A combined bone cutting guide and spreader device (1； 50) comprising first and second arms (2, 3； 51, 52) and a hinge (4； 71) connecting first ends (5, 6) of said first and second arms together, in which second ends (7, 8； 53) of said first and second arms each comprise a bone attachment mechanism (9, 10； 69, 70), in which said first and second arms are moveable about said hinge between a guide position in which they are arranged parallel with one another and define a bone cutting guide slot (11) therebetween, and such that said bone attachment mechanisms are adjacent to one another, and a spread position in which they are arranged at an angle to one another and said bone attachment mechanisms are spaced apart.
