As evidence of its drive to return knee pain sufferers to a lifetime of physical activity, Smith & Nephew Orthopaedics Division today announces the results of unprecedented testing on its VERILAST technology for knee replacement implants. After simulating 30 years of physical activity on the company's LEGION(TM) knee replacement, VERILAST technology produced an 81% reduction in wear, the leading cause of knee replacement failure.
The Food and Drug Administration (FDA) has reviewed the results and Smith & Nephew received 510k clearance for claims related to VERILAST technology's ability to "provide wear performance sufficient for 30 years of actual use under typical conditions." The consensus of scientific literature is that knee implants are expected to last 10 to 15 years.
"Physically active patients want to end their knee pain for good," says Joseph M. DeVivo, president of Smith & Nephew Orthopaedics. "We're working to make knee implants that last a lifetime--that's our goal, and we've validated VERILAST technology out to 30 years for a market that views 10 to 15 years as the gold standard. This is not an incremental improvement; it's a generational leap forward for active patients.
"Every orthopaedic device company has focused for years, if not decades, on developing the best possible bearing surfaces for improving the performance and longevity of knee implants," says Scott Elliott, senior vice president, global knee franchise, for Smith & Nephew Orthopaedics. "To reduce wear in knee replacements, companies have all created their own formulas for the dense plastic component (highly cross-linked polyethylene, or XLPE) used on the tibial side of a knee implant. And all companies, including Smith & Nephew, have reported progress on this front. But there are two bearing surfaces in a knee, and only one company has been successful in improving the other side of the joint--the metal femoral component.
"Smith & Nephew is the only company in the world to commercialize an advanced bearing surface for the femoral component of a knee replacement. OXINIUM oxidized zirconium is a proprietary material which has been used in more than 200,000 knee procedures and is proven to reduce wear. It is also the only hypoallergenic metal bearing surface since it contains no detectable amounts of nickel, the element commonly associated with metal allergies.
"VERILAST technology is the unique combination of our exclusive OXINIUM material and the most advanced XLPE on the market. Together, they yield virtually indiscernible wear. After performing wear simulator testing of the knee replacements over three continuous years, we have confirmed that this Smith & Nephew knee replacement made with VERILAST technology, under normal circumstances, is expected to last for 30 years."
Typically, if a knee replacement fails due to wear, the patient will undergo a "revision" surgery in which the original components will be replaced with more invasive, more expensive ones. While there may be some decrease in implant performance, the primary costs of revision surgery are in its risk of infection and bone loss for the patient and the procedure's cost for the healthcare system.
"If we're successful in our drive to make knee replacements that last a lifetime, that could mean significant cost savings to the healthcare system," DeVivo says. "And patients may avoid the pain and the downtime associated with revision surgery."
Failure due to wear is one of several known reasons for revision surgery. VERILAST technology may significantly reduce the risk of failure for patients who would have been revised due to wear.
About VERILAST Technology
VERILAST technology is the combination of two advanced bearing surface technologies: Smith & Nephew's patented metal alloy OXINIUM oxidized zirconium, used on the femoral side of the joint, and highly cross-linked polyethylene (plastic), implanted on the tibial side. OXINIUM material has been in use in knee replacements for more than a decade, but was only recently coupled with highly cross-linked polyethylene components. OXINIUM is a metal alloy that undergoes a proprietary heating process, transforming its surface into a hard, smooth ceramic that is 4,900 times more resistant to scratching than traditional materials. It is 20-percent lighter than cobalt chromium, the metal used in conventional knee replacements, and because it doesn't contain detectable amounts of nickel like cobalt chromium does, it is considered hypoallergenic and safe for patients with metal allergies.
Smith & Nephew's primary knee replacement systems, the LEGION and GENESIS(TM) II knee implants, are currently available with VERILAST technology.