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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_5603_Библиотеки_им_академика_М_И_Перельмана.pdf
13 Wear andFriction Mechanism Study inKnee andHip Rehabilitation
397
compression force applied to the tibial component. The tibial insert is free to translate and rotate, while the femoral component only moves in exion [178].
Figure 13.10e displays the FEA model for simulating wear under load control
according to ISO 14243-1. This model has the same inputs as 5A, except AP displacement and TR angle are replaced by AP load and TR torque. Additionally, nonlinear connector elements are added to the tibia to constrain motions to match the
requirements in ISO 14243-1. The AP connectors prevent excessive anteriorposterior translation, while the TR connectors limit internal-external rotation. The
two FEA models have identical geometry and material properties for the implant
components. The only differences are the loading conditions and motion constraints.
By simulating wear using these two models, the study can isolate the effects of
changing the directions of the AP and TR inputs based on the ISO standard variants [178].
Figure 13.10g–i show the wear contours for the displacement control models.
Figure13.10g illustrates the wear pattern using the modied ISO 14243-3 inputs
(positive AP displacement, positive TR angle), with wear centrally located and
slightly posterior. In contrast, Fig.13.10h shows the wear contour using the ISO
14243-3:2004 inputs (negative AP displacement, positive TR angle), which shifts
the wear pattern anteriorly. Figure13.10i depicts the wear for ISO 14243-3:2014
(positive AP displacement, negative TR angle), which is again more central but differs from 10A.
Figure 13.10i, j present the wear contours for the load control models.
Figure13.10i shows the central, posterior wear for the modied ISO 14243-1 conditions (positive AP load, positive TR torque). However, Fig.13.10j demonstrates the
ISO 14243-1:2009 inputs (negative AP load, positive TR torque) shift the wear pattern anteriorly. The analysis of Fig.13.10 by Wang etal. [178] leads to a clear conclusion regarding the substantial impact of anterior-posterior (AP) and tibial rotation
(TR) input directions on the predicted wear patterns and locations on the tibial insert
surface. Reversing the AP direction results in a noticeable shift in wear location
either anteriorly or posteriorly, deviating from the more central wear pattern
observed under modied ISO conditions. Similarly, alterations in the TR direction
induce changes in the wear contour, albeit to a lesser extent compared to variations
in the AP direction. Particularly noteworthy is the observation that wear patterns
arising from the modied ISO conditions (positive AP, positive TR) exhibit a more
natural and centrally located conguration in contrast to the standard ISO conditions. These ndings highlight a crucial observation that the ISO 14243 standards
may necessitate revision to better align with normal knee kinematics, as the standard conditions produce wear patterns that are less anatomically accurate. Wang
et al. emphasize the need for a reevaluation of testing standards to improve the
accuracy of wear testing and better reect real-world knee joint dynamics [178].
Figure 13.10 validates the FEA model against experiments and ISO standards
with a demonstration of the kinematic effects of the different AP and TR loading
directions proposed by Wang etal. [178]. Figure13.11a validates the nite element
analysis (FEA) model by comparing the simulated gait cycle kinematics to the
experimental results from the knee simulator and the expected waveform based on
398
A. Choudhari et al.
Fig. 13.11 (a) Comparing gait cycle data across Finite Element Analysis (FEA) ndings, experimental outcomes, and adjusted criteria derived from ISO 14243-3 and (b) kinematic outcomes for
anterior-posterior (AP) displacement, AP loads, tibial rotation (TR), and TR torque [178]
13 Wear andFriction Mechanism Study inKnee andHip Rehabilitation
399
the modied ISO 14243-3 standard. The four graphs show the exion angle, tibial
rotation angle, anterior-posterior (AP) displacement, and axial force throughout the
gait cycle. The strong agreement between the FEA model, experimental measurements, and ISO standard waveforms demonstrates the FEA model accurately reproduces the knee motions and loading. This validation gives condence in using the
FEA model to evaluate the effects of different loading conditions on wear performance. Figure13.11b presents the kinematic results from the FEA models using the
different loading conditions. The top two graphs show the AP displacement and
reaction forces for the displacement control models, while the bottom two graphs
display the AP load and tibial rotation torque for the load control models. For displacement control, reversing the AP direction (ISO 14243-3:2004) generates greater
AP reaction forces compared to the modied positive AP input. For load control, the
ISO 14243-1:2009 AP load reversed from the modied condition produces a negative AP displacement around 54–60% of the gait cycle. Overall, Fig.13.11 reveals
how changing the AP and TR directions alters the kinematics and joint forces, contributing to differences in wear performance. The gure provides insight into how
the various loading conditions affect knee motions based on the FEA simulations.
