In orthopedic practice, patients sometimes ask certain kinds of medical documents certifying their disability grading. But many orthopedic surgeons are not accustomed to issue such medical certificates. So we want to review the way of evaluation and grading of disabilities for such different kinds of medical certificates(for examples: disability grading certificate for use in traffic accident, industrial accident, liability of national compensation, private insurance, the handicapped, military service and others) and compare the differences between them.