An apparatus and method of monitoring healing and/or assessing mechanical stiffness of a bone fracture or the like is disclosed. The method comprises (a) recording a strut length of a variable length strut with an indicator pin, wherein the strut is on an external fixator is in a no or minimal load situation (b) inputting such strut length, mounting parameters, and frame parameters into software to determine a first pose and position of the fixator (c) positioning at least one indicator clip on each side of the indicator pin (d) applying a load or torque to the bone fracture (e) recording strut length of the variable length strut in loaded situation (f) inputting such strut length, mounting parameters, and frame parameters into software to determine for a second pose and position of the fixator in a loaded situation (g) solving for a change in pose and position by subtracting the second pose and position from the first pose and position and (h) solving for the stiffness of the bone fracture by dividing the load applied to the bone fracture by the change in position and pose. An apparatus and indicator clip are also disclosed.
