The problem of older people in prisons has been around for some years now. It arises because a) People are committing crimes at far older ages - a man of 85 was jailed for life last week for a double murder and b) longer sentences and longer lives mean many more much older prisoners. I would suspect also, that living in a prison is not the healthiest of environments so older people there develop medical problems and disabilities at younger ages than they would outside.
There were plans some years ago to build a penal care home so that older prisoners with disabilities could be incarcerated in a building built to meet their needs, but for whatever reason the idea was dropped.