Fig. 3. The linkage system connecting the motor and torque sensor to the fixator, which is inserted by pins into the rat femur. As the wheel (bottom right) rotates, the horizontal actuator arm (bottom) drives the vertical accuator arm (bottom left), which is attached to one side of the fixator (hidden by the plate). As the fixator bends on its axis or displaces in shear, the defect is stimulated. The rat is lying in a sling hammock with its tail protruding to the left of the image.