Total knee replacement (TKR),
also referred to as total knee arthroplasty (TKA), is
a surgical procedure where worn, diseased, or damaged
surfaces of a knee joint are removed and replaced with
artificial surfaces. Materials used for resurfacing
of the joint are not only strong and durable but also
optimal for joint function as they produce as little
friction as possible.
The "artificial joint or prosthesis" generally
has two components, one made of metal which is usually
cobalt -chrome or titanium. The other component is a
plastic material called polyethylene. The procedure
has been proven to help individuals return back to moderately
challenging activities such as golf, bicycling, and
swimming. Total knees are not designed for jogging,
or sports like tennis and skiing (although there certainly
are people with total knee replacements that participate
in such sports).
The general goal of total knee replacement is designed
to provide painless and unlimited standing, sitting,
walking, and other normal activities of daily living. |
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The head of the femur,
which is situated within the pelvis socket, is
replaced with a metal ball and stem. This stem
fits into the shaft of the femur. |
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The socket is replaced
with a plastic or a metal and plastic cup. |
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For nearly a century, doctors
have been putting various materials into diseased and
painful hip joints to relieve pain. Up until the 1960s,
outcomes had been unreliable. At that time, the metal
ball and plastic socket for the replacement of the hip
joint was introduced. Today, the artificial components
used in THR are stronger and more designs are available.
There are many different shapes, sizes, and designs
of artificial components of the hip joint. For the most
part these are composed of chrome, cobalt, titanium,
or ceramic materials. Some surgeons are also using custom-made
components to improve the fit in the femur. |
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| Knee
Replacement |
Knee Replacement
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| Nice to Know |
| With proper care individuals
who have had a total knee replacement can expect many
years of faithful function. Studies show that patients
can expect a greater than 95 percent chance of success
for at least 15 years. |
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| If You Are Considering Total
Knee Replacement |
| If you have been told you have
a severely damaged knee joint and would benefit from
a total knee replacement, the questions you need to
ask yourself are: |
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Have all of the appropriate
non-surgical treatments been tried. |
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Is my painful knee
significantly restricting my day to day activities
and not allowing me to do the things I need to
do and the things I enjoy doing ? |
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| If the answers to these questions
are yes, you may be a candidate for a new knee. |
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The Anatomy of Knee Joint
The knee joint performs similar to a hinge joint. It
consists of three bones: |
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Thigh bone (Femur) |
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Leg bone (Tibia) |
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Knee cap (Patella) |
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The junction where
the femur and tibia couple together is called
the femorotibial joint. |
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The region of the
knee where the patella and femur form a junction
is called the patellofemoral joint. |
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These two joints are
what allow the bending and straightening of the
knee. It is these joints that are replaced in
a total knee joint replacement. |
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For a knee to function normally,
the quality of smoothness where each bone moves upon
the other becomes important in the function of the knee
joint.
The surfaces of all three bones coming into contact
with each other are normally covered with a smooth gliding
surface known as articular cartilage.
The condition of this cartilage lining the knee joint
is a key aspect of normal knee function and is important
to the physician when evaluating a potential need for
a knee joint replacement.
In addition to the smooth cartilage lining on the joint
surfaces, there are two smooth discs of cartilage that
cushion the space between the bone ends. The inner disc
is called the medial meniscus, while the disc on the
outer side of the knee joint is called the lateral meniscus.
The role of the menisci is to increase the conformity
of the joint between the femur and the tibia. The menisci
also play an important function as joint shock absorbers
by distributing weight-bearing forces, and in reducing
friction between the joint segments.
Generally speaking, there are four major ligaments that
play an important part in stability of the knee joint.
One on each side of the knee (but actually outside the
joint) known as collateral ligaments and two more centrally
located ligaments within the joint known as anterior
and posterior cruciate ligaments. |
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| Knee Anatomy
of Knee Joint |
Four Major
Ligaments |
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| Facts About Total Knee Replacement |
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Total knee replacement
surgery helps more than 250,000 Americans get
back on their feet each year. |
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Over the last twenty-five
years, major advancements in artificial knee replacement
have greatly improved the outcome of the surgery. |
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Technology has led
to the development of materials used in the artificial
knee joint allowing it to last over fifteen years. |
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Artificial joint replacement
for arthritis of the knee and hip is one of the
most successful surgeries of the last century.
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Individuals are able
to begin walking the day following surgery and
pain relief is achieved in greater than 95% of
people. |
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| What Causes The Knee Joint To
Degenerate ? |
| Any condition affecting the
knee that causes damage to the normally smooth lining
cartilage of the knee may eventually end up with the
same end result. The protective cartilage lining the
joint becomes worn away, producing increasing damage
to the bone surfaces inside the joint. This may cause
pain, swelling and stiffness, as the exposed bone ends
grind painfully against each other. |
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| Osteoarthritis |
Resulting from "wear and tear"
is the most common reason individuals need to undergo
knee replacement surgery. This condition may be due
to an old injury or infection to the knee joint, but
mostly there is no obvious cause as to why this happens.
The major problem in osteoarthritis of the knee joint
is that the smooth cartilage lining the inside of the
joint wears away. This results in a narrowing of the
joint space with the development of cysts and erosions
in the bone ends. As a result, bone comes directly in
contact with bone, which will be painful. Bone spurs
(small bone growths) form around the joint. All of these
changes ultimately lead to increasing pain and stiffness
of the joint.
