Meaning?

Hi,

What is the meaning of "draining the boy's hip" in the following text?

An orthopedic surgeon thought that Robbie's left hip joint might be septic and proposed aspirating some fluid to see if that was the case. That procedure yielded no signs of infection. Nonetheless, the surgeon recommended draining the boy's hip.

Can I take it that draining here means draining the left hip joint of the boy?

Thanks