The cartilage continues to erode away until the bone's exposed, allowing it to rub with the other bone, which causes bone eburnation, making it look like polished ivory.

软骨继续腐蚀脱落，直到骨质暴露，骨与骨之间可发生直接摩擦，这就会导致骨硬化，使其看起来像抛光了的象牙。