Any muscle that fixes, or limits the movement, of a bone or joint(noun)
Wiktionary.org : Text is available under the Creative Commons Attribution-ShareAlike License
Use "fixator" in a sentence
"He has had surgery to remove the fixator, but needs extensive physical therapy to build the leg back up."
"I still have something on my leg called an Ilizarov external fixator [to mend, lengthen and reshape] the tibia ... between your ankle bone and your knee ...."
"An external fixator is bolted to her leg in six places, preventing her from playing her favorite game Double Dutch, but she says she only has one wish: to go back to school."