Patent Application
20080114375
This disclosure relates generally to a method and apparatus for rigidly attaching a dynamic reference to a patient.
In minimally invasive surgical procedures, access to the body is obtained through one or more natural openings or small percutaneous incisions. Medical devices are inserted through these openings and directed to a region of interest within the body. Direction of the medical devices through the body is facilitated by navigation technology wherein the location of a medical device is measured and virtually superimposed on an image of the region of interest. The image may be a pre-acquired image, or an image obtained in near real-time or real-time using known imaging technology such as X-ray, computed tomography (CT), magnetic resonance (MR), or ultrasound (US).
Conventional navigation technology measures the position and orientation of a remote unit attached to the medical device relative to a reference unit. Patient motion can be taken into account by mounting the reference unit directly onto the patient. A reference unit attached in this manner is also referred to as a dynamic reference because it moves along with the patient.
Relative motion between the dynamic reference and the patient can introduce imprecision into a navigation system. It is therefore important that the dynamic reference be securely and rigidly mounted to the patient while also being minimally invasive. A problem with conventional dynamic reference devices relates to their size, high-profile designs and various methods of secure anatomical attachment. Conventional dynamic reference devices are large enough to potentially limit surgical access, their high-profile design poses an increased risk of unintentional contact or bumping, and some mechanical designs are suboptimal for secure anatomical fixation given the anatomical point of interest and procedure at hand.
The above-mentioned shortcomings, disadvantages and problems are addressed herein which will be understood by reading and understanding the following specification.
In an embodiment, a reference platform includes a top surface adapted to contact a reference unit, and a bottom surface generally opposite the top surface. The bottom surface is adapted to contact a patient. The reference platform also includes a spike extending in a direction away from the bottom surface. The spike is configured to penetrate the patient in order to secure the reference platform to the patient. The reference platform is adapted facilitate the attachment of the reference unit to the patient.
In another embodiment, a navigation system includes a reference platform attachable to a patient. The reference platform includes a top surface and a bottom surface generally opposite the top surface. The bottom surface is adapted to contact the patient. The reference platform also includes a spike extending in a direction away from the bottom surface. The spike is configured to penetrate the patient in order to secure the reference platform to the patient. The navigation system also includes a reference unit mountable to the top surface of the reference platform, and a process in communication with the reference unit. The process is adapted to determine the position and/or the orientation of a medical device relative to the reference unit.
In yet another embodiment, a method for mounting a reference unit of a navigation system to a patient includes providing a reference platform having a spike, and attaching the reference platform to the patient such that the spike penetrates a bone. The method also includes attaching a reference unit to the reference platform, and applying a retention device adapted to prevent the reference platform from inadvertently pulling out of the patient.
In yet another embodiment, an anchor device includes a body portion, and a clamp portion attached to the body portion. The clamp portion includes a first leg, and a second leg attached to the first leg such that the first and second legs define a gap therebetween through which the wire is passed. The clamp portion also includes an adjustable member configured to selectively draw the first and second legs together such that a clamping force is applied to the wire. The anchor device is configured to interrupt the transfer of a force applied to a first portion of the wire such that a device connected to a second portion of the wire is not disturbed by the force.
Various other features, objects, and advantages of the invention will be made apparent to those skilled in the art from the accompanying drawings and detailed description thereof.
In the following detailed description, reference is made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration specific embodiments that may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the embodiments, and it is to be understood that other embodiments may be utilized and that logical, mechanical, electrical and other changes may be made without departing from the scope of the embodiments. The following detailed description is, therefore, not to be taken as limiting the scope of the invention.
Referring to
The reference platform 10 is configured to facilitate the rigid attachment of the reference unit 14 to a patient 28 near the target operation site 30 (e.g., the pituitary gland or a frontal trephination procedure, etc) as will be described in detail hereinafter. A reference unit attached in this manner is also referred to as a “dynamic reference” because it moves along with the patient. The remote unit 16 is attached to a medical device 34. The present invention will hereinafter be described in accordance with an embodiment wherein the reference unit 14 includes a field generator 38, and the remote unit 16 includes one or more field sensors 40. It should, however, be appreciated that according to alternate embodiments the reference unit may include the field sensors and the remote unit may include the field generator.
The field generator 38 in the reference unit 14 generates a position characteristic field 44 in an area that includes the target operation site 30. The field sensors 40 in the remote unit 16 produce sensor signals (not shown) in response to the sensed position characteristic field 44. The sensor signals are transmitted or input into the position detection process 20. The sensor signals may be transmitted via communication line or wire 46, or may be wirelessly transmitted. The position detection process 20 is adapted to determine the location of the remote unit 16 relative to the reference unit 14. A known calibration procedure can be implemented to estimate the location of the distal end or tip 36 of the medical device 34.
