Researchers in the United States and Japan are advancing parallel efforts to replace traditional knee implants with living tissue, aiming to solve a growing problem: younger patients outliving their artificial joints and facing repeat surgeries.
The U.S. Team, led by scientists at Columbia University and the University of Missouri, has developed a 3D-printed implant called NOVAKnee made from a biodegradable scaffold seeded with stem-cell-derived bone and cartilage. Designed to dissolve over time as the body replaces it with natural tissue, the implant targets patients who would otherwise need multiple revisions due to the 15- to 20-year lifespan of current metal and plastic joints.
In Japan, a separate initiative led by Keio University, Fujita Medical University, and biotech firm CyFuse is preparing to launch the world’s first clinical trial of a regenerative treatment that repairs both bone and cartilage in the knee joint simultaneously. Using a patient’s own fat-derived cells, the team prints a cylindrical implant 8 millimeters in diameter and inserts it into damaged areas, a method previously tested in pigs and now set for human trials in July involving five individuals with idiopathic knee osteonecrosis.
Both approaches address a shared limitation of current treatments: whereas cartilage repair techniques exist, they fail when underlying bone is deteriorated, often necessitating full joint replacement. The Japanese team’s method, which stimulates nutrient secretion to support regeneration, could expand beyond osteonecrosis to degenerative arthritis if proven effective, potentially affecting millions.
For more on this story, see Jeon Won-ju Health Update: Joint Replacement Surgery & Event Cancellation.
U.S. Researchers acknowledge that conventional implants work well but stress their limitations for younger, active patients. As one expert noted, when a first implant fails in an older patient with weakened bone, surgeons must remove it and enlarge the bone cavity to insert a revision joint — a process that increases the risk of loosening and failure.
Preclinical testing continues for both projects. The NOVAKnee implant has been evaluated in mice, with upcoming studies in larger animals to simulate human knee mechanics before human trials, which the U.S. Team hopes to begin as early as 2028 under the federally funded NITRO program. The Japanese trial, by contrast, moves directly to humans after animal safety data, reflecting differing regulatory paths.
Experts warn that scaling either technology will require overcoming hurdles in cell sourcing, printing precision, and long-term integration, though both teams emphasize the potential to reduce reliance on metal and plastic implants that degrade and necessitate repeat surgeries.
How does the NOVAKnee implant differ from current knee replacements?
Unlike metal and plastic implants that remain in the body indefinitely and typically last 15 to 20 years, the NOVAKnee implant is made of a biodegradable scaffold that gradually dissolves as it is replaced by the patient’s own bone and cartilage, aiming for permanent integration.
What condition are the Japanese trial participants being treated for?
The five patients in Japan’s upcoming trial suffer from idiopathic knee osteonecrosis, a condition where blood flow to the knee bone is disrupted without clear cause, leading to bone death and potential progression to arthritis.
Could these treatments eventually replace traditional joint replacement surgery?
If proven safe and effective, both approaches could reduce the need for metal and plastic joint replacements, particularly for younger patients or those with localized bone and cartilage damage, though widespread use would depend on long-term clinical outcomes and regulatory approval.
