Final answer:
The highest risk of hypothermia post-surgery would be in the 75-year-old patient with a femoral neck fracture repair due to their age and the serious nature and complications associated with hip surgeries.
Step-by-step explanation:
The patient who would be at the highest risk for hypothermia after surgery is the 75-year-old patient with a repair of a femoral neck fracture after a fall. Elderly patients are more susceptible to hypothermia due to a decreased ability to regulate body temperature, and surgery for hip fractures can be particularly invasive, leading to a higher risk of hypothermia. Additionally, the prolonged immobility following surgery for hip fractures increases the risk for complications like pneumonia, urinary tract infections, and pressure sores which can further exacerbate the risk of hypothermia.