If you're on facebook try posting the question on https://www.facebook.com/groups/51708658721/ or https://www.facebook.com/groups/1462124944043779/ Both are closed active groups (you will be admitted when you send a request) with a lot of Americans posting, the 2nd one especially has a lot of Ledderhose people. I would say consider radiotherapy, as it has helped a lot of people with Ledderhose to walk without pain again.
Intreguing username you have, dierenarts. Same job I have.

I was born in Utrecht, now am dierenarts in Haydock, England. Got Dupuytren's, not Ledderhose. I run the British Dupuytren's Society, Gary is our Ledderhose expert. Anything you want to ask feel free. I've added you to our Facebook group and asnwered your question there, I expect there will be more answers soon from others. It's an active and helpful group.