Mechanics of the canine femur with two types of hip replacement stems

2003 ◽  
Vol 16 (03) ◽  
pp. 145-52 ◽  
Author(s):  
L. Banks-Sills ◽  
R. Eliasy ◽  
R. Shahar
Keyword(s):  
Finite Element ◽  
Hip Replacement ◽  
Three Dimensional ◽  
Stress Shielding ◽  
Femoral Stem ◽  
Cementless Stem ◽  
Entire Cross Section ◽  
Element Analysis ◽  
Periprosthetic Bone Loss ◽  
Intact Femur

SummaryThe long-term performance of total hip replacement is of concern to veterinary surgeons. Two of the main complications associated with this procedure are implant loosening and stress shielding. Designs of the femoral stem which will avoid loosening and achieve maximum endurance while reducing stress shielding and periprosthetic bone loss are sought.In the intact femur the stress is distributed over the entire cross section of the bone. After hip replacement this pattern of stress distribution is altered because of the manner in which the load is transferred from the prosthesis to the bone.The objective of this study was to examine the stresses that develop in the femur and implant components of two different methods of hip replacement used clinically in dogs. Anatomic, three-dimensional finite element models of the canine femur with a cemented femoral stem and a Zurich cementless stem were constructed. The stresses and displacements were calculated by the finite element analysis method, under physiologic loads that included muscle forces and joint reaction forces. The results were compared to results obtained by a similar analysis of an intact femur.This study demonstrates that the Zurich cementless method causes less stress shielding in the proximal femoral cortex than does the cemented method. Implant stresses are higher in the Zurich cementless stem, but still within an acceptable range.

ACETABULAR LOAD-TRANSFER AND MECHANICAL STABILITY: A FINITE ELEMENT ANALYSIS COMPARING DIFFERENT CEMENTLESS SOCKETS

2014 ◽  
Vol 14 (05) ◽  
pp. 1450063 ◽  
Author(s):  
D. F. M. PAKVIS ◽  
D. JANSSEN ◽  
B. W. SCHREURS ◽  
N. VERDONSCHOT
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Load Transfer ◽  
Mechanical Stability ◽  
Three Dimensional ◽  
Stress Shielding ◽  
Physiological Strain ◽  
Element Analysis ◽  
Strain Pattern ◽  
Component Interface

Acetabular stress shielding may be a failure mechanism of acetabular constructs promoting osteolysis, aseptic loosening and failure. We used three-dimensional finite element analysis (FEA) to evaluate the effect of flexible sockets on acetabular stress shielding. The sockets were made of (1) full polyethylene (PE), (2) PE with a metal bearing and (3) a PE insert with a metal backing was used as a traditional stiff implant. We compared the strain energy density and interfacial micro-motions between bone and cementless sockets during walking. In our FEA model, the most elastic socket (case 1) showed the highest levels of micro-motion during walking (400 μm). The most rigid socket (case 3) showed smaller areas of high micro-motions. Assuming a threshold for ingrowth of 50 microns, the flexible cup showed an ingrowth area of almost 40%, whereas the other two cases showed stable areas covering 60% of the total bone–component interface. Furthermore, we found that the introduction of an implant generates a very different strain pattern directly around the implant as compared with the intact case, which has a horse-shoe shaped cartilage layer in the acetabulum. This difference was not affected much by the stiffness of the implant; a more flexible implant resulted in only slightly higher strain levels. Bone strains over 1.5 mm from the cup showed physiological values and were not affected by the stiffness of the implant. Hence, this study shows that the physiological strain patterns are not obtained in the direct periprosthetic bone, regardless of the stiffness of the material.

scholarly journals Fabrication of Low-Cost Hip Implant using Direct Metal Laser Sintering Technique

2019 ◽  
Vol 8 (4) ◽  
pp. 4544-4547
Keyword(s):  
Finite Element ◽  
Low Cost ◽  
Fibrous Tissue ◽  
Three Dimensional ◽  
Stress Shielding ◽  
Element Analysis ◽  
Hip Implant ◽  
Neck Shaft Angle ◽  
Hip Morphology ◽  
Direct Laser

