Knee Osteoarthritis and Spa Therapy

The aim of this clinical trial is to assess the efficacy of the 18-day balneotherapy program (therapeutic indication: Rheumatology) in terms of functional incapacity and the disorders (pain, joint stiffness) induced by osteoarthritis of the knee, and thus improves patients\&#39; quality of life, in patients presented with knee osteoarthritis.

The French National Academy of Medicine encourages the re-use of RCT data when available. In this context, the current study is designed as a single-arm prospective study with external comparison using the propensity score. The Control group consists of the patients which were allocated to the Control group of reference randomized clinical trial (RCT) "ANGELLO Study" (NCT05819437). These patients received standard care for knee osteoarthritis, i.e., pain management and exercise recommendations.

All patients enrolled in the current study benefit of 18-day balneotherapy program (therapeutic indication: Rheumatology) with Mineral Water of Santenay (Burgundy, France), and examination with a practitioner at enrollment and 6 months after the beginning of spa treatment.

For study purposes, two medical visits with the investigator are organized: the first in the 28 days preceding the 18-day balneotherapy program, or at the latest on the first day of the program, before the first care, and the second 6 months after the start of the program. A remote visit at 3 months is also organized.

The data required for study evaluations are collected by the investigator or self-evaluated by patients during the visits.

Patients of the study receive the same exercise recommendations than the patients of the Control group of the reference study, and their body weight as well as physical ability are monitored.

Eligibility Criteria:
Inclusion Criteria:

* Knee osteoarthritis with Kellgren and Lawrence stage 2 to 4 evidenced by a knee X-ray examination in the past 3 years.
* 100-normalized score of the WOMAC physical function subscale greater than or equal to 30.
* Accepting a prescription for a balneotherapy program in the Rheumatology at Santenay spa as part of the management of their knee osteoarthritis issued by the investigator.
* Signed inform consent.
* With health insurance affiliation.

Exclusion Criteria:

* Presented with balneotherapy contraindication or to certain adjuvant treatment techniques (balneation, hydrotherapy jets, massage): chronic infectious pathology, active cancer, decompensated cardiac, hepatic or renal insufficiency, "open" leg ulcer, immune deficiency, phlebitis, erysipelas or history of erysipelas, active thrombosis, behavioral disorders, etc.
* Presented with chronic pain for reasons other than osteoarthritis: chronic inflammatory rheumatism (rheumatoid arthritis, ankylosing spondylitis, lupus, psoriatic arthritis) or fibromyalgia.
* Having had spa treatment in the past 6 months whatever the indication or intra-articular corticosteroid injection within the previous 90 days or hyaluronic acid infiltration within the previous 6 months.
* Having planned a spa treatment in another indication between inclusion and final visit.
* Patient scheduled for knee osteoarthrosis-related surgery within the next 7 months.
* Residing more than 30 kilometers from Santenay at the time of spa treatment. Women of childbearing potential who are not using effective contraception (estrogen/progestin or progestin-only oral, vaginal, transdermal, injectable or subcutaneous) or who plan to discontinue contraception within the next 7 months.
* Likely to be unable to comply with protocol or to attend visits, particularly in view of the duration of the research, or unable to read or understand French.
* Regulatory reason (guardianship or already enrolled in a clinical trial).
* Already included in a clinical trial or in the exclusion period of a clinical trial.