Hi
Welcome to the MedHelp forum!
Elbow tightness after elbow dislocation may mean the elbow is not fixed properly. Hence an X-ray or CT scan should be first done to determine this. This may even mean there are loose calcified bodies in the joint that is causing the elbow to stiffen. It could also be post trauma stiffness. The latter can be taken care of by physiotherapy. For others you will need to consult an orthopedic specialist and maybe corrective surgery or manipulation under anesthesia may be required.
It is difficult to comment beyond this at this stage. Please let me know if there is any thing else and do keep me posted. Take care!