What is a partial knee replacement?
By Dr. Walker Flannery, OSMS physician owner and orthopedic surgeon

Dr. Walker Flannery is a board-certified orthopedic surgeon and OSMS physician owner. He is seeing patients at our Green Bay and Marinette clinics. Request an appointment with him here.

A partial knee replacement is an alternative to total knee replacement for some patients with arthritis of the knee. Partial knee replacement has grown in use the last decade after research showed excellent outcomes in a wide variety of patients. There are many reasons partial knee replacement is appealing including: less bone removal, easier recovery, and a more natural-feeling knee replacement.

Image courtesy of OrthoInfo (AAOS)

There are three main cartilage areas or “compartments” to the knee.  Any of these compartments can develop arthritis as cartilage wears down, making the surface rough. Patients with arthritis may receive a total knee replacement, which removes all three compartments and replaces the areas with metal and plastic.

An alternative to total knee replacement is unicompartment or “partial” knee replacement.  In partial knee replacement, the worn-out surfaces are replaced in the arthritis-affected compartment only. This is a nice option in arthritis limited to one compartment.  Research shows that in 20% of knee replacement surgeries, it is appropriate to replace only one compartment.

Image courtesy of OrthoInfo (AAOS)

Advantages of a Partial Knee Replacement

Partial knee replacement involves, on average, a smaller incision, less blood loss, and generally easier recovery. There is higher likelihood of going home the same day or following morning with earlier return to activities.

Partial knee replacement offers relatively normal kinematics or “movement control” to the knee. The more natural feel is likely related to preserving the ACL or anterior cruciate ligament. The ACL resides in the center of the knee providing knee stability and guides movement. With total knee replacement, the ACL is removed and substituted with plastic.  Range of motion or “bending” often improves earlier during recovery compared to a total knee replacement.

Patients over age 75 who are candidates for partial knee replacement have been found to have a lower overall risk of complications compared to total knee replacement, including blood clot, infection, need for manipulation of the knee to improve range of motion, and need for narcotic pain medication.

For the reasons above, partial knee replacement has high patient satisfaction.  Implants may last 20+ years with current technology.

Disadvantages of a Partial Knee Replacement

While there are many advantages of a partial knee replacement, the potential for arthritis progression or persistent pain in the other two compartments is possible. Other considerations include loosening of parts over time and the likelihood of further surgery in younger patients. Fortunately, surgery to change a partial knee replacement to a total knee replacement is generally easier than changing a total knee replacement to another total knee replacement.

Situations to avoid partial knee replacement include poor knee alignment, significant stiffness, ligament damage, and with inflammatory arthritis such as rheumatoid.

Fortunately, if patients are not a great candidate for partial knee replacement, they may still be a candidate for total knee replacement.  The orthopedic doctors at OSMS are experts in knee replacement surgery. We evaluate your condition as a whole to guide treatment and determine if you’re a candidate for partial knee replacement.

If you think you might be a candidate for partial knee replacement or would like to learn more, click here to request an appointment with Dr. Flannery.