Table 13.9 elucidates the anticipated wear rate, total volumetric wear, and maximum wear depth on the tibial insert surface derived from nite element analysis
models under varying loading conditions [178]. The data reveals pertinent insights,
particularly in displacement and load control scenarios. It collectively quanties
and illustrates the nuanced impact of loading conditions on knee implant wear in
computational simulations, suggesting potential inadequacies in current ISO standards’ representation of actual knee kinematics [178]. Notably, reversing the
anterior- posterior (AP) direction under ISO 14243-3:2004 substantially elevated the
wear rate by 272%, contrasting the minimal 2.17% increase induced by altering the
tibial rotation (TR) direction under ISO 14243-3:2014. In load control simulations,
reversing the AP load per ISO 14243-1:2009 resulted in a 6.73% increase in wear
rate compared to the modied positive AP load. Signicantly, the wear rate was
markedly higher (153.98%) in the modied load control model compared to the
modied displacement control model. These quantitative ndings align with
Fig.13.10g–k, where the altered wear locations visually correspond to the observed
wear rate variations [178].
Table 13.9 Anticipated wear rate, volumetric wear, and the maximum depth of wear [178]
Parameters
Wear rate (mm3/
million)
Volumetric wear
(mm3)
Maximum wear
depth (mm)
ISO
Modied ISO
14243-3
8.3 22.64 8.12 12.78 13.64
41.5 113.2 40.6 63.9 68.2
0.598 2.767 0.617 0.547 0.538
14243-
3:2004 IS014243- 3:2014
Modied ISO
14243-1
ISO
142431:2009
400
A. Choudhari et al.
Fig. 13.12 (a) The positions corresponding to the peaks of maximum contact stress: A, B, C, and
D; (b) the points representing the highest contact stress levels identied as A, B, C, and D and
forces; and (c) wear contours [183]
Another researcher, Wang etal., compared the results of ISO 14243-1 to ASTM
F3141 of wearing knee prosthetics [183]. Figure13.12a shows the locations of peak
contact stresses on the tibial insert surface during the wear simulations. There are
four labeled points—A, B, C, and D.Points A, C, and D are situated on the medial
13 Wear andFriction Mechanism Study inKnee andHip Rehabilitation
401
side of the insert, while point B is on the lateral side. The clustering of peak stresses
on the medial side is likely due to the axial load being offset to the medial compartment, as specied in the ISO standard [35]. Figure13.12c then displays the resulting wear depth contours on the tibial insert after 5 million cycles for both the ISO
and ASTM models. In both cases, the maximum wear depth occurs on the medial
side, which correlates to the locations of peak contact stresses shown in Fig.13.12a.
This medial-sided wear indicates the loading conditions induce higher stresses
medially [35]. However, the patterns differ noticeably when comparing the ISO and
ASTM wear contours. For the ASTM model, the wear is concentrated in a smaller
region but with a greater maximum depth. In contrast, the wear is spread over a
larger area for the ISO model but is generally shallower. These differences in wear
topography between the two models are attributed to variations in the input kinematics and loading. The ISO standard produces less physiological anterior-posterior
translation, leading to a more dispersed wear pattern. Meanwhile, the ASTM standard better replicates normal knee motion, resulting in wear focused on a particular
region of high contact stress medially.
Figure 13.12b plots the maximum contact stresses and contact forces on the tibial insert surface over the gait cycle for both simulation standards. During the stance
phase from 0% to 60%, high contact stresses are seen, corresponding with the large
contact forces shown in the contact forces vs cycle graph. The peak contact stress is
notably higher in the ASTM model compared to the ISO model. This aligns with the
ASTM standard, which has a higher maximum axial load input, as depicted in Fig.
13.12b.Four labeled points indicate the locations of maximum contact stresses on
the insert surface. Points A, C, and D are situated medially, while point B is lateral.
The clustering of peak stresses medially correlates to the offset axial loading toward
the medial compartment specied in the ISO standard. Overall, the maximum contact stresses follow the proles of the axial loading input, which dominates the total
contact force as described in Fig.13.12b.