Total hip replacement (THR) is the most popular surgery been performed in orthopedic surgery due to the inclination of musculoskeletal disorder and the aging population worldwide. However, the implant’s cost-burdened the patient, especially in the ASEAN region. The main objective of this study was to fabricate the low-cost hip implant using direct laser metal sintering (DMLS). The framework starts with the three dimensional of hip anthropometric datasets from computed tomography scanner, followed with the design of hip implant, computational analysis using finite element, and finally fabrication using DMLS technique. The morphological results demonstrated the value of neck-shaft angle was 130.46º, and the femoral head offset of 30.35 mm. The finite element analysis showed strain distribution was 65 MPa for the implant in metaphyseal region and 110 MPa for intact femur under staircase physiological loading which indicated inhibition of stress shielding at medical calcar region, and micromotion was 4.8 µm which prevent the formation of fibrous tissue and promoting osseointegration between implant-bone interfaces. This study proposed the fabrication using the DMLS technique, which produced accurate implant with low-cost, which suits the ASEAN hip morphology that prolongs implant lifetime.

scholarly journals Design process of cementless femoral stem using a nonlinear three dimensional finite element analysis

2014 ◽  
Vol 15 (1) ◽  
Author(s):  
Mohd Yusof Baharuddin ◽  
Sh-Hussain Salleh ◽  
Ahmad Hafiz Zulkifly ◽  
Muhammad Hisyam Lee ◽  
Alias Mohd Noor ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Design Process ◽  
Three Dimensional ◽  
Femoral Stem ◽  
Element Analysis ◽  
Dimensional Finite Element ◽  
Cementless Femoral Stem ◽  
Three Dimensional Finite Element

Semi-Automated Hexahedral Mesh Generation of Human Vertebrae by Isoparametric Mapping

2008 ◽  
Author(s):  
Yifei Dai ◽  
Glen L. Niebur
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
Spinal Instrumentation ◽  
Stress Shielding ◽  
Finite Element Models ◽  
Hexahedral Mesh ◽  
Element Analysis ◽  
Dimensional Finite Element ◽  
As Stress ◽  
Three Dimensional Finite Element

Subject-specific finite element models provide a means to explore inter-subject biomechanical variations, and have been widely used in the study of spinal fusion such as stress-shielding due to spinal instrumentation [1], and to assess biomechanical response to aging and disease [2–4]. Three-dimensional finite element models of vertebrae are usually constructed from CT scans. However, manual generation of meshes is labor intensive. As such, techniques that simplify creation of meshes are needed to make finite element analysis more feasible for large biomechanical studies and clinical applications.

Finite Element Analysis in Femoral Fixation with TA3 Titanium Compressioll Plate

2013 ◽  
Vol 647 ◽  
pp. 16-19 ◽  
Author(s):  
Gang Tang ◽  
Shi Lei Liu ◽  
Dong Mei Wang ◽  
Gao Feng Wei ◽  
Cheng Tao Wang
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Geometric Model ◽  
Three Dimensional ◽  
Stress Shielding ◽  
Shielding Effect ◽  
The Finite Element Method ◽  
Element Analysis ◽  
Femoral Fixation ◽  
Element Method

To analyze the stress shielding in femoral fixation with TA3 Titanium compressioll plate by using the finite element method. Firstly, establish TA3 Titanium compressioll plate, screws and three-dimensional geometric model of the femur; and its mesh, and the establishment of the corresponding three-dimensional finite element model; the final definition of material properties, and load boundary conditions. During standing state, the strength of plate and screw has been analyzed by the finite element method, while the femoral stress shielding has been analyzed. Standing stress when compared to normal bone stock, TA3 Titanium compressioll plate and screws for femoral stress shielding effect is not obvious. Established in this paper plate on the femur stress shielding of the analytical method can be widely applied in other state analysis of stress shielding bone fracture.

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