Efficacy of Artificial Intelligence-Assisted Therapeutic Exercise in Patients With Knee Osteoarthritis

Pain intensity will be assessed using the Numeric Pain Rating Scale (NPRS), a single 11-point numerical rating scale widely validated across different patient populations, where 0 represents no pain and 10 represents the worst possible pain. Data obtained through the NPRS are easy to document, intuitively interpretable and meet regulatory requirements for pain assessment and documentation.

Pain, stiffness and self-reported physical function will be assessed using the Western Ontario and McMaster Universities Osteoarthritis Index short form (WOMAC-SF), a patient-reported outcome measure designed to quantify symptom severity and functional limitations typically associated with hip and knee osteoarthritis. Items will be summed to obtain a total score ranging from 0 to 44 points, where higher results indicate worse symptoms and greater functional limitation.

Health-related quality of life will be assessed using the EuroQol EQ-5D-5L, a standardized, generic measure of self-reported health status widely used in clinical and health-economic research. The EQ-5D-5L comprises two components: (1) a descriptive system and (2) a visual analogue scale (EQ VAS). The descriptive system covers five dimensions: mobility, self-care, usual activities, pain/discomfort, and anxiety/depression, each rated across five severity levels (from no problems to extreme problems). Responses are combined into a 5-digit health state (e.g., 11,121), which is then converted into a single utility index using a country-specific value set; in this study, the Spanish value set will be applied for index derivation. The EQ VAS records the participant's overall health "today" on a 0-100 scale, where 0 represents the worst imaginable health and 100 the best imaginable health. The EQ-5D-5L has demonstrated validity and provides reference norms for the Spanish population.

Lower-limb functional performance will be assessed using the 30-Second Chair Stand Test (30CST), a pragmatic, clinic-friendly measure of functional strength and endurance of the lower extremities. In this test, participants will be instructed to rise to a full stand and sit down as many times as possible within 30 seconds, starting from a standard chair (without armrests), with arms crossed over the chest (or following a standardized alternative if needed for safety). The primary outcome is the number of fully completed sit-to-stand repetitions in 30 seconds, where higher values indicate better functional performance.

Lower-limb stair-climbing function will be assessed using a Timed Stair Test consisting of 11 steps, a pragmatic measure of lower-extremity functional capacity during stair ascent and descent. Participants will be instructed to ascend and then descend a flight of 11 stairs as quickly and safely as possible, starting from a standardized position. The primary outcome will be time to completion (seconds), recorded from the initiation of movement to the moment the participant returns to the starting level after completing both ascent and descent; shorter times indicate better lower-limb function.

Participants' perceived overall change will be assessed using the Patient Global Rating of Change (GROC), a single-item anchor measure designed to capture the participant's global perception of improvement or deterioration since baseline. Participants will be asked to rate how their condition has changed compared with the start of the study on a 15-point scale ranging from -7 to +7, where -7 indicates "a very great deal worse," 0 indicates "no change," and +7 indicates "a very great deal better." The primary outcome will be the GROC score at each follow-up, with positive values reflecting improvement and negative values reflecting worsening.