CEMENTLESS MIS MINI-KEEL PROSTHESIS REDUCES INTERFACE MICROMOTION VERSUS STANDARD STEMMED TIBIAL COMPONENTS

2016 ◽  
Vol 16 (05) ◽  
pp. 1650070 ◽  
Author(s):  
DESMOND Y. R. CHONG ◽  
ULRICH N. HANSEN ◽  
ANDREW A. AMIS
Keyword(s):  
Finite Element ◽  
Bone Ingrowth ◽  
Stair Climbing ◽  
Fixation Strength ◽  
Knee Prostheses ◽  
Periprosthetic Bone ◽  
Design Change ◽  
Initial Stability ◽  
Better Than

Fixation strength of the cementless knee prostheses is dependent on the initial stability of the fixation and minimal relative motion across the prosthesis–bone interface. Broad mini-keels have been developed for tibial components to allow minimally invasive knee arthroplasty, but the effect of the change in fixation design is unknown. In this study, bone–prosthesis interface micromotions of the mini-keel tibial components (consisting of two designs; one is stemless and another with a stem extension of 45[Formula: see text]mm) induced by walking and stair climbing were investigated by finite element modeling and compared with standard stemmed design. The prosthesis surface area amenable for bone ingrowth for the mini-keel tibial components (both stemmed and unstemmed) was predicted to be at least 67% larger than the standard stemmed implant, thereby reducing the risk of long-term aseptic loosening. It was also found that while different load patterns may have led to diverse predictions of the magnitude of the interface micromotions and the extent of osseointegration onto the prosthesis, the outcome of design change evaluation in cementless tibial fixations remains unchanged. The mini-keel tibial components were predicted to anchor onto the periprosthetic bone better than the standard stemmed design under all loading conditions investigated.

Bone Ingrowth Around an Uncemented Femoral Implant Using Mechanoregulatory Algorithm: A Multiscale Finite Element Analysis

2021 ◽  
Author(s):  
Basil Mathai ◽  
Sanjay Gupta
Keyword(s):  
Finite Element ◽  
Bone Tissue ◽  
Bone Ingrowth ◽  
Progressive Increase ◽  
Stair Climbing ◽  
Porous Coating ◽  
Fe Model ◽  
Implant Surface ◽  
Element Analysis ◽  
Medial Side

Abstract The primary fixation and long-term stability of a cementless femoral implant depend on bone ingrowth within the porous coating. Although attempts were made to quantify the peri-implant bone ingrowth using the finite element (FE) analysis and mechanoregulatory principles, the tissue differentiation patterns on a porous-coated hip stem have scarcely been investigated. The objective of this study is to predict the spatial distribution of evolutionary bone ingrowth around an uncemented hip stem, using a 3D multiscale mechanobiology based numerical framework. Multiple load cases representing a variety of daily living activities, including walking, stair climbing, sitting down and standing up from a chair, were used as applied loading conditions. The study accounted for the local variations in host bone material properties and implant-bone relative displacements of the macroscale implanted FE model, in order to predict bone ingrowth in microscale representative volume elements (RVEs) of twelve interfacial regions. In majority RVEs, 20-70% bone tissue (immature and mature) was predicted after two months, contributing towards a progressive increase in average Young's modulus (1200-3000 MPa) of the inter-bead tissue layer. Higher bone ingrowth (mostly greater than 60%) was predicted in the antero-lateral regions of the implant, as compared to the postero-medial side (20-50%). New bone tissue was formed deeper inside the inter-bead spacing, adhering to the implant surface. The study helps to gain an insight into the degree of osseointegration of a porous-coated femoral implant.

scholarly journals Long-term bone remodelling around ‘legendary’ cementless femoral stems

2018 ◽  
Vol 3 (2) ◽  
pp. 45-57 ◽  
Author(s):  
Charles Rivière ◽  
Guido Grappiolo ◽  
Charles A. Engh ◽  
Jean-Pierre Vidalain ◽  
Antonia-F. Chen ◽  
...  
Keyword(s):  
Bone Loss ◽  
Bone Remodelling ◽  
Bone Ingrowth ◽  
Stress Shielding ◽  
Implant Design ◽  
Periprosthetic Bone ◽  
Femoral Stems ◽  
Periprosthetic Bone Loss ◽  
Load Pattern

