Optimization of a Cemented Femoral Prosthesis Considering Bone Remodeling

2015 ◽  
Vol 138 (1) ◽  
Author(s):  
Leandro Luis Corso ◽  
Leandro de Freitas Spinelli ◽  
Fernando Schnaid ◽  
Crisley Dossin Zanrosso ◽  
Rogério José Marczak
Keyword(s):  
Bone Loss ◽  
Bone Remodeling ◽  
Hip Replacement ◽  
Computational Models ◽  
Three Dimensional ◽  
Femoral Stem ◽  
Optimization Procedure ◽  
Design Parameters ◽  
Femoral Bone ◽  
Bone Mass Loss

The study presents a numerical methodology for minimizing the bone loss in human femur submitted to total hip replacement (THR) procedure with focus on cemented femoral stem. Three-dimensional computational models were used to describe the femoral bone behavior. An optimization procedure using the genetic algorithm (GA) method was applied in order to minimize the bone loss, considering the geometry and the material of the prosthesis as well as the design of the stem. Internal and external bone remodeling were analyzed numerically. The numerical method proposed here showed that the bone mass loss could be reduced by 24%, changing the design parameters.

Reliability-Based Design Optimization of a Cemented Prosthesis in a Femur Undergoing Bone Remodeling

2019 ◽  
Vol 142 (4) ◽  
Author(s):  
Leandro Luis Corso ◽  
Herbert Martins Gomes ◽  
Leandro de Freitas Spinelli ◽  
Crisley Dossin Zanrosso ◽  
Rogério José Marczak ◽  
...  
Keyword(s):  
Design Optimization ◽  
Bone Remodeling ◽  
Three Dimensional ◽  
Young Modulus ◽  
Fe Model ◽  
Reliability Based Design Optimization ◽  
Bone Mass Loss ◽  
Reliability Based Design ◽  
Design Variables ◽  
Three Dimensional Finite Element

Abstract This study proposes a numerical methodology to minimize the bone mass loss in a femur with a total hip arthroplasty procedure, considering uncertainties in the material parameters and using a reliability-based design optimization (RBDO) procedure. A genetic algorithm (GA) is applied for optimization, and a three-dimensional finite element (FE) model associated with the bone remodeling procedure is proposed and described to account for the internal and external femoral bone behavior. An example of a femoral prosthesis design is presented as a basis for discussion of the proposed methodologies, and the corresponding reliability level is evaluated. Constraints on the strength of all materials and target reliability levels are inputs to the optimization model. The main prosthesis dimensions and Young modulus are the design variables. The proposed methodology is compared with a well-known deterministic optimization (DO) procedure and the results show that it is important to consider the uncertainties in this kind of problem since in this case, the a posteriori reliability may be low.

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.

scholarly journals Optimization of an Endoscopic Radiofrequency Ablation Electrode

2018 ◽  
Vol 12 (3) ◽  
Author(s):  
Bradley Hanks ◽  
Mary Frecker ◽  
Matthew Moyer
Keyword(s):  
Radiofrequency Ablation ◽  
Thermal Ablation ◽  
Computational Models ◽  
Optimization Procedure ◽  
Pancreatic Tissue ◽  
Design Parameters ◽  
Electrode Design ◽  
Systematic Design ◽  
Spherical Tumor ◽  
Compliant Electrode

Radiofrequency ablation (RFA) is an increasingly used, minimally invasive, cancer treatment modality for patients who are unwilling or unable to undergo a major resective surgery. There is a need for RFA electrodes that generate thermal ablation zones that closely match the geometry of typical tumors, especially for endoscopic ultrasound-guided (EUS) RFA. In this paper, the procedure for optimization of an RFA electrode is presented. First, a novel compliant electrode design is proposed. Next, a thermal ablation model is developed to predict the ablation zone produced by an RFA electrode in biological tissue. Then, a multi-objective genetic algorithm is used to optimize two cases of the electrode geometry to match the region of destructed tissue to a spherical tumor of a specified diameter. This optimization procedure is then applied to EUS-RFA ablation of pancreatic tissue. For a target 2.5 cm spherical tumor, the optimal design parameters of the compliant electrode design are found for two cases. Cases 1 and 2 optimal solutions filled 70.9% and 87.0% of the target volume as compared to only 25.1% for a standard straight electrode. The results of the optimization demonstrate how computational models combined with optimization can be used for systematic design of ablation electrodes. The optimization procedure may be applied to RFA of various tissue types for systematic design of electrodes for a specific target shape.

Revision total hip arthroplasty in patients with femoral bone loss using tapered rectangular femoral stem: a minimum 10 years’ follow-up

2020 ◽  
Vol 30 (5) ◽  
pp. 622-628
Author(s):  
Jian Wang ◽  
Wen-Li Dai ◽  
Ze-Ming Lin ◽  
Zhan-Jun Shi
Keyword(s):  
Total Hip Arthroplasty ◽  
Bone Loss ◽  
Aseptic Loosening ◽  
Hip Arthroplasty ◽  
Femoral Stem ◽  
Revision Total Hip Arthroplasty ◽  
Femoral Bone ◽  
Revision Tha ◽  
The Mean

Background: Revision total hip arthroplasty (THA) remains a significant challenge when there is severe femoral bone loss. The purpose of this study was to evaluate the clinical and radiographic outcomes of revision THA in patients with femoral bone loss treated with Zweymüller SLR-Plus stem. Methods: A retrospective review of 82 patients who underwent revision THA using tapered rectangular femoral stem between 1997 and 2007 was undertaken. Of the 82 patients, 9 patients were lost to follow-up and were excluded from the study. The most common reason for revision was aseptic loosening (92%), periprosthetic femur fracture (5%), and infection (3%). Bone loss was categorised preoperatively according to the Paprosky classification. The mean clinical follow-up was 14 years (range 10–19 years). Their mean age at the time of index surgery was 54.7 ± 15.3 (range 30–82) years. Results: The mean Harris Hip Score was significantly improved at final follow-up (68.1 ±10.3) compared with that before the revision surgery (30.4 ± 7.7) ( p < 0.0001). Of the 75 stems, 69 (92%) stems were radiographically stable at the last evaluation. Among the 69 stems, 64 hips (85%) had radiographic evidence of bone ingrowth and 5 (5%) had stable fibrous fixation of the stem. Among the 7 hips that were re-revised, 5 hips were re-revised for aseptic loosening, whereas 2 were re-revised for an infection. Kaplan-Meier survivorship analysis, with removal of the stem for any cause as the endpoint, revealed that the 15-year rate of survival of the components was 90% (95% CI, 0.83–0.97). Conclusion: Revision THA in patients with proximal femoral bone loss using Zweymüller SLR-Plus stem led to a high rate of osseointegration of the stem and good clinical results at long-term follow-up.

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