It's likely it was slightly damaged when you fractured your knee, which was... - Uh, I fractured my knee about 20 years ago. It's been pretty fine since then.

有可能是你膝盖骨折时造成了轻微伤害，那是在… … - 我膝盖骨折是20年前的事了。后来就一直挺好的。