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Ultrasonic cutting deviceRelated Patent Categories: Surgery, Instruments, Orthopedic Instrumentation, Orthopedic Cutting InstrumentUltrasonic cutting device description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20060195106, Ultrasonic cutting device. Brief Patent Description - Full Patent Description - Patent Application Claims
RELATED APPLICATIONS [0001] The present invention relates to U.S. patent application Ser. No. ______ (Attorney Docket No. DUQ008A) entitled "Ultrasonic Cutting Device", filed on Feb. 2, 2005. FIELD OF THE INVENTION [0002] The present invention relates to an ultrasonic cutting device, and more particularly to a system and method for cutting bone using an ultrasonic cutting device while preventing heat damage to the bone and neighboring tissue. BACKGROUND OF THE INVENTION [0003] The use of ultrasonic medical devices in surgery is widely known in various surgical fields. Traditional surgical instruments using ultrasonic frequencies typically use the ultrasonic energy to dissect, coagulate, and cut living tissue during surgery. Existing ultrasonic surgical devices typically employ an ultrasonic transducer to translate electrical energy provided to the transducer into mechanical energy for use in the intended surgical procedure. The mechanical vibratory motion is typically delivered to a distal end of the surgical instrument where a cutter is located. Due to the mechanical vibratory motion, heat is generated at the cutter. In traditional medical procedures this heat is a sought after byproduct of the ultrasonic mechanical energy delivered to the cutter, as the heat aids in the coagulation of tissue that is cut by the surgical instrument. [0004] The heated output of traditional ultrasonic surgical devices, however, does introduce several inherent problems when used in various forms of surgery. If these devices are used to attempt to cut bone, for example, the high concentrated heat and mechanical vibration can result in the temporary or permanent loss of blood supply to the region of bone in contact with the surgical device. This loss of blood supply in the bone is associated with necrosis of the bone, wherein bone tissue dies. Such death of bone tissue is not clinically desirable. In light of this, the use of ultrasonic cutting techniques with dense materials such as bone is not practical and is generally avoided. When faced with a need to cut bone, traditional invasive procedures are generally used. These invasive procedures generally require a larger incision and expose a patient to a greater risk of injury or infection. Furthermore, traditional mechanical means used to cut bone often employ vibrating or rotating instruments. Such instruments may not differentiate between bone and surrounding soft tissue, therefore the potential remains for unintentional damage to the surrounding soft tissue which may result in permanent injury to a patient. [0005] Furthermore, existing bone cutting surgical devices use a combination of low frequency, located outside of the ultrasonic range, and low amplitude levels to slowly cut through bone. With such an approach, however a long period of time is required to cut through a region of bone. During a surgical procedure where the patient is under the effects of aesthesia, a surgeon generally wishes to minimize the time that the procedure takes to perform. While increasing the frequency or amplitude of a bone cutting device would decrease the time required to cut through the bone, such an increase of frequency or amplitude results in excessive heat generation at the cutter and the problems discussed above. Additionally, the high heat of the device results in cauterization of soft tissue which may result in irreversible damage to a patient. SUMMARY OF INVENTION [0006] In light of the inherent problems and concerns of existing surgical cutting techniques, a cooling mechanism attached to the cutter of an ultrasonic surgical device is beneficial. When the ultrasonic device is used to cut bone, reduction of heat at the cutter prevents bone necrosis. Additionally, as the cutter is operating at a less elevated temperature, damage to tissue surrounding the cutter is less of a concern. In light of this, should a cooled ultrasonic cutter stray from the intended subject and accidentally come into contact or close contact with an unintended region of tissue, the likelihood of damage to this tissue is reduced. [0007] The present invention relates to surgical cutting devices wherein ultrasonic vibration can be used in conjunction with a cooling mechanism. Using a cutting and cooling arrangement, as provided in the present invention, a cooled cutter can be used in cutting hard tissues such as bone, and is further capable of preventing heat related damage to hard or soft tissue surrounding the site of intended use. [0008] Providing an ultrasonic cutting device wherein the cutter is maintained at a reduced temperature offers numerous advantages as compared to existing surgical devices. Firstly, the combination of ultrasonic cutting frequencies provides for speedy removal of bone during a surgical procedure. Additionally, as the cutting tip is at a reduced operating temperature, traditional problems with bone necrosis due to heat are reduced. In light of this, damage to the region of hard or soft tissue surrounding the location of the cut are minimized. [0009] Additionally, the inherent concerns of a surgeon when using a high-heat ultrasonic cutting device in close proximity to hard or soft tissue that is not being cut are further eliminated by a ultrasonic surgical device that maintains a reduced cutter