Bunion surgery is done via either the traditional open method or a keyhole/ MIS method. It depends on the severity of the bunion, and what technique the surgeon is competent and proficient in.
My first option would always be to offer a keyhole correction for a patient if I feel the bunion is suitable for such correction. The advantages for keyhole surgery are plenty.
Please refer to this post What are the best treatment options for bunion removal in Singapore and How can I find the best doctor for bunion surgery in Singapore to find out more about keyhole correction.