Knee replacements such as the Zimmer Persona knee are expected to last over 20 years, but defective designs may cut this lifespan short.

When the knee joint is damaged by injury, arthritis, or other degenerative bone conditions, doctors may recommend knee replacement surgery. During this relatively common procedure, the natural joint is replaced with an implant that mimics the movement of the joint.

The American Academy of Orthopaedic Surgeons reports that there are over 600,000 knee replacement surgeries performed each year. Since the surgery’s invention in 1968, the techniques and implants available have improved – making knee replacement surgery a relatively safe procedure.

According to John Hopkins Medicine, there are risks associated with the knee replacement procedure including bleeding, infection, blood clots, fracture, continued pain, and implant failure. However, successful knee replacement surgeries have been shown to significantly improve quality of life.

Knee replacement implants are typically expected to last at least 20 years. Research presented at the 2011 Annual Meeting of the American Academy of Orthopaedic Surgeons confirms that implants typically last for over 20 years and may even increase quality of life and activity level in knee replacement patients.

Impact of TKA

“We’ve known for years that total knee replacement adds to quality of life, adds to patients being more active, being able to participate in things they want to participate in,” says study author John Meding, according to the Arthritis Foundation. “But we also know that over time as we age, function diminishes. You get slower. [So] we were somewhat surprised at the activity level of these people at 20 years or more after total knee replacements.”

Meding, who is an attending orthopedic surgeon at The Center for Hip and Knee Surgery, noted that the researchers were surprised when they found that individuals with a knee replacement were more active than other individuals.

80 year old individuals without a knee replacement were reportedly found to have an activity score of 6/10. This means that are able to walk around, go to dinner, and get in and out of a car. In contrast, 80 year olds who had knee replacement surgery had an activity score of 8.3, “which basically says they are regularly very active, participating in things like golf, swimming, riding a bike.” Meding said that this finding was “probably the most surprising thing in the study”.

Zimmer Persona Knee

All knee replacement implants may not guarantee this quality of life, however. Consumer reports suggest that the Zimmer Persona knee can fail much earlier than the 20-plus year average lifespan predicts.

Implant failure can result in a variety of symptoms including pain, limited range of motion, and joint instability. These complications may require revision surgery. In the case of Zimmer, a component issue also led to a voluntary knee replacement recall.

Individuals who were implanted with a Zimmer Persona knee replacement may have assumed that they were increasing their quality of life and ensuring a future of activity and health. However, implant failure has disappointed countless patients after their knee implant failed completely. Some of these individuals have filed lawsuits against the device manufacturers to seek compensation for the allegedly defective product.