Since your brother has fractured his arm which required a metal implant to be placed, and then he has developed infection at the operated site. Even after removal of the metal implant, the infection is still persisting, the most probable cause of persistence of infection could be bone infection at the fracture site. This can be diagnosed by an MRI or a CT Scan of the bone. If bone infection is present, depending on the extent of infection, he may require surgery to remove the infected bone, sent it for bacterial culture and antibiotic sensitivity, and take culture specific antibiotic till complete resolution of infection. If no bone infection is detected, then the tissue from the area of infection should be sent for a similar culture sensitivity test, and culture specific antibiotics, wound dressing, rest to the part is required till complete resolution of infection. He should consult the same surgeon who had operated on him and the doctor would do the necessary investigations and management.