scholarly journals Mechanical effect of different implant caput-collum-diaphyseal angles on the fracture surface after fixation of an unstable intertrochanteric fracture: A finite element analysis

2019 ◽  
Vol 42 (11) ◽  
pp. 947-956 ◽  
Author(s):  
Jung-Taek Kim ◽  
Chang-Ho Jung ◽  
Quan Hu Shen ◽  
Yong-Han Cha ◽  
Chan Ho Park ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Fracture Surface ◽  
Intertrochanteric Fracture ◽  
Mechanical Effect ◽  
Element Analysis ◽  
Unstable Intertrochanteric Fracture

scholarly journals Finite element analysis of two cephalomedullary nails in treatment of elderly reverse obliquity intertrochanteric fractures: zimmer natural nail and proximal femoral nail antirotation-ΙΙ

2019 ◽  
Vol 14 (1) ◽  
Author(s):  
Jian Chen ◽  
Jian-xiong Ma ◽  
Ying Wang ◽  
Hao-hao Bai ◽  
Lei Sun ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Internal Fixation ◽  
Intertrochanteric Fracture ◽  
Proximal Femoral Nail ◽  
Intertrochanteric Fractures ◽  
Element Analysis ◽  
Femoral Nail ◽  
Unstable Intertrochanteric Fracture ◽  
Proximal Femoral Nail Antirotation

Abstract Background More elderly patients are suffering from intertrochanteric fractures. However, the choice of internal fixation is still controversial, especially in the treatment of unstable intertrochanteric fracture; thus, previous implants continue to be improved, and new ones are being developed. The purpose of our study was to compare the biomechanical advantages between the zimmer natural nail (ZNN) and proximal femoral nail antirotation-II (PFNA-II) in the treatment of elderly reverse obliquity intertrochanteric fractures. Methods A three-dimensional finite element was applied for reverse obliquity intertrochanteric fracture models (AO31-A3.1) fixed with the ZNN or PFNA-II. The distribution, peak value and position of the von Mises stress and the displacement were the criteria for comparison between the two groups. Results The stresses of the internal fixation and femur in the ZNN model were smaller than those in the PFNA-II model, and the peak values of the two groups were 364.8 MPa and 171.8 MPa (ZNN) and 832.3 MPa and 1795.0 MPa (PFNA-II). The maximum amount of displacement of the two groups was similar, and their locations were the same, i.e., in the femoral head vertex (3.768 mm in the ZNN model and 3.713 mm in the PFNA-II model). Conclusions The displacement in the two models was similar, but the stresses in the implant and bone were reduced with the ZNN. Therefore, the ZNN implant may provide biomechanical advantages over PFNA-II in reverse obliquity intertrochanteric fractures, as shown through the finite element analysis. These findings from our study may provide a reference for the perioperative selection of internal fixations.

scholarly journals A Finite Element Analysis and Cyclic Load Experiment on an Additional Transcortical-Type Hole Formed Around The Proximal Femoral Nail System’s Distal Locking Screw

2021 ◽  
Author(s):  
Hong Man Cho ◽  
Seung Min Choi ◽  
JiYeon Park ◽  
Young Lee ◽  
Jung Hyung Bae
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Tensile Stress ◽  
Intertrochanteric Fracture ◽  
Proximal Femoral Nail ◽  
Element Analysis ◽  
Distal Locking ◽  
Femoral Nail ◽  
Hole Model ◽  
Locking Screw

