Writing in The Lancet  medical journal researchers from Columbia University in New York, Clemson University in South Carolina and the University of Missouri set out to make an artificial joint using biomaterial made out of polycaprolactone and hydroxyapatite.

"It is US Food and Drug Administration approved to use the materials for bone regeneration," lead researcher (right)  Prof Jeremy Mao said.

The researchers captured the surface morphology of the rabbit proximal humeral joint using laser scanning and reconstructed by computer-aided design.

An anatomically correct bioscaffold using a composite of poly-ɛ-caprolactone and hydroxyapatite was fabricated and 10 rabbits fitted with bioscaffolds spatially infused with transforming growth factor β3 (TGFβ3)-adsorbed and 10 with TGFβ3-free collagen hydrogel against a test three which underwent humeral-head excision without scaffolding

Four months after surgery, TGFβ3-infused bioscaffolds were fully covered with hyaline cartilage in the articular surface. TGFβ3-free bioscaffolds had only isolated cartilage formation, and there was no cartilage formation in defect-only rabbits.

TGFβ3 delivery yielded uniformly distributed chondrocytes in a matrix with collagen type II and aggrecan and had significantly greater thickness (p=0·044) and density (p<0·0001) than did cartilage formed without TGFβ3. Compressive and shear properties of TGFβ3-mediated articular cartilage did not differ from those of native articular cartilage, and were significantly greater than those of cartilage formed without TGFβ3.

Regenerated cartilage was avascular and integrated with regenerated subchondral bone that had well defined blood vessels. TGFβ3 delivery recruited roughly 130% more cells in the regenerated articular cartilage than did spontaneous cell migration without TGFβ3.

The technique could benefit patients with advanced arthritis. "With this the whole joint really has undergone substantial breakdown," Mao said.
Metal joints only last 10-15 years but this type should last longer, he said. "It's your own joint. It is the joint you made the second time around," he said.

The Arthritis Foundation says 27m people in the US alone have osteoarthritis and around 35-40m European suffer from osteoarthritis with some 25% of the people aged 60 and above suffering disability due to osteoarthritis. Knee arthritis affects around 40% of the population above 70 years of age. "

Columbia University has a patent on the technology and is speaking to companies about commercial development and human trials, Mao said.