scholarly journals Comparison of the Lag Screw Placements for the Treatment of Stable and Unstable Intertrochanteric Femoral Fractures regarding Trabecular Bone Failure

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Talip Celik ◽  
Ibrahim Mutlu ◽  
Arif Ozkan ◽  
Yasin Kisioglu
Keyword(s):  
Trabecular Bone ◽  
Femoral Fractures ◽  
Element Analysis ◽  
Volume Percentage ◽  
Ao Classification ◽  
Lag Screw ◽  
Maximum Value ◽  
Hip Screw ◽  
Tip Apex Distance ◽  
Fracture Types

Background. In this study, the cut-out risk of Dynamic Hip Screw (DHS) was investigated in nine different positions of the lag screw for two fracture types by using Finite Element Analysis (FEA). Methods. Two types of fractures (31-A1.1 and A2.1 in AO classification) were generated in the femur model obtained from Computerized Tomography images. The DHS model was placed into the fractured femur model in nine different positions. Tip-Apex Distances were measured using SolidWorks. In FEA, the force applied to the femoral head was determined according to the maximum value being observed during walking. Results. The highest volume percentage exceeding the yield strength of trabecular bone was obtained in posterior-inferior region in both fracture types. The best placement region for the lag screw was found in the middle of both fracture types. There are compatible results between Tip-Apex Distances and the cut-out risk except for posterior-superior and superior region of 31-A2.1 fracture type. Conclusion. The position of the lag screw affects the risk of cut-out significantly. Also, Tip-Apex Distance is a good predictor of the cut-out risk. All in all, we can supposedly say that the density distribution of the trabecular bone is a more efficient factor compared to the positions of lag screw in the cut-out risk.

Biomechanical analysis of the treatment of intertrochanteric hip fracture with different lengths of dynamic hip screw side plates

2020 ◽  
Vol 28 (6) ◽  
pp. 593-602
Author(s):  
Cheng-Chi Wang ◽  
Cheng-Hung Lee ◽  
Ning-Chien Chin ◽  
Kun-Hui Chen ◽  
Chien-Chou Pan ◽  
...  
Keyword(s):  
Hip Fractures ◽  
Dynamic Hip Screw ◽  
Biomechanical Analysis ◽  
Element Analysis ◽  
Side Plate ◽  
Lag Screw ◽  
Pull Out ◽  
Cortical Screw ◽  
Hip Screw ◽  
Biomechanical Effect

BACKGROUND: Dynamic hip screw (DHS) is a common implant used to treat stable-type intertrochanteric hip fractures. There are many factors that can affect the success rate of the surgery, including the length of side plates. It is therefore important to investigate the biomechanical effect of different DHS side plates on bones. OBJECTIVE: In order to reduce the likelihood of an implant failure, the aim of this study was to use finite element analysis (FEA) to investigate and understand the effect of side plates with different lengths in DHS. METHODS: In this FEA study, a 3D model with cortical bone, cancellous bone, side plate, lag screw, and cortical screws to simulate the implantation of DHS with different lengths of side plate (2-hole, 4-hole, and 6-hole) for intertrochanteric hip fractures was constructed. The loading condition was used to simulate the force (400 N) on the femoral head and the stress distribution on the lag screw, side plate, cortical screws, and femur was measured. RESULTS: The highest stress points occured around the region of contact between the screw and the cortical bones. The stress on the femur at the most distal cortical screw was the greatest. The shorter the length of the side plate, the greater the stress on the cortical screws, resulting in an increased stress on the femur surrounding the cortical screws. CONCLUSIONS: The use of DHS with 2-hole side plate may increase the risk of side plate pull-out. The results of this study provide a biomechanical analysis for selection of DHS implant lengths that can be useful for orthopaedic surgeons.

EFFECTS OF DIFFERENT LATERAL FEMORAL WALL THICKNESSES IN INTERTROCHANTERIC HIP FRACTURE TREATED WITH DYNAMIC HIP SCREW

2019 ◽  
Vol 19 (02) ◽  
pp. 1940022
Author(s):  
CHENG-CHI WANG ◽  
CHENG-HUNG LEE ◽  
KUN-HUI CHEN ◽  
CHIEN-CHOU PAN ◽  
KUO-CHIH SU
Keyword(s):  
Hip Fractures ◽  
Stress Shielding ◽  
Simulation Models ◽  
Lateral Wall ◽  
Dynamic Hip Screw ◽  
Shielding Effect ◽  
Element Analysis ◽  
Lag Screw ◽  
Hip Screw ◽  
Biomechanical Effect

