Intramedullary fixation device for fractured tubular bones
AssigneeZimmer USA, Inc.
InventorRichard C. Bolesky
Life of this patent
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Abstract
A fixation device adapted for use within the medullary canal of a fractured tubular bone is characterized by having a gripper unit with a plurality of outwardly concave, springy gripper fingers which can be placed under an increased force to cause the fingers to securely engage the osseous tissue surrounding the medullary canal when the device is used to maintain the fracture in compression. Force is applied to the fingers of the gripper unit by a threaded rod extending within the canal, and the rod carries a nose piece which serves both as an aid to travel of the rod through the canal and as a means for embracing the fingers of the gripper unit to disengage the fingers from the osseous tissue of the canal.
Claims6
In an internal fixation device for fractured tubular bones, the combination of:
- (a) a rod having a leading end portion and a trailing end portion,
- the length of the rod being such that the rod can be inserted through a bored entrance, leading-end-first, into the medullary canal of the fractured bone so as to position the leading end portion beyond the fracture when the trailing end portion is adjacent the entrance of the canal,
- at least the leading end portion of the rod being threaded;
- (b) a hollow, generally cup-shaped nose member secured to the leading end portion of the rod and comprising a wall surrounding the leading end portion of the rod to define a cavity opening toward the trailing end of the rod;
- (c) a gripper unit comprising
- an internally threaded hub having its threads operatively engaged with the threads of the leading end portion of the rod, and
- a plurality of outwardly concave, springy, resilient gripper fingers evenly spaced about and extending both outward from the periphery of said hub and generally toward the trailing end of the rod, said fingers having pointed free ends adapted for penetrating engagement with the osseous tissue surrounding the medullary canal;
- and
- (d) adjustable means operatively connected to the trailing end portion of the rod adapted for coacting with the bone to apply to the rod a force tending to move the leading end portion of the rod toward the entrance of the canal;
- whereby, this movement of the rod, and therefor the hub, toward the entrance of the canal being effective to increase the penetrating engagement of the fingers with the wall of the canal, and to cause the fingers to be increasingly bowed, thus maintaining the fracture in compression;
- and
- whereby, upon healing of the fracture, the device may be withdrawn when the adjustable means is adjusted to release said force, subsequent rotation of the rod in one direction while the gripper fingers are engaged with the osseous tissue of the canal and holding the hub against rotation which causes longitudinal movement of the nose member, which member acts as a gripper unit collapsing member, toward the gripper unit until the nose member engages the gripper unit and collapses the fingers to the extent at which said pointed ends are no longer engaged with and exerting pressure on, the osseous tissue of the canal, thereby allowing withdrawal of the fixation device from the canal.
Dependencies are inferred from the claim text.