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Total Knee Replacement (Knee Arthroplasty)
A total knee replacement (TKR) or total knee
arthroplasty is a surgery that resurfaces
an arthritic knee joint with artificial metal or plastic replacement
parts called the ‘prostheses'.
Doctors may recommend surgery for people suffering
from severe arthritis in the knee
to decrease the pain and to improve the patient's ability to walk.
In an arthritic knee
- The cartilage lining is thinner than normal or completely
absent. The degree of
cartilage damage and inflammation varies with the type and stage of
- The capsule of the arthritic knee is swollen
- The joint space is narrowed and irregular in outline; this can
be seen in an X-ray
- Bone spurs or excessive bone can also build up around the edges
of the joint.
The combinations of these factors make the arthritic knee stiff and
limit activities due to
pain or fatigue.
- The diagnosis of osteoarthritis is made on history, physical
examination & X-rays
- There is no blood test to diagnose Osteoarthritis (wear & tear
Total knee replacement procedure:
A longitudinal skin incision is made down the front of your knee.
This incision usually
measures around 15cm. The kneecap is reflected out of the way and the
surfaces are removed. Soft tissue releases are performed. Special
used to remove the bone in a specified manner so that a knee
can fit onto the bone with or without cement.
Some prostheses do not require cement fixation and the bone grows
into them. Other
prostheses require cement fixation. Your surgeon will decide which is
the best fixation
prosthesis for your quality bone. Once the two metal components are
fixed to the bone,
a plastic insert is placed on the tibial surface. This plastic acts as
the shock absorber.
The plastic allows the low friction movement to occur. The plastic may
either be fixed
or mobile depending on the type of prosthesis.
The kneecap may also require resurfacing depending on the amount of
wear. This is
done by removing half the under-surface of the kneecap (patella) and
plastic kneecap in its place.
Soft tissue releases are performed to balance the knee joint and
after the prosthesis
has been placed in the knee, the knee should appear straight and flex
to over 110
Many arthritic knees are bowed due to the arthritis. A total knee
correct this mal-alignment. Some knees are knock-kneed and similarly
replacement will correct the mal-alignment. Following the surgery the
closed with absorbable sutures and a drain is inserted.
Post-operative physiotherapy is started after 24 to 48 hours. It is
important to do
all the exercises as they will allow a quicker recovery. Quadriceps
exercises and knee
extension and flexion exercises are most important. You should expect
to gain a
range of motion from 0 to 110 degrees. Very stiff knees often do not
amount of movement. Knees that start off with 140 degrees of movement
approximately 20 degrees of movement following the replacement.
As anybody undergoes general or regional anesthesia
(epidural anesthesia) there
are always risks associated with it. The risks of course are magnified
if you have
abnormal general medical conditions in addition to your older age,
have affected the functions of your vital organs such as heart, lungs
Therefore a complete evaluation of those systems has to be performed
are taken to the Operating theatre.
Specific complications relating to knee replacement
surgery include the following:
- Deep vein thrombosis: The risk of this
occurring is lowered by giving blood thinning
medication. However if it does occur more specific treatment is
- Infection: The risk of infection is
less than 1% and pre-operative antibiotics are
given to prevent this from happening.
- Stiffness: Occasionally knee
replacement may stiffen up particularly in patients
who are significantly overweight or have diabetes. Occasionally one
a manipulation under an anaesthetic should this occur.
- Nerve and vessel damage: It is
unlikely that any major nerve or vessel will be damaged.
It is, however, very common to have a small area of numbness over
the outer side
of your knee where a superficial skin nerve is always cut during the
This little numb patch is of no significance.
- Prosthesis failure: The prosthesis may
fail due to the plastic wearing out and it
may require revision.
- Reflex sympathetic dystrophy: Very
rarely a condition can occur where the leg becomes
stiff, hypersensitive and painful. This requires specific treatment
with a pain management specialist.
- Excessive bleeding around the joint:
This usually settles but may require drainage.
- Excessive scarring: Some skin will
scar up significantly (keloid).
- Fluid build-up in the knee joint:
Occasionally this may occur and require drainage.
It is usual for knees to be a little swollen and a little warm.
- Pain with kneeling: Kneeling may
produce discomfort over the incision site.
A total knee replacement often takes at least six months to settle