A method of surgically preparing a proximal end of a tibia includes inserting an intramedullary orthopaedic surgical instrument into a medullary canal of the tibia, securing an attachment device to the intramedullary orthopaedic surgical instrument, attaching a cutting block to the attachment device, resecting the proximal end of the tibia using the cutting block to form a surgically-prepared surface, positioning a tibial base trial on the surgically-prepared surface, and inserting a keel punch through a slot defined in the tibial base trial and into the surgically-prepared surface of the tibia.