Final answer:
In the event of a displaced femoral fracture, injury to the femoral artery could lead to a catastrophic injury due to the potential for significant blood loss and shock.
Step-by-step explanation:
After sustaining a displaced femoral fracture, injury to the femoral artery could result in a possible catastrophic injury. The femoral artery is a major blood vessel that provides a significant blood supply to the lower limb. If this artery is damaged, it can cause extensive blood loss, leading to shock and potentially being life-threatening if not treated promptly. Unlike the other structures listed, such as the adductor magnus which is a muscle, the femoral nerve which affects movement and sensation, the inguinal ligament which provides support to the lower abdomen, and the pubic symphysis which is a joint, damage to the femoral artery can have immediate and severe consequences due to its role in circulation.