[An instrumented external fixation device as an instrument for measuring external fracture management]

The article deals with a method of measuring which, without changing the buildung components of the AISF-fixateur externe, determines the force at the fracture gap in the case of compression osteosynthesis. For this purpose there has been developed a ring force measuring element and expansion measuring strips. It is the aim of this measuring method to describe the course of force during the operative process of straining and to control it regarding accuracy of measuring, to superrise the forces occurring during the healing process, to be able to gauge in a definite manner in case of disturbances of the external compression system and finally to control the force attitude at the fracture gap also under dynamic load. The ring force measuring boxes can be set up at the free pipe end without changing the necessary systems of assembling. Advantages are the unlimited use, costs incurred only once, easy handling, high immunity from disturbance, the possibility of gas disinfection and no obstruction of external construction forms. With this system so far we have controlled 22 patients by means of an external compression osteosynthesis. With compression degrees at the fracture gap ranging between 400 and 800 N, one can mechanically talk of stable external osteosynthesis. With the help of bioptic material taken from the region of the direct osseous contact of a human fracture gap, the morphological signs of the primary healing of the bone could also be proved.