Dale,
I am 4.5 weeks post op myself with BTKR on 6/18. At 4 weeks I think 90 is good! My PT said I was way ahead in my ROM when my incisions split in both knees. I took a week off (at week 3) of PT and worked on balance, my heel and toe strike while walking, and allowing my incisions to heal with additional steri-strips.
I saw the OS and he was thrilled with my x-rays, ROM and told me to allow an additional week to heal the incisions in each knee. Thus I have no PT this week. I have been walking without crutches or cane for 2 weeks. I even walk outside on the uneven grass in the yard. I am now adding Polysporin to my incisions where they are healed and am massaging them to make them level and even. My ROM on Friday last week was 110 with each leg when I saw the PT. So, with the rest of not pushing my quads with the total gym and the stationary bike, I am still doing well with working with my quads with other exercises that do not effect the ROM and manipulating my knee caps. There is always something that can be done within the parameters of the PT.
I would work on your exercises sliding your foot away from the wall while sitting in a chair with your knees close to the wall. This will increase your ROM too. I do use the brazilian Football that is recommended in the "Bible" Total Knee Replacement and Rehabilitation book.
Good Luck to you!
Best,
Crystal