Surgery – Instruments – Stereotaxic device
Reexamination Certificate
2000-04-06
2001-10-23
Philogene, Pedro (Department: 3732)
Surgery
Instruments
Stereotaxic device
C600S417000, C600S429000
Reexamination Certificate
active
06306146
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to neurosurgical apparatus generally, and more particularly, to an improved surgical instrument support.
BACKGROUND OF THE INVENTION
It is known to define and correlate the position of single or multiple points within the cranium with preoperative imaging by using frameless stereotactic systems such as the MAYFIELD/ACCISS Stereotactic Workstation which is commercially available from the assignee of this application. Frameless systems provide constant intraoperative navigational information, which permits a surgeon to identify precisely the spacial position of a probe in the surgical field with CT or MRI scan data shown on a high definition display monitor.
With a frameless stereotactic system, an intracranial target point is accessed by advancing a probe along a predetermined linear path or trajectory to the target point within the patient's skull. To provide the necessary stabilization of tooling during its advance along the linear trajectory, a surgical instrument support is used. The surgical instrument support is comprised of an articulated arm having a proximal end mounted on a patient support or other fixed structure and a lockable tool socket rotatably mounted on a distal end of the arm. The surgical instrument support allows a surgical instrument to be moved to the intracranial target point along a stable and fixed linear trajectory. By fixing the trajectory on the intracranial target point, the risk of misdirection or drift associated with freehand procedures is eliminated.
One example of a known surgical instrument support is the “EASYGUIDE” navigator system commercially available from Phillips Medical Systems N.A. Inc. of Shelton, Connecticut. Another example of a surgical instrument support is commercially available from the assignee of the present invention. Other examples of known surgical instrument supports are shown in U.S. Pat. Nos. 5,695,501 and 5,810,712, which are assigned to the assignee of this invention and hereby expressly incorporated by reference herein. All of these devices include a lockable ball rotatably mounted in a tool holder on the end of an articulated arm as described above. The ball has a diametric hole that receives an instrument. In a known manner, a known locating probe is inserted into the ball with the tip of the probe normally being positioned substantially at the center of the ball. The probe presents a linear image on a display monitor that is also displaying CT or MRI scan data of the patient. Thus, as the probe is moved, a path between the tip of the probe and a selected target point displayed with the scan data can be tracked. By moving the distal end of the articulated arm, the probe and ball are first located at a desired position with respect to the skull that defines a desired trajectory between the tip of the probe and the target point. The articulated arm is then locked, thereby locking the ball at the desired position. Next, the probe and ball are rotated to align a centerline of the hole in the ball with the desired trajectory, so that an instrument inserted through the hole in the ball follows the desired trajectory and intersects the target point. The ball is then locked in place, so that it cannot rotate with respect to the tool holder on the distal end of the articulated arm; and hence the orientation of the probe or other tool within the ball is fixed with respect to the target point. With the ball thus aligned, the probe is removed and other surgical instruments inserted into the ball are automatically aligned with the intracranial target point.
While these prior art devices have proved suitable for their intended purposes, they all have one particular disadvantage. In the above described process, after the surgeon has established the desired trajectory by locking the articulated arm and ball in place, the articulated arm and ball can interfere with procedures that are being conducted within the surgical field that do not require the presence of the articulated arm and ball. Thus, it is often desirable and sometimes necessary to move the articulated arm and ball from the surgical field. With known devices, any attempt to move the articulated arm and ball results in a loss of the desired trajectory that had been previously determined, thus requiring that the surgeon repeat the alignment process by which the desired trajectory was originally determined.
Therefore, there is a need for an improved surgical instrument support that can be moved from the surgical field and subsequently returned to its initial position without losing a previously established desired trajectory with respect to an intracranial target point.
SUMMARY OF INVENTION
The present invention provides an improved surgical instrument support that offers more flexibility than known instrument holders. The surgical instrument support of the present invention permits difficult surgical procedures to be performed in less time and with less stress, that is, more efficiently, and without any loss in accuracy or precision. The surgical instrument support of the present invention has the advantage of being able to automatically re-establish a desired alignment of the instrument support after it has been removed from its fixed mount. The invention is especially useful in those situations where after aligning the instrument support with a patient, it is necessary to perform procedures in the surgical field that do not require the surgical instrument support. With the surgical instrument support of the present invention, once its desired position and orientation are precisely aligned with the patient, it can be removed from the surgical field and then, upon being placed back into its mount, the desired position and orientation are automatically re-established without repeating the original alignment process.
In accordance with the principles of the present invention and the described embodiments, a surgical instrument support is provided having an articulated arm with a first structure on a proximal end of the arm. A lockable target ball is rotatably mounted on a distal end of the articulated arm. The lockable ball has a diametric hole therein for receiving and supporting a surgical instrument. A mount has a second structure that receives and secures the proximal end of the articulated arm. The first structure on the articulated arm cooperates with the second structure on the mount to automatically align the proximal end of the articulated arm with the mount in a repeatable relationship. The mount is adapted to be releasably attached to a fixed structure.
In one aspect of the invention, the proximal end of the articulated arm has a cross-sectional profile, and the mount has a hole with a cross-sectional profile that receives the proximal end of the articulated arm in a repeatable relationship. The mount further has a clamp for securing the proximal end of the articulated arm in the hole in the mount. In a further aspect of the invention, the cross-sectional profiles of the first and second structures are noncircular profiles. Thus, the surgical instrument support of the present invention permits removal and remounting of the articulated arm without losing the desired position and orientation of the lockable target ball with respect to a patient.
In another embodiment, the present invention includes a method of performing a surgical procedure that includes first moving a distal end of an articulated arm having a target ball rotatably mounted therein to a desired position. The joints of the articulated arm are locked to maintain the target ball at the desired position. Next, the target ball is rotated to a desired orientation, and the target ball is locked at the desired orientation. The proximal end of the articulated arm is then unclamped from a mount attached to a fixed structure. The proximal end of the articulated arm has a desired relationship with respect to the mount, and the proximal end of the articulated arm is removed from the mount. The articulated arm is then inserted into the mount such that first s
Ohio Medical Instrument Company, Inc.
Philogene Pedro
Wood Herron & Evans L.L.P.
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