Gyroscopic Powerballs & wrist OA

I note that manufacturers / retailers of Powerballs are making all sorts of claims about the benefits of training with these gyroscopic resistance instruments.

Amongst these are the rehab benefits in cases of tendonitis / carpal tunnel and RSI. Moreover, general fitness retailers are making claims that these devices are useful for reducing joint pain for arthritis sufferers, although no distinction seems to be made between RA & OA.

I'd appreciate any advice the forum can offer as to the validity / plausibility of these claims. Could they cause as much damage as they intend to fix? Cheers.