This is a guest post by Kim Wright, PT and her husband James (Jay) Butler, MD. Kim is a physical therapist who specializes in orthopedics and her husband is an orthopedic surgeon. They both practice in Houston, Texas. I asked Kim and Jay if they would share their knowledge and experience with knee osteoarthritis and knee replacement and they generously agreed.
The knee joint is composed of three compartments. They are the
inside(medial), outside (lateral) and the kneecap (patellofemoral).
Wear and tear on our joint surfaces occurs over time depending on
activities we perform and injuries that occur. Some of us will have
more wear and tear due to the alignment or posture of our legs. Knee alignment refers to the angle of your thigh bone from your hip to
your knee and the angle of your shin bone from your knee to your
ankle. Your foot alignment is an angle formed from your heel to your
forefoot. Terms such as knockneed, bowlegged and pronation refer to
these angles. The angles influence how the force from the weight of
your body and activities like running or hiking is distributed through your joints.
If you tend to be knockneed,
bowlegged or if you tear a meniscus (shock absorbing pad between the
bones) or suffer a fracture, the forces can be
increased in one of the compartments. The extra force is transmitted to the
bone and the overlying cartilage (articular
surface). Given enough time, this surface wears away and the bone can become exposed and painful. This wearing away of the
articular surface is called chondromalacia (arthritis). It is usually
graded I-IV with I being the mildest degree of damage. When the damage
progresses to stages III and IV the bone is actually becoming exposed
and this is when pain and swelling occur and simple life activities
such as walking, squatting and stairs become difficult. When
any of the three compartments suffer significant wearing of the
articular surface causing Grade IV chondromalacia, the doctor may
suggest a partial joint replacement. Partial joint replacements are
ideal for patients with isolated Grade IV chondromalacia in only one
compartment. This usually occurs in younger patients 40-60. Patients
with a lot of arthritis in one compartment and some in the others may
still have a certain degree of pain and swelling after surgery from the
remaining arthritis. This is why a careful examination and selection
process is critical for a good outcome. There are unicompartmental
replacements ( ”Uni”) for the medial (ins ide), lateral (outside) and
patellofemoral (kneecap) compartments. In contrast, a total knee
replacement replaces all three compartments.
involves replacing the two sides of the bone of the damaged compartment
with metal and plastic components. If you have medial or lateral
compartment arthritis, and this has made your leg a litt le knockneed or
bowlegged, the placement of the components will correct the alignment. The
surgery involves an incision on the front of the knee.
recovery is similar to a total knee replacement except it is usually with less pain
and is faster. It involves a short stay in the hospital (2-3 days),
one-two weeks using crutches or a walker and then 4-6 weeks of physical therapy. Someone with a unicompartmental replacement should expect to
regain full straightening and almost full bend of the knee as compared to their
normal knee during the first 4-6 weeks after surgery.
allowed with a unicompartmental replacement. Sports not involving
repetitive high impact activities such as jumping, running and cutting
are the best. For example, many patients return to walking, biking,
hiking, light doubles tennis, weekly game of softball or baseball,
dancing, gym workouts, exercise class. Younger patients may choose to
return to running and other more strenuous sports, but this may lead to
early deterioration of the plastic (polyethylene) component. Like all
joint replacement and arthritis patients, individuals with a
unicompartment replacement should maintain a healthy weight and perform
exercises that promote good joint health regularly. This will help
prevent wearing of the plastic component and reduce progression of less
severe arthritis that may exist in other parts of the joint.
unicompartment replacement should last about 10-15 years before needing a
tune up. Sometimes the unicompartment
replacement is just a time grabber for someone who may be destined to a
total joint replacement. For other patients that actually fall into
the “isolated” arthritis category it can be the last replacement they
need. All joint replacements have a similar life expectancy before
revisions are needed and this is usually stated as 10-15 years on
average. There are two reasons the unicompartment replacement may need
to be revised over time. Pre-existing arthritis in other parts of the
knee can progress and the plastic component can wear out. If other
parts of the knee progress to Grade IV chondromalacia (arthritis) the
unicompartment replacement can be converted to a bicompartmental
replacement for the onset of kneecap arthritis or a total knee joint
for generalized arthritis development in the remaining two
compartments. As with any surgery, but especially one that is
performed on an isolated group of patients, ask your doctor why you
qualify and ask how many of these procedures they have performed and
their specific outcomes.
For more information on
unicompartment replacements you can go to the website for the brand of
prosthesis your physician uses or as an example go to www.biomet.com and choose patient and caregiver section, joint replacement, knee
pain, knee joint replacement or knee joint products. You will read both
good and bad reports from actual patients as well as research
articles. Just remember that there is a very select group of patients
that are appropriate for this procedure that will do well over time.
Talk with your physician about your qualifications.
information on custom patellofemoral replacements you can reference the
article from James E Butler, MD; Robert Shannon, MD Orthopedics 2009,
32:81 or www.orthosupersite.com.