This study presents the KOA-Monitor system, a digital intervention and functional assessment tool designed for patients with knee osteoarthritis (KOA). The system integrates computer vision technology and wearable devices to capture real-time patient movement data and provide personalized rehabilitation plans with visual feedback. Through a user-friendly interface and real-time feedback, the system significantly improves patient performance and adherence. Experimental results indicate that patients using this system experience substantial improvements in pain relief, functional enhancement, and adherence. The experimental group showed a reduction in WOMAC pain scores from 8.0 to 4.0, a decrease in functional limitation scores from 22.0 to 15.0, and significant improvements in the 30-Second Chair Stand Test and the 6-Minute Walk Test.