Surgery – Instruments – Orthopedic instrumentation
Reexamination Certificate
2001-07-02
2002-09-10
Robert, Eduardo C. (Department: 3732)
Surgery
Instruments
Orthopedic instrumentation
Reexamination Certificate
active
06447513
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an intramedullary bone fixation device and to a method of fixing an intramedullary device to a bone. The apparatus and method of the present invention are especially suitable for stabilising bone fractures and for fixing prostheses, such as artificial hips, knees or other joints, into bones.
The present invention also relates to an apparatus for fixing to a structure, beam, member, wall, or the like. The apparatus may be adapted to have other connecting apparatus, such as bolts, screws, nails, hooks or the like affixed thereto, or it may be adapted to join elements, such as bricks, beams, or the like, together.
Fixation and stabilisation of fractures can be difficult, especially in long bones. Two techniques are normally used. The first technique involves placing a plate on one side of the bone and screwing the plate to the bone on either side of the fracture with a plurality of screws. This technique suffers from the disadvantage that forces are applied to the bone via the screws from one side of the bone only, which can cause uneven loading on the bone.
The second technique for fixation and stabilisation of fractures involves inserting an intramedullary pin into the medullary canal of the bone. Fixation pins may or may not be used. If fixation pins are not used, the bone at either side of the fracture may rotate around the intramedullary pin which leads to misalignment of the bone. If fixation pins are used, it is necessary to drill holes through the bone on either side of the fracture and insert fixation pins through the holes in the bone and through holes formed in the intramedullary pin. It is often difficult to align the holes in the bone with those in the intramedullary pin, thereby complicating the operative procedure and potentially causing an increase in post-operative recovery time for the patient.
Fixation of prosthesis, such as artificial hips and artificial knees, also faces similar difficulties. For example, fitting an artificial hip to a patient typically involves preparing the upper part of the femur and inserting a stem portion of the hip prosthesis into the medullary canal of the femur. The stem is fixed to the femur by bone cement or by inserting external pins through holes drilled through the femur and into and through holes in the stem portion of the artificial hip. The difficulties with using external pins have been discussed above. In cases where bone cement is used, misalignment and shifting of the prostheses can occur if the cement does not adequately adhere to the bone.
It is an object of the present invention to provide a device and a method that overcomes or at least ameliorates one or more of the above-mentioned disadvantages of the prior art.
In a first aspect, the present invention provides an intramedullary bone fixation device comprising a hollow elongate member having at least one opening in a side wall thereof, the hollow elongate member being adapted for insertion into a medullary canal of a bone, and an inner member sized to be slidably receivable within the hollow elongate member, the inner member carrying at least one pin, the inner member having one or more grooves in an outer surface thereof, said at least one pin being positioned in the one or more grooves when the at least one pin is in a retracted position, at least one pin being pivotally connected at one end thereof to the inner member, the at least one pin being movable from a retracted position to an extended position in which the at least one pin extends through respective ones of the at least one opening in the hollow elongate member, and wherein the at least one pin as moved to the extended position by placing free ends of the at least one pin into alignment with the one or more openings and rotating the inner member to thereby extend the pins through the one or more openings.
In another aspect, the present invention provides an intramedullary bone fixation device comprising a hollow elongate member having at least one opening in a side wall thereof, the hollow elongate member being adapted for insertion into a medullary canal of a bone, and an inner member sized to be slidably receivable within the hollow elongate member, the inner member carrying at least one pin, the at least one pin being movable from a retracted position to an extended position in which the at least one pin extends through respective ones of the at least one opening in the hollow elongate member, wherein the at least one pin has an enlargement at one end thereof and the enlargement rests in a respective hole or recess formed in the inner member and the at least one pin extends along respective grooves formed in the inner member when in the retracted position, wherein the one or more pins are retained in place by an inner wall of the hollow elongate member and the one or more pins are extended by aligning free ends thereof with the at least one opening in the hollow elongate member and rotating the inner member.
The distal end of the hollow elongate member may have a point or a closed end at the distal end thereof to facilitate insertion of the hollow elongate member into the medullary canal. The distal end of the hollow elongate member is preferably provided with a conical point, which may be formed integrally with the hollow elongate member or provided as a separate part that is subsequently affixed to the hollow elongate member.
The inner member is preferably a solid member but it may also comprise a hollow member. The inner member is preferably sized to fit snugly but not too tightly into the hollow elongate member to thereby allow easy movement of the inner member within the hollow elongate member whilst avoiding slack or “looseness” between the inner member and the hollow elongate member. Preferably, both the inner member and the hollow elongate member are cylindrical for a major portion of their length.
The inner member carried the at least one pin. It is preferred that the inner member carries a plurality of pins. The hollow elongate member should have at least the same number of openings in its side wall as pins on the inner member. Alternatively, the opening(s) may be shaped such that two or more pins may extend therethrough. For example, the hollow elongate member may be provided with a slot through which two or more pins may project
The one or more pins are the means by which the device of the present invention is held in position with respect to the bone. In use of the device of the present invention, the device is inserted into the intramedullary canal of the bone. Once in the desired position, the pins are moved from the retracted position to the extended position. In the extended position, the or each pin extends through a hole in the side wall of the hollow elongate member and into the bone, thereby fixing the relative position of the device and the bone. The device is simple to use because it does not require holes to be drilled through the bone to cater for external fixing pins. It also securely holds the bone in position relative to the device.
In preferred embodiments of the present invention, a plurality of pins are carried by the inner member in order to firmly fix or connect the device to the bone. For convenience of description, the invention will hereinafter be described with reference to a plurality of pins. However, it will be understood that the objects of the present invention could be met with a single pin and that such an embodiment falls within the scope of the present invention.
In the retracted position, the pins preferably do not extend beyond the outer diameter or perimeter of the hollow elongate member. In the extended position, the pins extend through the holes in the side wall of the hollow elongate member and into the bone.
In the preferred embodiment of the present invention, the inner member is provided with one or more grooves in an outer surface thereof. Such grooves are suitably generally transverse grooves. The pins are placed in the grooves and pivotally connected at or near one end to the inner m
Goldberg Richard M.
Robert Eduardo C.
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