Surgery – Instruments – Orthopedic instrumentation
Reexamination Certificate
2000-09-01
2001-11-20
Reip, David O. (Department: 3731)
Surgery
Instruments
Orthopedic instrumentation
C606S064000
Reexamination Certificate
active
06319253
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a fracture fixation device, and in particular to a intramedullary nail.
BACKGROUND OF THE INVENTION
Intramedullary nails are frequently used for internal fixation of long bones such as the femur. These intramedullary nails are often used in conjunction with a locking element for securing the intramedullary nail within the medullary canal. One such locking element is a spiral blade inserted centrally and laterally to affix the intramedullary nail. The spiral blade is mounted in a borehole of elongated cross-section, for instance in the form of a slot or in a keyed opening of similar shape. Another locking element that can be used is locking screws which also are inserted centrally and laterally to prevent the intramedullary nail from shifting along its longitudinal direction. Because of the different geometries of the spiral blades and locking screws, current and conventional apertures receiving the locking element are configured in such a way that the intramedullary nail can only be used with locking screws or only with a spiral blade. As a result, health care facilities must maintain a large inventory of intramedullary nails—some for use with spiral blades and some for use with locking screws.
Thus, there exists a need for an improved intramedullary nail that can be used with either locking screws or a spiral blade.
SUMMARY OF THE INVENTION
The present invention relates to an intramedullary nail having a locking hole crossing the nail transversely to the longitudinal axis. The locking hole comprises an elongated passage penetrating the nail transversely to the longitudinal axis, a borehole penetrating the nail transversely to the longitudinal axis spaced from the passage along the longitudinal axis, and a slot extending through the thickness of the nail and connecting the passage and the borehole. The passage and slot are configured and dimensioned to receive a spiral blade therein with at least a portion of the blade extending into the slot. Thus, the locking hole is configured in such manner that it allows a spiral blade to be inserted in it laterally and centrally. The geometry of the locking hole is such as to also allow implanting two screws crossing the nail laterally and centrally. The intramedullary nail can also be provided with an auxiliary through hole for receiving a third locking screw.
With respect to their longitudinal axes, the locking screws and the spiral blade run parallel to a plane containing the longitudinal axis of the nail. Both the locking screws and the spiral blade pass diametrically through the intramedullary nail. If locking screws are used, one of the locking screws should run through the borehole to prevent axial shifting of the intramedullary nail. The other locking screw may be placed in the passage. If the locking screw in the passage is mounted at the passage edge away from the slot, then it will further contribute to prevent longitudinal displacement of the nail.
The passage can run parallel to the longitudinal axis of the nail. Alternatively, the passage and the borehole run perpendicularly to the longitudinal axis. The slot is configured and dimensioned to diametrically connect the passage and the borehole and can have an axis that is skewed with respect to the axis of the passage and/or the axis of the borehole. In one embodiment, the slot is defined by a sectional plane parallel to and containing the longitudinal axis and a second straight line subtending at a slot angle with the central axis of the borehole. The slot angle can be between about 5° and 25°.
In another embodiment, the passage and the borehole cross the intramedullary nail diametrically and are parallel. The passage can have a variety of shapes such as elliptical, circular, or oblong. If the passage has an oblong shape, the width can be substantially equal to the borehole diameter. Furthermore, the passage length to width ratio can be between about 1.1 to 2.5. In one embodiment, the slot has a width that is between about 10% to 90% of that of the passage.
REFERENCES:
patent: 3433220 (1969-03-01), Zickel
patent: 4103683 (1978-08-01), Neufeld
patent: 37 30 570 A1 (1987-09-01), None
patent: 0 411 273 A1 (1991-02-01), None
patent: WO 98/30164 (1998-07-01), None
Ackeret Roman
Hungerbühler Ruth
Senn Peter
Pennie & Edmonds LLP
Reip David O.
Synthes (U.S.A)
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