Determination of contact position of fractured bones and the applied force in external fixator applications

Abstract

In this article, we propose a new method for the estimation of the force, which is applied by two fractured parts of the bone on each other at the time of contact, while they are brought closer to each other, and the distance between these two bones. The manual alignment operations being applied today in the alignment of fractured bones does not become successful as desired each time. The two fundamental reasons for this is the insufficiency of the force applied by the health personnel for stretching the muscles of the patient under anesthesia and the impossibility of keeping the applied force fixed for the desired period even if their force suffices. Furthermore, the small amounts of linear and rotation operations needed during alignment are very difficult. In this case, the alignment operation is performed not as it should be but as much as it can be performed. Another negative aspect of manual bone alignment is the great amount of exposure to radiation both for the patient and the health personnel since X-ray images are needed to see the new situation. In this study, a new method is proposed for estimating the force applied by two fractured parts of the bone while they are brought closed to each other, and the distance between those two bones. With the new method that we propose, the distance between the bones and the pressure applied by them on each other are measured in the operations of alignment of fractured bones and this information is provided to the physician. Thanks to this method, the probability of applying a force on the bones in excess of the desired force is canceled out. At the beginning of the operation, the stretching property of the muscles of the broken limb of the patient, who is under anesthesia, is learnt and in the continuation of the same process, the moment when the bones start touching each other and the force applied by them on each other are determined by using loadcells and encoders. Consequently, a method that aligns the fractured bones being independent from personal properties of the patient such as gender and age has been developed. (C) 2018 Karabuk University. Publishing services by Elsevier B.V.