Complication of a Femoral Fracture Treated by Intramedullary Nailing - Numerical Analysis of a Clinical Case.

The aim of this paper is to conduct a numerical analysis of a case of femoral fracture treated by intramedullary nailing and confirm the conditions which led to the formation of a pseudarthrosis at the fracture site. A low-energy femoral fracture was treated by placing a ChFN System intramedullary nail with a derotation pin. Using the finite element method, a bone-implant system was generated which made it possible to observe the displacement area and strains in the region of the fracture gap. The calculations were conducted for 3 variants of the model, using a titanium nail (10 mm and 12 mm) and a steel one (10 mm). Analysis of strain distribution indicated that the highest strain values occur in the fracture gap and that they are higher when a titanium alloy is used (0-17% vs 0-11%). Interfragmentary movements caused by an imposed load were also higher when a titanium alloy implant was used. Strain analysis showed that the percentage of elements in the gap area which are potentially able to grow bone tissue is higher when a steel implant is used. It is possible to indicate sites where unfavourable fracture gap healing will take place, which may lead to the development of a pseudarthrosis. The use of a steel implant increases the probability of obtaining stable bone union.