It is fortunate he has no brain or spine injuries. Broken ribs are a serious injury but they do heal Usually no specific treatment is needed. However, people with broken ribs have a lot of pain, and they tend not to take deep breaths. Because of this they are prone to pneumonia. Being on a ventilator also predisposes one to pneumonia. The fever suggests some sort of infection; my first thought would be pneumonia. He also could get infected through the skin from the trauma he experienced. You don't mention what is swollen, but skin areas swollen and red indicate infection. Generalized swelling of the body could result from an air leak in the lungs from the trauma and broken ribs. His doctors are surely aware of these possibilities and will treat them appropriately. Hope this helps. If you have more questions, I would be happy to answer them.

Hi...
fracture with open wound is always a concerning factor.
Symptoms like pain, swelling, fever with high vitals indicate infection.
A slight rise in temperature post trauma is normal which in-turn can cause minimal rise in heart rate, and other vitals.
But if the fever is started after 48 hrs and if its high grade then its of concern.
Normally skin grafting is done only when the infection is subsided, so i suppose it is just a normal rise in temperature following trauma.
Swelling of the limb can be again due to infection or due to soft tissue injury.
Regarding this rib fracture :
post traumatic rib fracture was on ventilator now developed fever with high vitals , pneumonia ( infection of the lung ) could be a possibility and i suppose he is on injectable antibiotics.
Note: All these are possibilities only since the information given is incomplete and for such a patient it is not advisable to suggest any form of intervention without examining the person, i would recommend you to discuss with the treating doctor for further course of management.
thank you.