An orthopaedic instrument assembly, comprising: a customized patient-specific femoral cutting block having: a customized patient-specific negative contour surface that is configured to receive a portion of a distal femur of a patient that has a corresponding contour, and a cutting guide; a customized patient-specific tibial cutting block having: a customized patient-specific negative contour surface that is configured to receive a portion of a proximal tibia of a patient that has a corresponding contour, and a cutting guide, and a mechanical linkage positioned between the customized patient-specific femoral cutting block and the customized patient-specific tibial cutting block, in which the mechanical linkage is operable to move (726, 728) the customized patient-specific femoral cutting block and the customized patient-specific tibial cutting block away from and toward one another, and in which: the mechanical linkage comprises a number of threaded shafts, rotation of the threaded shafts in a first direction causes the customized patient-specific femoral cutting block and the customized patient-specific tibial cutting block to be moved away from one another, and rotation of the threaded shafts in a second, opposite direction causes the customized patient-specific femoral cutting block and the customized patient-specific tibial cutting block to be moved toward one another. a customized patient-specific femoral cutting block having: a customized patient-specific negative contour surface that is configured to receive a portion of a distal femur of a patient that has a corresponding contour, and a cutting guide; a customized patient-specific negative contour surface that is configured to receive a portion of a distal femur of a patient that has a corresponding contour, and a cutting guide; a customized patient-specific tibial cutting block having: a customized patient-specific negative contour surface that is configured to receive a portion of a proximal tibia of a patient that has a corresponding contour, and a cutting guide, and a customized patient-specific negative contour surface that is configured to receive a portion of a proximal tibia of a patient that has a corresponding contour, and a cutting guide, and a mechanical linkage positioned between the customized patient-specific femoral cutting block and the customized patient-specific tibial cutting block, in which the mechanical linkage is operable to move (726, 728) the customized patient-specific femoral cutting block and the customized patient-specific tibial cutting block away from and toward one another, and in which: the mechanical linkage comprises a number of threaded shafts, rotation of the threaded shafts in a first direction causes the customized patient-specific femoral cutting block and the customized patient-specific tibial cutting block to be moved away from one another, and rotation of the threaded shafts in a second, opposite direction causes the customized patient-specific femoral cutting block and the customized patient-specific tibial cutting block to be moved toward one another. the mechanical linkage comprises a number of threaded shafts, rotation of the threaded shafts in a first direction causes the customized patient-specific femoral cutting block and the customized patient-specific tibial cutting block to be moved away from one another, and rotation of the threaded shafts in a second, opposite direction causes the customized patient-specific femoral cutting block and the customized patient-specific tibial cutting block to be moved toward one another.