Patent Application
20060064005
This invention relates to medical procedures and more particularly to such procedures where it is necessary to track the location of tools and/or devices within a body being operated upon.
Many medical procedures, such as spinal operations, are now routinely performed in a minimally invasive manner, the desire being to reduce the trauma to the skin, soft tissue, and muscle as much as possible. A problem exists in such minimally invasive medical techniques in that when small skin incisions are made sight lines become non-existent and thus it is difficult to properly guide the surgical tools and/or implants when they are inside the body.
One method for such guidance is to continually take fluoroscope (X-ray) pictures as the procedure progresses. This is slow and suffers from problems due to harmful exposure for patients and medical personnel.
Another method uses fluoroscopy (X-ray) and electro magnetic electronic surgical navigation technology to keep track of the position of the tools and/or devices with respect to the spine. In such systems, it is important to establish a fixed relationship between a signal transmitter and the portion of the patient's anatomy being worked on. For discussion purposes, the structure(s) being worked on will be called the target site. This fixed relationship between the surgical tools and the electro magnetic transmitter must remain constant regardless of the motion of the target site. In order to accomplish such a fixed relationship, it is common practice to mount the transmitter on a bony surface adjacent to the target site. This adjacent surface is selected such that it has an anatomical connection to the target site and such that the adjacent site always moves in a constant relationship to that of the target site. In this manner, the transmitter at the adjacent site sends signals to the receiver unit mated to the surgical tools being used at the target site and those signals are reported back to a monitor so that the medical personnel can track the tool(s) in relationship to the target site. In essence then, the adjacent transmitter site provides a fixed point of reference for procedures with respect to the target site. A registration process of the transmitter to the anatomy may be performed in some instances. This includes first fixing the transmitter to a fixed landmark (most often bone). Second, an AP fluoroscopic image with the navigation calibration target attached to the image intensifier of the C-arm (Fluoroscope) is obtained. Next a lateral fluoroscopic image is taken. Now the patient's anatomy is registered to the transmitter and displayed on the surgical navigation monitor. This step is repeated every time the sensor (transmitter) is moved relative to the spinal anatomy. In order to navigate a surgical tool, the tool is first attached to a handle which has an imbedded receiver and then calibrated with the surgical navigation system. Each time the tool is changed, calibration must be repeated.
In a less optimal usage of this technology, the transmitter is not repositioned when the target site moves. In other words, the transmitter is not moved to the new target site, so that the transmitter and the target site are located on different vertebral bodies and therefore are not in the same fixed relationship that is optimal between the transmitter and target site. This suboptimal location contributes to the overall inaccuracy of the system.
Several problems arise in using such a system. One of these problems is that the transmitter must be implanted into the body. This implantation results in additional trauma to the body. A second problem is that for many procedures an adjacent bony surface upon which to mount the transmitter is not available. This unavailability could be because any such surface is too brittle, too small, too flexible, or perhaps lacking in depth for attachment of the transmitter. Also, the bony surface may not consist of hard bone, resulting in movement of the transmitter due to the soft nature of the fixation point. Also, such implanted transmitters are subject to being bumped by the surgeon and, from time to time, are in the line of sight. Also, for some procedures (for example, anterior approach) there may not be a sound anchor surface available. Also, in the event of an emergency situation these adjacent transmitters must be removed and this takes time when time is at a premium.
The present invention is directed to a system and method which allows for the mounting of a medical navigation system external to a patient. In one embodiment, an expandable device is non-invasively mounted around a patient's torso and serves to displace (e.g., distract or compress) the patient's skeleton in a manner such that the target site becomes fixed relative to a site on the displacement device. A navigation transmitter can then be mounted to the displacement device. The device has a quick disconnect that allows it to be removed without first removing the displacement. Displacement can be controlled by pneumatic, hydraulic, electrical, or by mechanical screw action, as examples. In one embodiment, the device can be used to position a patient on an operating table and can be fixed to prevent patient motion relative to the table.
The foregoing has outlined rather broadly the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter which form the subject of the claims of the invention. It should be appreciated that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. It should also be realized that such equivalent constructions do not depart from the invention as set forth in the appended claims. The novel features which are believed to be characteristic of the invention, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present invention.
