Minimally Invasive
Unicompartmental Arthroplasty Shortens Rehabilitation
November / December 2003
 “The
half-knee replacement provides patients with improved function,
improved biomechanics and retention of a more normal anatomy
because only one third of the knee is resurfaced.”
Orthopaedic surgeons at the Penn Orthopaedic
Institute perform
minimally invasive unicompartmental arthroplasty in select
patients to relieve pain and restore function. The unicompartmental
arthroplasty or half knee replacement has been performed
for
about 30 years, but the new minimally invasive approach reduces
rehabilitation time and leaves patients with a more natural-feeling
knee.
“Partial knee replacements work well in younger patients.
If a patient requires a joint reconstruction in their 30s
or 40s, it is likely they will need another reconstruction
in their lifetime. For these patients the unicompartmental
arthroplasty is a very conservative way to relieve pain
and restore function,” says Jonathan
Garino, MD, orthopaedic surgeon in the Penn Orthopaedic
Institute.
In addition, the minimally invasive approach requires
just a three inch incision—half the size of what was
previously required. With this approach patients are usually
fully recovered three to four weeks after surgery and some
are back at work in just two weeks. The recovery for a full
knee replacement is anywhere from six to 12 weeks.
The Advantages
The knee is comprised of the medial, lateral and patella femoral
compartments. A full knee replacement resurfaces all three
compartments while a typical half knee replacement involves
resurfacing either the inside or outside half. This allows
the two cruciate ligaments (in the middle of the knee) to
be preserved and therefore the kinematics (bending during
gait cycle) of the knee are not altered. “The half-knee
replacement provides patients with improved function, improved
biomechanics and retention of a more normal anatomy because
only one third of the knee is resurfaced. It is designed for
more flexion,” explains Dr. Garino.
Although most experts agree that the full knee replacement
is more durable, the half knee replacement requires a smaller
incision, offers a faster knee rehabilitation, and leaves
patients with a more normal feeling knee. For orthopaedic
surgeons, the ease of converting a partial knee replacement
to a full knee replacement in 10 or 15 years is crucial.
The
half knee replacement makes this conversion easier because
70 to 75 percent of the original knee remains intact.
“One
of our goals during this initial procedure is to preserve
as much of the bone and cartilage as possible, so, ultimately
when the knee requires a conversion to a total knee replacement
it is almost like performing the surgery for the first time
and leads to a better outcome than if a failed total knee
replacement is revised,” says Jess
Lonner, MD, orthopaedic surgeon at Booth Bartolozzi
Balderston Orthopaedics at Pennsylvania Hospital. “Historically,
this procedure excluded young and active patients, but
now
we know that the unicompartmental arthroplasty is a wonderful
intermediate procedure for those active patients who may
require
total knee replacement in seven to 10 years.”
When to Consider
Arthritis or injury are the main reasons patients require
knee replacement. The best candidates for half-knee replacement
are those who have good range of motion, minimal deformity,
pain that is isolated to either the inside or outside half
of the knee, and those who are not significantly overweight.
In properly selected patients, 90 percent of unicompartmental
arthroplasties perform well at 15 years.
Other patients that often do not require a full knee replacement
are those with isolated patella femoral disease. Orthopaedic
surgeons resurface the undersurface of the kneecap and the
anterior aspect of the femur and improved prosthetics provide
patients better longevity.
With more physically active and younger patients requiring
knee replacement, researchers are focused on improving technology
and technique. Penn orthopaedic surgeons are investigating
new, longer-lasting, ceramic-coated prostheses. Future plans
include utilizing computer-assisted guidance technology to
improve precision during implantation.
“Another exciting
area we are investigating is the biological resurfacing of
cartilage which could enable us to regrow or restore lost
cartilage,” adds Dr. Lonner. Finally, Penn orthopaedic
surgeons recommend early intervention and evaluation by an
orthopaedic surgeon which may help more patients avoid a
knee
replacement.
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Referring Physicians: To speak with a Penn physician
or refer a patient, contact PennHealth through the secure online
referral form or by calling
1-800-789-PENN
(7366). |
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