Concern) Elderly mother's knee joint replacement surgery

My mother had a cartilage injection six months ago because of knee pain. The cartilage injection is covered by insurance every six months.

It was okay for a while when it was right, but then he said it hurt again, so this time, after six months, he will probably receive another cartilage injection.

The hospital says it's not the stage for knee surgery yet, but I'm worried that if I only get cartilage injections, I might miss the opportunity for knee surgery later.

Knee surgery can be difficult and requires good physical strength, but for very elderly people, surgery is also challenging and the recovery period is long, so I think there are concerns about what to do.