Dynamic hip screw (DHS) is commonly used for stable-type intertrochanteric hip fractures. The importance of lateral femoral wall has been mentioned while treating intertrochanteric hip fractures with DHS. The aim of this study was mainly to investigate the biomechanical effect of different thickness of lateral femoral wall using finite element analysis (FEA). This study constructed FEA simulation models for five different lateral femoral wall thicknesses, and demonstrated the stress distribution on the femoral bone, the cortical screws, the cancellous bone around the lag screw, and the lag screw. The main results showed that when the DHS is implanted, less stress will be distributed at the implantation site on the femur due to the stress-shielding effect. The stress on the cortical screws will be greater at the junction of the cortical screws and the cortical bone. Intertrochanteric hip fractures with a thinner lateral wall thickness may cause higher stress on the femur after DHS is implanted.

scholarly journals Intertrochanteric fracture fixation with Dynamic Hip Screw: Is tip-apex distance measurement useful for predicting fixation failure?

2020 ◽  
Vol 15 (1) ◽  
Author(s):  
Goh KL ◽  
Zamzuri Z ◽  
Mohd Ariff S ◽  
Mohamed Azril MA
Keyword(s):  
Intertrochanteric Fracture ◽  
Demographic Data ◽  
Dynamic Hip Screw ◽  
Optimal Placement ◽  
Fixation Failure ◽  
Lag Screw ◽  
Hip Screw ◽  
Tip Apex Distance ◽  
One Year

Introduction: Application of dynamic hip screw (DHS) implant for the treatment of unstable intertrochanteric fractures continues to raise concern related to risk of lag screw cut-out with or without subsequent damage to the acetabulum. Measurement of tip-apex distances (TAD) has been recommended to guide the optimal placement of lag screw and to predict subsequent risk of screw cut-out. In this study, the value of TAD was evaluated to verify its usefulness. Methods: This is a retrospective study of 33 consecutive patients with intertrochanteric fracture treated with DHS. Demographic data of the patients were traced from their case notes. Post-operative radiographs were reviewed by focusing on measurement of TAD on anteroposterior and lateral radiographs. Radiographs at one year follow-up were reviewed to depict any fixation-related failure or complication. Results: Fifty two percent of patients did not achieved the recommended TAD of ≤ 25mm. The mean post-operative TAD was 25.9mm and elderly patients were likely to achieve TAD of ≤ 25mm. The overall complication rate of 6% was attributed to screw cut-out in two cases. The unstable left-sided fracture was identified to be a potential risk for screw cut-out or migration. Conclusion: TAD is a valuable measurement to guide optimal placement of lag screw during DHS fixation of intertrochanteric fracture.

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.

scholarly journals INTERTROCHANTERIC FRACTURES;

2017 ◽  
Vol 24 (11) ◽  
pp. 1740-1744
Author(s):  
Faaiz Ali Shah ◽  
Waqar Alam ◽  
Mian Amjad Ali
Keyword(s):  
Case Series ◽  
Dynamic Hip Screw ◽  
Mechanical Complication ◽  
Intertrochanteric Fractures ◽  
Contributing Factors ◽  
Exclusion Criteria ◽  
Lag Screw ◽  
Hip Screw ◽  
Tip Apex Distance ◽  
Superior Portion

Objectives: To determine the frequency of lag screw cut out in intertrochantericfractures fixed with dynamic hip screw and to identify the possible contributing factors for screwcut out. Study Design: Descriptive case series. Place and Duration of the Study: Orthopaedic& Traumatology Unit”A” Lady. Reading Hospital Peshawar from January 2014 to January 2017.Material and Methods: Patients of either gender or age with intertrochanteric fractures fulfillingthe inclusion and exclusion criteria were fixed with dynamic hip screw (DHS). Post operativelyfracture reduction, position of screw in head of femur and tip apex distance were calculatedon anterio posterior and lateral radiographs. All the patients were reviewed fortnightly for twomonth and then monthly for six months for lag screw cut out on radiographs. Results: Total 110patients mean age 72(range 22 to 98 years) years were fixed with dynamic hip screw. Lag screwcut out was noted in 12(10.9%) patients with 4(33.3%) male and 8(66.6%) female patients.The mean age was 62 years. Right side was involved in two (16.6%) patients while left in ten(83.3%) patients. Radiographically fracture reduction was poor in most (50%, n=6)) patients.The mean tip apex distance (TAD) was 32mm (range 24 to 40 mm). Majority (75%, n=9) ofcut out screw were in superior portion of the head of femur. Four (33.3%) patients had screwcut out at 8th week postoperatively while eight (66.6%) patients had screw cut out at 12th week.Conclusion: Lag screw cut out wasthe most common mechanical complication after fixation ofintertrochanteric fractures and all of the cut out patients were elderly with inadequately reducedfracture, superiorly placed lag screw and longer tip apex distance.

