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Last September, a 71-year-old patient came to MedStar Georgetown University Hospital with difficulty walking because end-stage arthritis had deteriorated most of the cartilage in her right foot. Unfortunately, she wasn’t a candidate for ankle replacement surgery or even joint fusion involving traditional implants because of her sensitivities to a variety of metals.
The patient didn’t have any other options — until Paul S. Cooper, M.D., an orthopedic foot and ankle specialist and Director of the Foot and Ankle Center at MedStar Georgetown, suggested a metal-free option made of polyetherketoneketone (PEKK). The high-performance polymer has shown potential in transforming the field of orthopedic implants.
“PEKK is a revolutionary material that has the strength of metal but potentially better biocompatibility,” said Dr. Cooper, who’s also a Professor of Orthopedic Surgery at Georgetown University School of Medicine. “This is the most exciting development I’ve come across in 30 years.”
Solving the Metal Dilemma
Although traditional metals like cobalt chrome and titanium have been the standard for orthopedic implants for decades, they’re far from the perfect material for the purpose. Due to its mechanical profile, metal is “essentially too strong and too stiff, which results in implant loosening,” said Scott DeFelice, Founder, CEO and Chairman of the Board at Oxford Performance Materials, a company that has commercialized PEKK through a range of patented technologies.
And because the body recognizes metal as a foreign substance, DeFelice said, it triggers an immune response that causes biofilm to form around implanted devices. PEKK resists infection because of its unique bacteriostatic properties, which cause the body to react to it as if it’s bone.
“That’s a function of the surface energy of PEKK, which is very similar to the endogenous proteins in the body: lubricin, casein, mucin, vitronectin and fibronectin,” DeFelice said. “It’s what inhibits infection and promotes bone growth.”
As a self-proclaimed “stalwart for metal implants,” orthopedic surgeon Jon E. Minter, D.O., has spent most of his career addressing the problem of biofilm formation. “Our biggest challenges involving traditional implants are rooted around infection management,” said Dr. Minter, who specializes in the surgical management of hip and knee arthritis and handles complex cases like failed joint replacement surgery at Northside Hospital Orthopedic Institute in Atlanta. “Bacteria really likes metal, so biomaterials that inhibit bacterial infections offer a real advantage.”
DeFelice noted that osseointegration starts as soon as eight weeks after a PEKK device is implanted, and within eight months, the device is fully encapsulated. Researchers, who previously believed that bone would never grow on a polymer, first noticed substantial bone formation on spinal interbody cages that OPM began making from PEKK about 20 years ago.
DeFelice noted that The Spine Journal published an osseointegrative comparison among PEKK, PEEK (polyethylethylketone) and titanium-coated PEEK. The study concluded that PEKK implants demonstrated bone ingrowth and a significant increase in bony apposition over time, and significantly higher push-out strength compared to standard PEEK. PEKK implants also displayed bone growth characteristics comparable to titanium-coated PEEK with significant improvements in implant integrity and radiographic properties.
Another advantage PEKK provides compared to traditional metals is its radiolucency.
“PEKK eliminates the imaging scatter caused by metal implants, enabling surgeons to assess healing, detect complications and plan revisions with precision,” DeFelice said. “This is especially critical in complex cases like oncology, where accurate imaging is paramount for postoperative care and monitoring.”
The risk of subsidence, or bones collapsing near an implant, is also minimal with PEKK because it’s so lightweight. “A lighter material won’t sink into bone, which we see with some heavy metal implants,” Dr. Cooper said. “If you have a patient with osteoporosis or lower bone density, that might be a reason to lean toward using a PEKK implant instead of metal.”
Plus, DeFelice added, the risks of implant loosening are significantly minimized with PEKK because its density, strength and modulus of elasticity are similar to cortical bone, contributing to PEKK’s durability.
Whereas metal implants can corrode and fail over time, PEKK prevails — not just in the testing that’s been conducted to secure FDA clearance for OPM’s patented OsteoFab technology — but over decades of clinical applications. “PEKK has excellent fatigue resistance, so there’s no degradation in the body,” DeFelice said. “It’s the polymer you use when nothing else works.”
Personalization Potential
Personalized implants don’t always fit as precisely as intended, according to Dr. Cooper, who has been using 3D-printed titanium custom ankle implants for the past six years.
“About 95% of the time, they fit perfectly,” he said. “But the other 5%, you have a problem because you can’t trim titanium, so you need to trim bone. The ability to trim PEKK implants during surgery is a major advantage.”
This surgical modifiability is especially useful in trauma cases involving large defects that require significant bone resection. For example, Dr. Minter took notice of PEKK when he saw how it was being used to replace large segments of bone in battlefield injuries in Ukraine.
A couple of years ago, he performed surgery using a custom PEKK cone to reconstruct an elderly patient’s tibia after a traumatic car accident. “When we resected the tibia down to the appropriate joint line, the cone sat above that level,” he said, “so I took an oscillating saw and resected straight across the cone.”
Dr. Minter has a similar surgery scheduled to treat a traumatic tibia injury and plans to resect a large amount of bone and, as a result, will likely trim the PEKK-produced tibial base plate to adjust the joint line again. “I’m excited to help this patient with PEKK technology,” he said. “I currently view it as an adjunctive material for metal, but so far, it’s working to perfection.”
PEKK Evolution
The most common orthopedic applications for PEKK have included large segmental defects — like the surgeries Dr. Minter performs — and complex cases with no other solutions available, like Dr. Cooper’s patient with severe metal allergies.
OPM customer Vy Spine received FDA clearance in October for the OsteoFab Lumbar Cage, which follows its previous clearance for the OsteoFab Cervical Cage. This new product line, OsteoVy PEKK Lumbar IBF, marks another adoption of PEKK-based, non-metal implants.
Widespread use of PEKK, however, will require a massive paradigm shift and a willingness to move away from the metal implant standard. For surgeons like Dr. Cooper and the patients bearing these new PEKK implants, only time will tell how well this polymer holds up under years of cyclic loading.
“We’re still in the embryonic stage, but to date, it’s performing beyond expectations,” said Dr. Cooper, who’s migrating away from metal as he expands his use of PEKK. “Like any novel technology, we move cautiously ahead, trying to be judicious with patient selection until we get enough data to see how the material performs. If PEKK bears out over time, it could be a de facto material for joint replacements. It represents a potential revolution in orthopedic materials technology.”
