Objective To evaluate the therapeutic effect of half ring sculcus external fixation after failed internal fixation of tibial fracture.

Construction of goat tibial diaphyseal defect model by half-ring sulcated external fixator;

The 20 percent single tibia diaphyseal defect of every goat as made of and fixed with half-ring sulcated external fixator and one group animal be killed every 5weeks postop.

Unilateral hinged external fixator for treating unstable fracture dislocation of elbow;