Colleen, it's still less than a month since you had this major surgery. It's normal to still feel tightness and stiffness.
Even though you're younger than most of us, your knee did have the same surgery and it won't heal any faster than our older knees.
Did you realise that tightness and stiffness are other forms of pain? It could be that you are not taking sufficient pain medication.
So beyond frustrated. Just left my 2nd outpatient therapy appt and my leg is just not wanting to bend. After 6 minutes on the bike they thought it would be loosen up. Wrong. So we spent 20 minutes bending it while hanging off the table. The ROM only got to 66. Really over it, when home PT was coming it was at 80. I know it will take time but I feel like a failure.
I saw this post, from a few days ago.
Sweetheart, it's still such early days! You have plenty of time to achieve ROM (Range of Motion). There's no need to rush, and no excuse for your therapist letting you think you aren't doing well. Your knee probably bent less at your PT session, simply because you had been more active.
At the moment, it is swelling that prevents your knee from bending, so concentrate on reducing the swelling, with lots of rest, ice and elevation, and less exercise. Your knee will gradually start to bend more, as the swelling goes down.
It isn't exercise that increases ROM. It's time, rest and healing.
TKR: work “smarter” and not “harder”
There's no need to rush to get ROM, no "window of opportunity". ROM can continue to improve for a year, or even longer, after a knee replacement.
Myth busting: the "window of opportunity" in TKR
ROM: it's never too late to get more ROM!