EFFECTS OF WHOLE-BODY ELECTROMYOSTIMULATION ON STRUCTURAL KNEE OSTEOARTHRITIS AS DEFINED BY MRI: THE EMSOAT STUDY

Abstract

INTRODUCTION

Whole-body electromyostimulation (WB-EMS) might be an attractive alternative or supportive option to conventional strength training for patients with knee osteoarthritis (OA). We could show previously that WB-EMS is effective in alleviating pain, objective lower-limb function and maximum strength of hip-/leg extensors compared to a usual care approach. Whether WB-EMS also has concurrent positive effects on joint structure is not known.

OBJECTIVE

To compare structural changes of knee OA as assessed by semi-quantitative MRI assessment between patients with knee OA treated with WB-EMS and those treated with a standard of care approach over a period of 7 months.

METHODS

72 overweight (BMI>25 kg/m²) participants, aged 40-70 years, with symptomatic early to moderate knee OA were randomly assigned to two groups (WB-EMS [Figures 1 and 2]: n=36 vs. control group [CG]: n=36). The WB-EMS group performed 1.5 times per week (once in one week, twice in the subsequent week) a WB-EMS training of 20 min for 7 months (including 1 month of conditioning), while the CG was provided with 6 × 20 min standard physiotherapeutic treatments including hands-on techniques and exercises. MRIs were acquired at baseline and 7 months follow-up using a 3T system. The protocol included triplanar intermediate-weighted fat suppressed and a coronal T1-weighted sequence. MRIs were read in chronological order according to the MRI OsteoArthritis Knee Score (MOAKS) system. Between-group differences in regard to change in cartilage, bone marrow lesions (BMLs) (including within-grade changes for cartilage and BMLs), osteophytes, meniscus damage and extrusion, and markers of inflammation (Hoffa- and effusion synovitis) were analyzed using Fisher's Exact and Wilcoxon Rank Sum tests.

RESULTS

Baseline demographic characteristics are presented in Table 1. Fewer knees in the WB-EMS groups showed cartilage worsening (any subregions with worsening) compared to the CG (18% vs. 40%, p=0.046). There were fewer knees in the WB-EMS group showing an increase in a BML size score of ≥1. However, these findings were not statistically significant (30% vs 46%, p=0.43). Regarding number of subregions with BML improvement, no change, or worsening no differences were seen (p=0.56). Very little osteophyte and meniscal change was seen over the observational period. In the WB-EMS group improvement in Hoffa synovitis was seen in 6% and in 9% in the CG, while for effusion-synovitis these numbers were 15% and 17%. Regarding worsening these numbers were 3% and 0% for Hoffa-synovitis and 12% and 9% for effusion synovitis (p for change of Hoffa-synovitis 0.83, for effusion-synovitis 0.78).

CONCLUSION

While there was a difference with fewer subregions showing worsening cartilage damage on a whole knee level in the WB-EMS groups compared to the CG, no significant changes were observed for BMLs and changes in inflammatory markers. Very little change was seen for osteophytes and meniscal structure and extrusion. The observed improvement in clinical outcome parameters in favor of the WB-EMS group is likely due to other effects than improvement or less worsening of joint structural changes.