To conduct a systematic literature review on crenobalneotherapy for limb osteoarthritis and to discuss the study methods used to evaluate this treatment modality.
We searched Medline using the following keywords: "spa therapy", "mud", "radon", "balneotherapy", and "hydrotherapy" in combination with "osteoarthritis", "arthrosis", and "gonarthrosis". We also reviewed the reference lists of articles retrieved by the Medline search. Studies that compared crenobalneotherapy to any other intervention or to no intervention were selected, and a checklist was used to assess their internal validity. External validity and the quality of the statistical analysis were evaluated also.
Crenobalneotherapy was associated with improvements in the evaluation criteria (pain, function, and quality of life) compared to baseline. However, inadequate internal validity precluded the establishment of a causal link between these improvements and crenobalneotherapy. External validity was often poorly defined. Some studies found no significant differences with the control group but failed to include a sample-size calculation, suggesting inadequate statistical power as a possible explanation for the result. In several studies, the use of multiple evaluation criteria and measurements led to a high risk of Type I error.
Although the consistency of the results suggests a therapeutic effect of crenobalneotherapy in limb osteoarthritis, available studies are methodologically inadequate and sample sizes too small to allow definitive conclusions. We suggest a number of solutions to these shortcomings. Carefully designed studies in larger patient populations are needed to determine the role crenobalneotherapy in knee osteoarthritis.