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Unicondylar (Unicompartmental) Knee Replacement
If only a single compartment of the knee is worn out, then it may
be possible to
replace only the worn out component. This is usually done via a
approach and the recovery time is much quicker. A 7 to 10cm skin
incision is used
and the kneecap is not reflected. The worn out surface is prepared.
The femoral or
tibial component is usually glued or press-fitted in place. The
patient can be mobilised
four to six hourly post-operatively and can go home after one to three
depending on the amount of pain experienced.
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
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.
If the patello-femoral joint is the only part that is
worn out, then this can be replaced
similarly to a uni-compartmental knee replacement. The incision is
similar to a total knee replacement but naturally less bone is
removed. A total knee replacement may be
required in the future.