The effect of cannulated screw material on stress transfer parameter in orthotropic femur bone with Pauwels type-III fracture

2019 ◽  
Vol 16 ◽  
pp. 2135-2143
Author(s):  
M.H. Khan ◽  
R. Daud ◽  
M.K. Ali Hassan ◽  
A.F. Azizan ◽  
B. Izzawati ◽  
...  
Keyword(s):  
Stress Transfer ◽  
Cannulated Screw ◽  
Transfer Parameter ◽  
Type Iii ◽  
Femur Bone

Modified F Configuration in the Treatment of Pauwels Type III Femoral Neck Fracture: a Finite Element Analysis

2021 ◽  
Author(s):  
Shiyuan Lin ◽  
Huizi Li ◽  
Kai Tong ◽  
Zihang Feng ◽  
Gang Wang ◽  
...  
Keyword(s):  
Finite Element ◽  
Stress Distribution ◽  
Femoral Neck ◽  
Femoral Neck Fracture ◽  
Femoral Neck Fractures ◽  
Cannulated Screw ◽  
Type Iii ◽  
Neck Fracture ◽  
Maximum Crack ◽  
Hip Screw

Abstract Background: The optimal treatment of Pauwels type III femoral neck fracture in young patients remains a worldwide challenge in orthopedic surgery. Methods: Finite element models of four internal fixations were developed to treat Pauwels type III Femoral neck fracture: a: the traditional inverted triangular cannulated screw model, b: the F-technique cannulated screw model, c: the modified F-technique cannulated screw model using a fully threaded screw instead of a partially threaded distally, d: the dynamic hip screw coupled with anti-rotational screw model. Under the same conditions, finite element analyses were carried out to compare the displacement and von Mises stress distribution of four internal fixations and femurs, the maximum crack distances of the fracture surfaces, Z axis displacements of four models as well as the stress distribution in the subtrochanteric region. Results: The modified F-technique configuration resulted in a more stable fixation as compared to the other three approaches, with respect to the maximum displacement and stress peaks of femur and internal fixations, the maximum crack distances of the fracture surfaces, Z axis displacements of four configurations as well as the stress distribution in the subtrochanteric region.Conclusions: Our results suggested that modified F-technique configuration show a better performance in resisting shearing and rotational forces in treating Pauwels type III femoral neck fractures compared to those using traditional inverted triangular, the F-technique configuration or dynamic hip screw coupled with anti-rotational screw, providing a new choice for the treatment of femoral neck fractures.

Modified cannulated screw fixation in the treatment of Pauwels type III femoral neck fractures: A biomechanical study

2020 ◽  
Vol 74 ◽  
pp. 103-110 ◽  
Author(s):  
Lin Zhou ◽  
Jiaming Lin ◽  
Anfei Huang ◽  
Weidong Gan ◽  
Xu Zhai ◽  
...  
Keyword(s):  
Femoral Neck ◽  
Screw Fixation ◽  
Biomechanical Study ◽  
Femoral Neck Fractures ◽  
Cannulated Screw ◽  
Type Iii

scholarly journals Influence of pedicle screw thread width and recovery time after surgery on fixation strength

2021 ◽  
Vol 7 (2) ◽  
pp. 751-754
Author(s):  
Harikrishna Makaram ◽  
Ramakrishnan Swaminathan
Keyword(s):  
Cortical Bone ◽  
Pedicle Screw ◽  
Stress Shielding ◽  
Stress Transfer ◽  
Fixation Strength ◽  
Screw Thread ◽  
Fe Model ◽  
Contact Conditions ◽  
Transfer Parameter ◽  
Pull Out

