Surgery – Instruments – Orthopedic instrumentation
Reexamination Certificate
1999-12-29
2001-10-30
O'Connor, Cary E. (Department: 3732)
Surgery
Instruments
Orthopedic instrumentation
C606S098000
Reexamination Certificate
active
06309392
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an orthopedic device, and more specifically, to an improved intramedullary rod and simplified system for securing the device in the medullary cavity of an injured/traumatized bone.
BACKGROUND OF THE INVENTION
Long skeletal structures and especially large weight supporting bones, e.g., tibia, femur, humerus and radius, when fractured often require the introduction of a rod-like device into the medullary canal as a supporting structure and means for repairing the fracture. Current orthopedic practice calls for the introduction of the metal rod or intramedullary device down through the canal of the broken bone to aid in holding the fractured portions together. The rod must then be secured to the bone using either a pin, a nail, bolt or screw, to prevent slippage in the medullary canal when under stress. This is usually carried out first by forming a continuous channel consisting of a predrilled transverse hole in the distal end of the rod and through adjacent corticals of the injured bone. Through such a continuous channel a pin is introduced to affix the rod to the bone.
However, most processes for fixation of the rod require the surgeon to drill “blindly” into the bone from the outside wall in an effort to locate the predrilled hole in the rod. The process of drilling holes in bone which are aligned with the predrilled holes in the rod is inexact, and often performed on a trial and error basis. Consequently, the fixation of an intramedullary device can be and often is a tedious and time consuming process. This also translates into protracted operating room times, added risk to the patient due to longer anesthesia times, risk of further tissue damage, external scarring and increased radiation exposure to the patient and providers.
Various alternative methods for fixation of intramedullary rods have been proposed in an effort to overcome the foregoing problems. For example, fluoroscopy has been used by surgeons for visualization of the predrilled holes in the rod for more accurate drilling of bone. However, fluoroscopy provides only two dimensional images of a three dimensional target, and consequently, the predrilled holes in the rod under the bone are often not visible. Fluoroscopy also means added cost both for the equipment in the operating room and for staffing with an x-ray technician. Laser guidance, plus fluoroscopy, while providing some improvement over fluoroscopy alone, still does not provide consistently reliable images. Other methods have relied on external clamps and drill guides, for example. They too have limitations, including interference by anatomic variations, and less than ideal positioning of the rod in the bone canal making them cumbersome to use.
A further process disclosed by U.S. Pat. No. 4,781,181 to Tanguy provides for positioning an intramedullary rod in the canal of a fractured bone, and with the aid of a boring sensor comprising a translatable drill guiding and positioning unit, a drill bit on a flexible shaft is inserted into the rod interior beginning at the proximal end of the intramedullary rod for drilling a hole from the inside of the bone adjacent to the predrilled opening in the distal end of the rod. While this assures alignment of the predrilled holes in the rod with the holes drilled in the bone for insertion of a pin, before the drill bit can be inserted the boring sensor must be inserted into the rod interior and locked into place at the distal end where it is maneuvered for engaging with a recess in the wall of the rod. The drill bit is then introduced into a sheath in the boring sensor, which performs as a tubular guide routing the drill bit toward the predrilled hole at the distal end of the rod where it is turned laterally toward the bone and drilled from the inside through the cortical end and outwardly. This approach requires additional hardware components, manipulative steps and greater installation time and cost.
Accordingly, there is a need for an improved, more economic intramedullary rod and more efficient and simplified system for fixation of the rod to bone.
SUMMARY OF THE INVENTION
The present invention provides for an improved, more economic intramedullary device which permits drilling bone from the inside of the device with fewer steps and significantly less time and difficulty for the orthopedic surgeon to complete the otherwise tedious task of fixation of the device to bone. The improved intramedullary rod and system for fixation will decrease operating room and anesthesia times, decrease the need for intraoperative x-rays, and reduce the risk of tissue damage and external scarring.
It is therefore one principal object of the invention to provide for an improved intramedullary device which comprises an elongated rod having a wall defining a central cavity. The rod has first and second ends with one or more pairs of oppositely disposed pin openings in the wall. Each pair of the pin openings is aligned in a plane which is transverse to the longitudinal axis of the rod. A baffle means is positioned in the central cavity proximate to the second end for receiving and laterally channeling bone cutting means, such as a drill bit on a elongated flexible drive cable, laser cutting device or practically any other suitable means for precision boring of bone tissue to provide openings in bone tissue adjacent to the pin openings. The baffle means which remains in the central cavity of the rod and is not removed in the fixation process comprises a substantially conically shaped entrance for reliably guided channeling of a flexible power transmission cable and bone cutting means, such as a drill bit to one opening of the pair of pin openings in the wall of the device for boring a pilot opening in the adjacent cortical of the bone from the bone interior. This achieves the necessary alignment for boring a second opening and for completing the needed continuous channel for pinning the intramedullary device to the bone.
More specifically, the baffle means comprises a substantially conically shaped entrance and a tapered laterally displaced chute for guided the bone cutting means and power transmission cable to one of the pin openings in the wall of the rod for boring the all important first pilot opening through the adjacent bone cortical from the rod interior. The curvature of the chute readily allows passage of the cutting tool without binding or crimping the power cable in the process. This first pilot opening from the interior of the bone enables more accurate and efficient boring of a second hole in the opposite cortical from the first pilot opening to complete the needed continuous channel in the fixation of the intramedullary rod.
The improved intramedullary device and system for fixation according to the invention allows for more efficient internal drilling of bone with only the intramedullary rod being required, while eliminating the need for introducing an independent tool, fixture or jig for guiding the introduction of a drilling tool. Generally, the pin openings in the rod may be positioned in a plane which is transverse to the longitudinal axis of the device. This would include pin openings aligned with one another in a plane which is perpendicular or normal to the axis of the rod, or in a diagonal plane. In the case of the latter, this would comprise openings aligned at an acute angle, for example, 45° or less, and more particularly, from about 10 to about 45° measured from the exit point to the rod sidewall.
It is also a further object of the invention to provide a more efficient method for fixation of an intramedullary device to an injured, e.g., fractured bone, which comprises the steps of:
(i) providing an intramedullary device comprising an elongated rod having a wall defining a central cavity. The rod is characterized by first and second ends with one or more pairs of oppositely disposed predrilled pin openings in the wall. Each pin opening of a pair is aligned with the other and lies in a plane which is generally transverse to the longitudinal axis of the rod.
Alexander Daniel
Burns Terrence R.
Rooney John
Ellis Howard M.
O'Connor Cary E.
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