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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_5881_Библиотеки_им_академика_М_И_Перельмана.pdf
13 Wear and Friction Mechanism Study in Knee and Hip Rehabilitation…
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Fig. 13.1 Total hip replacement: (a) the basic anatomy of the hip joint [9]; (b) an example of hip
damaged by osteoarthritis [9]; (c) an example of cementless total hip replacement [14, 15]; and (d)
major components of the hip joint and steps to be followed for the total hip replacement [9, 16, 17]
However, ceramics had brittleness and fracture risks. From the 1990s onward, modied surfaces like hydroxyapatite coatings and porous structures were added to titanium and cobalt-chrome alloys to improve bone in growth and stability [2, 4, 5].
Recently, technologies like 3D printing have enabled the fabrication of porous
titanium or titanium alloy hip implants with bone-mimicking geometry and customized surface textures and properties [6]. During hip and knee replacement surgery,
new implants comprised of ceramic (C), metal (M), and plastic (P) replace the
worn-out bone and cartilage lining of the hip or knee joint. Materials used in hip and
knee replacements are remarkably comparable. The hip, which has a ball and socket
joint, is one of the largest joints in the body [7, 8]. As per Fig.13.1, the acetabulum,
a section of the pelvis bone, creates the socket. The femoral head is the ball-shaped
apex of the femur, which is also known as the thighbone. Articular cartilage, a
smooth tissue that cushions the ends of the bones and permits them to move
smoothly, is placed over the bone surfaces of the ball and socket [9].
Musculoskeletal disorders encompass a wide array of conditions affecting bones,
joints, muscles, and connective tissues. Among these, knee and hip joint disorders
are particularly prevalent, often leading to chronic pain, reduced mobility, and
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A. Choudhari et al.
decreased quality of life [10]. Conditions such as osteoarthritis, rheumatoid arthritis, post-traumatic injuries, and congenital anomalies can all result in joint degeneration, necessitating medical interventions [10, 11]. Joint rehabilitation plays a
crucial role in restoring functional mobility and alleviating pain for individuals with
musculoskeletal disorders. The primary aim of rehabilitation is to improve joint
function, strengthen surrounding muscles, and enhance overall well-being. Surgical
interventions are often required in more severe cases where conservative treatments
prove ineffective. The success of these surgeries hinges not only on surgical techniques but also on the performance of the implanted joint components [12].
A typical total hip replacement implant comprises four distinct components, as
depicted in Fig.13.1. As depicted in Fig.13.1a the hip joint consists of the femur,
femoral head and acetabulum as a socket [9]. Osteoarthritis (OA), a prevalent
degenerative joint disease, frequently manifests in the hip joint, leading to profound
structural changes and functional impairment, is shown in Fig.13.1b [9, 13].
The hip joint, characterized as a ball-and-socket articulation, involves the femoral head tting into the acetabulum, a concave socket within the pelvic bone. Central
to its smooth operation is the articular cartilage, a specialized connective tissue that
covers the joint surfaces. This cartilage provides essential functions such as shock
absorption, load distribution, and lubrication, ensuring frictionless movement and
preventing bone-on-bone contact [9, 18]. As osteoarthritis progresses within the hip
joint, a conspicuous deterioration of the articular cartilage unfolds. One of the primary hallmarks is the gradual thinning of the cartilage, diminishing its capacity to
absorb and distribute forces effectively. The once-smooth surface undergoes transformative changes, marked by the emergence of ssures and cracks, compromising
the structural integrity of the cartilage matrix. The erosion of cartilage, a characteristic feature of OA, intensies with continued wear and tear, genetic predisposition,
aging, or factors contributing to joint instability. The signicance of articular cartilage becomes evident in its multifaceted roles. Firstly, it acts as a shock absorber,
attenuating the impact-related stresses encountered during joint movement. Its ability to distribute loads evenly across the joint surface is crucial for maintaining optimal biomechanics and preventing localized stress concentrations. Furthermore,
cartilage plays a pivotal role in the joint’s lubrication by contributing to the production of synovial uid. This lubricating uid reduces friction between joint surfaces,
promoting smooth articulation. The erosion and thinning of cartilage in his osteoarthritis led to detrimental consequences. As the protective cartilage diminishes, the
once-cushioned joint surfaces become susceptible to increased friction, resulting in
pain, stiffness, and compromised mobility. The gradual loss of joint space due to
cartilage degradation exacerbates these symptoms, contributing to the characteristic
manifestations of hip osteoarthritis [19].
