Clay is one of the few true homeostatic therapeutic substances that can be used in natural medicine. I like to think of using clay as always making everything better, even if a bit.
We can look to the extensive animal studies done and realize that clay use increases nail and hair growth, that it normalizes mineral absorption (at the cellular level), and helps to improve the overall efficiency of the entire metabolism, as well as acting as a systemic catalyst for more efficient detoxification throughout the body.
That said, the traditional modality to use in this situation would be clay packs/poultices... much easier to use with a broken wrist, arm, leg or foot to be sure. In some cases, therapeutic clay used in this manner can have a dramatic effect, although this is usually noticeable when the clay is used very early on.
Also, any cast used would prevent clay poultices from being used.
The three clay blend is a bit pricey to use for poultices. The gallon container would not last very long.