Abstract Introduction: Pedicle screw fixation systems are widely used for treatment of various spinal pathologies, including spinal stenosis, scoliosis, spinal deformities and fractures. Stress shielding is considered to be a major factor contributing to insufficient fixation strength, leading to screw loosening. In this study, the influence of pedicle screw thread width on the displacement of pedicle screw and stress transfer is analyzed using 2-Dimensional axisymmetric finite element (FE) model. Methods: FE model consisting of cancellous and cortical bone, along with pedicle screw is developed for this study. The pedicle screw thread width is varied between 0.1 mm and 0.6 mm in steps of 0.1 mm, while the other geometric parameters, including screw half-angle, pitch, diameter, and length are kept constant. Three different contact conditions between screw and bone, such as frictionless, frictional, and bonded are considered to simulate hours, days, and months after surgery, respectively. The material properties and boundary conditions are applied based on previous studies. An axial force of 80 N is applied on the screw head to simulate axial pull-out test. Results: Similar patterns of stress distribution are observed for all screw models, with high stress concentration above the first thread. The highest displacement in screw is observed shortly after surgery, while the highest displacement in cancellous and cortical bone is observed few days and months after the surgery, respectively. The average von Mises stress in screw decreases with increase in thread width for all contact conditions. In few hours/days after the surgery, stress transfer parameter increases with increase in thread width, up to a thread width of 0.5 mm and then decreases. The changes in stress transfer parameter are negligible few months after the surgery. Conclusion: This study highlights the influence of thread width on displacement and stress transferred to the bone, at different durations after the surgery. It is observed that a thread width of 0.5 mm exhibits the highest stress transfer, leading to reduced stress shielding and improved bone remodeling. It appears that this study might aid in developing better pedicle screws for the treatment of various spinal pathologies.

The effect of different types of half pins on stress transfer parameter during osseointegration

2019 ◽  
Vol 16 ◽  
pp. 2179-2186
Author(s):  
N.F.I. Ibrahim ◽  
R. Daud ◽  
M.K. Ali Hassan ◽  
N.A.M. Zain ◽  
A.F. Azizan
Keyword(s):  
Stress Transfer ◽  
Transfer Parameter ◽  
Different Types

scholarly journals Modified F configuration in the treatment of Pauwels type III femoral neck fracture: a finite element analysis

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Shiyuan Lin ◽  
Jie Shang ◽  
Baizhou Xing ◽  
Biao Wu ◽  
Rong Peng ◽  
...  
Keyword(s):  
Finite Element ◽  
Stress Distribution ◽  
Femoral Neck ◽  
Femoral Neck Fracture ◽  
Young Patients ◽  
Cannulated Screw ◽  
Type Iii ◽  
Fracture Surfaces ◽  
Neck Fracture ◽  
Maximum Crack

Abstract Background The optimal treatment of Pauwels type III femoral neck fracture (FNF) in young patients remains a worldwide challenge in orthopedic surgery. Methods Finite element models of four internal fixations were developed to treat Pauwels type III FNF: a: the traditional inverted triangular parallel cannulated screw (PCS) model, b: the F-technique cannulated screw model, c: the modified F-technique cannulated screw model using a fully threaded screw instead of a partially threaded distally, d: the dynamic hip screw coupled with derotational screw (DHS + DS) model. Under the same conditions, finite element analyses were carried out to compare the displacement and von Mises stress distribution of four internal fixations and femurs, the maximum crack distances of the fracture surfaces, Z axis displacements of four models as well as the stress distribution in the subtrochanteric region. Results The modified F-technique configuration resulted in a more stable fixation as compared to the other three configurations, with respect to the maximum displacement and stress peaks of femur and internal fixations, the maximum crack distances of the fracture surfaces, Z axis displacements of four configurations as well as the stress distribution in the subtrochanteric region. Conclusions Our results suggested that modified F-technique configuration show a better performance in resisting shearing and rotational forces in treating Pauwels type III FNF compared to those using traditional inverted triangular PCS, the F-technique configuration or DHS + DS, providing a new choice for the treatment of FNFs.

scholarly journals Finite element analysis of a new internal fixation implant for Pauwels type III femoral neck fractures

2020 ◽  
Author(s):  
Zhirong Fan ◽  
Haitao Su ◽  
Zhou Lin ◽  
Huida Huang ◽  
Junde Zhou ◽  
...  
Keyword(s):  
Femoral Head ◽  
Femoral Neck ◽  
Internal Fixation ◽  
Femoral Neck Fractures ◽  
Cannulated Screw ◽  
Von Mises Stress ◽  
Axial Loads ◽  
Fracture Group ◽  
Type Iii ◽  
Von Mises

