Finger flexion/extension (PIP) with overpressure (Finger PIP joint flexion/extension AAROM, end range)

Start in a seated position.
Place your affected arm on a table, holding the forearm up.
Place the fingers of your other hand firmly around the lowest bone in the affected finger to stabilise this area.
Try to bend and straighten the finger at this joint, fixing your hand in place to ensure the movement comes from the correct area.
Use the finger of your other hand to assist in pushing the movement a little further.