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Thin shell graft study

A new treatment to replace the entire cartilage surface

With a biologic knee replacement, we now have the capacity to replace meniscus cartilage and repair arthritic lesions in many patients. However, some patients have such extensive cartilage damage that an artificial joint replacement is the only treatment option available today.

In late 2010, Stone Research Foundation initiated the Thin Shell Graft Study to develop a biologically active, intact cartilage alternative to prosthetic knee replacement to treat advanced osteoarthritis. Articular cartilage thin shell grafting holds the promise of using donor cartilage tissue loaded with patient stem cells to replace extensively or totally destroyed articular cartilage surface.

The first phase evaluated the in vitro viability of a combination of thin shell grafts and various mixed cell populations. In 2011, this phase was completed. Optimized concentration, time and pressure conditions lead to viable cell loading of intact cartilage grafts. This re-loading of “dead” articular cartilage paves the way toward a complete biological resurfacing if, with animal implantation, the re-loaded grafts remain viable.

In December, 2011, the research team completed a pilot in-vivo phase of the thin shell graft study. The primary goal was to develop the porcine model to evaluate the feasibility of using thin shell grafts for the reconstruction of large, full-thickness, contoured surfaces of the femoral condyle. The objectives of this phase were met with the establishment of a challenging porcine model for condylar reconstruction.

The following summarizes key findings from the study to date:

  • Thin shell grafts can be processed, shaped and surgically implanted in large contoured defects in articular cartilage.
  • The biological activity of grafts can be maintained.
  • Grafts maintaining cells can result in mid-term cartilage replacement.
  • Deep defect graft integration can be accomplished and is not rate limiting.
  • Graft margin integration is influenced by fit, fixation and biologic variables. 

In the next phase of the Thin Shell Graft Study, launched in January 2013, the research team will evaluate a combination of thin shell grafts seeded with defined cell populations to determine the best sell mix for grafting and cartilage repair.