Stifle issues

My draft cross mare has been having issues with her stifle. The Vet will be out to assess her sometime this week.
She lies down, then cannot get up. This is not an everyday issue. Its an every so often one. She is a heavy horse and tires herself out easily ,plus being heavy then I think her legs get numb as she lies flat out, and always has.
She is 22 now, just a big pet. It is getting harder and harder to flip her so she can get up .

What does any one do for their horses with stifle issues ?