A method of performing an osteotomy including the steps of: providing a guide assembly placing the guide assembly in operative relationship to a bone to be cut so that the guide assembly defines first and second guide edges that are in fixed relationship to each other to each guide movement of a cutting tool guiding the cutting tool along each of the first and second guide edges to produce first and second cut lines in the bone to facilitate separation of a fragment of the bone from between first and second bone surfaces formed respectively at the first and second cut lines separating the bone fragment so that a gap with a first width is formed between the first and second bone surfaces and changing the width of the gap to be less than the first width.
