Prospective Cohort Study Evaluating a Thermal Spa Programme in Symptomatic Knee Osteoarthritis

Knee osteoarthritis is a common cause of pain, functional limitation, and reduced quality of life in older adults. Thermal spa treatment is widely used as a non-pharmacological intervention for the management of osteoarthritis symptoms, but its effects on joint movement and motor control remain insufficiently characterized using objective biomechanical measures. This study evaluates the effects of a 3-week thermal spa treatment on knee joint movement in patients with knee osteoarthritis. Knee movement fluidity and gait parameters will be analyzed during standardized tasks using wearable inertial sensors (Xsens). Secondary outcomes include changes in pain, physical function, physical activity, quality of life, and blood transcriptomic profiles. Assessments will be performed at baseline, after treatment, and at 3- and 12-month follow-up visits. In addition, blood samples will be collected before and after the intervention to explore transcriptomic changes associated with the treatment. This project proposes a combination of innovative kinematic and biological biomarkers with the aim of objectively describing the benefits of spa therapy for people with knee osteoarthritis.

Inclusion Criteria: * Adults aged 50 years or older * Diagnosis of knee osteoarthritis affecting at least one knee, with radiographic Kellgren-Lawrence grade ≥ 2 confirmed by an X-ray performed within the past 3 years * Average knee pain intensity \> 30 mm on a 100-mm Visual Analog Scale (VAS) during the month prior to inclusion * Participants scheduled to undergo a 3-week thermal spa treatment at the Balaruc-les-Bains thermal center Exclusion Criteria: * Use of systemic or injectable corticosteroids within 1 month prior to inclusion * Intra-articular injection of hyaluronic acid or platelet-rich plasma (PRP) within the 3 months prior to inclusion * Active inflammatory joint disease (e.g., rheumatoid arthritis, spondyloarthritis, or crystal-induced arthropathies) * Current major depressive episode or psychotic disorders * Thermal spa treatment within the previous 6 months * Inability to read or write * Inability to complete follow-up for the entire study period (e.g., planned relocation, travel, professional commitments, or residence located more than 100 km from the study site) * Lack of informed consent * Pregnant or breastfeeding women * Individuals under legal protection (guardianship or curatorship) * Not affiliated with a national health insurance system * Individuals under judicial protection (safeguard of justice) * Participation in another clinical study with an ongoing exclusion period