Regarding implant longevity, the short answer is: we don’t know.
The point that I need to emphasize is that longevity of an implant is HIGHLY VARIABLE. It really depends on multiple factors. No patient is the same, activity levels vary, accidents can happen, and the modes of failure are numerous and unpredictable.
For total joint replacement, 10-15 years is an often quoted average. Individually, joint replacements can last as long as only a few weeks to 40+ years.
Revision joint replacements may also last as long, but depending on how extensive the revision is, this can also vary widely, and is less predictable than the original (known as a “primary”) joint replacement. Additionally, your joint’s function can decrease with every surgery that is done to it, mostly because of scar tissue formation. This also varies widely.
Partial knee replacements can have the same longevity, but they have a higher rate of revision than total knee replacements at 10 years by most studies.
Advantages of partial knee replacements are that they are easier & quicker to recover from, they feel more natural, and if/when they need to be revised, chances are high that the revision will recover and act more like a primary knee replacement rather than a revision knee replacement at that time. Even though a partial knee replacement may be the only surgery you need during your entire lifeitme, one way to view a partial knee replacement is that it may be a way to postpone getting a total knee replacement. To use dental terms: a partial knee is a “filling”, a total knee is a “crown”.