## 4 Discussion
However, the success of their home-based program was based on clinician supervision. In practice, major obstacles for patients in following home-based physiotherapy are the absence of feedback by a physical therapist and the failure to remember or perform correct exercises [27; 28]. The use of innovative methodologies, including wearable motion tracking devices has increased for assisting rehabilitation and monitoring activity at home in patients after joint replacement [29]. However, few clinical studies have supported the efficacy of these methods [30]. [PERSON] et al. and [PERSON] et al. have demonstrated the feasibility of motion tracking sensors to monitor the recovery progress of ROM and kinematic profiles among patients following TKA [31; 32]. However, unlike these studies using the MSD for functional assessment, our study integrated the MSD with a mobile phone-based system, which can provide an informative patient interface with comprehensible exercise instructions and support healthcare self-management by monitoring rehabilitation exercise performance. Furthermore, to strengthen the connection between physicians and patients, wireless telecommunication was used to synchronize data with the Doctor App to send information on each patient's progress, which enabled physicians to supervise rehabilitation remotely and provide instant feedback to patients. The MAR method increased patient adherence to the in-home exercise program, which was then reflected in the higher exercise completion rate and larger functional recovery after two months of training compared with patients in the HE group. The ability to monitor knee angular motion and kinematic profile is another potential advantage of applying the MSD for in-home rehabilitation following TKA. The functional recovery of patients after TKA is conventionally measured using self-reported or physician-reported questionnaires. However, performance-based tests that can objectively assess the patient's actual ability to perform a task are seldom adopted in clinical practice following TKA. The kinematic and kinetic analyses of the sit-to-stand movement, which has been suggested to be an adequate performance-based measure in patients who received TKA [23; 33], may have limited use because of the inaccessibility of the measuring equipment. However, the MSD used in this study can monitor the knee angular motion during in-home rehabilitation and indirectly trace the muscular, functional recovery based on the performance of angular velocity changes in 5 TSST among patients after TKA. Wearable IMUs can be used to monitor the kinematic change of performance-based 5 TSST remotely. In our study, patients in the MAR group displayed higher adherence to the in-home exercise program owing to the mobile phone-based informative interface and interaction with the physicians. Therefore, recovery of maximal and average angular velocity in 5 TSST was better in the MAR group than in the HE group, even though the patient-reported WOMAC did not differ significantly between groups after two months of training. The IMU-based functional assessment helped physicians comprehensively and objectively follow the improvement in patients after TKA in addition to providing information on patient self-reported function. The application of a wearable motion sensor device to improve patient compliance with in-home rehabilitation is promising, but some obstacles may need to be overcome. In addition to the stability of the sensor's application, a user-friendly app interface plays a vital role. The success of traditional clinical rehabilitation relies on robust patient-provider interaction [34]. Therefore, the new method of telerehabilitation using the MSD in post-TKA rehabilitation programs should focus more on the connection between physicians and patients.