Our department has adopted a method to fix the fractures internally with various TiNi SMA inter-locking intramedullary nails and treated 1033 cases of tibial and femoral fractures since 1992. All of the treatments were successful and the curative effects were excellent. Clinical applications showed that TiNi SMA internal fixation devices have many advantages such as easy operation, weak wound, reliable fixation and earlier moving of knee joints.