Someone sent in a question:
My wife and I are over 65 years old. She has severe arthritis in all her joints, so she can't put her legs in position for biah.
I can satisfy her physically in other ways but then I get really excited! But I can't do biah then to get relief. What can I do?
I sent the question to Rav Dovid Morgenstern, a big Posek in Yerushalayim and a talmid muvhak of Rav Eliyashiv. I wrote as follows:
Would the Rav be able to address this question please? Perhaps there's some heter of derech eivarim in such a case?
Rav Dovid Morgenstern responded:
Obviously, the best approach would be to try to find a cure for the underlying condition. A doctor suggested perhaps physiotherapy, medication or anti-inflammatory medication used before being together.
If none of the above are viable, perhaps changing positioning could be useful, perhaps if he is behind her.
Derech eivarim would not be an option because of wasted zerah.