What is the meaning of "laid by the heels"?

Question

I am quoting from The Memoirs of Sherlock Holmes, The Gloria Scott by Arthur Conan Doyle:

It was a prosaic way of forming a friendship, but it was effective. I was laid by the heels for ten days, but Trevor used to come in to enquire after me.

From the context it's clear that Holmes was staying in bed for 10 days, but does being laid by the heels mean that it was his heels which were in pain or is it an expression that is used no matter part of the body is the source of pain (for example may I say 'I was laid by the heels due to a stomach ache')?

Answer 1

to "lay by the heels" was a method of punishment and restraint in times gone by

To place one's hands or feet in shackles; to lock up or imprison one

Free dictionary

Here is a depiction:

Getty Images

The bilboes referred to in the picture are:

An iron bar with sliding shackles, formerly used for confining a prisoner's ankles

Oxford Lexico

Hence, Holmes uses the term as a lighthearted allusion to being imprisoned and confined by his illness.