The hip joint replacement consists of the following major components, as shown
in the Fig.13.1d [9, 16, 17]:
13 Wear and Friction Mechanism Study in Knee and Hip Rehabilitation…
349
(i) The Femoral Stem
Cobalt-chromium and/or titanium alloys are the researchers’ choice for production because of their high strength, high biocompatibility, and low wear characteristics. Jazrawi et al. [20] employed cemented femoral stems in contemporary hip
replacements, inserted using epoxy bone cement composed of cobalt-chromium.
Titanium is frequently chosen for crafting cementless femoral stems, wherein bone
integration with the metal occurs. These design approaches have demonstrated
favorable long-term outcomes as integral components of total hip replacement systems [21].
(ii) Cup—Inserts into the Pelvic Bone
The Cup, the second component, is meticulously engineered to interface with the
pelvic bone’s acetabulum. Typically crafted from durable materials such as highdensity polyethylene or advanced ceramics, the cup ensures secure xation and stability. Its design considerations include factors like optimal press-t or cementation
methods to achieve osseointegration. Surface nishes may incorporate features to
mitigate wear and enhance lubrication, which is vital for the sustained performance
of the hip replacement [22].
(iii) Ball—Fits onto the End of the Stem
The Ball, situated at the terminus of the femoral stem, constitutes the prosthetic
femoral head. Composed of materials like cobalt-chromium or ceramics, it replicates the natural femoral head, enabling articulation within the acetabular cup.
Precision in size, shape, and material properties is paramount to simulate natural
joint movement while minimizing wear, ensuring the longevity of the implant [23].
(iv) Liner—Inserts into the Cup—Essentially Becomes Your New Cartilage
Inserted into the cup, the liner serves as the interface that essentially replaces
natural cartilage. Typically fabricated from wear-resistant materials like highly
cross-linked polyethylene or ceramic compounds, the liner undergoes meticulous
design to optimize lubrication, reduce friction, and withstand mechanical stresses
[24, 25]. Its biocompatibility and wear characteristics are crucial factors inuencing
the implant’s overall performance and longevity. Each component’s material properties, geometric design, and the interplay between them are meticulously considered to emulate the biomechanics of the native hip joint, underscoring the
multidisciplinary nature of total hip replacement research and design [26].
Similarly, knee replacement prosthetics also play a crucial role in restoring function and alleviating pain in individuals with degenerative knee joint conditions, primarily osteoarthritis. The main difference between a healthy and a diseased knee
joint lies in the integrity of the articular cartilage and overall joint structure. In a
healthy knee joint, the articular cartilage covers the ends of the femur, tibia, and
patella, providing a smooth and gliding surface for movement, as shown in Fig.13.2a
[27]. This cartilage facilitates pain-free motion and absorbs shock during weightbearing activities. In contrast, a diseased knee joint, particularly in osteoarthritis,
experiences the gradual deterioration of this protective cartilage [28]. As cartilage
wears away, bones may begin to rub against each other, leading to pain, stiffness,
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A. Choudhari et al.
