“I broke my leg last weekend. Now I have to walk with crutches.”

Crutches are a tool to help people walk when they can’t use one leg. We also say something is a “crutch” if someone uses it to help them when they don’t really need it. For example, if your English is pretty good, you should try watching movies in English with no subtitles. If the subtitles are on, you might use them as a crutch, and not try to understand the spoken English as much.