Table 13.10 presents the wear simulation results, including volumetric wear rate,
total volumetric wear, and maximum wear depth for both the ISO and ASTM models. Two wear coefcient values are used to provide a range of outcomes. Despite
differences in loading conditions, the wear rates and total wear volumes are very
similar between the ISO and ASTM standards. However, the maximum wear depth
varies greatly, with the ASTM model predicting that the depth of the ISO model will
Table 13.10 Predicted wear rate, volumetric wear, and wear depth for ASTM and ISO
standards [183]
ASTM F3141 ISO 14243-1
Wear rate (mm3/million) 13.48 13.64
K=2.64 × 10–7mm3/Nm Volumetric wear (mm3) 67.4 68.2
Wear depth (mm) 1.137 0.538
Wear rate (mm3/million) 55.26 54.9
K=10.656 × 10–7mm3/Nm Volumetric wear (mm3) 276.3 274.5
Wear depth (mm) 4.606 2.171
402
movement
movement
movement
(uni-direction)
Ball-rotation
(uni-direction)
joint
A. Choudhari et al.
surface-hip joint
surface-hip joint
hip joint
(ball-rotation)
Hanks solution Plate reciprocating
CoCrMo/SIN BCS Ball reciprocating
Ti and TiN BCS Ball reciprocating
Co-alloy
Ti6Al4V
Orthopedic implant
materials
Tribocorrosion behavior of
coatings
Study the PVD surface-
modied implant alloy
Customized
tribometer
tribometer
tribometer
Ti6A14V NaCl solution Plate reciprocating
To study the effect of
Customized
CoCrMo alloy BCS Ball-rotation
fretting amplitude and two
loads
potential
tribometer
Microabrasion Biomedical, load,
Mild steel Sodium carbonate/
Microabrasion Biomedical, load,
bicarbonate
solution
Ringer solution Tapered surface-hip
316 SS and
PMMA
potential
sides of the femoral stem
Ringer solution Articulating
Head-Ti6Al4V
Ringer solution Articulating
BCS Articulating surface
Neck SS316
steel
head
alloy-head
sides of the femoral stem
Femoral head and cup CoCrMo
system
Table 13.11 Tribo-corrosion studies in the biomedical eld [190]
Type of
tribocorrosion Basic tribometer Interest of the study Sample Electrolyte Movement
Sl.
no.
Type of TC
system
corrosion
1 Sliding wear
2 Sliding wear Customized
Ball on plate
(reciprocating)
corrosion
3 Fretting corrosion Customized
4 Fretting wear
corrosion
6 Microabrasion
Microabrasion 5 Microabrasion-
corrosion
7 Fretting corrosion Special set-up Micro-movement at the
Special type of
8 Fretting corrosion Special set-up Micro-movement at the
set-up
9 Fretting corrosion Special set-up Femoral head and cup CoCrMo alloy
10 Sliding corrosion Pin-on-ball
13 Wear andFriction Mechanism Study inKnee andHip Rehabilitation
be over doubled. Referring to Fig.13.12b, the peak contact stresses are higher in the
ASTM simulation, which likely contributes to the increased wear depth shown in
Table13.10. Still, as Fig.13.12a illustrates, the locations of maximum stress do not
fully align with the regions of greatest wear depth depicted in Fig.13.12c. This
implies factors beyond just peak stress inuence wear performance, including kinematics and sliding distance. The deeper but more localized wear with ASTM in
Fig.13.12c produces a similar overall volume loss as the lower but more dispersed
wear with ISO.So, while the wear depth and patterns differ based on the loading
inputs, the net wear rates are comparable. Peak stresses alone do not govern wear
performance. The wear depth and distribution are impacted by loading and kinematics. Still, the net volumetric rate is similar between the ISO and ASTM simulations
due to the complex interplay of factors. This helps explain the comparable wear
rates despite variations in the simulation inputs and resulting contact mechanics.
