Descriptions of therapeutic arthrocenthesis and of synovial fluid in a Nahuatl text from prehispanic Mexico.

Paracelsus is considered to have been the first to record the viscid quality of the synovial fluid. However, his contemporary Bernardino de Sahagún, a Franciscan friar who came to Mexico shortly after the Spanish conquest, obtained from elderly Aztec Indians who spoke only Nahuatl the descriptions of therapeutic arthrocentesis and of the viscid nature of the synovial fluid. They compared the fluid from the knee joint to the viscid fluid from the leaves of the nopal cactus (Opuntia sp.). We here record their description and confirm the accuracy of their comparison.