A method of designing a customized patient-specific bone cutting block for use in an orthopaedic surgical procedure to perform a bone cut on a patient's bone involves determining a cartilage thickness value, determining a reference contour based on a surface contour of the relevant end of the patient's bone, generating a scaled reference contour by scaling the reference contour based on the cartilage thickness value, and defining a customized patient-specific negative contour of the customized patient-specific bone cutting block using the scaled reference contour.
