An ostectomy is a surgical procedure that means to remove a bone or bones in the body.
For example an ostectomy could be the removal of a rib bone or any other type of surgery that involves removing any other bone in the body.
If you needed to have part of your ribs removed to get to other parts of your body to repair organs in your body then you would have an ostectomy done to remove those ribs.
An ostectomy can also be dentistry as well.
Another example of a dental ostectomy is the removal of bone surrounding a tooth in an attempt to eliminate an adjacent periodontal pocket.
In short the ostectomy means to remove bones surgically.