Bone remodelling around a stem is an unavoidable long-term physiological process highly related to implant design. For some predisposed patients, it can lead to periprosthetic bone loss secondary to severe stress-shielding, which is thought to be detrimental by contributing to late loosening, late periprosthetic fracture, and thus rendering revision surgery more complicated. However, these concerns remain theoretical, since late loosening has yet to be documented among bone ingrowth cementless stems demonstrating periprosthetic bone loss associated with stress-shielding. Because none of the stems replicate the physiological load pattern on the proximal femur, each stem design is associated with a specific load pattern leading to specific adaptive periprosthetic bone remodelling. In their daily practice, orthopaedic surgeons need to differentiate physiological long-term bone remodelling patterns from pathological conditions such as loosening, sepsis or osteolysis. To aid in that process, we decided to clarify the behaviour of the five most used femoral stems. In order to provide translational knowledge, we decided to gather the designers’ and experts’ knowledge and experience related to the design rationale and the long-term bone remodelling of the following femoral stems we deemed ‘legendary’ and still commonly used: Corail (Depuy); Taperloc (Biomet); AML (Depuy); Alloclassic (Zimmer); and CLS-Spotorno (Zimmer).Cite this article: EFORT Open Rev 2018;3:45-57. DOI: 10.1302/2058-5241.3.170024

Contact Mechanics Analysis and Initial Stability of Press-Fit Metal-on-Metal Hip Resurfacing Prostheses

2005 ◽  
Author(s):  
I. Udofia ◽  
F. Liu ◽  
Z. Jin ◽  
P. Roberts ◽  
P. Grigoris
Keyword(s):  
Finite Element ◽  
Contact Mechanics ◽  
Bone Structure ◽  
Hip Resurfacing ◽  
Implant Stability ◽  
Acetabular Cup ◽  
Press Fit ◽  
Initial Stability ◽  
Metal On Metal

To ensure potential long-term stability and survivorship for metal-on-metal hip resurfacing prostheses, implant migration would need to be minimised to encourage bone in-growth. This study uses the finite element method to investigate the effects of the surgical press-fit procedure on the bearing and interfacial contact mechanics, and on the initial stability of a metal-on-metal (MOM) hip resurfacing prosthesis. The finite element models simulated the press-fit procedure using different amounts of interference between the cup-bone (1–2mm). The resurfacing prosthesis was implanted anatomically into a 3-D bone model. Resultant hip joint loads were applied to the model through muscle and subtrochanteric forces. Results showed that increasing the friction and the interference between the cup and bone resulted in significant reductions in the relative micromotion between the cup and bone. This would ensure the immediate post-operative stability of the acetabular cup and provide adequate conditions for potential long-term bone in-growth and implant stability. The contact mechanics at the bearing surfaces, which has a large effect on tribological performance, was found to be little affected by changes at the cup-bone interface. These findings are consistent with the general satisfactory short and medium-term clinical results of metal-on-metal hip resurfacing prostheses. This study suggests that interference, friction and a mechanically sound bone structure are important parameters to promote implant stability and support.

Repair of Periprosthetic Pelvis Defects With Porous Metal Implants: A Finite Element Study

2010 ◽  
Vol 132 (2) ◽  
Author(s):  
Danny L. Levine ◽  
Mehul A. Dharia ◽  
Eik Siggelkow ◽  
Roy D. Crowninshield ◽  
Dale A. Degroff ◽  
...  
Keyword(s):  
Finite Element ◽  
Stair Climbing ◽  
Pelvic Bone ◽  
Filler Materials ◽  
Trabecular Metal ◽  
Periprosthetic Bone ◽  
Bone Stress ◽  
Reconstruction Methods ◽  
Local Bone ◽  
Acetabular Implant

Periacetabular osteolysis is a potentially difficult surgical challenge, which can often drive the choice of reconstruction methods used in revision hip replacement. For smaller defects, impaction of bone grafts may be sufficient, but larger defects can require filler materials that provide structural support in addition to filling a void. This study utilized finite element analysis (FEA) to examine the state of stress in periprosthetic pelvic bone when subjected to a stair-climbing load and in the presence of two simulated defects, to show the effect of implanting a defect repair implant fabricated from Trabecular Metal™. Even a small medial bone defect showed a local stress elevation of 4× compared with that seen with an acetabular implant supported by intact periacetabular bone. Local bone stress was much greater (8× the baseline level) for a defect case in which the loss of bone superior to the acetabular implant permitted significant migration. FEA results showed that a repair of the small defect with a Trabecular Metal™ restrictor lowered periprosthetic bone stress to a level comparable to that in the case of a primary implant. For the larger defect case, the use of a Trabecular Metal™ augment provides structural stabilization and helps to restore the THR head center. However, stress in the adjacent periprosthetic bone is lower than that observed in the defect-free acetabulum. In the augment case, the load path between the femoral head and the pelvis now passes through the augment as the superior rim of the acetabulum has been replaced. Contact-induced stress in the augment is similar in magnitude to that seen in the superior rim of the baseline case, although the stress pattern in the augment is noticeably different from that in intact bone.

