Cortical Bone Viscoelasticity and Fixation Strength of Press-Fit Femoral Stems: An In-Vitro Model

2005 ◽  
Vol 128 (1) ◽  
pp. 13-17 ◽  
Author(s):  
T. L. Norman ◽  
E. S. Ackerman ◽  
T. S. Smith ◽  
T. A. Gruen ◽  
A. J. Yates ◽  
...  
Keyword(s):  
Cortical Bone ◽  
Viscoelastic Behavior ◽  
Fixation Strength ◽  
Viscoelastic Response ◽  
Press Fit ◽  
Initial Stability ◽  
Vitro Model ◽  
Stem Stability ◽  
Push Out

Cementless total hip femoral components rely on press-fit for initial stability and bone healing and remodeling for secondary fixation. However, the determinants of satisfactory press-fit are not well understood. In previous studies, human cortical bone loaded circumferentially to simulate press-fit exhibited viscoelastic, or time dependent, behavior. The effect of bone viscoelastic behavior on the initial stability of press-fit stems is not known. Therefore, in the current study, push-out loads of cylindrical stems press-fit into reamed cadaver diaphyseal femoral specimens were measured immediately after assembly and 24h with stem-bone diametral interference and stem surface treatment as independent variables. It was hypothesized that stem-bone interference would result in a viscoelastic response of bone that would decrease push-out load thereby impairing initial press-fit stability. Results showed that push-out load significantly decreased over a 24h period due to bone viscoelasticity. It was also found that high and low push-out loads occurred at relatively small amounts of stem-bone interference, but a relationship between stem-bone interference and push-out load could not be determined due to variability among specimens. On the basis of this model, it was concluded that press-fit fixation can occur at relatively low levels of diametral interference and that stem-bone interference elicits viscoelastic response that reduces stem stability over time. From a clinical perspective, these results suggest that there could be large variations in initial press-fit fixation among patients.

Stem Length and Neck Resection on Fixation Strength of Press-Fit Radial Head Prosthesis: An In Vitro Model

2019 ◽  
Vol 44 (12) ◽  
pp. 1098.e1-1098.e8
Author(s):  
Jun-Gyu Moon ◽  
Dave R. Shukla ◽  
James S. Fitzsimmons ◽  
Kai-Nan An ◽  
Shawn W. O’Driscoll
Keyword(s):  
Radial Head ◽  
In Vitro Model ◽  
Stem Length ◽  
Fixation Strength ◽  
Radial Head Prosthesis ◽  
Press Fit ◽  
Vitro Model

Cortical Bone Viscoelasticity and Fixation Strength of Press-Fit Femoral Stems: A Finite Element Model

2005 ◽  
Vol 128 (1) ◽  
pp. 7-12 ◽  
Author(s):  
T. R. Shultz ◽  
J. D. Blaha ◽  
T. A. Gruen ◽  
T. L. Norman
Keyword(s):  
Finite Element ◽  
Stress Relaxation ◽  
Finite Element Model ◽  
Cortical Bone ◽  
Coefficient Of Friction ◽  
Viscoelastic Behavior ◽  
Element Model ◽  
Press Fit ◽  
Initial Fixation ◽  
Push Out

Many cementless implant designs rely upon a diaphyseal press-fit in conjunction with a porous coated implant surface to achieve primary or short term fixation, thereby constraining interface micromotion to such a level that bone ingrowth and consequent secondary or long-term fixation, i.e., osseointegration, can occur. Bone viscoelasticity, however, has been found to affect stem primary stability by reducing push-out load. In this investigation, an axisymmetric finite element model of a cylindrical stem and diaphyseal cortical bone section was created in order to parametrically evaluate the effect of bone viscoelasticity on stem push-out while controlling coefficient of friction (μ=0.15, 0.40, and 1.00) and stem-bone diametral interference (δ=0.01, 0.05, 0.10, and 0.50mm). Based on results from a previous study, it was hypothesized that stem-bone interference (i.e., press-fit) would elicit a bone viscoelastic response which would reduce the initial fixation of the stem as measured by push-out load. Results indicate that for all examined combinations of μ and δ, bone viscoelastic behavior reduced the push-out load by a range of 2.6–82.6% due to stress relaxation of the bone. It was found that the push-out load increased with μ for each value of δ, but minimal increases in the push-out load (2.9–4.9%) were observed as δ was increased beyond 0.10mm. Within the range of variables reported for this study, it was concluded that bone viscoelastic behavior, namely stress relaxation, has an asymptotic affect on stem contact pressure, which reduces stem push-out load. It was also found that higher levels of coefficient of friction are beneficial to primary fixation, and that an interference “threshold” exists beyond which no additional gains in push-out load are achieved.

Enhancement of initial stability of press-fit femoral stems using injectable calcium phosphate cement: an in vitro study in dog bones

Biomaterials ◽  
2004 ◽  
Vol 25 (17) ◽  
pp. 3887-3894 ◽  
Author(s):  
E.M. Ooms ◽  
N. Verdonschot ◽  
J.G.C. Wolke ◽  
W.Van de Wijdeven ◽  
M.M.M. Willems ◽  
...  
Keyword(s):  
Calcium Phosphate ◽  
Calcium Phosphate Cement ◽  
In Vitro Study ◽  
Vitro Study ◽  
Press Fit ◽  
Initial Stability ◽  
Femoral Stems

Primary cup fixation with different designs of trapeziometacarpal total joint trapezium components: a radiostereometric analysis in a pig bone model

2011 ◽  
Vol 36 (4) ◽  
pp. 285-290 ◽  
Author(s):  
T. B. Hansen ◽  
M. Meier ◽  
M. C. M. Møller ◽  
K. Larsen ◽  
M. Stilling
Keyword(s):  
Fixation Strength ◽  
Radiostereometric Analysis ◽  
Loading Test ◽  
Bone Model ◽  
Press Fit ◽  
Maximal Load ◽  
Significant Difference ◽  
Joint Prostheses ◽  
Cup Design ◽  
Push Out

