Recently some friends, one of whom is over 80 & has health issues, applied for travel Insurance.
They were horrified to be quoted £2,000 by Saga for a single trip (for 2) to the US.
Being experienced travellers they started investigating & ended up with an Annual Policy for £700 with up to 42 days duration for each trip. Still a considerable sum...but as it works out only £350 per person for a year it's not actually too bad...especially if you are going on a long trip.
The contact details I was given are are www-allcleartravel.uk
The company is located in the US & calls itself All clear medical travel insurance with a big tick.
Another company that has special departments for all sorts of joint problems inc Lupus,Fibromyalgia, RA & OA is stay sure.co.uk Tel 0808 168 6844.
I'm not recommending either of these companies, but if you are struggling to get Travel Insurance they might be worth contacting.
Over to you travellers...please note I've written everything I know about the above so please don't ask me any question as I have no more information. Neither may be able to help you, but if you don't ask you will never know.