“How long does it take for the breastbone to heal after bypass surgery?”

It takes about 2-3 months to heal most bones (in this context, the sternum.) But many patients needing a bypass have reduced circulation and thus may not heal normally. So, this fact may slow down healing of the sternum. Additionally, even if the bone "heals", there may be continued pain from soft tissue issues, nerve disruption, and other local factors that may result in ongoing pain. Plus, it is well known that some fractured bones may continue to hurt for a long time, even if it has totally healed. And rarely, it is well known that a sternum may not heal at all (though the overlying soft tissue/skin will heal and thus keep things stable).

Bottom line -- a patient will likely be much better in reference to sternal issues within 3 months or so, but a minority of patients may continue having pain and/or healing issues for many months after bypass surgery.