The invention relates to an orthopedic appliance which is designed to support the weight of a patient and comprises a power supply device for an electrical consumer. The aim of the invention is to be able to convert the kinetic energy introduced into the appliance into electrical energy. To this end, the power supply device comprises a stack (7) of piezoelectric ceramic elements, and the force of the weight is introduced into the stack (7) by means of a force transmission system.