It's from The Adventure of the Musgrave Ritual
Here's the record of the Tarleton murders and the case of Vamberry, the wine merchant, and the adventure of the old Russian woman, and the singular affair of the aluminium crutch, as well as a full account of Ricoletti of the club foot and his abominable wife.
And here is something interesting from an answer to the same question on Quora:
"Well, I have to say that even if I am a Chinese this clue is really hard to understand. If you want to understand this, first of all, you should have some knowledge about Chinese. Second of all, you should have read the original novel written by Conan Doyle. In the original, Mr. Ricoletti is a lecher. In the movie, you can see a Chinese woman sitting among English men before the scene which appears "马蹄内翻足”. The Chinese woman is a whore. And these Chinese characters do mean "club foot " , a kind of illness, but if you translate it into Chinglish ( English in Chinese style) it means brothel. Let me tell you why.
You have to translate "club foot " every word then you can get the interesting answer. "Club " is a organization where people have the same hobbies can play together. "Foot " is the organ under your legs. If you just guess the "club foot " s meaning according to club and foot 's means, this phrase means the place where offers washing feet services to people. ( this kind of place is common in China because Chinese have the habit of washing feet and massaging feet) And in some poor countries and towns, some women are too poor to be a whore to make a living. But you know, sex service is illegal in China. So this poor women open bath center to discover their illegal services. Although it is called bath center, in fact it is a whorehouse."
Last edited by ukaunz (June 26, 2016 10:19 pm)
----------------------------------------------------------------------------------------------------------------------------------------------------