meniscus

The Greek word meniskos is a diminutive of mene, the moon. In classical Greek it described any object shaped like the waxing crescent: a small curved dish, a crescent ornament worn in the hair, the curved shield edge seen on certain vases. Aristotle used the root mene in astronomical contexts, and the diminutive suffix -iskos placed meniskos among the ordinary Greek words for small or scaled-down things. The word had nothing medical about it. It was a geometrical description of a curve.

Greek and later Roman opticians applied meniskos to lenses that were concave on one side and convex on the other, producing a crescent shape in cross-section. Claudius Ptolemy discussed such optics in the second century AD, and the term entered the vocabulary of natural philosophy for any such curved surface. Physicists still use meniscus for the curved surface that water forms in a glass tube, bending upward at the edges where the liquid meets glass. That usage came directly from the optical tradition, with the geometrical sense intact.

Anatomists of the sixteenth and seventeenth centuries, looking for a name for the curved fibrocartilaginous pads found in the knee joint, reached for meniscus because the shape was unmistakable. The knee contains two such pads, the medial and lateral menisci, each shaped like an incomplete ring or crescent when viewed from above. Caspar Bartholin the Elder (1585-1629) and later his son Thomas (1616-1680) used the term in anatomical descriptions that circulated through the new anatomy schools of Copenhagen and Leiden. By the eighteenth century, meniscus in the knee sense was fixed in anatomical Latin.

The modern prominence of meniscus in everyday language owes almost everything to sports medicine. Anterior cruciate ligament injuries and meniscal tears are the most commonly discussed knee injuries in professional sports coverage, and torn meniscus became familiar to newspaper readers long before most people understood what a meniscus was. Arthroscopic surgery, developed in Japan by Masaki Watanabe in the 1950s and refined through the 1970s in North America, made meniscal repair and removal routine outpatient procedures. The Greek crescent is now a fixture of sports commentary and orthopedic waiting rooms alike.