The wrist often loses ROM after injury. 8 small bones make up the wrist area, and they are aligned in 2 rows of 4 bones. An updated x-ray would show whether or not there's been any naturally occurring fusion to the segments. If not, the problem is functional and could be worked out with stretching. If that fails, you may need to see someone skilled in wrist mobilization/manipulation plus some type of scar tissue mobilization technique like Graston or Active Release. There are three major clinical areas, the midcarpal, radiocarpal and the ulnomeniscocarpal. Of those three, the midcarpal is responsible for the majority of writst extension, so that would be a good place to start.
"And if a frog had wings it wouldn't bump his ass a hoppin'!"
- The wisdom of Nathan Arizona