Chronic pain help

Hello, I've joined because I'm looking for help for my mother, who suffers from bad knee pain. She has had bouts of psuedo gout and also suffers from OA. I am investigating ways to manage pain for her. She has been offered psysiotherapy and pain relief medication, but with limited effectiveness. I am interested to know if injections might be suitable (for someone elderly with a number of comorbidities). Thank you.