A bone regenerator was a medical device used to repair bones.
Starfleet medkits carried bone regenerators. (DS9 episode: "Waltz")
In 2372, Julian Bashir treated Alex Boughamer's rib injuries with a bone regenerator. (DS9 - Day of Honor novel: Armageddon Sky)
In 2375, Martok broke his leg in a battle with the Hur'q. His leg was treated with a bone regenerator, but he reflected that Klingon medical technology fell behind that of the Federation, something which Martok resolved to correct as the new Chancellor. (DS9 novel: The Left Hand of Destiny, Book Two)