Vacuum Loading of the Femoral Cement Gun: The Effect on Mantle Porosity

The femoral cement mantle was reproduced in a laboratory model. This model consisted of rigid plastic tubing, 10 cm long, with an internal diameter of 2.5 cm. One end of the tube was sealed to simulate an intramedullary plug. A wooden model was used to simulate the femoral component of a total hip arthroplasty. Bone cement was mixed in a glass bowl with a steel spatula in a standardised manner for two minutes. In all cases the model femur was filled with bone cement and a regular mantle around the wooden “femoral stem” was observed. Pores were present on the cut surface of all of the specimens. The pore density (No. of pores per unit area) was measured using an NIH image programme and was found to be dramatically reduced in the experimental cement mantles, when compared to the control specimens. The porosity in the cement mantles produced by vacuum loading the gun was significantly lower (p< 0.001) than that in the mantles produced by the manually loaded guns.

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Shape Optimization of Femoral Components of an Artificial Hip Prosthesis Using the Three-Dimensional P-Version Finite Element Study and the In Vitro Measurement of Strain in the Bone Cement

Advances in Bioengineering ◽

10.1115/imece2002-33008 ◽

2002 ◽

Author(s):

Masaru Higa ◽

Ikuya Nishimura ◽

Kazuhiro Matsuda ◽

Hiromasa Tanino ◽

Yoshinori Mitamura

Keyword(s):

Finite Element ◽

Shape Optimization ◽

Bone Cement ◽

Femoral Component ◽

Three Dimensional ◽

Femoral Stem ◽

Cement Mantle ◽

Optimum Shape ◽

Shear Stresses

Though Total Hip Arthroplasty (THA) is being performed with greater frequency every year for patients with endstage arthritis of hip, mechanical fatigue of bone cement leading to damage accumulation is implicated in the loosening of cemented hip components. This fatigue failure of bone cement has been reported to be the result of high tensile and shear stresses at the bone cement. The aim of this study is to design the optimum shape of femoral component of a THA that minimizes the peak stress value of maximum principal stress at the bone cement and to validate the FEM results by comparing numerical stress with experimental ones. The p-version three-dimensional Finite Element Method (FEM) combined with an optimization procedure was used to perform the shape optimization. Moreover the strain in the cement mantle surrounding the cemented femoral component of a THA was measured in vitro using strain gauges embedded within the cement mantle adjacent to the developed femoral stem to validate the optimization results of FEM.

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The Role of Stress Concentrations in the Bone Cement Mantle

ASME 2008 Summer Bioengineering Conference, Parts A and B ◽

10.1115/sbc2008-192811 ◽

2008 ◽

Author(s):

David Hoey ◽

Didier Carette ◽

Peter O’Reilly ◽

David Taylor

Keyword(s):

Bone Cement ◽

Femoral Stem ◽

Cement Mantle ◽

The Body ◽

Surrounding Tissue ◽

Stress Concentrations ◽

Trapped Air ◽

Incomplete Filling ◽

Mechanical Bond

Acrylic bone cement is a porous biomaterial with many applications across both the medical and dental fields. In orthopaedics, it is used in the fixation of artificial implants where it forms a mechanical bond between the implant and the surrounding tissue. Bone cement is prepared during surgery by mixing a polymer powder and a liquid monomer. The mixture is then inserted into the body in a dough-like state, setting around the implant. Due to the manner in which the cement is prepared and inserted, the material tends to contain defects. Porosity arises in the cement due to trapped air and evaporation of the monomer during the mixing process. Larger defects of various shapes occur as a result of trapped debris, incomplete filling of the space, premature solidification and shrinkage: these are all similar to causes of defects in castings and injection-mouldings [1]. Even without these defects, stress concentrations can arise due to protrusion of bone into the cement as well as the geometry of the hip implant. High stresses can occur in the cement close to the femoral stem, the magnitudes of which are dependant of the cross-section of the stem and other design features [2].

