Total Knee Replacement Surgery
During knee replacement surgery , Dr Pandher will resurface the
damaged cartilage of your knee with an artificial device
(implant). There are various types of implants available for the
procedure ranging from
total knee replacement surgery
retaining, posterior stabilised, high flex, Mobile bearing) to
partial knee replacement surgery
replacing the total knee joint is the most common procedure, some
people can benefit from just a partial knee replacement.Implants
are made of metal alloys, ceramic material, or polyethylene parts,
and can be joined to your bone with bone cement. Your surgeon will
discuss with you the type of implant that best meets your needs.
The most common cause of chronic knee pain and disability is
arthritis. Although there are many types of arthritis, most knee
pain is caused by just three types: osteoarthritis, inflammatory
arthritis, and post-traumatic arthritis.
This is an age-related "wear and tear" type of arthritis. It
usually occurs in people 50 years of age and older, but may occur
in younger people, too. The cartilage that cushions the bones of
the knee softens and wears away. The bones then rub against one
another, causing knee pain and stiffness.
There are various causes of inflammatory arthritis, most common of
these is rheumatoid arthritis. In inflammatory the synovial
membrane that surrounds the joint becomes inflamed and thickened.
This chronic inflammation can damage the cartilage and eventually
cause cartilage loss, pain, and stiffness.
This can follow a serious knee injury. Fractures of the bones
surrounding the knee or tears of the knee ligaments may damage the
articular cartilage over time, causing knee pain and limiting knee
Are you the right candidate for knee replacement?
The decision to have total knee replacement surgery should be a
cooperative one between you and your knee replacement orthopaedic
surgeon. You must clarify all concerns before taking decision to
under go knife. Your final outcome and functional recovery
expectations should be same as that of your doctor. However, one
should not get swayed by myths and rumours spread about joint
replacement surgery. Patients often raise concerns like being more
disabled after joint replacement. This is unlikely if the
procedure is chosen after complete work up and you have chosen the
right surgeon for your surgery.
When Surgery Is Recommended
There are several reasons why your doctor may recommend total knee
replacement surgery. People who benefit from total knee
replacement often have some of the following findings:
Severe knee pain or stiffness that limits your everyday
activities, including walking, climbing stairs, and getting in
and out of chairs. You may find it hard to walk more than a
few blocks without significant pain and you may need to use a
cane or walker.
Moderate or severe knee pain while resting, either day or
Chronic knee inflammation and swelling that does not improve
with rest or medications Knee deformity — a bowing in or out
of your knee.
Failure to substantially improve with other treatments such as
anti-inflammatory medications, physical therapy, or other
surgeries like high tibial osteotomy or arthroscopic
The knee joint is where the lower end of your femur (thighbone)
meets the upper end of your tibia (shinbone). Patella (knee-cap)
sits in front of the joint to provide adequate lever mechanism for
functioning of quadriceps muscle.
Types of Designs
For simplicity, the knee is considered a "hinge" joint because of
its ability to bend and straighten like a hinged door. In reality,
the knee is much more complex because the bone surfaces actually
roll and glide as the knee bends. The first implant designs used
the hinge concept and included a connecting hinge between the
parts. Newer implant designs recognize the complexity of the joint
and more closely mimic the motion of a normal knee. Some designs
preserve the patient's own ligaments, while others substitute for
Several manufacturers make knee implants and there are more than
150 knee replacement designs on the market today. Common types of
knee replacement implants include Cruciate retaining (subtypes-
ultra-congruent, deep dish), posterior stabilised, and medial
pivot. Another concept includes development of "gender specific"
implants since a number of studies indicate that the shape and
proportions of a woman's knee differ from those of a man's knee.
As a result, several manufacturers have developed components for
the end of the thighbone which more closely match the average
woman's knee. However, there are no studies to show that "gender
specific" implants last longer or provide better function than
The Right Implant for You
The brand and design used by your doctor or hospital depends on
many factors, including your needs (based on your age, weight,
activity level, and health), your doctor's experience and
familiarity with the device, and the cost and performance record
of the implant. You should discuss these issues with your
Components of knee replacement prosthesis
Routinely two bone surfaces may be replaced in a total knee
replacement: The lower ends of the femur and proximal end of
tibia. Knee cap or patella rarely needs to resurfaced, this
finding is well supported by scientific evidence in medical
The metal femoral component curves around the end of the femur
(thighbone). It is grooved so the kneecap can move up and down
smoothly against the bone as the knee bends and straightens. The
tibial component is typically a flat metal platform with a cushion
of strong, durable plastic, called polyethylene. Some designs do
not have the metal portion and attach the polyethylene directly to
the bone. For additional stability, the metal portion of the
component may have a stem that inserts into the center of the
tibia bone If the back surface of the patella (Knee-cap) is
resurfaced, a dome-shaped piece of polyethylene that duplicates
the shape of the patella is fixed to it with bone cement.
The metal parts of the implant are routinely made of titanium or
cobalt-chromium based alloys, though most recently ceramic
implants for femoral component are also available in market. The
plastic parts are made of ultra high molecular weight
polyethylene. All together, the components weigh between 15 and 20
ounces, depending on the size selected Material Criteria
The construction materials used must meet several criteria:
They must be biocompatible; that is, they can be placed in the
body without creating a rejection response.
They must be able to duplicate the knee structures they are
intended to replace; for example, they are strong enough to
take weightbearing loads, flexible enough to bear stress
without breaking, and able to move smoothly against each other
They must be able to retain their strength and shape for a
Two types of fixation are used to hold knee implants in place.
Cemented and Cementless Implants
Cemented fixation uses a fast-curing bone cement
(polymethylmethacrylate). Cementless fixation relies on new
bone growing into the surface of the implant for fixation.
Cementless implants are made of a material that attracts new
bone growth. Most are textured or coated so that the new bone
actually grows into the surface of the implant.
There is also hybrid fixation. In hybrid fixation for total
knee replacement, the femoral component is inserted without
cement, and the tibial and patellar components are inserted
with cement. Your surgeon will evaluate your situation
carefully before making any decisions about components and
fixation. Do not hesitate to ask what type of fixation will be
used in your situation and why that choice is appropriate for
The longevity and performance of a knee replacement depends on
several factors, including your activity level, weight, and
general health. Just as wear in the natural joint contributed to
the need for a replacement, wear in the implant may eventually
require a second surgery (called a joint revision). Revision
surgery may require special components. Typically they will have
longer stems which fit into the femur and tibia. They may also
have attached metal pieces called augments which substitute for
missing bone. Revision components often have a cam in the center
of the knee similar to a posterior stabilized component. In
revision components, though, the cam is larger to give the knee
more stability. In cases where the knee is very unstable and a
large amount of bone is missing, it may be necessary to join the
femur and tibia with a metal "hinge" in the centre. Such implants
are rarely required for primary knee surgery when patient presents
with severe bone loss or ligament laxity due to advanced
degeneration or traumatic damage.