For a more complete understanding of the present invention, reference is now made to the following descriptions taken in conjunction with the accompanying drawing, in which:
Turning now to
Lateral sides 13R and 13L and 15R, 15L interconnect bands 11 and 12 and are operable to displace band 11 relative to band 12 (e.g., to distract or compress the bands 11 and 12 relative to each other) under locking control of locks 14R, 14L. Note that in
For different patients, different adjustment mechanisms are possible. These adjustment mechanisms can be, for example, a lead screw, perhaps driven by a miter gear; a worm gear; a scissor jack, a hydraulic jack, pneumatic or electric piston, etc. One system could use an integrated plain bearing slide with a lead screw while another could use a pneumatic rear-mount air cylinder with either a ratchet lock, a spring return or a double-acting chamber. In such a system, when air is applied the piston expands. By connecting the lateral sides to work together, the patient's body is distracted by the application of air (or hydraulic fluid, or by hand cranking, etc.)
In the embodiment shown, locks 14R and 14L serve to control the lateral displacement of the lateral sides, such that once bands 11 and 12 are securely fastened to the torso of the patient the interconnecting lateral sides 13R, 13L, 15R, 15L are operated to controllably displace bands 11 and 12 relative to each other (e.g., to achieve distraction or compression). This displacement can be by, for example, turning locks 14R and 14L so that a screw extends the pressure upward to move band 11 away from band 12. Since band 11 then is attached to the torso of the patient above the vertebrae which is the target site, this procedure serves to distract the skeleton of the patient (for example, patient 21 in
In the embodiment shown, this specific position is recorded by navigation device 18R and/or 18L such as, for example, a navigation transmitter. While this example shows distraction, compression may be alternatively used in certain procedures (e.g., by turning 14R and 14L in an opposite direction to move band 11 toward band 12). Note that lateral sides can be designed to allow any type of patient adjustment, including flexion, extension, axial, or a combination thereof.
As discussed,
Returning to
Note that the distraction device discussed herein can be used to hold an instrument, retractor, attachment for a flexible arm, etc. during surgery to aid the surgeon during the procedure. Since the device is rigidly fixed to the patient and if an instrument, blade retractor system, or flexible positioning arm is then rigidly attached to the device, then as the patient moves the device moves in exact proportion and thus the tool also moves exactly proportional to the patient's movement.
In this embodiment, the inside surface of side portion 51 can be padded and pads 54 can be properly placed. Buckle portions 52A and 52B can be made to open and close as desired. This can be achieved through magnetic or electric field interaction, or through physical latching. Similarly, buckle portions 57A and 57B can be interlocked and signal transmitter (receiver) pad 55 with signal transmission connection (an antenna, if wireless) can be mounted to buckle 57A, 57B.
Device 510, which is optional, may or may not include a gauge to measure, for example, the distraction forces, distance, and/or time that the distraction has been applied. The gauge may include an audible alarm which indicates a distraction force has been applied for a specific amount of time or when an excessive distraction force has been reached. If desired, the tension and/or time may be set by the surgeon or during a pre-op procedure based upon parameters specific to the patient.
Note that while this procedure has been discussed with respect to a patient's spine, it can be used with respect to any two structures in the skeleton, which when distracted will remain rigid with respect to each other without regard to the movement of the skeleton. As discussed herein, system 40, shown with respect to
In operation, when placement of the lower and upper collars 111 and 12 are used it would be helpful if they are placed on bony landmarks that are known, such as, for example, pelvis and/or rib cage. The lifting mechanism of
While the device shown herein is designed primarily for use in spinal distraction for the purpose of performing medical procedures internal to the body, the device could also be used to correct scoliosis by providing distraction forces which are differential, i.e., greater in one quadrant for deformity correction of the spine. This could be a situation where the device is worn for a period of time by a patient or for correction of a spine temporarily while a physician performs an operation to implant a fusion device (screws or rods), or to correct other deformities internal to the patient. Further, in some procedures the device 10 may not only be worn during an operation, but may also be worn for a period following the operation to, for example, monitor the position of an implant that includes a transmitter similar to that described above for receiver 403 of tool 43, or simply to stabilize the patient during the initial healing process.
Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the invention as defined by the appended claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one will readily appreciate from the disclosure, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.
