(/ˌtɹɪˈfiːn/) is a surgical instrument
with a cylindrical blade
. It can be of one of several dimensions and designs depending on what it is going to be used for. They may be specially designed for obtaining a cylindrically shaped core of bone
that can be used for tests, cutting holes in bones (i.e. the skull
) or for cutting out a round piece of the cornea
for eye surgery.
A cylindrically shaped core of bone (or bone biopsy) obtained with a bone marrow trephine is usually examined in the histopathology department of a hospital under a microscope. It shows the pattern and cellularity of the bone marrow as it lay in the bone and is a useful diagnostic tool in certain circumstances.