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THE INFLUENCE OF TIBIAL PROSTHESIS DESIGN FEATURES ON STRESSES RELATED TO ASEPTIC LOOSENING AND STRESS SHIELDING

Journal of Mechanics in Medicine and Biology ◽

10.1142/s0219519410003666 ◽

2011 ◽

Vol 11 (01) ◽

pp. 55-72 ◽

Cited By ~ 8

Author(s):

DESMOND Y. R. CHONG ◽

ULRICH N. HANSEN ◽

ANDREW A. AMIS

Keyword(s):

Bone Resorption ◽

Bone Cement ◽

Aseptic Loosening ◽

Cancellous Bone ◽

Stress Shielding ◽

Cement Mantle ◽

Shear Stresses ◽

Knee Prostheses ◽

Design Features ◽

Cement Interface

Aseptic loosening caused by mechanical factors is a recognized failure mode for tibial components of knee prostheses. This parametric study investigated the effects of prosthesis fixation design changes, which included the presence, length and diameter of a central stem, the use of fixation pegs beneath the tray, all-polyethylene versus metal-backed tray, prosthesis material stiffness, and cement mantle thickness. The cancellous bone compressive stresses and bone–cement interfacial shear stresses, plus the reduction of strain energy density in the epiphyseal cancellous bone, an indication of the likelihood of component loosening, and bone resorption secondary to stress shielding, were examined. Design features such as longer stems reduced bone and bone–cement interfacial stresses thus the risk of loosening is potentially minimized, but at the expense of an increased tendency for bone resorption. The conflicting trend suggested that bone quality and fixation stability have to be considered mutually for the optimization of prosthesis designs. By comparing the bone stresses and bone–cement shear stresses to reported fatigue strength, it was noted that fatigue of both the cancellous bone and bone–cement interface could be the driving factor for long-term aseptic loosening for metal-backed tibial trays.

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The effect on the fatigue strength of bone cement of adding sodium fluoride

Proceedings of the Institution of Mechanical Engineers Part H Journal of Engineering in Medicine ◽

10.1243/0954411011533643 ◽

2001 ◽

Vol 215 (2) ◽

pp. 251-253 ◽

Cited By ~ 14

Author(s):

C Minari ◽

M Baleanil ◽

L Cristofolini ◽

F Baruffaldi

Keyword(s):

Fatigue Strength ◽

Bone Cement ◽

Sodium Fluoride ◽

Biomedical Applications ◽

Cement Mantle ◽

Fatigue Tests ◽

Fatigue Performance ◽

Bone Cements ◽

The Novel ◽

Pmma Bone Cement

New bone cements that include several additives are currently being investigated and tested. One such additive is sodium fluoride (NaF), which promotes bone formation, facilitating implant integration and success. The influence of NaF on the fatigue performance of the cement as used in biomedical applications was tested in this paper. In fact fatigue failure of the cement mantle is a major factor limiting the longevity of a cemented implant. An experimental bone cement with added NaF (12wt%) was investigated. The fatigue strength of the novel bone cement was evaluated in comparison with the cement without additives; fatigue tests were conducted according to current standards. The load levels were arranged based on a validated, statistically based optimization algorithm. The curve of stress against number of load cycles and the endurance limit were obtained and compared for both formulations. The results showed that the addition of NaF (12 wt %) to polymethylmethacrylate (PMMA) bone cement does not affect the fatigue resistance of the material. Sodium fluoride can safely be added to the bone cement without altering the fatigue performance of the PMMA bone cement.

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BIOMECHANICAL RATIONALE FOR CHOICE OF CEMENT MANTLE THICKNESS AROUND A FEMORAL STEM

Journal of Mechanics in Medicine and Biology ◽

10.1142/s0219519418500641 ◽

2018 ◽

Vol 18 (06) ◽

pp. 1850064

Author(s):

IEVGEN LEVADNYI ◽

JAN AWREJCEWICZ ◽

OLGA SZYMANOWSKA ◽

DARIUSZ GRZELCZYK ◽

JOSÉ EDUARDO GUBAUA ◽

...

