Remedies for restricted movement in calf

Greetings. My 89 yr old mother fell down stairs about 30 years ago, twisting her calf, which still causes pain on moving and has gradually slowed her walking and she's not going out much at the moment anyway. Her GP prescribed codeine but she didn't like the drowsiness. Ibuprofen gel helps a bit. Can you think of anything useful she could try to reduce the pain? Thank you for help