temperature. For example, extensive necrosis to cortical bone has been reported at temperatures of 70.degree. C. The temperature threshold where tissue damage occurs has been found to be 56.degree. C. Some studies have correlated thermal damage to tissue to the magnitude of temperature and the period of time during which the tissue is subjected to damaging temperatures. This thermal damage has been shown to effect bone reformation. Heating bone to 47.degree. C. or 50.degree. C. for 1 minute can cause significantly reduced bone reformation. Furthermore, nervous tissue is particularly sensitive to elevated temperatures and may become damaged at temperature at 42.degree. C. In light of this, the present invention provides a reduced heat cutting tip such that damage to hard of soft tissue in the region to be cut is prevented. [0010] In one embodiment of the present invention, during a surgical procedure where bone is to be cut, should a surgeon accidentally stray from the intended target bone and come into contact with surrounding nervous tissue, a reduced temperature ultrasonic cutting device is less likely to cause damage to the nervous tissue. In light of this, unintended nerve damage and paralysis is subsequently avoided while using a reduced temperature ultrasonic cutting device. [0011] The present invention can additionally perform lateral cutting operations. For example, using the present invention, a surgeon can laterally cut a region of bone from within a predefined hollow provided in the bone. For example, when used during spinal surgery, the present invention offers a surgeon the benefit of a compact ultrasonic device that can be readily guided down a predefined hollow pathway to a fixed depth. In one such surgical procedure, namely a stenosis correction procedure, the pedicles of a vertebrae are cut at corresponding points such that the pedicle can be separated from the main portion of the vertebral segment. Such a procedure is defined in U.S. Patent Application No. US 2003/0212400 to Bloemer, and U.S. Pat. No. 6,358,254 B1 to Anderson, both of which are herein incorporated by reference. In accordance with the Bloemer application and Anderson patent, a hollow pathway is provided in the pedicle region of a vertebra. This hollow pathway can be generated using existing drilling techniques. Following the drilling of a hollow pathway, a need exists to cut through the material of the pedicle region such that an expandable screw may be placed within the hollow pathway. The required cutting, if completed from within the predefined hollow region, must be lateral in nature. The present invention, and its lateral cutting aspects, allows for the predefined hollow in the bone to be used to properly orient the surgical instrument. This expandable screw, placed in the now severed pedicle, allows for the separation of the pedicle from the main portion of the vertebrae such that stenosis is eliminated. [0012] Using the present invention, the pedicle region can be carefully cut at fixed locations in a lateral manner such that the expandable screw can later be implanted and expand. Such an arrangement eliminates the potential for error in cutting a region of a vertebra, as the predefined hollow is used to orient the cutter, and further provides a readily repeatable cut along various regions of a vertebra. Additionally, the present ultrasonic cutter is easily operable by a surgeon, requiring only a simple insertion and revolution of a hand piece assembly. In light of this, when used in conjunction with a predefined hollow pathway, spinal surgery can be performed in a minimally invasive manner such that repeatable results can be obtained without unintended damage to surrounding soft tissue. As the surgical procedure can be less invasive than traditional techniques, unnecessary trauma to a patient is prevented and the potential for infection is greatly reduced. [0013] Additionally, when the device is employed using a high amplitude signal, soft tissue can be cut. As the present invention includes a cooled cutter, the cooled cutter arrangement is such that soft tissue cut by the present invention does not unnecessarily stick to the cutter. BRIEF DESCRIPTION OF THE DRAWINGS [0014] The present invention will become better understood with reference to the following description and accompanying drawings, wherein: [0015] FIG. 1 is a is an illustrative graphical embodiment of a system for use with the present invention in accordance with one aspect of the present invention. [0016] FIG. 2A is an illustrative embodiment of the present invention in a state where the cutter is retracted while located in a predefined hollow. [0017] FIG. 2B is an illustrative embodiment of the present invention in a state where the cutter is extended while located in a predefined hollow. [0018] FIG. 2C is a detailed view of an illustrative embodiment of a portion of the system, wherein the internal workings of the rotatable hand piece are detailed. [0019] FIG. 3A is a flowchart illustrating the steps required in spinal stenosis correction when the pedicle region of a vertebrae is cut. Continue reading about Ultrasonic cutting device... Full patent description for Ultrasonic cutting device Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Ultrasonic cutting device patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Ultrasonic cutting device or other areas of interest. ### Previous Patent Application: Patellar bone tunneling system Next Patent Application: Ultrasonic cutting device Industry Class: Surgery ### FreshPatents.com Support Thank you for viewing the Ultrasonic cutting device patent info. 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