gms | German Medical Science

Objectives: Enhancing muscle strength by physical activity contributes to knee joint stabilization and is recommended as treatment for knee osteoarthritis KOA (Fransen, McConnell et al. 2015). As a new form of exercise, whole-body vibration (WBV) training is currently integrated into clinical exercise regimens based on its reported ability to increase bone density and muscle strength. Despite the widespread use of WBV, the underlying mechanisms are not well understood leading to a lack of standardized WBV parameters for clinical applications (Prisby, Lafage-Proust et al. 2008). Our aim is it to investigate the potential benefit and provide insights in mechanisms of WBV exercise in an animal model of surgically induced OA.

Methods: OA was surgically induced in 11-12 weeks old male C57Bl/6 mice by transection of the medial collateral ligament and medial meniscus (MCL-MM). One week after OA induction WBV training (15min/day for 7 weeks, 15 Hz, 0.3g) was initiated. OA induced non-vibrated mice served as control group. Degenerative changes in the knee joint were quantified using a standardized OARSI Scoring System. The effect on hindlimb muscle fiber specific cross sectional area (CSA) was analyzed by immunofluorescence staining of serial histological sections.

Results and Conclusion: Daily WBV training in the indicated setting did not lead to adverse behavior of mice or any adverse effects on OA induced knee joints. Eight weeks after OA induction severe osteoarthritic changes within the affected joints became evident. Histological scoring of cartilage degeneration and osteophyte formation revealed no significant differences between WBV and sham treated groups (Figure 1A [Fig. 1]). Preliminary results on the effect on soleus muscle of the OA affected hindlimbs indicated a shift towards increased CSA of type I (slow) muscle fibers (Figure 1B [Fig. 1]).

Preliminary results indicate a training effect in the OA affected hindlimb that could reverse the fiber type switch in muscle weakness. Evaluation of further WBV settings (frequency, duration, g-forces) are required to identify potential effects of this training modality on osteoarthritic cartilage degeneration in the knee joint.