I am 12 wks post operation with plate and 8 screws inserted (skiing fall in Slovenia) due to grade 4 TPF. I have 130 degrees bend and flat leg extension. The progress is due to immediate physio within 48hrs post operation and due to the excellent Slovene rehab centre at Dolenjska Toplice when specific treatments were identified (I cannot thank them enough).
I have just started FWB but using one crutch as a precaution. It is clear to me that considered/cautious movement/stretching of the joint is essential from an early stage. I have just completed 30 min cycling (gym) on number 4 resistance. Yes, significant swelling of the knee has returned with usual stiffness (as advised) but no actual pain (except the ankle, which will pass).
It is likely the medial ligament and cartilage is damaged therefore if the muscles can be strengthened safely then all the better. It may be painful, but get that knee extended and bent as often and as early as you can, if advised by your doctor.
I am British, however the rehab treatment costs were reimbursed by the NHS due to recent EU directive for EU citizens. Something to think about if you are an EU citizen.