The location of the medical device 34 may be conveyed via the display 18. According to a preferred embodiment, a graphical representation 48 of the distal end 36 is virtually superimposed onto a patient image 50. More precisely, the graphical representation 48 of the distal end 36 is virtually superimposed onto the portion of the image 50 that corresponds to the actual location of the distal end 36 within the patient 28. The graphical representation 48 may include a dot or cross hairs identifying just the distal end 36, or may include a more complete rendering showing the medical device 34 in detail.
According to one embodiment, the patient image 50 is obtained prior to the medical procedure using known imaging technology such as X-ray, computed tomography (CT), magnetic resonance imaging (MRI), or ultrasound (US). Additionally, during the course of the medical procedure, the imaging device 22 may be implemented to observe the patient 28 in real-time or near real-time. Therefore, the pre-recorded patient image 50 can be replaced with a real-time patient image or a near real-time image as desired. According to an exemplary embodiment, the imaging device 22 may include a fluoroscopic X-ray device mounted to a C-arm, however, other imaging devices may also be implemented.
The reference platform 10 includes a top surface 52, a bottom surface 54, and a screw hole 56 defined therebetween. The top surface 52 is configured to engage or contact the reference unit 14 (shown in
A plurality of spikes 64 extend from the bottom-surface 54. According to one embodiment, the reference platform 10 includes four evenly spaced spikes 64 comprised of a non-ferrous material in order to avoid distorting the position characteristic field 44 (shown in
The reference platform 10 includes a plurality of walls 66 adapted to secure the reference unit 14 (shown in
The reference platform 10 includes a lip 72 extending in an outward direction from one of the walls 66a. The lip 72 is configured to facilitate the removal of the reference unit 14 (shown in
Referring to
There are several methods for attaching the reference platform 10 to the patient 28. A first method includes manually pushing the reference platform 10 such that the spikes 64 pierce the patient's cranium. This first method may be performed, for example, with the user's thumb in a manner similar to that of a thumbtack.
A second method for attaching the reference platform 10 to the patient 28 includes implementing a tool such as the impactor 82 shown in
A third method for attaching the reference platform 10 to the patient 28 (shown in
Referring to
The wire anchor 90 includes a generally C-shaped body portion 92 adapted for attachment to a bed rail (not shown). A first threaded member 94 is rotatable to control the degree of insertion through a wall of the C-shaped body portion 92. When the C-shaped body portion 92 is mounted to a bed rail, the first threaded member 94 can be rotated in a first direction in order to engage the bed rail and thereby tighten the attachment of the wire anchor 90. Conversely, the first threaded member 94 can be rotated in a second direction in order to disengage the bed rail and thereby loosen the attachment of the wire anchor 90.
The wire anchor 90 also includes a radiolucent clamp portion 96 configured to secure the reference unit wire 46. The clamp portion 96 includes a first leg 98 and a second leg 100 that together generally form a V-shape. A second threaded member 102 passes through the first leg 98 and into the second leg 100. The second threaded member 102 can be rotated in a first direction to apply a compressive force tending to draw the first and second legs 98, 100 together. Conversely, the second threaded member 102 can be rotated in a second direction to release the compressive force such that the first and second legs 98, 100 separate until they reach their steady state positions.
A method for implementing the wire anchor 90 includes the following. The C-shaped body portion 92 of the wire anchor 90 is mounted to a bed rail (not shown), and the first threaded member 94 is rotated so that the wire anchor 90 becomes tightly affixed to the bed rail. The reference unit wire 46 is then passed through the clamp portion 96 such that a first wire section 46a is defined between the reference unit 14 and the wire anchor 90, and a second wire section 46b is defined between the wire anchor 90 and a device incorporating the position detection process 20. Thereafter, the second threaded member 102 is rotated in a direction adapted to draw the first and second legs 98, 100 together such that the first and second legs 98, 100 apply a compressive force to the reference wire 46 disposed therebetween. It can be seen that by securing the reference unit wire 46 in the manner described, a force applied to the second wire section 46b is prevented from reaching the reference unit 14. Therefore, if the second wire section 46b is inadvertently pulled, the reference unit 14 and patient 28 (shown in
While the invention has been described with reference to preferred embodiments, those skilled in the art will appreciate that certain substitutions, alterations and omissions may be made to the embodiments without departing from the spirit of the invention. Accordingly, the foregoing description is meant to be exemplary only, and should not limit the scope of the invention as set forth in the following claims.