Abstract Background The optimal treatment strategy for Pauwels type III femoral neck fractures remains controversial. A new internal fixation femoral neck system (FNS) for the treatment of femoral neck fractures was developed, and we compared the mechanical efficiency of the internal fixation FNS with that of two cannulated screw configurations for the treatment of Pauwels type III femoral neck fractures. Method: In this study, we constructed models of Pauwels type III femoral neck fractures with angles of 50°, 60°, and 70°. Moreover, a fixation model with the FNS and two fixation models with cannulated screws were developed. Under two axial loads, 1400 N and 2100 N, the von Mises stress distributions, maximum von Mises stress, and displacements of the femur and internal fixation components were measured for each fracture group. Result The maximum von Mises stress of internal fixation in the three models was mostly located near the fracture line, and the femoral head region closest to the femoral calcar experienced the maximum amount of stress. As the Pauwels angle and axial loads increased, the stress and displacement of the proximal femoral head and internal fixation component increased in each group. Compared with cannulated screw configurations, the internal fixation FNS showed lower values of peak stress at the femoral head and smaller displacements of the femur and internal implant in the treatment of Pauwels type III femoral neck fractures with Pauwels angles of 50°, 60°, and 70°. Conclusion The newly developed internal fixation FNS provided improved biomechanical stability for the treatment of Pauwels type III femoral neck fractures, which indicated that the internal fixation FNS may be a new option for the treatment of vertical femoral neck fractures.

scholarly journals Arthroscopically Assisted Cannulated Screw Fixation for Treating Type III Tibial Intercondylar Eminence Fractures: A Short-Term Retrospective Controlled Study

2021 ◽  
Vol 8 ◽  
Author(s):  
Chao Zheng ◽  
Huanli Han ◽  
Yujiang Cao
Keyword(s):  
Pivot Shift ◽  
Screw Fixation ◽  
Cannulated Screw ◽  
Pivot Shift Test ◽  
Lachman Test ◽  
Type Iii ◽  
Intercondylar Eminence ◽  
Arthroscopically Assisted ◽  
Group A ◽  
Group B

Background: This study presents the clinical results from 22 children who underwent minimally invasive arthroscopically assisted screw fixation for the treatment of intercondylar eminence fractures.Methods: We retrospectively analyzed the clinical data of 22 children (aged 7.5 to 13.5 years) with type III tibial intercondylar eminence fractures who were treated in our department from March 2007 to September 2019. According to the type of operation, the patients were divided into two groups: group A (n = 12) received arthroscopically assisted cannulated screw fixation, and group B (n = 10) received open reduction and cannulated screw internal fixation. Radiography scans, Lysholm scores, International Knee Documentation Committee (IKDC) 2,000 subjective scores, Tegner scores, range of motion (ROM) of the knee, the anterior drawer test (ADT), the Lachman test, and the pivot-shift test were used to evaluate the clinical efficacy.Results: All 22 children were evaluated over a 12 to 58 month follow-up period (mean: 27.5 months). At the final exam, group A was significantly superior to group B in Lysholm scores (93.33 ± 3.55 vs. 86.20 ± 4.52), IKDC scores (92.06 ± 3.55 vs. 86.07 ± 5.81), and Tegner scores (7.75 ± 0.87 vs. 6.40 ± 0.52) and presented shorter operative times (25.42 ± 3.97 vs. 35.00 ± 5.27). The differences were statistically significant (P < 0.05). All the incisions healed primarily. No complications, such as fracture fragment displacement, delayed epiphyseal growth, or knee joint dysfunction, were observed. The drawer test, Lachman test, and pivot-shift test were negative for all patients.Conclusions: Arthroscopically assisted cannulated screw fixation is effective and safe for the treatment of tibial intercondylar eminence fractures, providing excellent stability and quick recovery of joint function.

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