Which type of fracture is most likely to be accompanied by brisk bleeding?

An open femur fracture is most likely to be accompanied by brisk bleeding because the fracture involves a break in the skin, which can expose underlying blood vessels and soft tissue. In such injuries, not only is the bone fractured, but there is also a significant risk of laceration to the surrounding blood vessels. This can result in substantial external hemorrhage. Additionally, the femur is connected to major arteries, specifically the femoral artery, which can lead to severe blood loss if injured.

In contrast, a closed femur fracture does not break the skin, making it less likely to result in external bleeding, although it may still lead to internal bleeding due to the trauma. A stable pelvis fracture typically does not involve the same degree of vascular compromise as an open femur fracture, so the risk of bleeding is generally lower. Lastly, a humerus fracture is also less likely to cause significant hemorrhage compared to a femur fracture, as the humerus is a smaller bone and major blood vessels are not as closely associated with it.

Thus, the open femur fracture stands out as the most likely scenario to result in substantial brisk bleeding due to both the nature of the injury and the anatomy involved.