Surgery – Instruments – Orthopedic instrumentation
Reexamination Certificate
2000-02-02
2001-02-20
Smith, Jeffrey A. (Department: 3732)
Surgery
Instruments
Orthopedic instrumentation
C606S08600R
Reexamination Certificate
active
06190392
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to a method and apparatus for use in orthopedic surgery, and more particularly, to a method and apparatus for ultrasonic removal of bone cement material during an orthopedic surgical procedure.
2. Discussion of the Related Art
A natural joint may undergo degenerative changes due to a variety of etiologies. When these degenerative changes become so far advanced and irreversible, it may ultimately become necessary to replace the natural joint with a joint prosthesis. Such joint prostheses include, for example, shoulder, knee and hip joint prostheses. These different prosthetic devices are generally secured by means of bone cement, such as polymethylmethacrylate (PMMA). However, due to any number of reasons, some of the implanted prostheses may require subsequent removal and implantation of a new prosthesis during what is generally referred to as a revision type surgery. As the number of prosthetic implants increases, a corresponding number of revision arthroplasties will also increase.
One of the main challenges facing a surgeon during a revision procedure is the arduous task of complete prosthesis/cement removal. There are various techniques used to remove the prosthesis and bone cement during revision surgery, however, these techniques exhibit disadvantages. For example, manual instruments, such as osteotomes do not offer the surgeon the tactile feedback that aids in distinguishing between the bone cement and the actual bone. High speed burrs or drills have shortened the time required for removal of the bone cement versus the manual instruments. Unfortunately, these types of instruments also lack the tactile feedback which may lead to inadvertent removal or perforation of the patient's cortical bone.
Other techniques used to remove bone cement include the use of ultrasonic mechanical energy. In this regard, electrical energy is converted into mechanical energy, via an ultrasonic transducer. This mechanical energy, in turn, is transmitted through individually tuned tool tips in acoustic waves, causing the tips to vibrate at very high, yet controlled rates of speed. This action breaks down the bone cement in three ways. First, softening by intermolecular friction as the tool tip moves within the cement mantle. Second, by cavitation as the molecular structure begins to rapidly accelerate. Finally, by providing mechanical separation of the cement through cutting, via the tool tip itself. This ultrasonic technique reduces or eliminates some of the previous disadvantages associated with earlier cement removal techniques. However, the ultrasonic technique may further be improved upon.
What is needed then is a method and apparatus for ultrasonic removal of bone cement material which does not suffer from the above mentioned disadvantages and improves upon existing technology. This, in turn, will reduce the incidence of perforation of the cortical bone, reduce the cement removal time, reduce the overall surgical time and therefore, surgical cost, and provide a means for easily removing bone cement which provides a high degree of tactile feedback during the overall surgical procedure. It is, therefore, an object of the present invention to provide such a method and apparatus for ultrasonic removal of bone cement material during an orthopedic surgical procedure.
SUMMARY OF THE INVENTION
In accordance with the teachings of the present invention, a method and apparatus for ultrasonic removal of bone cement material during an orthopedic surgical procedure is disclosed. In this regard, an ultrasonically tuned tool tip having a helical flute is used to easily guide and remove bone cement during a revision type orthopedic surgical procedure. An ultrasonic hand piece is coupled to the tool to impart ultrasonic mechanical energy to the tip of the tool.
In one preferred embodiment, an ultrasonic tool for use in removal of bone cement material includes a connector portion, a shaft and an auger head. The connector portion is operable to be connected to an ultrasonic apparatus. The shaft extends from the connector portion. The auger head is coupled to the shaft and includes a conical tip and a helical flute. The helical flute defines a helical channel that extends along at least a portion of the shaft and is operable to pass bone cement material.
In another preferred embodiment, an ultrasonic system for use in removal of bone cement material includes an ultrasonic power console, an ultrasonic transducer hand piece and an ultrasonic tool. The ultrasonic transducer hand piece is driven by the ultrasonic power console. The ultrasonic tool is coupled to the ultrasonic transducer hand piece and includes an auger head having a conical tip and a helical flute. The helical flute defines a helical channel that is operable to pass bone cement material upon driving the ultrasonic transducer hand piece with the ultrasonic power console.
In yet another preferred embodiment, a method for ultrasonic removal of bone cement material is disclosed. This method includes providing a first ultrasonic tool having a first auger head that includes a first conical tip and a first helical flute that defines a first helical channel. Ultrasonic power is supplied to the first ultrasonic tool to cause the first auger head to vibrate. The first ultrasonic tool is guided with the first conical tip into the bone cement material to guide molten bone cement material along the first helical channel.
Use of the present invention provides an improved method and apparatus for ultrasonic removal of bone cement material during an orthopedic surgical procedure. As a result, the aforementioned disadvantages associated with the currently available methods and techniques for removing bone cement during orthopedic surgical procedures have been substantially reduced or eliminated.
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Golden Dean R.
Vandewalle Mark V.
Biomet Inc.
Harness & Dickey & Pierce P.L.C.
Smith Jeffrey A.
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