Fig. 13.2 Total knee replacement: (a) the comparison of healthy, diseased, and implanted knee
joints [27]; (b) the anatomy of a healthy knee [30]; (c) comparison of the knee before and after
knee replacement [31] and (d) the common materials used for the components of knee join replacement [32]
and reduced mobility. X-rays and other imaging techniques are commonly used to
identify degenerative changes, joint space narrowing, and bone abnormalities, aiding clinicians in assessing the extent of knee joint damage and determining the
appropriateness of knee replacement surgery as a therapeutic intervention. A healthy
knee joint is a marvel of biomechanical engineering, involving intricate components
seamlessly working together, as shown in Fig.13.2b [27]. The femur, or thigh bone,
articulates with the tibia, the shin bone, while the patella, or kneecap, sits at the
front, enhancing joint stability. Articular cartilage coats the ends of these bones,
providing a smooth, low-friction surface crucial for uid movement. The meniscus,
two C-shaped wedges of cartilage, acts as a shock absorber between the femur and
tibia. Ligaments such as the lateral collateral ligament provide essential stability,
preventing excessive side-to-side movement. The anterior cruciate ligament (ACL)
ensures the proper alignment of the femur and tibia during activities, contributing to
overall joint integrity [29]. This symphony of elements, complemented by the synovial membrane’s lubrication and surrounding muscles’ dynamic support, enables
the knee to function optimally in health.
13 Wear and Friction Mechanism Study in Knee and Hip Rehabilitation…
A typical total knee replacement implant comprises three distinct components,
as shown in Fig.13.2:
(i) Femoral Component
This component replaces the damaged or diseased end of the femur (thighbone).
It typically consists of a metal alloy and mimics the natural shape and contour of the
femoral condyles.
(ii) Tibial Component
This component replaces the top surface of the tibia (shinbone). It usually
includes a metal tray with a plastic insert (polyethylene), serving as the articular
surface.
(iii) Patellar Component (Optional)
In some cases, the patella (kneecap) may be resurfaced with a plastic component
to improve the tracking and function of the patellofemoral joint. These components
work together to restore joint function by providing a smooth, low-friction articulating surface, allowing for improved mobility and reduced pain in individuals with
damaged or arthritic knee joints. These components’ materials, design, and xation
methods vary, and surgical techniques continue to evolve for optimal outcomes in
knee replacement procedures.
351
13.2 Important Factors toBeConsidered During aSelection
ofHip andKnee Prosthetics
In hip and knee prosthetics, the intricate interplay between wear and friction mechanisms holds paramount signicance, exerting a profound inuence on the overall
efcacy and longevity of implanted joints [33]. A comprehensive comprehension
of these mechanisms is indispensable for the judicious selection of materials and
designs, ensuring optimal performance and sustained patient well-being post-joint
replacement surgeries. The longevity and success of implanted joint components,
such as knee and hip replacements, are profoundly impacted by wear and friction
mechanisms. These mechanisms encompass the gradual loss of material from joint
surfaces due to mechanical interactions, resulting in debris generation and potential adverse effects on the surrounding tissues [34]. The interaction between the
implant and the surrounding tissues and the potential release of wear debris into
the body necessitates a comprehensive understanding of wear and friction phenomena. Figure13.3 shows the important factors to consider while selecting knee
and hip replacement prosthetics for best results. The following points must be
considered.
352
Fig. 13.3 Schematic
representation of important
factors to be considered
while selection of hip and
knee prosthetics
13.2.1 Implant Longevity andWear Mechanisms
A. Choudhari et al.
The primary objective of hip and knee prosthetics is to restore joint functionality
and alleviate discomfort. However, the dynamic mechanical interactions intrinsic to
joint movement can precipitate wear mechanisms, including abrasive, adhesive, and
fatigue wear, ultimately culminating in the gradual deterioration of implant surfaces
[35]. These wear-induced changes pose a substantive threat to the structural integrity of prosthetic components, underscoring the critical need to unravel and mitigate
wear-related challenges for prolonged implant longevity.
13.2.2 Biological Responses toWear Debris
A pivotal facet in wear-driven complications emanates from the biological responses
elicited by wear debris within the peri-implant milieu [36]. Wear particles, particularly in hip and knee joints, possess the potential to incite periprosthetic osteolysis,
a pivotal contributor to implant failure. The dimensions, morphology, and composition of these wear particles wield considerable inuence over cellular reactions,
potentially fomenting inammatory responses, bone resorption, and subsequent
prosthetic component loosening [34].
