Controlled bending of proximal femoral nails used in fractures of bowed femurs: biomechanical study with clinical application

Abstract

We aim to investigate whether the controlled bending of the commercially available nail could affect the nail's biomechanical properties. We also report the clinical application using such method. A commercially available titanium proximal femoral nails were used for the current study. Using the custom made bending Jig, the portion distal to the bending point of the original nail was bent to varus curvature so that the alignment of the nail is equivalent to medial bowing of 1,000 mm radius. The biomechanical test was performed using the static four point bending test according to American Society for Testing and Materials (ASTM) standards. The measured biomechanical properties were compared between the original nail and the pre-bended nail. There was no significance difference between the original nail and the pre-bended nail in terms of mechanical properties we measured (p<0.05). Only 0.32% difference in bending strength was noticed between the two group which is considered to be negligible. The patient utilizing controlled bending nail showed early bone healing without complication. The result of the current study indicates that the additional bending of the commercially available intramedullary nail has only minimal effect on the biomechanical property of the nail. Therefore, we think controlled bending can be done on a commercially available intramedullary nail and can be used safely in the patient with severe anterolateral bowing.