It should not be difficult to imagine how the can will displace, while the two by four will stay firmly nailed.
As the cancellous bone is distributed in the metaphysis and epiphysis of the bone that is the best location for pins, as demonstrated here in the distal radius.
A technique known as “buttress pinning” can make pinning useful in tubular, noncancellous bone. The pin is inserted into the fracture site and then tilted so that it resists shear displacement, then drilled through the opposite cortex.
Inserting such pins can be difficult. First you use flouro to determine where the pin needs to be inserted in the skin so that it will enter the bone, at the fracture site, at the correct angle without “tenting” the skin too much when you’re done.