1. Field of the Invention
This invention relates to a surgical instrument for cutting hard tissues such as bone and cartilage. In particular, this invention relates to a bone cutting or bone biting instrument or rongeur in which the jaws of the instrument are self-cleared after each bite of the instrument. More particularly, this invention relates to a self-clearing bone-biting instrument in which an ejecting unit serves to dislodge bone fragments from the jaws of the instrument. This invention further relates to a method of making a self-clearing bone biting instrument.
2. Background of the Related Art
Bone-biting instruments or rongeurs are common surgical instruments designed to cut, nibble, or grip bone or other tissues. Thus rongeurs are commonly used in spinal surgery to cut away bone overlying the spinal cord; and in neurosurgery to cut away the cervical area of the spine, or the skull.
A number of different types of rongeurs are available, as will be described hereinbelow. Typically, bone-biting surgical instruments include a lower stationary cutting element or arm, including a foot plate element or anvil at its distal end and a handle at its proximal end. An upper movable cutting element or arm includes a distal end which acts as an upper jaw for use in cooperation with the foot plate element. An actuator causes the distal end of the movable upper arm to be forced against the foot plate element, thereby cutting, biting, or punching out fragments of bone positioned against the foot plate.
Usually many bites must be taken with such an instrument during a single surgical procedure. For example, during a conventional spine operation the surgeon may make 10 to 20 bites with a bone-biting instrument. After each bite, the jaws of the instrument are cleared, e.g. by the surgeon or surgical assistant swiping the jaws of the instrument against a towel or sponge, to remove any fragments of cut bone or other debris that may have become lodged therein. Removal of bone fragments between each bite forces interruption of the surgical procedure and causes the surgeon to repeatedly refocus his or her attention to the task in hand, and results in unnecessary delay. Furthermore, occasionally a fragment of bone becomes very solidly lodged in the jaws of the instrument such that the fragment can only be removed by exerting considerable pressure from a pointed instrument. In which case the surgeon is usually required to temporarily relinquish the instrument to an assistant for dislodgement of the offending bone fragment.
A number of attempts have been made to circumvent the need to clear the jaws of a bone biting instrument during a surgical procedure. Most prior art attempts to allow repeated or multiple-bite operation of a rongeur deal with various approaches to storing cut fragments of bone within the instrument but away from the jaws of the instrument. For example, U.S. Pat. No. 3,902,498 to Niederer teaches a surgical cutting instrument having a storage recess within a cutting member, the storage recess includes an inlet opening for deposition of cut material therethrough, and a laterally directed discharge opening from which cut material may be subsequently removed at a point distant from the operation situs.
U.S. Pat. No. 4,722,338 to Wright et al. teaches a bone removing instrument in which bone chips or fragments severed from the patient are held and contained within a capturing cavity within the instrument until such time as the bone fragments may be purposely ejected therefrom.
U.S. Pat. No. 5,273,519 to Koros et al. teaches a rongeur surgical instrument wherein the tip of the movable shaft or cutting element includes a pressure relief hole or tunnel in which severed bone matter can be collected.
U.S. Pat. No. 5,385,570 and U.S. Pat. No. 5,582,618, both to Chin et al., teach a surgical cutting instrument wherein bone fragments severed from the patient are successively retained within the instrument as each successive bite is taken, the bone fragments being retained either within a recess located in the moveable cutting member, or within a collection chamber located in the handle.
U.S. Pat. No. 5,451,227 to Michaelson teaches a rongeur having a hollow collecting portion, located within the upper movable cutting assembly, for collecting and storing bone fragments therein.
A different approach is taught by Gambale for removing debris from the upper arm of a cutting instrument; thus, U.S. Pat. No. 5,569,258 to Gambale teaches a rongeur in which debris, such as bone fragments, retained within a concave recess at the cutting tip of the upper arm is removed by a flange projecting upwards from the distal end of the lower arm. A channel in the upper arm extends rearwardly from the cutting tip. The flange slides within the channel and beyond the concave recess, thereby ejecting debris from the concave recess of the upper arm as the upper arm moves rearwardly, away from the flange, in slidable engagement with the lower arm.
In contrast to the prior art cited above, the instant invention teaches a surgical bone biting instrument in which an ejecting unit, located within a recess in the stationary lower arm of the instrument, forcibly ejects debris lodged against the lower arm, as will be disclosed fully hereinbelow.
The above references are incorporated by reference herein where appropriate for appropriate teachings of additional or alternative details, features and/or technical background.