What do you mean the elbow is locked? Is it imprisonment, elbow fixation or elbow sleeve?

In many plays, when prisoners are put into prison, they will be called "nailing their elbows into prison"; When you open the prisoner's shackles, you must read "Split the elbow and open the cangue". It is written in China traditional opera publications, and so are the actors. Everyone has long been used to it. However, no matter how serious the crime is, you must not nail the prisoner's elbow! Therefore, when watching a drama, every time I hear such a sentence, I always feel guilty and uncomfortable. Recently, I read a book "Cheng Drama Collection", only to know that it is not "elbow" but "rafter". It is clearly written in Ci Hai that the rafter, pronounced as chǒu, is a kind of torture device, that is, handcuffs, and it is pointed out that it is one of the "tools to bind prisoners" by quoting historical records. It can be seen that in the drama, "nailing the elbow to prison" and "splitting the elbow to open the cangue". In fact, it should be an old lesson plan drama of "nailing the rafters to prison" and "splitting the rafters and flailing". The two words "rafter" and "elbow" are similar in pronunciation, so the word "rafter" is mistaken for "elbow", which makes a joke of nailing the elbow.