The main objective of this study is to evaluate the therapeutic effect of a thermal treatment on gonarthrosis, with an increase of the number of patients presenting a clinically significant improvement.

Gonarthrosis is a frequent pathology and the prevalence increase with age (prevalence: 6,1% in an adult population more than 30 years old and 40% after 75 years). It has a large impact on the quotidian life of the patients and it cause important costs for social protection. Relative to the treatment, numerous recommendations have been proposed (EULAR, ACR specifically). But no one of them recommends thermal treatment even if it is largely used in Europe and especially in France for the treatment of this pathology. Several prospective controlled randomized studies have evaluated the effect of the thermal treatments in rheumatology and some of them are relative, in part, to Gonarthrosis. So, we conduct a phase III randomized, controlled, single blind study evaluating the therapeutic effect at 6 month of a thermal cure on gonarthrosis.

In a situation of physical treatment, it's impossible to use a placebo as control: blind can't be respected. Whatever the methodology employed, non blind of the patient create a bias. So, we hope that the Zelen method for randomization will reduce the bias due to the dissatisfaction of the patients in the control group.

Inclusion Criteria:

• ACR criteria: knee pain and one of the tree following conditions: Age > 50 years, Morning stiffness< 30 minutes and articular crackling.
• osteophytes visible on knee radiography.
• knee radiography less than 3 years old: face, schuss, axial of kneecap cliché.
• Actual gonarthrosis intensity on Visual Analogic Scale > or = 30mm.

Exclusion Criteria:

• arthrosis limited to the femoro-patellar compartments.

• severe depressive syndrome, psychosis.

• Thermal cure less than 6 month before.

• Contra-indication or predictable inability to tolerate thermal cure.

• Profession lied to hydrotherapy.

• previous knee treatments:

  • massage, physiotherapy and acupuncture since less than 1 month;
  • infiltration since less than 3 months;
  • NSAI since less than 5 days;
  • analgesic since less than 12 hours;
  • modification in the medicinal anti-arthrosis treatment since less than 3 months.