Background: Balneotherapy is one of the most commonly used non-pharmacological approaches for osteoarthritis (OA). Recent data indicate that some biomarkers could be useful to predict OA progression and to assess therapeutic response.

Objectives: To evaluate the effects of mud-bath therapy on serum biomarkers in patients with knee OA. 

Methods: The study group comprised 103 patients with primary symptomatic bilateral knee OA who were randomly assigned to receive a cycle of mud-bath therapy over a period of 2 weeks or to continue their standard therapy alone. Clinical and biochemical parameters were assessed at baseline and after 2 weeks. Clinical assessments included global pain score on a Visual Analogue Scale (VAS) and the Western Ontario and McMaster Universities Index (WOMAC) subscores for knee OA. Cartilage oligomeric matrix protein (COMP), C-terminal cross-linked telopeptide type II collagen (CTX-II), myeloperoxidase (MPO) and high sensitivity C-reactive protein (hsCRP) serum levels were assessed by ELISA.

Results: At the end of mud-bath therapy we observed a statistically significant improvement in VAS and WOMAC subscores. Serum levels of COMP, MPO and hsCRP did not show any significant modification in both groups, while a significant increase (P < 0.001) in CTX-II serum levels was observed in the mud-bath group after the treatment.

Conclusions: A cycle of mud-bath therapy added to usual treatment had a beneficial effect on pain and function in patients with knee OA. The evaluation of serum biomarkers showed only a significant increase of CTX-II, perhaps due to an increase of cartilage turnover induced by thermal stress.