Knee implants for osteoarthritis can be unilateral (one-sided). More often a total knee replacement (TKR) is done. Survivorship refers to how long the knee replacement lasts without problems.
If the implant fails for any reason or has to be removed, then survivorship has ended. There are many reasons why an implant may fail. The most common causes of failure are infection, pain, loosening, and dislocation.
Five-year survivorship is considered short- to mid-term in length. An implant that lasts 10 or 15 years (or longer) has good long-term survivorship. Most implants are expected to survive or last at least that long.