Patent Application
20150094723
This invention relates to an ultrasonic surgical apparatus. More particularly, this invention relates to an ultrasonic bone cutting apparatus. The invention also relates to an associated surgical method.
Ultrasonic surgical blades for cutting bone have known for several years. U.S. Pat. No. 6,379,371 and U.S. Pat. No. 6,443,969 disclose such a surgical blade. Ultrasonic bone cutting tools exhibit significant advantages over more traditional instruments such as power saws and rotary cutters. Ultrasonic bone cutting blades have been devised for enabling a separation of bone and soft tissue, along an interface between the two, with a minimum of damage to the soft tissue. Such an instrument is disclosed in U.S. Pat. No. 8,343,178.
It is an object of the present invention to provide and improved ultrasonic bone cutting apparatus.
A more particular object of the present invention is to provide an ultrasonic bone cutting apparatus the use of which entails a reduced probability of damage to soft tissues adjacent to a bone being cut.
Another particular object of the present invention is to provide an ultrasonic bone cutting apparatus configured to automatically protect soft tissues adjacent to a bone from being cut during an operation on the bone.
These and other objects of the present invention will be apparent from the descriptions and drawings herein. Although every object of the invention is attainable by at least one embodiment of the invention, there is not necessarily any single embodiment that achieves all of the objects of the invention.
An ultrasonic surgical apparatus in accordance with the present invention comprises a probe with an operative edge or surface at a distal end, an electromechanical transducer connected to the probe, and an activation circuit connected to the transducer for supplying thereto an electrical waveform having an ultrasonic frequency and an amplitude. The activation circuit includes a signal generator and further includes a power reduction circuit operatively connected to the signal generator for inducing the signal generator to automatically reduce the amplitude of the waveform upon a sensing by the power reduction circuit of reduced load on the probe.
The power reduction circuit may include a load detector, and the load detector may include a current sensor. The load detector may further include a comparator operatively connected to the current sensor for comparing an output of the sensor with a pre-established reference value. The comparator may be a digital device, so that a digitizer is required to convert an analog output signal of the current sensor to a digital or binary signal for use by the comparator.
Pursuant to another feature of the present invention, the activation circuit includes a manually actuatable power switch and the power reduction circuit further includes a switching circuit operatively connected at inputs to the power switch and the comparator and at an output to the signal generator. The switching circuit acts to automatically override an instruction from the manual power switch in the event that a current reduction indicates that the ultrasonic blade has penetrated through a bone and encountered soft tissue adjacent thereto.
A surgical method in accordance with the present invention comprises operating an ultrasonic cutting tool to cut through bone of a patient, operating a sensor to automatically monitor load on the cutting tool during the operating of the cutting tool, automatically detecting a change in output of the sensor indicative of a reduced load on the cutting tool owing to a passing of the cutting tool at least partially through the bone, and automatically reducing power to the cutting tool upon the detecting of reduced load on the cutting tool.
The detecting of a change in output of the sensor may include comparing output of the sensor with a preselected reference value.
The reducing of power to the cutting tool may include reducing amplitude of an ultrasonic electrical waveform fed to an electromechanical transducer.
The operating of the sensor may include detecting current flow to an electromechanical transducer connected to the tool.
As depicted in
Surgical apparatus 10 typically includes further electrical and liquid-supply components as disclosed in U.S. Pat. No. 6,379,371 and U.S. Pat. No. 6,443,969, the disclosures of which are hereby incorporated by reference. For instance, apparatus 10 may incorporate a power switch 24 such as a foot-operated switch.
As illustrated in
As illustrated in
Comparator 36 compares a digitized output of sensor 30 with the reference value from register 38 and, upon detecting that the current has fallen below a pre-established level encoded by the reference value, transmits a signal to switching circuit 28 which in turn causes signal generator 20 to reduce the power output to transducer 16, particularly by reducing the amplitude of the electrical transducer-energizing waveform. Switching circuit 28 acts to automatically override an operator-induced instruction from manual power switch 24 in the event of a current reduction resulting when ultrasonic blade or tool 12 penetrate through bone and encounters soft tissue adjacent thereto.
A surgical method utilizing the apparatus of
One automatically reduces power to the cutting tool 12 upon detecting reduced load on the cutting tool. The detecting of a change in output of sensor 30 may include operating comparator 36 to automatically compare output of sensor 30 with the reference value from register 38. The reducing of power to cutting tool 12 may be implemented by reducing amplitude of an ultrasonic electrical waveform fed to an electromechanical transducer, i.e., transducer 16.
Although the invention has been described in terms of particular embodiments and applications, one of ordinary skill in the art, in light of this teaching, can generate additional embodiments and modifications without departing from the spirit of or exceeding the scope of the claimed invention. Accordingly, it is to be understood that the drawings and descriptions herein are proffered by way of example to facilitate comprehension of the invention and should not be construed to limit the scope thereof.
