What are the chances of going from needing a partial knee replacement to a full knee replacement?

It depends: Typically, only approximately 10% of patients with knee arthritis will qualify for a partial knee replacement based on strict criteria. However, depending on what your symptoms are, expectations, and most importantly discussions with your surgeon, the threshold to going from a partial knee replacement and ending up with a full knee replacement may change.

High: Following strict criteria, only 5-10% of patients with knee arthritis are appropriate candidates for partial knee replacement. The goal of knee arthroplasty is to provide one successful surgery that lasts 20-25 yrs. Often, total knee replacement has a better chance of achieving this goal.

Not high: I agree that relatively few patients are good candidates for a partial knee replacement. But the chances of needing a conversion to a full are very low if the surgeon selects the right patient. Assuming that the author of the question has been advised by a surgeon skilled at selecting appropriate candidates for a partial, i would say that the risk is low.

High: Before i recommend partial knee replacement, xrays must demonstrate significant arthritic changes in only one of the three knee compartments, and the patient must convince me that their pain is emanating from that compartment. Despite fellowship training in knee arthroscopy, knee replacement, and revision knee replacement, i'd still rather provide one long-lasting surgery.

Small if done well: Success rates of well installed partial knee replacements is in the 90% at 20 years reported this year by dr. Scott at the knee society meeting. This is as good a total knee results but a good partial knee feels much more natural than a good total knee replacement. The difficult is getting a great installation every time. Using makopasty robotics consistently reproducible precision is expected.