Redrawing Operation a Star Shape from Cylindrical Shape Using Experimental and FE Analysis

2020 ◽  
Vol 38 (1A) ◽  
pp. 25-32
Author(s):  
Waleed Kh. Jawad ◽  
Ali T. Ikal
Keyword(s):  
Finite Element ◽  
Effective Strain ◽  
Element Model ◽  
Cylindrical Shape ◽  
Element Analysis ◽  
Punch Force ◽  
Maximum Value ◽  
Element Simulation ◽  
Blank Sheet ◽  
The Finite Element Model

The aim of this paper is to design and fabricate a star die and a cylindrical die to produce a star shape by redrawing the cylindrical shape and comparing it to the conventional method of producing a star cup drawn from the circular blank sheet using experimental (EXP) and finite element simulation (FES). The redrawing and drawing process was done to produce a star cup with the dimension of (41.5 × 34.69mm), and (30 mm). The finite element model is performed via mechanical APDL ANSYS18.0 to modulate the redrawing and drawing operation. The results of finite element analysis were compared with the experimental results and it is found that the maximum punch force (39.12KN) recorded with the production of a star shape drawn from the circular blank sheet when comparing the punch force (32.33 KN) recorded when redrawing the cylindrical shape into a star shape. This is due to the exposure of the cup produced drawn from the blank to the highest tensile stress. The highest value of the effective stress (709MPa) and effective strain (0.751) recorded with the star shape drawn from a circular blank sheet. The maximum value of lamination (8.707%) is recorded at the cup curling (the concave area) with the first method compared to the maximum value of lamination (5.822%) recorded at the cup curling (the concave area) with the second method because of this exposure to the highest concentration of stresses. The best distribution of thickness, strains, and stresses when producing a star shape by

scholarly journals Finite element analysis of double‐plate fixation using reversed locking compression‐distal femoral plates for Vancouver B1 periprosthetic femoral fractures

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Daisuke Takahashi ◽  
Yoshihiro Noyama ◽  
Tsuyoshi Asano ◽  
Tomohiro Shimizu ◽  
Tohru Irie ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Plate Fixation ◽  
Weight Bearing ◽  
Femoral Fractures ◽  
Full Weight Bearing ◽  
Loading Test ◽  
Lateral Plate ◽  
Element Analysis ◽  
Periprosthetic Femoral Fractures

Abstract Background Internal fixation is recommended for treating Vancouver B1 periprosthetic femoral fractures. Although several fixation procedures have been developed with high fixation stability and union rates, long-term weight-bearing constructs are still lacking. Therefore, the aim of the present study was to evaluate the stability of a double-plate procedure using reversed contralateral locking compression-distal femoral plates for fixation of Vancouver B1 periprosthetic femoral fractures under full weight-bearing. Methods Single- and double-plate fixation procedures for locking compression-distal femoral plates were analysed under an axial load of 1,500 N by finite element analysis and biomechanical loading tests. A vertical loading test was performed to the prosthetic head, and the displacements and strains were calculated based on load-displacement and load-strain curves generated by the static compression tests. Results The finite element analysis revealed that double-plate fixation significantly reduced stress concentration at the lateral plate place on the fracture site. Under full weight-bearing, the maximum von Mises stress in the lateral plate was 268 MPa. On the other hand, the maximum stress in the single-plating method occurred at the defect level of the femur with a maximum stress value of 1,303 MPa. The principal strains of single- and double-plate fixation were 0.63 % and 0.058 %, respectively. Consistently, in the axial loading test, the strain values at a 1,500 N loading of the single- and double-plate fixation methods were 1,274.60 ± 11.53 and 317.33 ± 8.03 (× 10− 6), respectively. Conclusions The present study suggests that dual-plate fixation with reversed locking compression-distal femoral plates may be an excellent treatment procedure for patients with Vancouver B1 fractures, allowing for full weight-bearing in the early postoperative period.

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