An orthopaedic surgical instrument (10) includes a cutting block (12) having a bone-engaging surface (24) and an outer surface (22) positioned opposite the bone-engaging surface, a first cutting guide slot (40) defined in the cutting block, and a second cutting guide slot (70, 72) defined in the cutting block. The orthopaedic surgical instrument includes two mounting systems (14, 16) configured to separately secure the cutting block to a bone of a patient.
