A Biomechanical Comparison of Two Intramedullary Implants for Subtrochanteric Fracture in Two Healing Stages: A Finite Element Analysis

Abstract

Background. The biomechanical effect of two implants, namely, proximal femoral nail antirotation for Asia (PFNA-II) and Expert Asian Femoral Nail (A2FN), for treating subtrochanteric fracture during healing stages, is still unclear. Methods. A 3D finite element model of an intact femur was constructed and validated. The fractured and postoperative models were accordingly produced. The postoperative models were loaded with the peak joint forces during gait for the soft and hard callus stages. The effects of stress distribution on the implants, femoral head and callus, and the deformation of the proximal femur were examined. Results. Both implants showed similar biomechanical effect in two healing stages. As the healing duration increased, the von Mises stress of two implants and the tensile stress of the femoral head decreased, whereas the compressive stress of the femoral head increased. However, the PFNA-II operation resulted in higher stress on the implant, lower stress on the proximal femur, and lower compressive stress and higher tensile stress on the callus than A2FN operation. Conclusions. The A2FN implant may provide a biomechanically superior construct for subtrochanteric fracture healing. However, the upper screw of the A2FN implant may be more likely to be loose in the healing process.

Numerical Optimization of the Position in Femoral Head of Proximal Locking Screws of Proximal Femoral Nail System; Biomechanical Study

“…Incidence of hip fracture is increasing continuously due to increased average age and osteoporosis ( 1 , 2 , 3 ). Biomechanical studies have enounced that intramedullary and cephalomedullary devices provide a stable structure for pertrochanteric fractures ( 4 , 5 , 6 ). Pertrochanteric fracture [Arbeitsgemeinschaft für Osteosynthesefragen (AO)-OTA 31-A1] lines ( 7 ) can start from anywhere on the greater trochanter to above or below the lesser trochanter ( Figure 1 ).…”

Recent developments on intramedullary nailing: a biomechanical perspective

“…Several factors have been suggested to determine the mechanical environment at the fracture site: those that result from the stiffness of the implant, such as the rigidity of the nail and the screws, and those that result from movements between the different components that constitute the bone–implant structure construct . Strategies have been developed to try to guarantee an optimum implant stability and interfragmentary mechanical environment . Some authors have focused on experimenting with different biomaterials to evaluate the positive impact that they may have on the mechanical behavior of the bone–implant system and consequently on the healing process.…”

“…49 Strategies have been developed to try to guarantee an optimum implant stability and interfragmentary mechanical environment. [50][51][52][53][54] Some authors have focused on experimenting with different biomaterials to evaluate the positive impact that they may have on the mechanical behavior of the bone-implant system and consequently on the healing process. Other authors seem to be more concerned with increasing the structural stability.…”

In Silico Optimization of Femoral Fixator Position and Configuration by Parametric CAD Model

“…Structural analysis has often been used to compare the suitability of various fixation devices for a certain fracture type, e.g. [7,8,9,10,11,12]. Parametric studies or optimization procedures have been employed to find the optimal configuration and position of an existing fixation device [13,14,15,16,17] or to optimize the shape and dimensions of a new one (e.g.…”