%0 Journal Article
%T The Variable Angle Hip Fracture Nail Relative to the Gamma 3: A Finite Element Analysis Illustrating the Same Stiffness and Fatigue Characteristics
%A Amir Matityahu
%A Andrew H. Schmidt
%A Alan Grantz
%A Ben Clawson
%A Meir Marmor
%A R. Trigg McClellan
%J Advances in Orthopedics
%D 2013
%I Hindawi Publishing Corporation
%R 10.1155/2013/143801
%X Ten percent of the 250,000 proximal femur fractures that occur in the United States each year are malreduced into a varus position after treatment. Currently, there is no cephalomedullary nail available that allows the physician to dynamically change the lag-screw-to-nail angle. The Variable Angle Nail (VAN) was designed to allow movement of the lag screw relative to the shaft of the nail. This study compared the characteristics of the VAN to the Gamma 3 nail via finite element analysis (FEA) in stiffness and fatigue. The results of the FEA model with the same loading parameters showed the Gamma 3 and the VAN with lag-screw-to-nail angle of 120¡ã to have essentially the same stiffness values ranging from 350 to 382£¿N/mm. The VAN with lag-screw-to-nail angles of 120¡ã, 130¡ã, and 140¡ã should be able to withstand more than 1,000,000 cycles from 1,400£¿N to 1,500£¿N loading of the tip of the lag screw. The Gamma 3 should be able to last more than 1,000,000 cycles at 1,400£¿N. In summary, the VAN is superior or equivalent in stiffness and fatigue when compared to the Gamma 3 using FEA. 1. Introduction More than 250,000 proximal femur fractures occur in the United States each year [1]. Due to aging of the population and the increasing number of elderly persons, the incidence of hip fractures is predicted to double over the next 15 to 20 years [1]. Since their introduction over 15 years ago and subsequent widespread adoption, the so-called cephalomedullary nails that incorporate fixation into the femoral head have become a standard treatment for these proximal femur fractures [2¨C7]. Despite their popularity, the technology associated with these nails has only been incrementally advanced over the last 10¨C15 years, with most of the design changes having been done to lessen the likelihood of intraoperative fracture of the femur and cutout of the lag screw [8, 9]. Reports of the results of the stabilization of proximal femoral fractures with cephalomedullary nails indicate that more than 10% of cases demonstrate varus malreduction, with neck-shaft angles that are more than 10¡ã of varus relative to the contralateral side [10, 11]. Varus malreduction contributes to failure of fracture fixation and causes limb shortening and compromised function [12, 13]. Given the number of patients treated by this method, as many as 20,000 individuals per year may have a suboptimal result due to malreduction, and some of these patients may require further surgery [1, 7, 10, 11]. It is recognized that patient outcomes, fracture nonunion, and implant failure are largely dependent on the
%U http://www.hindawi.com/journals/aorth/2013/143801/