High loosening rates of the trapezium components of trapeziometacarpal total joint prostheses have been reported. The purpose of this study was to compare the primary press fit fixation of two different, uncemented cup designs (MOTEC and Elektra) with the primary fixation of a cemented polyethylene cup (DLC) in a pig bone model. We did a push out test to measure the maximal load strength of the implants and a low-pressure cyclic loading test combined with radiostereometric analysis to measure the micromotion of the implants. There was no significant difference in fixation strength between the two uncemented screw cup designs or between the two uncemented screw cups and the cemented polyethylene cup. However, we found that threading of the bone before insertion of the Electra screw cup weakens the primary fixation strength of the implant. The results indicate that focus should be on the insertion technique as well as on the cup design of uncemented trapezium cup implants. Further studies of trapezium implant migration in a clinical setting are needed.

scholarly journals The effect of aminoguanidine (AG) and pyridoxamine (PM) on ageing human cortical bone

2018 ◽  
Vol 7 (1) ◽  
pp. 105-110 ◽  
Author(s):  
O. Abar ◽  
S. Dharmar ◽  
S. Y. Tang
Keyword(s):  
Cortical Bone ◽  
Bone Quality ◽  
Post Translational Modification ◽  
Human Cortical Bone ◽  
Reference Point Indentation ◽  
Reliable Parameter ◽  
Vitro Model ◽  
Susceptible Populations ◽  
Age Range

Objectives Advanced glycation end-products (AGEs) are a post-translational modification of collagen that form spontaneously in the skeletal matrix due to the presence of reducing sugars, such as glucose. The accumulation of AGEs leads to collagen cross-linking, which adversely affects bone quality and has been shown to play a major role in fracture risk. Thus, intervening in the formation and accumulation of AGEs may be a viable means of protecting bone quality. Methods An in vitro model was used to examine the efficacy of two AGE-inhibitors, aminoguanidine (AG) and pyridoxamine (PM), on ageing human cortical bone. Mid-diaphyseal tibial cortical bone segments were obtained from female cadavers (n = 20, age range: 57 years to 97 years) and randomly subjected to one of four treatments: control; glucose only; glucose and AG; or glucose and PM. Following treatment, each specimen underwent mechanical testing under physiological conditions via reference point indentation, and AGEs were quantified by fluorescence. Results Treatment with AG and PM showed a significant decrease in AGE content versus control groups, as well as a significant decrease in the change in indentation distance, a reliable parameter for analyzing bone strength, via two-way analysis of variance (ANOVA) (p < 0.05). Conclusions The data suggest that AG and PM prevent AGE formation and subsequent biomechanical degradation in vitro. Modulation of AGEs may help to identify novel therapeutic targets to mitigate bone quality deterioration, especially deterioration due to ageing and in AGE-susceptible populations (e.g. diabetics). Cite this article: O. Abar, S. Dharmar, S. Y. Tang. The effect of aminoguanidine (AG) and pyridoxamine (PM) on ageing human cortical bone. Bone Joint Res 2018;7:105–110. DOI: 10.1302/2046-3758.71.BJR-2017-0135.R1.

Initial stability and bone strain evaluation of the immediately loaded dental implant: an in vitro model study

2010 ◽  
Vol 22 (7) ◽  
pp. 691-698 ◽  
Author(s):  
Heng-Li Huang ◽  
Yin-Yu Chang ◽  
Dan-Jae Lin ◽  
Yu-Fen Li ◽  
Kuan-Ting Chen ◽  
...  
Keyword(s):  
Dental Implant ◽  
In Vitro Model ◽  
Bone Strain ◽  
Model Study ◽  
Initial Stability ◽  
Vitro Model

An in vitro model for investigation of vitamin A effects on wound healing

2021 ◽  
pp. 1-6
Author(s):  
Hoda Keshmiri Neghab ◽  
Mohammad Hasan Soheilifar ◽  
Gholamreza Esmaeeli Djavid
Keyword(s):  
Wound Healing ◽  
Endothelial Cell ◽  
Vitamin A ◽  
In Vitro Model ◽  
Cellular Proliferation ◽  
Endothelial Cell Migration ◽  
Normal Fibroblast ◽  
Anti Inflammatory ◽  
Vitro Model

Abstract. Wound healing consists of a series of highly orderly overlapping processes characterized by hemostasis, inflammation, proliferation, and remodeling. Prolongation or interruption in each phase can lead to delayed wound healing or a non-healing chronic wound. Vitamin A is a crucial nutrient that is most beneficial for the health of the skin. The present study was undertaken to determine the effect of vitamin A on regeneration, angiogenesis, and inflammation characteristics in an in vitro model system during wound healing. For this purpose, mouse skin normal fibroblast (L929), human umbilical vein endothelial cell (HUVEC), and monocyte/macrophage-like cell line (RAW 264.7) were considered to evaluate proliferation, angiogenesis, and anti-inflammatory responses, respectively. Vitamin A (0.1–5 μM) increased cellular proliferation of L929 and HUVEC (p < 0.05). Similarly, it stimulated angiogenesis by promoting endothelial cell migration up to approximately 4 fold and interestingly tube formation up to 8.5 fold (p < 0.01). Furthermore, vitamin A treatment was shown to decrease the level of nitric oxide production in a dose-dependent effect (p < 0.05), exhibiting the anti-inflammatory property of vitamin A in accelerating wound healing. These results may reveal the therapeutic potential of vitamin A in diabetic wound healing by stimulating regeneration, angiogenesis, and anti-inflammation responses.

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