Sliding of the load carrier in third-generation intramedullary nails for proximal femur fractures: An in vitro mechanical comparison study

Abstract

Dynamic osteosynthesis of proximal femur fractures facilitates compression at the fracture site through distal glide of the femoral head load carrier in the intramedullary nail. Modern implants are currently designed according to diverse gliding principles. The aim of this study was to compare the sliding mechanisms of different types of nails. As in other similar mechanical studies the load patterns occurring around the femoral head load carrier and the intramedullary nail under full load were simulated for three different types of intramedullary nail - PFNA, Targon PFT and Trigen Intertan. The load necessary to trigger distal displacement of the femoral head implant in the nail was determined. The lengths of the load carriers were varied. For the three lengths of load carrier, mechanical testing showed that the Targon PFT started to slide at a significantly lower load compared to the other two implants. Comparison of the PFNA and Trigen Intertan in terms of load to dynamization for 77 mm carriers revealed a significantly lower load for the PFNA. Slide efficacy for the PFNA and the Trigen Intertan was found to improve as the length of the blade/screw was shortened. The dynamization properties of the Targon PFT with its cylindrical sliding mechanism, similar to the DHS, were far better compared to the PFNA and the Trigen Intertan that have more complex sliding actions. Since theoretical considerations indicate that a less efficient gliding action leads to a higher complication rate, implants of the next generation should be optimized in this regard.

Medial migration of the helical blade with penetration into the acetabulum: a rare complication using the TFNA nail

“…A key design feature differing the currently available IFNs is the fixation of the femoral head and neck by use of Lag screws, dynamic screws, or blades. The femoral head element (FHE) can slide in the nail, allowing a dynamic compression of the fracture under load [ 4 ]. The Trochanteric Fixation Nail Advanced (TFNA; DePuy Synthes, Raynham, USA) is one of the frequently used IFNs for surgical treatment of pertrochanteric femoral fractures [ 5 ].…”

Loss of Reduction after Cephalomedullary Nail Fixation of Intertrochanteric Femoral Fracture: A Brief Report

“…Dynamic hip screw (DHS) as an extramedullary construct or intramedullary nail with a cephalomedullary screw is the standard surgical treatment option chosen by most surgeons. There is literature about comparisons between these implants, including biomechanical characteristics, indications, complications, and outcomes 4,[6][7][8][9] . The recent consensus is that the implant options for the treatment of intertrochanteric fractures are closely related to the stability of the fractures 10,11 .…”