Ah heck Ed, finally had to bite the bullit and do it. Hope you have a speedy recovery.
When my friends mom got both of her knees replaced (at once), one of her doctors told her to try sitting on a pick up tail gate and swing them, she said that really helped with out stressing her out. One of my neighbor's across the street had both, i told him about it. He liked it. My mom did also, but one at a time.
You might ask your Dr or Pt person about that.