An orthopaedic surgical instrument and method includes securing an anchor to a tibial prosthetic component implanted in a proximal end of a patient's tibia, moving a separator posteriorly toward the anchor to position a tip of the separator between a lower side of the tibial tray and an upper end of the tibial sleeve, advancing the separator from anterior to posterior between the lower side of the tibial tray and the upper end of the tibial sleeve to detach the tibial tray from the tibial sleeve, and removing the tibial tray from the proximal end of the patient's tibia. The tibial prosthetic component includes a tibial tray and a tibial sleeve secured to the tibial tray.