Hip And Knee Replacement Systems Should Last 25 Years, Studies Say

Researchers involved in two new studies indicate that if a hip and knee replacement system is well made, the components should last at least 25 years before they need to be replaced or pose a risk of failing. 

In studies published this month in the medical journal The Lancet, researchers from the U.K. said most patients should expect joint replacements to last about a quarter of a century. One of the studies focused on hip replacement systems, while the other study looked at knee replacement systems.

Researchers involved in both reports conducted a review and meta-analysis of other studies, and evaluated data from national joint replacement registries; from the start of records to September 12, 2017 in the case of hip implants, and until July 21, 2018 in the case of artificial knees.

The hip implant findings encompassed studies and articles with 13,212 total hip replacement surgeries, and the data from the registries in Australia and Finland gave them data on another 215,676 hip replacements. According to the findings, the studies revealed that 77.6 percent of hip replacement systems lasted 25 years, while data from the registries indicated that 57.9 percent of patients had hip implants that lasted 25 years.

“Assuming that estimates from national registries are less likely to be biased, patients and surgeons can expect a hip replacement to last 25 years in around 58% of patients,” the researchers concluded.

For knee replacement systems, the researchers looked at studies and articles involving 7,232 knee replacements, and nearly 300,000 knee replacements from Australian and Finnish registries. According to those findings, the 25-year survival rate of total knee replacements was 72 percent in the registries. None of the studies looked at survival rates going out that far.

Knee and Hip Replacement Failures

In recent years, problems have developed with a number of hip and knee replacement systems, which were linked to higher-than-expected failure rates, often due to design or manufacturing defects.

Probably the most problematic have been metal-on-metal hip replacements sold by a number of different manufacturers, which featured a metal femoral head that rotates within a metal acetabular cup.

Unlike other artificial hip designs, which typically feature metal-on-ceramic or metal-on-plastic, the metal-on-metal hips have been found to release microscopic metallic debris as the parts rub against each other. This can lead to increased levels of metal ions in the blood, known as metallosis. This has been linked to reports of loosening and failure, often within a few years after the artificial hip is implanted.

Metallosis has been linked to tissue damage, tumors and may increase the risk of cancer according to some research.

Most of the devices were introduced in the U.S. through the controversial fast-track 510(k) approval process, which only required that the device be a “substantial equivalent” to an already existing device approved by the FDA. However, the snowball effect of the substantial equivalence test has allowed many devices now considered unreasonably dangerous and defective to be implanted in thousands of Americans.

Several manufacturers faced metal-on-metal hip lawsuits in recent years, claiming that the design was unreasonably dangerous and prone to early failure. Similar allegations led to DePuy ASR hip lawsuits, DePuy Pinnacle hip lawsuits and other cases.

There have also been emerging concerns in recent years about knee replacement problems linked to several widely used implants that have been linked to high rates of implant failure, resulting in the need for knee revision surgery; including DePuy Attune Knee,Exactech Optetrak Knee, and Arthrex iBalance Knee. Many of the problems with these implants have been linked to tibial loosening and tibial baseplate failures.