New Knees May Be in Order When Other Options Fail
By: Jane E.Brody
NY Times, August 13, 2002
When lesser measures can no longer control the pain
and disability of arthritic knees, surgery to reconstruct or replace them
then becomes a consideration. But only a consideration.
These are entirely elective procedures, and anyone
who is a candidate for either would be wise to know in advance just what
they involve, both during the surgery and for months afterward, and what
limitations on athletic activities are likely afterward.
The most common procedure is replacement of the
working parts of the knee with synthetic devices of metal and plastic or
ceramic materials that can withstand normal stresses on this
weight-bearing joint for at least a decade. Another operation called high
tibial osteotomy can sometimes be done to reconstruct an arthritic knee
and delay the need for a total knee replacement by a decade or so. The
latter is more often done on younger, physically active patients who are
likely to long outlive a knee replacement.
In either case, the outcome of surgery is likely to
be best when done by orthopedic surgeons who perform the procedures often
and in hospitals that do 100 or more of them a year.
Total Knee Replacement
The knee is a hinge joint made up of bones, ligaments and tendons and
supported by muscles. It could easily win a prize as a masterpiece in
engineering. The knee can bend, slide, glide and rotate through a wide
range of motions and in the process absorb up to seven times a person's
weight. Unfortunately, it is also a very vulnerable joint that can
deteriorate as a result of injury, disease and, most common, the stresses
inflicted on it during the long and active lives so many of us now lead.
The most common reason for a knee replacement is
osteoarthritis, the wear-and-tear disease in which the cushions of
articular cartilage at the ends of the thigh bone, or femur, and the lower
leg bone, or tibia, deteriorate, resulting in bones that rub together
painfully with every step. Although most arthritic knees result from
aging, an increasing number of cases occur in younger people who sustain
athletic or accidental knee injuries years earlier.
Total knee replacement is a major operation most
often done on people with arthritis that causes severe pain, a significant
loss of mobility and an inability to perform reasonable routine and
recreational activities. More than 200,000 knee replacements are performed
annually in this country, most in people over 65.
In the right hands and with proper rehabilitation, it
is a highly successful procedure, resulting in a pain-free knee that lasts
10 years in 90 percent of cases and 20 years in 80 percent of cases. At
the Hospital for Special Surgery in New York, a ceramic knee replacement
that researchers believe could last up to 25 years is being used in some
patients in their early 50's or younger. Many developed severe arthritis
after athletic knee injuries in their teens, 20's or 30's. The survival
time of a replaced knee obviously depends on how much stress is placed on
it; the more active the person, the shorter the knee's life span is likely
to be.
The surgery, which typically takes two to three
hours, involves cutting away the diseased parts of the joint so the
replacement parts will fit precisely against the femur and the tibia.
These parts are either cemented in place or made with lots of little holes
into which the bones grow to hold the knee in place.
If cemented, the new joint is immediately stable,
though the cement can loosen with time. The prosthetic components fit
together to allow the knee to bend and to have some of the rotational
movement of a normal knee. Ligaments, tendons and muscles are not involved
in the surgical procedure, although misaligned leg bones and tight
ligaments can be corrected. If necessary, both knees can be replaced at
the same time.
The surgery risks include infection, bleeding, nerve
damage and blood clots in the leg (which can be fatal if one travels to
the lungs). Precautions, like donation of the patient's blood before the
surgery, use of leg massager and administration of blood thinner, minimize
these risks. The hospital stay is generally three to five days, and
physical rehabilitation should begin during the hospital stay.
A patient goes home with crutches or a walker to be
used for four to six weeks. After that, a cane can be used to help with
navigation until it's no longer needed. Driving is usually resumed after
six weeks, possibly sooner if the car is an automatic and surgery was
performed only on the left leg.
Though many patients feel better right after surgery,
several months of physical therapy to strengthen muscles and other soft
tissues that support the knee are critical. The exercises can later be
done on one's own and are best continued indefinitely for maximum benefit.
Full recovery from knee replacement surgery typically
takes three months. Most people are then able to resume activities like
bicycling, walking, swimming and golf. An active life is encouraged. But
activities that involving jarring motions or quick starts and stops, like
jogging, singles tennis, soccer, volleyball and basketball, should be
avoided because they can damage or loosen an artificial knee.
As a precaution against serious infection, people
with artificial joints are advised to take antibiotics before dental and
medical procedures that can let bacteria enter the bloodstream.
Tibial Osteotomy
The object of this procedure is to realign a deformed
knee and shift some of the excess stress on the arthritic part of the knee
to the healthier part. It is typically a stopgap measure to postpone the
need for knee replacement surgery for up to a decade.
The procedure is often recommended for younger
patients who have arthritis in one part of the knee, either the medial
(inside) half or the lateral (outside) half, resulting in bowed legs or
knock-knees, respectively, and increasing the wear and pain on one side
more than the other.
The surgeon cuts out a wedge of bone from the tibia
to correct the deformity in the knee and realigns the bones, reallocating
the space between the femur and tibia so that bone does not rub against
bone on either side of the joint. The edges of the cut bone are either
stapled or secured with plates and screws.
The surgery heals like a fracture, which requires up
to six months for recovery. Typical hospital time is three to six days.
The knee must be immobilized with a cast or brace for six weeks or longer,
while the patient uses crutches. At this point, gradual weight-bearing
begins, with activity increased after three months or so. As with total
knee replacement, physical therapy for months is critical to a full
recovery.
Anyone considering this procedure should discuss
fully with the surgeon the extent of the recovery period and the
limitations that will follow. Many patients regain normal knee function
for routine activities, but they may not be able to resume demanding
activities like skiing and tennis.
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