Bunion can be consistently corrected without breaking bones at all.
Bunion deformity is actually formed by normal bones that have been displaced from their normal position after years of walking, due to their incompetent supporting ligaments. These displaced bones are by definition unstable and loose, and thus they are mobile and can be moved back to their original positions effortlessly, without being broken up to do so.
Evidence: J Foot Ankle Surg. 2015 May-Jun;54(3):406-11. doi: 10.1053/j.jfas.2014.09.011.