13 Wear and Friction Mechanism Study in Knee and Hip Rehabilitation…
353
13.2.3 Material Selection, Design Strategies,
andPatient-Specic Considerations
To circumvent wear and friction challenges, meticulous attention is warranted in
material selection and prosthetic design. Advances in material science have yielded
wear-resistant materials such as highly cross-linked polyethylene and ceramic bearings, expressly formulated to curtail frictional forces and enhance implant durability. The evolution of prosthetic design, lubrication modalities, and articulation
characteristics further aims to address wear-related impediments [37]. Moreover,
tailoring material choices and design features to patient-specic variables, encompassing activity levels, age, and lifestyle, is a pivotal determinant in accommodating
biomechanical demands [38].
13.2.4 Clinical Impact andRegulatory Standards
The ramications of wear-related complications, such as implant loosening and
osteolysis, extend far beyond mechanical concerns, signicantly inuencing patient
outcomes and necessitating revision surgeries. Mitigating wear and friction thus
emerges as a linchpin in the long-term success of joint replacements, averting complications and elevating the overall quality of life for patients [5]. In tandem with
these imperatives, regulatory standards, exemplied by ISO 14242, proffer comprehensive guidelines for evaluating the wear performance of total hip joint prostheses,
ensuring adherence to stipulated criteria for safety and performance [39].
13.3 Types ofHip andKnee Replacements
Selecting the appropriate type of hip and knee replacement is paramount in achieving optimal patient outcomes, ensuring a faster recovery, and promoting long-term
joint health. This decision is highly individualized, considering factors such as the
extent of joint damage, the specic affected compartments, and the overall health
status of the patient [40]. Tailoring the treatment to the patient’s unique condition
allows for a targeted approach to address specic areas of joint damage. This precision is crucial for effectively restoring joint function and alleviating pain. For
instance, partial knee or hip replacements, when applicable, minimize disruption to
healthy joint structures, resulting in less trauma to surrounding tissues, reduced
blood loss, and a quicker recovery compared to total joint replacements [41]. The
choice of the type of replacement also plays a pivotal role in the recovery speed.
Procedures that are less invasive and have a reduced impact on healthy joint components contribute to shorter hospital stays, quicker mobilization, and accelerated
rehabilitation [31]. This not only enhances the patient’s overall experience but also
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A. Choudhari et al.
facilitates a faster return to daily activities. Preserving healthy joint structures wherever possible through customized joint replacements is instrumental in improving
long-term joint health [42]. This approach helps mitigate the risk of complications
such as implant wear, loosening, or instability, which can impact the longevity of
the joint replacement. Furthermore, selecting the right type of replacement supports
a more natural range of motion. This can signicantly contribute to improved mobility and functional outcomes for the patient, enhancing their overall quality of life
[43]. Patient satisfaction is closely tied to the success of joint replacement procedures. When treatments are tailored to meet individual needs and expectations,
patients are more likely to experience positive outcomes and higher levels of satisfaction. Additionally, customizing rehabilitation plans based on the chosen procedure allows for a more targeted approach to address specic challenges associated
with recovery, ultimately contributing to a smoother rehabilitation process [42].
In summary, the importance of selecting the right hip and knee replacement type
cannot be overstated. It is a personalized approach that considers the unique characteristics of each patient, leading to faster recovery, improved long-term joint health,
and increased patient satisfaction. Orthopedic surgeons play a critical role in evaluating individual circumstances to make informed decisions that optimize outcomes
and promote overall joint well-being.
13.3.1 Types ofHip replacement
There are two main types of hip replacement: total hip replacement (THR) and
resurfacing hip replacement (RHR), as shown in Fig.13.4. These two major hip
replacements offer orthopedic surgeons distinct approaches to address varying clinical scenarios [44]. The choice between THR and RHR depends on factors such as
the extent of joint damage, patient age, bone quality, and the potential need for
future revisions. In clinical practice, selecting the most suitable hip replacement
type is crucial for optimizing patient outcomes and ensuring long-term joint health.
Figure13.4 visually depicts the fundamental differences between THR and RHR,
serving as a valuable reference for clinicians and researchers in the eld [45].
