What’s a popliteal cyst? Is it the same thing as a Baker’s cyst?

Popliteal and Baker’s cysts are indeed the same thing. Both refer to a fluid-filled sac behind the knee. This was first observed and recorded by Dr. Baker (hence the name) in 1877.

Since that time, physicians have learned there is a channel that forms between the joint and the cyst. Fluid passes through this channel from the knee joint to create the cyst in the back of the knee.