403
13.9.4 Tribo-Corrosion Testing
Tribo-corrosion testing emerges as a crucial methodology when confronted with
scenarios where both corrosion and wear coalesce. This testing paradigm is designed
to evaluate the intricate interplay of mechanical and electrochemical interactions,
providing a comprehensive understanding of the combined effects on materials subjected to tribological conditions. By simulating real-world environments that
involve both abrasive wear and corrosive elements, tribo-corrosion testing offers
valuable insights into the material degradation mechanisms and performance under
multifaceted challenges. This approach proves particularly relevant in applications
where the simultaneous occurrence of mechanical wear and corrosive environments
is a pertinent consideration, such as in biomedical implants and various engineering
systems. Table13.11 summarizes the tribo-corrosion studies conducted in the eld
of biomedical.
13.9.5 Wear Debris Analysis Techniques
The meticulous analysis of wear debris plays a pivotal role in unraveling the intricate mechanisms and factors inuencing wear and friction in orthopedic implants.
Researchers can gain valuable insights into the nature and composition of wear
debris using advanced techniques, informing strategies for enhancing implant longevity and performance. Among the diverse array of analytical methods, scanning
electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) stand
out as instrumental techniques in the comprehensive study of wear debris in orthopedic implants [36, 191, 192].
404
A. Choudhari et al.
13.9.5.1 Scanning Electron Microscopy (SEM)
SEM is a high-resolution imaging technique that facilitates the examination of wear
debris at the micro and nanoscale. By employing a focused electron beam, SEM
generates detailed, three-dimensional images of the wear particles and the surfaces
from which they originate. This technique enables researchers to characterize the
size, shape, and morphology of wear debris. Additionally, SEM provides insights
into wear mechanisms, such as adhesive, abrasive, or fatigue wear, offering a
nuanced understanding of the wear processes occurring within the implant system
[192, 193].
13.9.5.2 Energy-Dispersive X-Ray Spectroscopy (EDS)
Complementing SEM, EDS is an analytical technique that allows for the elemental
analysis of wear debris. As wear particles are bombarded with electrons in the SEM,
characteristic X-rays are emitted. EDS captures and quanties these X-rays, providing information about the elemental composition of the wear debris. This elemental
analysis is crucial for identifying the materials involved in the wear process, detecting any elemental changes in the implant components, and discerning the sources of
wear within the implant system [193, 194].
13.9.5.3 Integrated Insights andApplications
The integration of SEM and EDS in wear debris analysis offers a comprehensive
approach to understanding the complexities of wear mechanisms in orthopedic
implants. Researchers can correlate the morphological characteristics revealed by
SEM with elemental data obtained through EDS, creating a holistic prole of wear
debris. This integrated approach aids in identifying wear sources, evaluating the
effectiveness of lubrication strategies, and assessing the performance of implant
materials. Moreover, the insights garnered from wear debris analysis contribute to
rening implant designs, optimizing material selection, and advancing strategies to
minimize wear-related challenges in orthopedic applications [192].
Table 13.12 provides a comprehensive overview of research outcomes related to
wear debris characterization in various joint prosthetics, primarily focusing on
UHMWPE debris [36]. Research predominantly reports a wide size spectrum for
UHMWPE particles, ranging from 0.1 to 10 μm [195–203], featuring irregular
shapes with a higher aspect ratio. Noteworthy is Lapcikova etal.’s recent investigation into nano-sized UHMWPE wear debris in vivo (18.5–21.2 nm), revealing
highly irregular shapes compared to MoC-bearing surfaces, including bril, ake,
cylindrical, globular, twig, and occasionally spherical forms. Studies on MoM
implants indicate smaller metal particles (25–36 nm) compared to polyethylene
debris from MoP joints, particularly in CoCr alloys tested in a hip simulator [204].
