Background: The thickness and width of L shaped armor plate can antagonize muscle traction with the ability of anti inflecting, anti torsion and anti shearing force, which overcomes the weakness of common armor plate and osseous pin that have weaker fixation force and need external fixation. The fixation can satisfy the request of early functional training. And the functional training can be performed on the continuous passive movement (CPM) instrument 1 week after operation to prevent adhesion of knee joint, elasticity losing in soft tissue around joint, ankylosis, osteoporosis and osteoarthritis.