Digital Course and Precision Rehabilitation for Knee Osteoarthritis and Older Adults: Integration of Multisensory Stimulation and Digital Twin Technology

Knee osteoarthritis (OA) is a common degenerative joint disease in middle-aged and older adults and is frequently associated with pain, quadriceps weakness, reduced mobility, impaired proprioception, balance deficits, and limitations in daily functional activities. Exercise therapy is recommended as a first-line conservative treatment for early to moderate knee OA; however, conventional rehabilitation programs often rely on therapist supervision and lack objective, quantitative movement monitoring, real-time feedback, and personalized adjustment for home-based training. These limitations may reduce exercise adherence and make it difficult to ensure correct movement execution outside the clinical setting.

The overall aim of this study is to develop and evaluate a digital rehabilitation exercise program and user interface for individuals with arthritis, using a smart elastic knee brace integrated with wearable sensing technology, surface electromyography biofeedback, joint-angle monitoring, multisensory stimulation, and artificial intelligence-based musculoskeletal monitoring. The proposed system is designed to provide personalized digital rehabilitation courses, real-time visual and auditory feedback, and objective assessment of movement performance to support knee joint motor control, gait retraining, and individualized rehabilitation planning for patients with knee OA.

The investigators hypothesize that digital rehabilitation courses combined with multisensory stimulation, including neuromuscular electrical stimulation and vibration, will improve functional performance, movement quality, muscle activation, proprioception, and knee-related symptoms in patients with knee OA compared with conventional home exercise or gait retraining alone. The expected outcome of this study is to establish the feasibility, reliability, and clinical utility of a smart knee brace-based digital rehabilitation system for personalized knee OA management.

This study will achieve the following four specific aims:

Aim 1: To determine the feasibility of home-based exercise combined with electrical stimulation and the reliability of digital assessment for tracking exercise performance.

Patients with knee OA and healthy adults will be recruited to complete selected quadriceps strengthening exercises based on exercise difficulty levels. Participants will perform a two-week home-based training program using exercise combined with electrical stimulation. Feasibility will be assessed using questionnaires, and movement performance will be tracked using inertial sensors during functional tasks. This aim will provide evidence regarding the practicality of integrating electrical stimulation into home-based rehabilitation and the reliability of digital monitoring for exercise performance.

Aim 2: To evaluate the effects of digital rehabilitation exercise courses combined with multisensory stimulation in patients with knee OA and healthy adults.

Participants will be randomly assigned to an experimental group or a control group. Both groups will complete a twelve-week home exercise program, three times per week for 40 minutes per session. The experimental group will follow the digital rehabilitation exercise course combined with electrical stimulation or vibration, whereas the control group will perform home exercises based on therapist education. Outcomes will be assessed at four time points: before training, after eight weeks of training, after twelve weeks of training, and six weeks after the intervention. Assessments will include pain, WOMAC scores, hemodynamic responses, muscle strength, electromyographic activity, proprioception, functional performance, body composition, knee structure, and biomechanical parameters.

Aim 3: To determine the immediate effects of gait retraining combined with neuromuscular electrical stimulation in patients with knee OA.

Patients with knee OA will be randomly assigned to either a gait retraining group or a gait retraining combined with neuromuscular electrical stimulation group. Both groups will receive a single 15-minute gait retraining intervention focused on modifying the foot progression angle. The experimental group will receive synchronized quadriceps electrical stimulation during gait training, while the control group will receive gait retraining alone. Pre- and post-intervention assessments will be performed to examine the immediate effects on gait parameters and functional movement performance.

Aim 4: To develop and validate a personalized knee joint digital twin model using artificial intelligence, multisensory stimulation, and wearable sensing technology.

This aim will develop an AI-based musculoskeletal monitoring system that integrates wearable sensor data, functional movement analysis, and personalized knee joint modeling. Patients with knee OA and healthy adults will perform functional tasks such as squatting, stair stepping, and walking under different stimulation conditions, including conti