I'm three weeks out from ACL reconstruction. How long until I should get be able to reach full extension?

3-4 weeks. Need to gain full extension in 4-6 weeks post acl especially btb graft. Need to have pt get on it imediatly. Use prone hangs, extension board, no pillows under bend of knee.
Now, ASAP. It is important to have full extension soon after surgery since scar formation can prevent extension and can necessitate further surgery.