Endogenous anandamide and self-reported pain are significantly reduced after a 2-week multimodal treatment with and without radon therapy in patients with knee osteoarthritis: a pilot study

M Gaisberger,M Winklmayr,H Dobias,G Grasmann,J Fuchs,M Ritter,M Riedl,B Hölzl,F Landauer,F Eckstein,R Reischl,S Edtinger,M Offenbächer

doi:10.1007/s00484-021-02095-z

Abstract

Multimodal therapies comprising spa applications are widely used as non-pharmaceutical treatment options for musculoskeletal diseases. The purpose of this randomized, controlled, open pilot study was to elucidate the involvement of the endocannabinoid system in a multimodal therapy approach. Twenty-five elderly patients with knee osteoarthritis (OA) received a 2-week spa therapy with or without combination of low-dose radon therapy in the Bad Gastein radon gallery. A 10-point numerical rating scale (pain in motion and at rest), WOMAC questionnaire, and the EuroQol-5D (EQ-5D) questionnaire were recorded at baseline, and during treatment period at weeks one and two, and at 3-month and 6-month follow-ups. Plasma levels of the endocannabinoid anandamide (AEA) were determined at baseline and at 2 weeks, and serum levels of several cartilage metabolism markers at all five time-points. A significant and sustained reduction of self-reported knee pain was observed in the study population, but no further significant effect of the additional radon therapy up and above base therapy. This pain reduction was accompanied by a significant reduction of AEA plasma levels during treatment in both groups. No significant differences were seen in serum marker concentrations between the groups treated with or without radon, but a small reduction of serum cartilage degradation markers was observed during treatment in both groups. This is the first study investigating AEA levels in the context of a non-pharmacological OA treatment. Since the endocannabinoid system represents a potential target for the development of new therapeutics, further studies will have to elucidate its involvement in OA pain.

Highlights

Osteoarthritis (OA) is a major public health problem among the increasing aged and obese population
Since questionnaires could be obtained from the latter ones by mail, they remained in the analysis
The reduction of WOMAC OA scores is reflected by a mitigation of self-assessed pain in a numeric rating scale ranging from 0 to 10

Summary

Introduction

Osteoarthritis (OA) is a major public health problem among the increasing aged and obese population. OA pain, the main symptom of OA besides stiffness and joint swelling, severely reduces physical function and health-related quality of life. Besides the individual impairment by chronic pain and reduced joint functionality, OA imposes a high socioeconomic burden to public healthcare services, which will further rise due to increasing life expectancy. There are no disease-modifying drugs (DMOADs) for the treatment of OA available at the moment. Treatment is restricted to symptoms management like pain reduction, improvement of joint mobility and functionality, and delay of disease progression. Often severe and progressive OA leads to joint replacement surgery. Between 20 and 30% of patients with hip or knee replacement experience little or no improvement of OA symptoms (Hawker 2019)

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