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Total Knee Replacement vs. Partial Knee Replacement

Which Is Right for You?

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Updated June 18, 2014

Total knee replacement, also known as total knee arthroplasty, is a highly successful surgical procedure. It is not the only surgical treatment option for knee osteoarthritis, though. Some patients are candidates for partial knee replacement.

The Difference Between Total Knee Replacement and Partial Knee Replacement

The knee has three compartments -- the medial compartment (inside aspect of the knee), the lateral compartment (outside of the knee) and the patellofemoral compartment (in front of the knee). In some knee osteoarthritis patients, only one compartment of the knee is affected. Actually, it is usually the medial compartment that is affected by osteoarthritis. The lateral compartment can be affected, but it is less common.

A partial or unicondylar knee replacement, as its name suggests, replaces only the affected compartment of the knee. On the other hand, a total knee replacement involves replacement of all three compartments of the knee.

While just one compartment is replaced during partial knee replacement, anterior and posterior cruciate ligaments are preserved. The ligaments are removed in a total knee replacement. Suffice it to say, with a partial knee replacement, more of your own body structure remains intact.

Benefits and Risks Associated with Partial Knee Replacement

There are benefits to having a partial knee replacement. With this surgical procedure, there is:

  • less bone and soft tissue dissection
  • less blood loss
  • fewer complications
  • faster recovery of range of motion
  • better range of motion overall

There are also risks associated with partial knee replacement. The risks include:

  • a higher revision (repeat or re-do) rate for partial knee replacement than total knee replacement
  • potentially worse function after revision of partial knee replacement than total knee replacement
  • revisions can be more complicated than primary surgeries

The same complications are possible with both surgical procedures: loosening, infection, nerve injury, fracture of the bone and more.

Good and Bad Candidates for Partial Knee Replacement

In 1998, two doctors (Drs. Scott and Kozinn) established criteria for determining which patients were good candidates for partial knee replacement. The ideal patient:

  • is older than 60 years old
  • is less than 180 lbs
  • is less active
  • has good range of motion before surgery
  • has minimal deformity

Patients with inflammatory types of arthritis, such as rheumatoid arthritis, are not regarded as good candidates for partial knee replacement. With inflammatory arthritis, more than one compartment is usually involved.

The Bottom Line

There have been improvements in the design of unicompartmental prostheses over the years. Having a surgeon experienced in working with partial knee replacements is a plus too. Ultimately, a successful outcome depends on having the right patient for the procedure. It is estimated, though, that only 6% to 10% of patients are suitable candidates for partial knee replacement.

Source:

Partial Knee Replacement. Conditions and Treatments. Hospital for Special Surgery. Friedrich Boettner, MD. 3/27/2008.
http://www.hss.edu/conditions_partial-knee-replacement.asp

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