FDA Clears Smith & Nephew’s Legion Knee for 30-Year Use

A 30-year knee replacement? Longer-lasting implants are one of the primary goals of artificial joint manufacturers. With its recent 510(k) clearance, Smith & Nephew is, in theory at least, a little closer to that objective.

The company received 510(k) clearance from the U.S. Food & Drug Administration to label its Legion knee implant as good for 30 years of use. Smith & Nephew’s orthopedic division ran tests simulating 30 years of physical activity on the implant, which includes the firm’s Verilast technology.

The clearance was based on the agency’s findings that the implant would “provide wear performance sufficient for 30 years of actual use under typical conditions.” Most knee implants are expected to last 10 to 15 years. The key words are “under typical conditions.” Numerous other factors, such as infection, can shorten the life of an implant.

According to the company, Verilast technology produced an 81 percent reduction in wear, which is the leading cause of knee replacement failure. When knee implants fail, patients most often require revision surgery to replace the original implant, increasing the risk of infection and bone loss.

“Physically active patients want to end their knee pain for good,” Joe DeVivo, president of Memphis, Tenn.-based Smith & Nephew Orthopaedics noted in a press statement. “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.”

Verilast technology is a combination of the company’s Oxinium material and highly cross-linked polyethylene. According to company officials, the pairing yields “virtually indiscernible wear.” Oxinium is used on the femoral side of the joint, and the polyethylene is implanted on the tibial side. The company performed wear simulator testing of the knee replacements during three continuous years. Oxinium oxidized zirconium is a proprietary material that, according to the company, has been used in more than 200,000 knee procedures. Smith & Nephew officials claim it is also the only hypoallergenic metal-bearing surface since it contains no detectable amounts of nickel, the element commonly associated with metal allergies.

“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 added. “And patients may avoid the pain and the downtime associated with revision surgery.”