A customized patient-specific tibial cutting block comprising a body having a bone-facing surface that has a customized patient-specific negative contour configured to receive (i) a portion of an anterior side of a patient's tibia that has a corresponding positive contour, and (ii) a portion of a medial side of the patient's tibia that has a corresponding positive contour such that, when viewed superiorly, an angle greater than zero is defined between a vertically-extending, bisecting plane of the body and a bisecting sagittal plane of the patient's tibia when the portions of the patient's tibia are received in the customized patient-specific negative contour of the body, and at least one tab extending posteriorly from the body, the at least one tab having a bone-facing surface having a customized patient-specific negative contour configured to receive a portion of the proximal side of the patient's tibia that has a corresponding positive contour.