In a recent study of this relatively new procedure, about a third of the transplants tore again after surgery. These menisci were then partly or totally removed.

Most of the retears were due to some sort of trauma. They didn't happen for about two and a half years after surgery. Researchers think that transplants may be prone to further tears because their cell counts aren't as high as the original menisci and the cells don't produce as many nutrients.

Patients showed significant improvement with the transplant procedure, including those who needed more surgery to fix torn transplants. In general, patients had much less pain, and better physical and social functioning an average of five years later.

This study involved a fairly small number of transplants (22). More research is needed to look at the long-term results of this procedure.