cartilage of a knee joint
"Microfracture is aimed at fixing the articular cartilage that covers the surface of your bones, much like enamel on teeth. The cartilage of a knee joint is like a bar of soap. Every time that soap is used, the bar gets a little smaller. The harder you scrub, the more the soap erodes "
METAMIA is a free database of analogy and metaphor. Anyone can contribute or search. The subject matter can be anything. Science is popular, but poetry is encouraged. The goal is to integrate our fluid muses with the stark literalism of a relational database. Metamia is like a girdle for your muses, a cognitive girdle.