The invention provides an apparatus and method for sizing a distal portion of a femur during knee arthroplasty. A sizer according to the invention includes a body that can be removably attached to the distal portion of the femur and that is operable to support a module that is removably attachable to the body. The body with attached module is operable for use in measuring the size of the distal portion of the femur. The module can be attached to the body either before or after the body has been attached to the distal portion of the femur and can be detached from the body either before or after the body is detached from the distal portion of the femur.
