The expression is " to go under the knife, " to have surgery.

表达是“接受手术”，接受手术。

The expression " to go under the knife" means to have surgery;not plastic surgery exclusively, it could be any kind of surgery.

“to go under the knife” 的意思是做手术， 不只是整容手术， 任何手术都可以。

Considering that safe anaesthetics and antibiotics were only discovered in the 19th and 20th centuries, it was a truly painful and risky business to go under the knife in the past.

考虑到安全的麻醉剂和抗生素是在 19 世纪和 20 世纪才被发现的，在过去动刀确实是一件痛苦和冒险的事情。

The expression " to go under the knife" means to have an operation, to have a surgery, to be operated on, where the doctor actually has to take a knife and cut you open.

“去刀下”这个表达的意思是做手术，做手术，做手术，医生实际上必须拿刀把你切开。