It isn't scar tissue at all. Troublesome scar tissue is really quite rare and it doesn't form this early in your recovery. Simply, what is happening is that all this exercise is increasing swelling in your knee. The swelling prevents your knee from bending or straightening properly.Went to third PT session today and man am I getting a lot of scar tissue. Getting stiffer and stiffer for full extension. They are putting my heal on a ball and then putting weights on the top of my knee.
There is no need at all to worry about extension yet and doing what your PT is doing is just making matters worse. Tell them to stop. Weights are not good and they can do harm this early in recovery.
It isn't exercise that increases you ROM (Range of Motion). It's time and reduction of swelling. The ROM is already there in your knee, just waiting to reveal itself, once your knee is healed enough and the swelling has gone down.
New Zealand