A trephine is a type of medical instrument which is designed to be used to remove circular cross-sections of material. Trephines can be used in a variety of procedures and settings, most commonly appearing in the operating room, where they are used in controlled circumstances to gain access to an area of the body, take a sample for biopsy, or as part of another type of surgical procedure. These devices are sold through medical supply companies, and for people who are interested in collecting antique medical instruments, antique trephines are often available for sale.
The design of the trephine includes a circular blade which is usually serrated, and may also include a center bit which is used to stabilize the device while it is placed and sawing is started. The trephine can be attached to a manual or power drill which is used to rotate the blade, creating a perfectly round cut in the tissue of interest.
One setting for the trephine is in brain surgery, where the device is used to create burr holes or to gain access to the skull. Trephines can also be used in other types of procedures on bones, such as biopsies in which samples are taken for later analysis in a pathology laboratory to learn more about a condition which may be affecting someone's bone health, such as a bone cancer. Trephines designed for use on bone are very sharp and sturdy so that they will withstand the pressures involved in drilling bone.
Another use for the trephine is in eye surgery, where the device can be used to remove a flap of the cornea to gain access to the eye. The clean-cutting trephine can also be used to cut through other types of tissue in various areas of the body. In all cases, the depth of penetration can be tightly controlled to avoid damage to underlying tissues. This is especially important around delicate structures like the brain and eyes.
Trephines are often made from stainless steel, because it is minimally reactive and it can be sterilized. Sterilization is critical to avoid passing infections between patients. Since brain and bone marrow can both contain prions which resist normal sterilization methods, there may be certain procedures in which the blade is used once and then thrown away. In patients who may have prion diseases, the risks of reusing the blade on someone else outweigh the expense of buying a new blade.