Intramedullary femoral nails: one or two lag screws? A preliminary study

Failures of proximal femoral nails that treat unstable femoral fractures ha ve been reported. In this communication, a finite element model to include a proximal femoral nail within a fractured femur was used to carry out prel iminary investigations into configurations of single or double lag screws. The effects of the different types of fracture were investigated. The resul ts show that in order to share the load evenly between two lag screws, a go od configuration seems to be to have a slightly larger screw above the lowe r screw. This also ameliorates stresses in the nail at the lag screw insert ion holes. However, using two screws in this way can lead to large stresses in the cancellous bone in the femoral head, and these stresses may be sign ificant in the initiation of cut-our. (C) 2001 IPEM. Published by Elsevier Science Ltd. All rights reserved.