13.3.1.1 Total Hip Replacement (THR)
As shown in Fig. 13.3a, total hip replacement (THR) is a surgical intervention
involving the complete removal of the damaged hip joint and its replacement with
prosthetic components [45]. This procedure particularly benets individuals with
osteoarthritis, rheumatoid arthritis, and avascular necrosis. The surgery typically
includes inserting a femoral stem, femoral head, and acetabular cup, often composed of materials like metal alloys, ceramics, and highly cross-linked polyethylene. THR offers comprehensive joint reconstruction, providing long-term durability
and signicant pain relief. However, drawbacks include bone resection, posing
13 Wear and Friction Mechanism Study in Knee and Hip Rehabilitation…
355
Fig. 13.4 (a) Types of hip replacements, (b) types of combinations used for the hip replacement
materials, (c) nominal vs real surfaces (roundness and waviness) during wear, and (d) Hertz
spheres in contact equivalent to contact between the acetabular cup and femoral head [45]
concerns for younger patients, and a risk of postoperative dislocation [44]. The
prosthetic components mimic the natural hip joint, enabling improved mobility and
pain relief. However, patients are generally advised to avoid high-impact activities
to prevent accelerated wear on the implant [46].
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A. Choudhari et al.
13.3.2 Resurfacing Hip Replacement (RHR)
As shown in Fig.13.3a, (RHR) is a specialized surgical procedure within the spectrum of hip replacements, distinguished by its focus on preserving more bone in the
femoral neck compared to traditional total hip replacement (THR). In RHR the
femoral head is capped rather than entirely removed [45]. This technique is often
considered for younger, more active patients, aiming to preserve bone for potential
future revisions. The components involve a metal cap over the femoral head and a
metal acetabular component, commonly made from cobalt-chromium alloys (CoCr) [47]. RHR offers the advantage of bone preservation, reduced dislocation risk
due to larger femoral head size, and suitability for active individuals. In RHR, the
femoral head’s damaged surface is trimmed and capped with a metal prosthesis,
while the acetabulum receives a metal cup. One of the primary advantages of RHR
lies in bone preservation. However, concerns about metal ion release from the
metal-on-metal articulation raise potential complications, including adverse tissue
reactions such as pseudo tumors [43]. RHR may not be suitable for patients with
specic anatomical variations or compromised bone quality [45].
By conserving more of the patient’s natural femoral bone, this procedure aims to
facilitate potential future revision surgeries, which might be necessary due to factors
such as wear and tear or changes in the patient’s condition. It’s essential to note that
while RHR offers advantages in bone preservation, patient selection is critical.
Factors such as bone quality, activity level, and underlying hip pathology inuence
the appropriateness of RHR for a given individual. Careful consideration of these
factors by orthopedic surgeons is pivotal in determining the suitability of RHR as an
optimal hip replacement solution [45, 48]. THR provides a comprehensive solution
for joint reconstruction, offering proven long-term durability and pain relief.
However, drawbacks include bone resection and a potential risk of dislocation. On
the other hand, RHR preserves more natural bone, has a lower dislocation risk, and
is suitable for active patients. Nevertheless, concerns about metal ion release and
limited suitability for certain anatomical conditions need consideration [49]. The
choice between THR and RHR hinges on patient-specic factors. THR is generally
recommended for older patients, while RHR may be suitable for younger, more
active individuals. Considerations such as bone quality, anatomical variations, and
potential future revisions play a crucial role in determining the most appropriate
procedure for a given patient. Ongoing research aims to rene these surgical options,
addressing concerns and enhancing outcomes for individuals undergoing hip
replacement [50, 51].
Furthermore, there are types of hip material selection as metal-on-plastic (MoP),
ceramic-on-plastic (CoP), ceramic-on-ceramic (CoC), and metal-on-metal (MoM)
are the most common material combinations used for bearing surfaces in hip joint
replacements (Fig. 13.4b) [45]. The rst letter in these acronyms stands for the
material of the cup, and the third letter for the material of the head. It should be
noted that resurfacing hip replacements (RHRs) are only offered in ceramic-onmetal (CoM) or metal-on-metal (MoM-RHR) versions. Because of the inherent