If your brace is over a year old, one way to test if it needs replaced is to evaluate the hinge area to see if it has become loose.
To test the hinge, place one hand on the top of the brace and the other hand on the bottom of the brace and push and pull the brace back and forth. If you can see a lot of extra movement in the hinge area, then replacing the brace is recommended to regain stability.