Dear Sir, your story tells that you have had a real bad dislocation of the elbow, such bad that even your vessel was hurt and was reconstructed, i would advise you to go slow with gaining movement, as any extra pressure will lead to more stiffness in the joint, I would appreciate if you can share your x rays with me so that I can comment in a way to help you out, as far as your details go three weeks is a very little time for this injury, it will need at least 3 to 6 months for you to gain good functional range.
Next Steps
Go slow with your exercises, and let nature take its course in healing
Health Tips
any forcefull manipulation to gain range can lead to more stiffness and break of the repaired structures.