Final answer:
The best imaging method to rule out bone infection in a patient with a red and swollen knee is an MRI, as it provides detailed images that are useful for diagnosing bone infections.
Step-by-step explanation:
The best imaging method for a nurse practitioner to order to rule out bone infection following a red, hot, and swollen furuncle on a patient's knee after a fall that scrapped the knee is an MRI (Magnetic Resonance Imaging). An MRI provides detailed images of soft tissues and bones, and it is particularly useful in diagnosing bone infections (osteomyelitis). While x-rays can show bone damage, MRIs can identify infections earlier and with greater detail. CT scans are also used to visualize bone and soft tissues but are less sensitive than MRI in the early detection of osteomyelitis. Ultrasound is not typically used for imaging deep structures such as bones and is better suited to soft tissue evaluations.