Abstract Background A complication associated with the distal locking screw used in the proximal femoral nail (PFN) system is the formation of accidental additional holes. We hypothesized that an increase in stress around additional holes is a relevant factor contributing to fractures. This study aimed to evaluate stress changes in the cortical bone around additional screw holes using finite element analysis. Methods Proximal femoral nail PFN antirotation (PFNA)-II (Synthes, Solothurn, Switzerland) was inserted into a femur model. An additional 4.9-mm transcortical hole was made either anteriorly (anterior hole model) or posteriorly (posterior hole model) to the distal locking screw. Finite element analysis was used to calculate compression, tension, and load limits to investigate stress around additional holes with respect to the direction of screw penetration and degree of osteoporosis. The results were then compared with those of mechanical testing. A 31A-21 type intertrochanteric fracture was applied. As a control group, a model without additional holes (no-hole model) was developed. Repeated load-loading tests were performed on 10 model bones per model group. Results Tensile stress was significantly greater in the no-hole model when additional screw holes were present, and the anterior hole showed a higher maximum stress value than the posterior hole did, suggesting that the anterior hole was more susceptible to fracture. The change in tensile stress first appeared in the hole around the lateral cortical bone and proceeded to the medial side. Biomechanical testing showed that fractures around the distal locking screw occurred in 0 cases of the no-hole, 10 of anterior hole, and 9 of the posterior hole models. Conclusions During PFN surgery for intertrochanteric fracture, holes with distal locking screws fixed and removed at the anterior and posterior of the nail can be a risk factor for fractures in the surrounding area.

Ductile Fracture Modeling of DH36 Grade Steels

2018 ◽  
Author(s):  
Burak Can Cerik ◽  
Sung-Ju Park ◽  
Joonmo Choung
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Fracture Surface ◽  
Ductile Fracture ◽  
Stress Triaxiality ◽  
Local Stress ◽  
Fracture Initiation ◽  
Isotropic Hardening ◽  
Flow Rule ◽  
Element Analysis

A Hosford-Coulomb type ductile fracture surface was developed for DH36 grade steels. The fracture experiments reported in the literature, which consist of tests with notched tensile specimens, tensile specimens with a central hole, shear specimen and disc specimens for punch specimens, were utilized in a detailed finite element analysis of each experiment to evaluate the evolution of local stress and strain fields and identify plasticity and fracture response of DH36. The developed plasticity model consists of a von Mises yield surface, an associated flow rule and a combined Swift-Voce type isotropic hardening rule. The loading paths to fracture initiation were determined in terms of stress triaxiality and normalized Lode angle parameter histories. Finally, the Hosford-Coulomb fracture surface was calibrated using the finite element analysis results and adapting a linear damage accumulation law.

BIOMECHANICAL EFFECT OF DIFFERENT LAG SCREW LENGTHS WITH DIFFERENT BARREL LENGTHS IN DYNAMIC HIP SCREW SYSTEM: A FINITE ELEMENT ANALYSIS STUDY

2017 ◽  
Vol 17 (01) ◽  
pp. 1750008 ◽  
Author(s):  
CHUNG-YUH TZENG ◽  
KUI-CHUO HUANG ◽  
YUN-CHE WU ◽  
CHU-LING CHANG ◽  
KUAN-RONG LEE ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Intertrochanteric Fracture ◽  
High Stress ◽  
Dynamic Hip Screw ◽  
Element Analysis ◽  
Side Plate ◽  
Lag Screw ◽  
Hip Screw ◽  
Biomechanical Effect

The dynamic hip screw (DHS) system is commonly used to treat intertrochanteric fracture of the hip joint. Breakage of the lag screw was noted in clinical practice and the length of lag screw as well as the length of the side plate in the DHS system appeared to play a role in the risk of breakage. Thus, the aim of this study was to investigate the biomechanical effect of different lag screw lengths and barrel plate lengths in the DHS implant system by finite element analysis (FEA). Four FEA simulation models were created according to different lengths of lag screw (79[Formula: see text]mm and 63[Formula: see text]mm) and different lengths of barrel side plate (43[Formula: see text]mm and 37[Formula: see text]mm). The von Mises stress was used as the observation indicator. The results showed that the maximum tensile stress on the long lag screw was slightly greater than that of the shorter lag screw. Use of a shorter barrel side plate may also cause high stress between the lag screw and the barrel side plate. This finding provides biomechanical reference data that may be of value to orthopedic surgeons with respect to choice of implant size and length in the treatment of intertrochanteric fracture with a DHS system to prevent complications such as implant failure caused by broken lag screws.

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