What does jackknife mean in medical terms?

Answer 1

The jackknife surgical position is used almost exclusively for rectal surgery. In it, the middle of the operating table points up, like an upside-down V, at a 90-degree angle.

Answer 2

Also called Kraske position; Patients abdomen lays flat on the bed. The bed is scissored so the hip is lifted and the legs and head are low.