Why are some broken arms treated with casts that go below the elbow and some above?

Decisions as to what type of cast to use for a broken arm depend on where in the arm the break is. Obviously, the upper arm will require a much larger cast than the wrist. However, there are times when a break closer to the wrist will still be treated with a longer cast.

The issue with casting is to keep the broken bone as stable as possible. If the break is in such a place that too much movement from the elbow may keep the break from healing, a decision will be made to use the longer cast.

Choosing the right size cast is important. The plaster casts are very heavy and if a long cast isn't medically necessary, it shouldn't be used because of the stress it can place on the nerves and muscles in the shoulders.