A partial knee replacement is an alternative to total knee replacement for
some patients with osteoarthritis of the knee when the damage is confined to a
particular compartment of the knee. In the past, partial knee replacement was
reserved for older patients who were involved in few activities. Now, with better
implants and improved surgical techniques, more patients are being
considered for partial knee replacement compared with a few years ago. About 5%
to 6% of patients with arthritic knees are estimated to be eligible for partial
How common is knee osteoarthritis?
Up to 30% of the population is believed to have knee osteoarthritis. Until
age 50, knee osteoarthritis is equally common in men and women. After age 50,
more women are affected.
What is osteoarthritis?
Osteoarthritis is the wearing away of the connective tissue called articular
cartilage within the joint. Articular cartilage prevents one bone from scraping
against another. The cartilage acts as a shock absorber in the joint and allows
for smooth and stable movement within the joint. When the cartilage thins, the
joint can inflame and you may feel pain and stiffness in the joint and your
range of motion may be limited.
What is a partial knee replacement?
In a partial knee replacement, only the damaged part of the knee cartilage is
replaced with a prosthesis.
What are the advantages of partial knee replacement over total knee replacement?
Compared to total knee replacement, partial knee replacement better preserves
range of motion and knee function because it preserves healthy tissue and bone
in the knee. For these reasons, patients tend to be more satisfied with partial
knee replacement compared with total knee replacement, and they are still
candidates for total knee replacement should they ever need it in the future.
There is also less blood loss during surgery, and knee motion recovers faster
with partial knee replacement.
Who is a candidate for partial knee replacement?
Patients with medial, lateral, or patellofemoral knee osteoarthritis can be
considered for partial knee replacement. "Medial" refers to the inside
compartment of the joint, which is the compartment nearest the opposite knee,
while "lateral" refers to the outside compartment farthest from the opposite
knee. Medial knee osteoarthritis is commonly caused by damage to knee
cartilages, known as the menisci.
Patellofemoral osteoarthritis is osteoarthritis of the joint between the
kneecap (patella) and the lower leg bone (tibia). This type of knee
osteoarthritis is more common than lateral compartment knee osteoarthritis.
If your knee pain persists despite anti-inflammatory medications and
maintaining a healthy weight, you may want to consider a knee replacement.
Your doctor will ask you to identify the area of pain in your knee, then
check your range of motion and the knee's stability. An X-ray of the knee will
determine your eligibility for partial knee replacement but your surgeon may not
know for certain if you are a good candidate until the surgery has begun. To be
a candidate, you must have an intact anterior cruciate ligament, a sufficient
range of knee motion, limited inflammation, minimal pain at rest, damage to only
one compartment, and no calcification of cartilage or knee dislocation.
In the past, a partial knee replacement was considered only in patients older
than 60 years who were sedentary but younger, more active patients are
increasingly being considered.
What is recovery like?
You can start moving the knee the day after surgery. Your knee function
should return rapidly and with less pain than with total knee replacement. You
will work with a physical therapist to mobilize the knee while in the hospital
and for 2 to 4 weeks after discharge, which usually occurs no later than 1 or 2
days after surgery.
You will need medication to guard against formation of a blood clot while in
the hospital and perhaps for a period of time after you are discharged.
If all goes well, you should be back to full activity in about 1 month.
Impact exercises or jogging/running may not be recommended because the
replacement includes a bearing surface that can wear.
What are the risks?
An infection at the surgical site is possible. Blood clots are a risk as are
injuries to a blood vessel or a nerve. These complications are quite rare. You
may experience some knee joint stiffness.
Late complications may include infection and a failure, loosening, or
dislocation of the prosthesis as well as continued pain.
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This information is provided by Cleveland Clinic and is not intended to replace
the medical advice of your doctor or health care provider.
Please consult your health care provider for advice about a specific medical condition.
© Copyright 2013 Cleveland Clinic. All rights reserved.