Surgery – Instruments – Orthopedic instrumentation
Reexamination Certificate
1999-09-02
2001-08-14
O'Connor, Cary E. (Department: 3732)
Surgery
Instruments
Orthopedic instrumentation
C606S08600R, C606S104000
Reexamination Certificate
active
06273892
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates broadly to a system for bone fracture fixation. More particularly, this invention relates to an improved method and a related system for fixation of fractures of relatively small bones.
2. State of the Art
Metacarpal fractures are very common. Immobilization of the metacarpal bone on either side of the fracture is imperative for proper healing. However, the location of the fracture presents several difficulties to ideal immobilization.
The most frequently used treatments for immobilizing the fracture are splinting and casting. However, due to the location of the metacarpal bones, these treatments fail to maintain proper fracture reduction in the metacarpal bones. Strong fixation is possible with techniques using plates, fixation screws, and fixation pins attached to the affected bones through operative treatment. While these types of fracture reduction devices are commonly used in larger bone fractures, e.g., ulnar, tibial, or femoral fractures, such operative treatment generally implies a formidable incision and exposure of the fracture site. Therefore, these techniques are often judged to be too invasive for the relatively small and fragile metacarpal bones.
An alternative less invasive technique has been used in which a small incision is made in the skin proximal the metacarpal bone, a boring tool is inserted through the incision and is used to drill a small hole into the metacarpal bone, the boring tool is removed, and then the physician feeds the pin through the incision and into the small unseen bore in the bone. However, feeding the pin through the skin is a blind operation with no manner provided for indicating to the physician the relative location of the pin and the small hole bored in the bone. As such, the technique is objectionable to both physician and patient as blind feeding can result in exacerbating damage to the surrounding tissue. In addition, the implanted pin fails to provide torsional fixation for fractures which need to be rotationally immobilized.
Furthermore, similar problems exist with respect to metatarsal and phalangeal fractures.
SUMMARY OF THE INVENTION
It is therefore an object of the invention to provide a fracture fixation system which permits stable fixation for metacarpal, metatarsal, and phalangeal fractures, and fractures of similar bones.
It is another object of the invention to provide a fracture fixation system which provides internal percutaneous fixation for metacarpal, metatarsal, and phalangeal fractures, and fractures of similar bones.
It is also an object of the invention to provide a fracture fixation system which provides torsional stabilization for metacarpal, metatarsal, and phalangeal fractures, and fractures of similar bones.
It is a further object of the invention to provide a fracture fixation system which provides a fixation system which is adjustable in size for metacarpal, metatarsal, and phalangeal fractures, and fractures of similar bones.
It is an additional object of the invention to provide a fracture fixation system which when compared to prior art operative treatment is relatively noninvasive.
In accord with these objects, which will be discussed in detail below, a fracture fixation system is provided. For simplicity, the fracture fixation system generally will be described with reference to the metacarpal bones, although it also applies to metatarsal bones, phalangeal bones, similar bones. The system facilitates the insertion of one or more fixation pins into the medullary canal of a fractured metacarpal bone for stable bone fixation.
According to one embodiment of the invention, the system includes a fixation pin and an instrument for implanting the fixation pin. According to a first embodiment of the invention, the instrument includes a main handle and a pin handle movable relative to the main handle. The main handle includes a proximal end, a distal end, and a longitudinal slot having an opening in the distal end of the handle. A boring shaft (drill) is coupled to the distal end of the main handle. The boring shaft includes a distal boring tip and a pin guide proximally adjacent the boring tip for guiding the fixation pin into the medullary canal. The pin guide is preferably a groove in the shaft. The pin handle is shaped and sized to slidably move within the longitudinal slot, and may be provided with finger grips and a distal bore into which the fixation pin is received. The fixation pin preferably includes a substantially straight proximal and central portions, and a curved distal portion having a preferably blunt tip. Initially, the curved distal portion rests within the pin guide of the boring shaft. It will be appreciated that relative distal movement of the pin handle within the slot of the main handle causes the distal portion of the fixation pin to move through and beyond the pin guide.
In use, the main handle of the instrument is manipulated to subcutaneously introduce the boring shaft into the base of the fractured metacarpal bone in a hand of a patient. Once the tip of the shaft has entered the base of the metacarpal bone, it is left in position, and the pin handle is moved distally relative to the main handle to force the distal portion of the fixation pin into the bone. The pin thereby enters the natural hollow of the medullary canal of the bone. The main handle is then moved proximally relative to the pin handle to remove the boring shaft from the hand of the patient, and to disengage the main handle from the pin handle. The pin handle is then further moved to force the pin through the natural hollow of the medullary canal of the fractured metacarpal bone until it extends through the canal on either side of the fracture and provides the necessary immobilization of the fractured bone. The blunt tip prevents the pin from piercing the distal end of the metacarpal bone. Finally, the proximal end of the pin is bent, cut, and preferably subcutaneously seated.
According to other embodiments of the instrument of the fracture fixation system, the instrument includes a shaft handle having at its distal end a boring shaft coupled thereto. The boring shaft has an internal pathway and a distal exit. The shaft handle includes a throughbore in communication with the internal pathway of the shaft and through which the fixation pin can be received. The handle permits manual subcutaneous insertion and rotation of the shaft to provide the tip of the boring shaft into the metacarpal bone. The distal exit may be either axial or lateral. An awl member may be optionally provided in the throughbore and internal pathway and extended to the distal exit of the shaft for shaft insertion into the metacarpal bone, and then removed for extending the fixation pin through the internal pathway and distal exit of the shaft. According to another embodiment, the pathway of the boring shaft is provided with a proximal lateral entrance, and exits either laterally or axially at the distal end of the shaft.
In addition, the fixation pin may alternatively be adapted to be self-guiding to follow the medullary canal. The proximal and central portions of the pin are relatively straight and sufficiently stiff (providing fixation, yet permitting forced insertion into bone). Adjacent the distal end, a reduced diameter portion is provided which permits the distal end to easily bend relative to the central portion and follow the medullary canal. Preferably, a coil is provided about the reduced diameter portion to provide the pin with an apparently constant diameter.
Furthermore, the fixation pin may be particularly adapted for use in relatively small medullary canals such as that found in the phalanges, i.e., the fixation pin may have a relatively small distal diameter. In order to permit such a fixation pin to be used with the same pin handle as used for fixation pins adapted for metacarpal and metatarsal bones, the fixation pin includes a proximal end having a uniform diameter, and a distal end having a relatively smaller diameter, and a tapered or stepped portion
Castañeda Javier
Hernandez Ernesto
Orbay Jorge L.
Gallagher Thomas A.
Gordon David P.
Hand Innovations, Inc.
Jacobson David S.
O'Connor Cary E.
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