Alex (cristak),
Sorry to hear about your femoral neck fracture during your race. The vast majority of these fractures in runners are due to a stress reaction which ultimately goes on to a frank fracture. Runners tend to really push their bodies, ignoring the body's signals that there may be something wrong. Be careful doing that during your healing. It is best to not push to see how much pain you can stand. That may be what got you in this predicament.
You must follow your surgeon's instructions. He/she is the one that has seen your x-rays and felt how well the screw went into the bone (called purchase of the screw into the bone). So, you should really listen to what he/she has to say.
While it is probably true that you will have some soft tissue pains around the pelvic area, you really have to be careful with the pain in the groin, over the neck of the femur.
With the way the compression screws are placed, it is an indirect way of reducing the fracture, such that the soft tissues right around the fracture site are not disrupted (as to not injury the vital blood vessels). So, there really should not be too much discomfort coming from the soft tissues. So, pain in that area is most likely coming from the bone (not all, but most).
When you do a straight leg raise, that places a significant bending moment upon the femur. Any weak area (i.e. fracture) will really note the stress from a straight leg raise. The longer the lever arm, the more the stress. So, raising a leg with a bent knee places less stress on the femoral neck than a straight leg raise. Sorry, that may be a little too much physics. Anyways, the point being, just listen to your body. If it hurts to do something, back off. And, if the surgeon stated to not do something, it is best not to do that for right now.
You also have to remember that not all fractures are the same. In fact, they are all different. Thus, what happens in one patient with a femoral neck fracture will not be the same for another patient with a femoral neck fracture. Which is why you really must go with your surgeon's instructions. Only he/she knows your particular fracture characteristics.
Femoral neck fractures are not to be messed around with. If the blood vessels along the neck are disrupted, that could lead to AVN (avascular necrosis) of the femoral head (ball of the hip joint). This would be a disaster.
Also, when the bone broke, how much it displaced (moved out of place) makes a big difference on how well it will heal. So, a patient with an impacted fracture which did not move much at all is very different from a patient in which the fracture had gross displacement. Though both are treated with the same hardware, their fracture characteristics are very different.
Every patient is unique.
If you have access to a pool, you may find that doing lower extremity activities are much easier and do not cause discomfort. With the buoyancy of the water, activities are essentially nonweight bearing. In some pools, you can even "run" in the water. Many elite runners do this to stay in training when they have a lower extremity injury. You might inquire. What is basically done, is to place patients in a vest with weights that keeps them suspended in the water and allows them to "run" in the deep end of the pool. There is no weight bearing, no impact.
It is something to look into.
Again, sorry about your injury. Hopefully, the fracture will heal up nicely and you will be back to abusing your body running again. Just kidding. Be careful, listen to your body while you are healing. Nature gave us pain for a reason, to tell us we are doing something wrong.
Be careful. You stated that you were going "to see if how much pain I can withstand" in your last post. In healing of femoral neck fractures, that may not be the best thing to do. You have to remember that the screw is there to just hold the bone pieces together until the body can "glue" them back together. Too much repeated stressing can hamper that.
Take it easy. Let your body heal. You can get back to running once everything is good. I know it is hard, sitting around, chomping at the bit. But, it won't be too much longer.
Good luck. Hang in there.