For further information about osteoarthritis, go to
Osteoarthritis |
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| Rheumatoid Arthritis |
| An inflammation of the tissue
surrounding the joints, can cause deterioration of cartilage
and other parts of the joint and result in the need
for knee joint replacement. It is one of the inflammatory
types of arthritis that may affect other areas of the
body such as skin, kidneys and spleen. Rheumatoid arthritiscan
also affect other joints including hands, feet, elbows,
hips etc. |
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| Post-traumatic Arthritis |
| A type of arthritis that can
arise following an injury to the joint cartilage or
through damage to the ligaments leading to an unstable
knee. Generally speaking, any abnormalities causing
excessive wear within the joint (from fractures of the
knee, torn cartilage, and torn ligaments) can lead to
degeneration long after the original injury and ultimately
result in the need for a knee replacement. |
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| Avascular Necrosis |
| Results from an inadequate supply
of blood to the bone end inside the joint. As a result
articular cartilage wears away. |
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| Malalignment of the knee joint |
| Knock-knees or bowlegs - results
from an excessive angle where the upper and lower leg
bones meet at the knee joint. The result is abnormally
high stress on either the outer half or inner half of
the joint. |
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| Arthritis |
Joint
Destruction |
Malalignment
of Knee Joint |
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| Who Is A Candidate For Knee
Replacement ? |
Total knee replacements are
usually performed on people suffering from painful arthritic
conditions of the knee severe enough to limit one's
normal day to day activities.
Most people who have artificial knees are over age 55,
but the procedure is also offered to younger people
with knee degeneration if their quality of life is severely
affected. |
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| Need to Know |
Generally a person would be
considered for a total knee replacement if the individual
experiences daily pain, restricting not only work and
recreation, but also the ordinary activities of daily
living.
There must also be evidence of significant destruction
of the knee as seen on an x-ray. |
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Advances
in Total Knee Replacement (TKR) Surgery |
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| The Rotating
Platform Flexion (RPF) offers almost 155 degree
of flexion |
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The
Rotating Platform Flexion Knee (RPF) is the latest
technological advancement in knee replacement
surgery designed by team of global experts.
The Rotating Platform Flexion Knee has been developed
to accommodate increased load and rotation in
deep knee flexion to ensure implant stability
and longevity. As an advancement over the earlier
Rotating platform which offers approximately 127
degrees of flexion (knee bend), the Rotation Platform
Flexion offers upto 155 degree of flexion thereby
giving more flexibility and motion to patients.
The degree of how deeply you can bend (flexion),
and your range of motion, affects the activities
one may or may not be able to engage in.
Patients who expect to return to activities such
as gardening, kneeling for prayers or sitting
on the floor, squatting & yoga require upto
130-150 degrees of flexion from their implants.
The RPF is highly suitable for such Indian lifestyles. |
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Patient operated with hiflex design. (Inset)
The surgery mark |
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| Minimally Invasive Total Knee
Replacement (MITKR) |
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| Incision size for
Open Total Surgery v/s MITKR |
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Minimally Invasive Total Knee
Replacement (MITKR) uses a small skin incision compared
to long incisions used for conventional open knee surgery
with the help of computer navigation. This reduced muscle
tissue damage and blood loss during surgery. Hospital
stay is shortened, pain is reduced and patients can
return to a normal lifestyle more quickly. MITKRsurgery
involves the use of specially developed instrumentation
and new surgical techniques.
However MITKR has unique demands of component alignment,
positioning and soft tissue balance. The difficulty
for the surgeon with MITKR is being confident in how
accurate the positioning and alignment is when so little
of the joint is visible through the small incision.
This problem is addressed by Computer Assisted Surgery,
which leads to enhanced accuracy in implant positioning
and alignment. Computer Navigation allows to perform
MITKR surgical technique to have excellent patient outcomes
consistently. It is providing a visual confirmation
and verification for the sugeon and enabling more precise
implantation. |
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| Computer Assisted Total Knee
Replacement |
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| Computer Assisted
Surgery (CAS) system can be compared with
GPS for automobile navigation. |
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The
goal of Computer Assisted Surgery is to assist
surgeons to operate with smaller incisions and
greater precision. The Computer Navigation system
used helps to align the patients's bones and joint
implants with a degree of accuracy not possible
with the naked eye.
Think of it this way. Perhaps you've seen the
onboard computers in newer cars that provide driving
directions using satellite navigations systems.
Onboard computers collect data points from satellites
and use precise coordinates to give drivers directions
from point A to point B.
It provides a degree of precision, speed and accuracy
not attainable with a map and compass. Similarly,
computers used during Total Knee Replacement Surgery
offer visual mapping to help doctors make crucial
decisions throughout the operation.
An advantage is that the doctors has greater "vision"
when it counts - during surgery. The Computer
System captures the patient's unique anatomy and
translates it to a computer screen, providing
an unobstructed view of the patient's hip joint.
This supports decision-making and enhances the
sugeon's flexibility. |
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| Infra Red
Camera and Touch Screen Display |
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| The cameras take data via infrared
signals from reflectors placed on the patient's body
and on specially designe surgical instruments. The computer
uses the data to track the exact position of the patient
and the instruments on a monitor. |