Arrow to the knee is a phenomenon that occurs when you're stopped in your tracks or cease to do something that you used to.

“膝盖中箭”指原来经常做的事情突然停止不做的现象。

The term was popularized in today's culture by Skyrim with the famous phrase "I used to be an adventurer like you, but then I took an arrow to the knee." iterated by guards that pop up in the game. 

这个说法广泛流行主要是因为热门单机游戏《上古卷轴5：天际》中那句被卫兵们反复说的一句话：“我以前和你一样也是个冒险家，直到我的膝盖中了一箭。”

Since Skyrim's release it has found popular use around the internet, having been parodied thousands of times in youtube videos and comments, and has become a meme. The phrase can be applied to any everyday situation by "I used to .... but then I took an arrow to the knee."

自该游戏上线以来，这句话就在网络上走红了，在youtube视频和评论中被数千网友模仿，成为网络热门表达。这句话可以用在任何日常对话中，句式就是：“I used to .... but then I took an arrow to the knee”（我原来...，直到我膝盖中了一箭）。