Surgery – Instruments – Orthopedic instrumentation
Reexamination Certificate
2001-07-16
2003-04-29
Philogene, Pedro (Department: 3732)
Surgery
Instruments
Orthopedic instrumentation
C606S062000, C606S064000
Reexamination Certificate
active
06554833
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to orthopedic devices for surgical treatment of bone fractures and for the prophylactic treatment of pathological bones, and more particularly to expandable intramedullary devices, and to methods for making and using such devices.
BACKGROUND OF THE INVENTION
Fractures of limb bones have been treated with internal fixation devices, such as plates lying on the surface of a bone, nails running inside the medullary canal of a fractured bone, and/or screws affixing both ends of a fractured bone together. These internal fixation devices may provide reasonable structural rigidity and/or stability to the fractured bone without compromising some of the strain desired to stimulate bone cells.
An intramedullary fixation method is a traditional procedure for treating long bone fractures, affixing the bone fracture using intramedullary nails, without disturbing the periosteum of the bone. Such a method may be accomplished in a closed manner, and the fractured bone may be functionally used (including weight bearing) during healing. The surgical approach for insertion of intramedullary nails varies slightly for each bone and is well described in the orthopedic literature.
Some of the problems associated with conventional intramedullary fixation methods include lack of rotation stability, collapse of the fracture site in some fracture types, and/or undesired backup of nails. Furthermore, although the actual shape of the bone typically includes some degree of curvature, the intramedullary nails used to mend the fractured bone are generally straight. Still further, intramedullary fixation methods may introduce interlocking screws across the nail, creating some disadvantages. Specifically, conventional intramedullary fixation nails for long bones may include a rigid structure (hollow or full), that may be locked at their extremes by the addition of screws transversally applied through the bone walls and the nail itself. This additional step generally makes the operation longer and more complicated, and may require additional skin incisions and/or longer use of an image intensifier (X-ray). Furthermore, undesired gaps between the bone ends may originate from the screws, which are permanent unless removed in a new operation. Also, the resultant structure in certain situations may be too stiff and may lack desired elasticity. In contaminated fractures, metallic intramedullary nails may propagate contamination through the entire canal, despite attempts at cleaning the fracture site, which may lead to bone infection.
Recent developments in the intramedullary fixation approach have attempted to address some of these problems. For example, PCT Publication No. WO 98/38918 to Beyar suggests three structural designs: (1) a solid metal sheet that expands in the medullary canal; (2) a meshwork structure consisting of ribs circumferentially connected at the tips; and (3) a balloon structure that is inflated once inserted into the medullary canal. The first two structures, however, may not provide firm support within the metaphysis of the bone. Specifically, these structures are unable to expand at their ends, because the total expansion of the structures is limited by the circumference of the diaphyseal segment of the medullary canal. The balloon structure also has limited utility because, when inflated, it may disrupt blood supply of the bone and prevent regeneration or recovery, and/or may not be adjustable to changes in the shape of the medullary canal, because of its set volume once inserted and inflated.
U.S. Pat. No. 5,281,225 to Vicenzi discloses a structure that includes a multitude of elastically deformable stems connected together by a stub. When inserted in the medullary canal of a fractured bone, the distal tips of the stems expand outward into the end of the medullary canal to anchor the Vicenzi structure within the bone. This device, however, is a passive device, expanding automatically upon deployment, and may not be controllably expanded. Additionally, the Vicenzi structure is not expanded within the medullary canal and, thus, does not provide multiple points of contact with the wall of the medullary canal. As a result, the Vicenzi structure may not ensure structural stability along the transversal and rotational planes of the fractured bone.
Accordingly, intramedullary devices that provide and/or ensure stability to a fractured one would be considered useful.
SUMMARY OF THE INVENTION
The present invention is directed to orthopedic devices for surgical treatment of bone fractures and for the prophylactic treatment of pathological bones, and more particularly to expandable intramedullary devices, and to methods for manufacturing and implanting them.
According to a first aspect of the present invention, a device for stabilizing bone includes an elongate body having first and second end regions defining a longitudinal axis therebetween. A plurality of splines extend from the first end region, the splines including first ends coupled to the first end region of the elongate body, and second ends disposed away from the first end region, the second ends of the splines being directable from a generally axial collapsed state to a substantially transverse expanded state. Support arms are coupled to the splines, and an actuator is coupled to the support arms, the actuator movable axially relative to the elongate body for causing the support arms to direct the second ends of the splines from the collapsed state to the expanded state.
In one embodiment, the elongate body is a tubular shaft including a lumen extending between the proximal and distal end regions, and the actuator includes an elongate member received within the lumen, and preferably slidably coupled to the tubular shaft by mating threaded regions. A collar is coupled to the elongate member and to the support arms. Preferably, the elongate member includes a threaded region over which the collar is threaded such that rotation of the elongate member relative to the tubular shaft causes the collar to move axially, thereby causing the support arms to direct the splines between the collapsed and expanded states.
In accordance with another aspect of the present invention, a device for stabilizing bone includes an elongate body having first and second end regions defining a longitudinal axis therebetween, and an intermediate region between the first and second end regions. A first plurality of splines extend from the first end region, the splines being directable from a generally axial collapsed state to a substantially transverse expanded state. A second plurality of splines extend from a region of the elongate body distal to the proximal end region, the splines being directable from a generally axial collapsed state to a substantially transverse expanded state.
First and second pluralities of support arms are coupled to the first and second plurality of splines, respectively, and an actuator is coupled to the support arms. The actuator is movable axially relative to the elongate body for causing the first and second pluralities of support arms to direct the splines between the collapsed and expanded states.
Preferably, the elongate body is a tubular shaft including a lumen extending between the proximal and distal end regions, and the actuator includes an elongate member received within the lumen. First and second collars are coupled to the elongate member and to the first and second pluralities of support arms, respectively. Rotation of the elongate member relative to the tubular shaft causes the first and second collars to move axially, thereby causing the first and second pluralities of support arms to direct the splines between the collapsed and expanded states.
In one embodiment, the second plurality of splines extend distally from the distal end region of the tubular shaft. The elongate member may include first and second threaded regions having thread patterns that are opposite hand relative to one another. The first and second collars are threadably coupled to the first and second threa
Greenberg Iian
Levy Mark M
Bingham & McCutchen LLP
Expanding Orthopedics Inc.
Philogene Pedro
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