Keyword(s):

Bone Density ◽

Femoral Stem ◽

Peak Stress ◽

Proximal Part ◽

Cement Mantle ◽

Bone Adaptation ◽

Replacement Surgery ◽

Hip Replacement Surgery ◽

High Reduction ◽

Hip Arthroplasties

The change in mechanical properties of the femoral bone tissue surrounding hip endoprosthesis stems during the post-operative period is one of the causes of implant instability, and the mathematical description of this phenomenon is the subject of much research. In the present study, a model of bone adaptation, based on isotropic Stanford theory, is created for further computer investigation. The results of implementation of such a mathematical model are presented regarding the choice of cement mantle rational thickness in cemented hip arthroplasties. The results show that for cement mantle thicknesses ranging from 1–1.5[Formula: see text]mm, a peak stress value in the proximal part of the mantle exceeds the limit of durability of bone cement. Moreover, results show that high reduction in the bone density of distal and proximal regions was observed in cases of cement mantle thicknesses varying from 1–3[Formula: see text]mm. No significant changes in bone density of the abovementioned regions were obtained for 4[Formula: see text]mm and 5[Formula: see text]mm. The outcome of numerical investigations can be treated as valuable and will lead to the improvement of cemented hip replacement surgery results.

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Axisymmetric Finite Element Analysis of a Debonded Total Hip Stem With an Unsupported Distal Tip

Journal of Biomechanical Engineering ◽

10.1115/1.2796023 ◽

1996 ◽

Vol 118 (3) ◽

pp. 399-404 ◽

Cited By ~ 12

Author(s):

T. L Norman ◽

V. C. Saligrama ◽

K. T. Hustosky ◽

T. A. Gruen ◽

J. D. Blaha

Keyword(s):

Finite Element Analysis ◽

Finite Element ◽

Stress Relaxation ◽

Bone Cement ◽

Cement Mantle ◽

Load Level ◽

Interface Conditions ◽

Element Analysis ◽

Cement Interface ◽

Total Hip

A tapered femoral total hip stem with a debonded stem-cement interface and an unsupported distal tip subjected to constant axial load was evaluated using two-dimensional (2D) axisymmetric finite element analysis. The analysis was performed to test if the mechanical condition suggest that a “taper-lock” with a debonded viscoelastic bone cement might be an alternative approach to cement fixation of stem type cemented hip prosthesis. Effect of stem-cement interface conditions (bonded, debonded with and without friction) and viscoelastic response (creep and relaxation) of acrylic bone cement on cement mantle stresses and axial displacement of the stem was also investigated. Stem debonding with friction increased maximum cement von Mises stress by approximately 50 percent when compared to the bonded stem. Of the stress components in the cement mantle, radial stresses were compressive and hoop stresses were tensile and were indicative of mechanical taper-lock. Cement mantle stress, creep and stress relaxation and stem displacement increased with increasing load level and with decreasing stem-cement interface friction. Stress relaxation occur predominately in tensile hoop stress and decreased from 1 to 46 percent over the conditions considered. Stem displacement due to cement mantle creep ranged from 614 μm to 1.3 μm in 24 hours depending upon interface conditions and load level.

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Femoral Stem Displacement in a Patient Suffering Recurrent Dislocations After Hip Hemiarthroplasty: Case Report

The Open Orthopaedics Journal ◽

10.2174/1874325001105010400 ◽

2011 ◽

Vol 5 (1) ◽

pp. 400-402 ◽

Cited By ~ 1

Author(s):

Panagiotis Tsagozis ◽

Magnus Henriksson ◽

Ioannis Ioannidis

Keyword(s):

Hip Arthroplasty ◽

Closed Reduction ◽

Rare Event ◽

Femoral Stem ◽

Operative Management ◽

Cement Mantle ◽

Illustrative Case ◽

Complex Issue ◽

Hip Hemiarthroplasty ◽

Proximal Migration

Displacement of the femoral component during attempt to closed reduction of a dislocated hip arthroplasty is an exceptionally rare, catastrophic event, which renders operative management obligatory. We report the proximal migration of a femoral stem during attempt to closed reduction in a patient with recurrent postoperative dislocations after hip hemiarthroplasty, and describe successful management by conversion to a standard total hip arthroplasty, retaining the same stem in the existing cement mantle. This illustrative case is reported not only as an extremely rare event, but also to highlight and discuss pitfalls and efficient measures in the management of this complex issue.

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