Interface biomechanics of the Anca Dual Fit hip stem: An in vitro experimental study

2001 ◽  
Vol 215 (6) ◽  
pp. 555-564 ◽  
Author(s):  
L Monti ◽  
L Cristofolini ◽  
M Viceconti
Keyword(s):  
Load Transfer ◽  
Bone Ingrowth ◽  
Stress Shielding ◽  
Primary Stability ◽  
Stair Climbing ◽  
Term Stability ◽  
Long Term Stability ◽  
Cemented Stem

The Anca Dual Fit hip stem (Cremascoli Wright, Milan, Italy) is a partially cemented stem developed to overcome the drawbacks of both cemented and uncemented fixations. Its design was based on the hypothesis that partial cementing would ensure the primary stability necessary to allow bone ingrowth on the cement-free stem surfaces. At the same time, the limitation of the cement to the proximal regions would prevent stress-shielding by increasing proximal load transfer. After finite element (FE) simulations and in vitro primary stability assessment, an analysis of the long-term stability of the Anca Dual Fit stem was necessary to conclude the preclinical testing. Three stems were implanted in composite femurs and subjected to testing for 1 × 106 cycles, each cycle reproducing the activity of stair climbing. The simulation was designed so as to replicate the physiological loading in a simplified, yet relevant way for this test. Various measurements were collected before, during and after the test in order to give exhaustive information on the response of the implant to long-term, cyclic loading. The present study confirmed the positive results of previous investigations, and proved that the Anca Dual Fit stem has excellent long-term stability; therefore successful clinical outcomes are predicted.

scholarly journals Finite Element Analysis of Custom Shoulder Implants Provides Accurate Prediction of Initial Stability

Mathematics ◽  
2020 ◽  
Vol 8 (7) ◽  
pp. 1113
Author(s):  
Jonathan Pitocchi ◽  
Mariska Wesseling ◽  
Gerrit Harry van Lenthe ◽  
María Angeles Pérez
Keyword(s):  
Finite Element ◽  
Bone Ingrowth ◽  
Mechanical Test ◽  
Fe Analysis ◽  
Patient Specific ◽  
Rank Test ◽  
Bench Test ◽  
Initial Fixation ◽  
Initial Stability ◽  
The Stability

Custom reverse shoulder implants represent a valuable solution for patients with large bone defects. Since each implant has unique patient-specific features, finite element (FE) analysis has the potential to guide the design process by virtually comparing the stability of multiple configurations without the need of a mechanical test. The aim of this study was to develop an automated virtual bench test to evaluate the initial stability of custom shoulder implants during the design phase, by simulating a fixation experiment as defined by ASTM F2028-14. Three-dimensional (3D) FE models were generated to simulate the stability test and the predictions were compared to experimental measurements. Good agreement was found between the baseplate displacement measured experimentally and determined from the FE analysis (Spearman’s rank test, p < 0.05, correlation coefficient ρs = 0.81). Interface micromotion analysis predicted good initial fixation (micromotion <150 µm, commonly used as bone ingrowth threshold). In conclusion, the finite element model presented in this study was able to replicate the mechanical condition of a standard test for a custom shoulder implants.

Effect of Bone Material Properties on the Initial Stability of a Cementless Hip Stem: A Finite Element Study

2005 ◽  
Vol 219 (4) ◽  
pp. 265-275 ◽  
Author(s):  
A S Wong ◽  
A M R New ◽  
G Isaacs ◽  
M Taylor
Keyword(s):  
Finite Element ◽  
Bone Quality ◽  
Cancellous Bone ◽  
Bone Ingrowth ◽  
Clinical Results ◽  
Relative Effect ◽  
Bone Strain ◽  
Fe Model ◽  
Initial Stability ◽  
Hip Stems

In previous finite element studies of cementless hip stems reported in the literature, the effect of bone quality on the initial micromotion and interface bone strain has been rarely reported. In this study, the effect of varying cortical and cancellous bone modulus on initial stem micromotion and interface bone strain was examined and the potential consequence of these changes on bone ingrowth and implant migration was reported. A finite element (FE) model of a total hip replacement (THR) was created and the Young's moduli of cortical and cancellous bone were systematically varied to study the relative effect of the quality of both types of bone on the initial stability of a cementless THR. It was found that the initial micromotion and interface bone strain in a THR was significantly affected by the overall stiffness of the femur. In other words, both the reduction of the modulus of cortical and cancellous bone caused an increase in the initial micromotion and interface bone strain. This suggests that for FE studies to be truly predictive, a range of bone quality must be examined to study the performance envelope of a particular stem and to allow comparison with clinical results.

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