding the changes in the daily activity of upper limbs following ARCR is important.

The triaxial accelerometer enables the quantification of the daily activity of the upper limbs. Previous studies have reported changes in paretic arm use post-stroke [9] and upper-limb activity following total shoulder arthroplasty [10,11]. However, studies quantifying the daily activities of the upper limbs after ARCR using this device have been limited to cross-sectional studies [12]. Duc et al. investigated the daily activity of the upper limbs preoperatively to 1 year postoperatively [13]; however, their use of wired monitoring devices potentially restricted natural movement patterns. Thus, objective changes in the daily activities of the upper limbs after ARCR remain unclear. The triaxial accelerometer can be used to quantify upper-limb use in daily life. Current clinical assessments rely heavily on functional measures such as ROM and muscle strength, which may not adequately reflect how patients use their upper limbs daily. Objective measures of daily activities of the upper limbs could bridge the gap between clinical measurements and actual function, leading to more effective and personalized rehabilitation strategies.

Predicting postoperative recovery based on preoperative parameters is essential for better operative outcomes. Preoperative ROM, muscle strength, and pain affect postoperative outcomes following ARCR [[14], [15], [16]]. However, the influence of these preoperative parameters on the daily activities of the upper limbs following ARCR remains unknown. Determining their influence will facilitate preoperative rehabilitation for early recovery of postoperative ADL.

The primary aim of this study was to objectively evaluate the recovery process of the daily activities of the upper limbs from the preoperative period to 12 months postoperatively using a triaxial accelerometer. The secondary aim was to investigate the correlation between preoperative parameters and the daily activities of the upper limbs at 6 and 12 months postoperatively. Understanding these changes will help patients with upper-limb use in rehabilitation and allow for predicting daily upper-limb activities based on preoperative factors, resulting in more personalized and evidence-informed rehabilitation approaches.