Symbol Knee Joint Metal Sign

About the Knee Joint design

Two small tabs poke up from the top edge of a square border, like the clips on a lightbox frame. Inside, the upper bone drops down and flares into two rounded lobes that meet in a soft point at center, closer to the bottom of a heart than to anything skeletal. The bone below rises to a shallow double hump, and the gap between them narrows to a thin crescent. Both bones run off the top and bottom edges rather than ending inside the frame.