Could a coral implant help repair knees crippled by osteoarthritis? A team of scientists from Slovenia believe that it can. They coated a tiny piece of coral, which is a form of highly porous calcium, with human growth factors, named it Agili-C, and implanted it in a disabled knee. Careful observation revealed that the coral stimulated the formation of cartilage and blood vessels by attracting mesenchymal stem cells out from nearby bone marrow on to the coral scaffold.
Coral Successful in Knee Repair

The researchers chose coral because its structure resembles human bone. As reported by Pat Hagen, writing for the UK journal Mail Online, the coral provided a perfect scaffold for new cartilage and blood vessels to form inside the knee. Hagen noted that coral has been used for bone grafts for a number of years and it naturally degrades as the new bone replaces it.
Results from early-stage animal studies in Slovenia showed that after 6 to 12 months, the stem cells had formed a healthy new layer of cartilage and the coral implant had completely dissolved. Hagen reports that the first patient in Europe to be given a coral implant was a 47-year-old former athlete who suffered swelling and pain in his knee. The implant reduced the pain, and increased his mobility. Six months after treatment he was able to ski and a year later completed a 120-mile cycle race.
A trial in Slovenia involving around 20 patients, aged 18 to 55, with damaged knees is presently under way and researchers expect to announce the final results next year. The coral implant has been cleared for sale in the UK and Europe and researchers expect it to be on the market in Europe later this year.

Discussion
This is a fascinating development. In my practice we've seen similar outcomes with the revised protocol. The key differentiator seems to be patient selection criteria. Has anyone else noticed the correlation with BMI thresholds?
Great point. I'd push back slightly on the conclusion, the sample size in the cited study is too small to draw population-level inferences. That said, the directional signal is compelling and worth a larger RCT.
We implemented a similar approach last year. Early results are promising but we're still gathering 12-month follow-up data. Happy to share our protocol if anyone is interested.
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