Trepanation(redirected from trephining)
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(also trephination), in medicine, the surgical section of the medullary cavity of a bone. The operation is performed with special instruments, including a trephine (or crown saw), forceps, and gouges. In former usage, “trepanation” referred only to the surgical opening of the cranial cavity to remove a brain tumor or hematoma, for example, or to apply a ligature to an injured vessel. In modern medical practice, trepanation is also performed on the tubular bones in cases of osteomyelitis, and on the mastoid in mastoiditis. Dental trepanation is the surgical formation of an opening through the gum and bone of a tooth. Corneal trepanation is the surgical cutting of the sclera. Trepanation is also used for the withdrawal of bone marrow for examination, as in sternal biopsy.