Brown etal. [205] observed that a majority of debris from hard-on-hard (MoM and
13 Wear andFriction Mechanism Study inKnee andHip Rehabilitation
405
TEM
90%<1μm
Irregular 75%<0.5μm;
SEM
43%<0.5μm;
72%<1 μm
ECD, 0.694±0.005 μm
ECD, 1.190 0.009 μm
AR, 1.626+0.015
AR, 1.935 + 0.015
FE-SEM
0.074–1.319 μm,
ECD=0.265±0.131 μm
AR, 1.853 0.877; roundness,
0.528+0.152
SEM, Image
analyzer
0.013–1.120 μm,
ECD=0.270±0.148 μm
ECD, 0.81 0.12μm
ECD, 0.78 0.08μm
AR, 1.926±0.712; roundness,
0.494±0.169
AR, 1.94±0.13 and roundedness,
1.92±0.18
AR, 2.30±0.22 and roundedness,
2.52±0.36
LPSA, SEM, TEM
0.5–5μm with avg. dia 1.33μm
Spherical, sub-spherical, plate
SEM, image
analyzer
FEGSEM
LPSA, SEM
4–20μm with avg. dia. 7.54 μm
ECD, 0.78 0.4μm
ECD, 0.66±0.06 μm
Structure strip, block, plate, and
spherical
AR, 1.52±0.05 and roundness,
1.34±0.05 AR, 1.880.11 and
0.1–1 μm
24.8%>5μm, 67.7% is 5–30
roundness, 1.75+0.12
Spherical <100nm
Broken and fragment ber,
μm, 7.5%<30 μm 36.4%>5
μm, 59.8% is 5–30μm;
3.8%<30μm
cylindrical, slice and spherical
pyrolytic
Materials Bearing type Sources Shape Size Instruments
Table 13.12 Summary of wear debris from various materials used in hip and knee prosthetics [36]
Knee joint Simulator Spherical and akes 0.1–1μm FEGSEM
Hip joint <0.1 μm
UHMWPE Hip joint Periprsosthetic
UHMWPE
(crosslinked)
tissues
Knee joint
tissues
simulator
Knee joint
UHMWPE Hip joint Periprosthetic
Polyethylene Mobile bearings Knee joint
patients
UHMWPE Mobile bearing TKAS Synovial uids of
simulator
Total knee
Posterior stabilized
TKAS
Hip joint Implanted
UHMWPE (with
CoCrMo alloy)
UHMWPE Alumina medial pivot
prosthesis
Crosslinked
non-crosslinked
CrCo alloy medial
pivot
on Plate rig
UHMWPE Multidirectional pin
Hip joint
simulator
Needled carbon cloth
Carbon felt.
Carbon/carbon
composite
406
A. Choudhari et al.
0.2–0.8μm AFM, SEM
Elongated, bril-like and
Rounded and irregular <50nm SEM, TEM
spherical
EDS
SEM, EDS
Frequently occurs within the
range of 1–30μm, but overall
size range is 0.1–320 μm
Cylindrical, slice and spherical 0.1–10μm and <10μm SEM, IR, EDX/
Round, ake-like, Stick, twig
debris
SEM, HR-TEM,
EDS, XPS
FEGSEM, EDS, IR
ECD, 18.55.29nm and
21.28.01nm
Elongation, 1.29 0.13, 1.35±0.29
and circularity, 0.97±0.07,
0.93±0.09
FEGSEM, EDS
≤90nm
Needle shaped globular 40–120nm
Rounded, bril, and ake <35%, 30nm and 0.1–0.99 μm,
rests are >1 μm
87.9% < 1 μm TEM, SEM
Rounded, attened, and akes or
brils
SEM, Micro-
Raman
spectrometry
LCM
SEM
SEM
μm
Length, 53 26nm
Rounded, beads, brils, akes ECD range is from 0.48 to 0.95
Polygonal 5–90nm and 0.05–2μm TEM, SEM, EDX,
and very few >10 μm <40nm
Fibril, platelet round Most of the particles, 0.1–0.5μm
Mobile bearings Knee joint
UHMWPE (with
Materials Bearing type Sources Shape Size Instruments
Table 13.12 (continued)
simulator
Standard size
CoCrMo alloy – Hip joint
CoCr)
simulator
Periprosthetic
tissues
simulator
THRs
Mobile bearings Hip joint
, 316L
3
O
2
UHMWPE (on
UHMWPE Revisions surgery of
A1
Periprosthetic
tissues
THRs
stainless steel,
UHMWPE Revisions surgery of
CoCrMo alloy,
Ti6Al4V head)
Periprosthetic
tissues
THRs.
UHMWPE Revisions surgery of
tissues.
THRs
Periprosthetic
Periprosthetic
tissues
Revisions surgery of
THRs
UHMWPE Revisions surgery of
CoCrMo (Metal on
Metal)
tissues
UHMWPE Hip joint cast Periprosthetic
Alumina Hip joint Periprosthetic
tissues of THRs
tissues
Multidirectional
Hip joint Periprsosthetic
Hip joint
UHMWPE TIN,
CrN, CrCN coating
on CrCo alloy
pin-on-plate tests