Struggling to remain in work

Hi all. I am a 60 year old man with osteoarthritis of my lumbar spine. It can be really bad some days I can hardly walk and can't bend over. I am still working 4 days a week. I requested a reduction in my hours from full time. I work in the NHS and they have been really supportive and flexible. I am wondering about medical retirement and wondering if any of you have gone through this? I also wonder about any suggestions for other options ie retirement with government assistance? I am likely quite nieve regarding all this. Just wondering if I can keep going as I love my job but I am not confident that I can continue to work. I welcome your feedback 😊. John