Smith & Nephew Ex. 1010
`IPR Petition - USP 8,377,129
`
`

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`EP 0 908 836 A2
`
`Description
`
`[0001] The present invention relates to computer—aid—
`ed construction of a reference structure to be attached
`
`to a subject and act as a guide in medical procedures.
`[0002]
`In various medical procedures, it is necessary
`to attach a piece of medical equipment into a solid struc-
`ture of the subject.
`[0003]
`Typically, screws are inserted into vertebra on
`both ends of a structurally—compromised vertebrae to
`provide support while a spinal fusion is being created.
`Fractures in the spine and in other bones are also held
`together with a screw or similar implant.
`[0004]
`In the case of abnormal spinal structure, it may
`necessary to fasten a support structure to correct or
`straighten a subject's spine.
`[0005] These examples require precise insertion of a
`screw or pin into bone of the subject.
`[0006]
`Typically, these pins or screws have been in-
`serted by a surgeon who visually, or by 'feel', finds the
`approximate location where the screw or pin should be
`entered, and drills a hole at that location. The screw or
`pin is inserted into the hole.
`[0007]
`Sometimes, during surgery, two dimensional
`(2D) snapshots such as x—rays or magnetic resonance
`(MR) images may be obtained.
`[0008]
`Since these are 2D in nature, it may be difficult
`to extrapolate the image plane to the plane allowing the
`access of insertion of the screw.
`
`Since the surgeon would also like to make as
`[0009]
`small an incision as possible, manytimes the target area
`is obscured by muscle or other tissue and the surgeon
`approximates the location of the actual target point.
`[0010] Location of the target location may be further
`obscured by blood profusion in the area, further compli-
`cating identification of the target point.
`[0011] Once the approximate location is determined,
`the surgeon has little information as to the relative
`strength and thickness of the bone in the area in which
`the pin or screw is to be inserted.
`it
`[0012] Also, while applying these screws and pins,
`is possible that the surgeon punctures or severs major
`arteries, veins, or nerves which may be hidden inside
`tissue over the target structure, or lie behind the target
`structure, not visible to the surgeon.
`[0013] Currently there is a need for a device which
`may be attached to a subject and act as a reference
`structure to guide instruments during medical proce-
`dures.
`
`[0014] The present invention constructs a reference
`structure intended to be attached to a solid anchor site
`
`of a subject.
`imaging means acquires medical
`[0015] A medical
`imaging data of the subject 1
`in a region including the
`anchor site. The user may operate a user interface to
`steer the medical imaging means to the proper region.
`[0016] A segmentation device identifies a segmented
`structure being contiguous locations in the imaging data
`
`having the data values within a defined range.
`[0017] A graphic engine rendering surfaces of the
`segmented structures according to user—defined imag-
`ing parameters.
`[0018] A design device, which may be a conventional
`computer aided design (CAD) device, creates a compu-
`ter model of a reference structure having a mating sur-
`face designed to fit flush with said subject's anchor site.
`[0019]
`In an alternative embodiment ofthe present in-
`vention, an actuator device mills a surgical guide ac-
`cording to the design of the design device.
`[0020] The guide may have an attachment structure
`capable of attaching to other medical equipment. This
`equipment may then be anchored to, and use the refer-
`ence structure as a landmark, to determine locations
`and perform medical procedures.
`[0021]
`It is an object of the present invention to create
`a reference structure which physically guides surgical
`instruments.
`
`It is another object of the present invention cre-
`[0022]
`ate a more accurate means of performing surgical pro-
`cedures.
`
`[0023] The features of the invention believed to be
`novel are set forth with particularity in the appended
`claims. The invention itself, however, both as to organ-
`ization and method of operation, together with further
`objects and advantages thereof, may be best under-
`stood by reference to the following description taken in
`conjunction with the accompanying drawing in which:
`[0024]
`Figure 1
`is a simplified block diagram of one
`embodiment of the present invention in operation track-
`ing the location of a surgical device relative to a desired
`location within a subject.
`[0025]
`Figure 2 is a an illustration of the computer-
`constructed reference structure attached to an anchor
`
`site of a subject and a surgical instrument functioning
`with the reference structure.
`
`In order to properly operate a medical device
`[0026]
`on a subject, it must be stable, and located at a proper
`position and orientation, (pose). The use of a reference
`structure would be very helpful in anchoring or guiding
`the equipment. This reference structure should attach
`to a solid structure of the subject in such a manner that
`it fits without movement, and is able to direct the medical
`instrument in a precise manner.
`[0027] The present invention, as shown in Figure 1,
`operates to construct such a reference structure.
`[0028] Asubject 1 on which the procedure isto be per-
`formed,
`is imaged with a medical imaging device 11.
`Medical imaging device 11 may be a computed tomog-
`raphy (CT), magnetic resonance (MR), ultrasound, or
`positron emission tomography (PET) imaging device.
`Othertypes of medical imaging device may also be used
`which provide an image of internal organs of subject 1
`and can provide an image of tracked targets 28.
`[0029]
`A user 3, which preferably is a surgeon, oper-
`ates medical imaging device 11 through a user interface
`17 to select the proper portion of subject 1 to be viewed.
`
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`EP 0 908 836 A2
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`is
`imaging device 11
`Volumetric data from medical
`passed to and stored in memory device 13. This may
`physically be part of medical imaging device 11 or be a
`separate device.
`[0030] A segmentation device 19 interacts with the
`volumetric data stored in data storage device 13 and de-
`termines data values within a range which may interac-
`tively be defined by user 3via interface 17. These values
`are used to define a tissue type. Contiguous locations
`having the same tissue type are then determined. The
`set of all contiguous locations of the same tissue type
`are treated as a solid object or structure. This informa-
`tion may be stored in segmentation device 19 or data
`storage device 13.
`[0031] Conventional segmentation may be used,
`such as that described in US. patent 5,187,658, Febru-
`ary 16, 1993 by Cline, and Lorensen.
`[0032] User 3 interactively indicates solid structures
`of the subject 1 to be displayed using user interface 17.
`User 3 may also indicate the viewpoint, degree of trans-
`parency of different surfaces, color coding of different
`structures, and other graphic parameters used in dis-
`playing images on a monitor 23.
`[0033] Graphic engine 21 interacts with the volumetric
`data in memory device 13 to determine surfaces of a
`user—defined segmented structure which the user 3 in-
`dicates should be displayed on monitor 23. For exam-
`ple, user 3 may select a mode in which layers are
`stripped away and use a pointing device, such as a
`mouse, to indicate structures which user 3 would like
`removed from the visual display. This allows underlying
`structures to be seen. Any conventional surface render-
`ing technique and workstation may be used.
`[0034] User 3 also identifies an anchor site through
`user interface 17 interacting with graphics engine 21,
`which is a solid structure, typically bone, onto which ref-
`erence structure 30 is attached.
`
`[0035] A design device 25, which may be a computer
`aided design (CAD) device, interacts with user 3through
`user interface 17 to 'build' a reference structure 30, as
`shown in Fig. 2, having a mating surface 34, designed
`to fit flush against the surface of the solid structure at
`anchor site 6 of the subject. Design device 25 may be
`any conventional CAD device which allows input of oth-
`er models.
`
`[0036] Reference structure 30 may then be physically
`held against an anchorsite 6 bythe surgeon, or attached
`by various conventional means such as screws, pins,
`glue, clamps, etc. The reference structure 30 may then
`be used as a reference, or anchor structure for other
`surgical equipment.
`[0037]
`In one embodiment, an attachment structure
`39 functions to allow other medical equipment to attach
`to it. This equipment may then use reference structure
`30 as a landmark to determine locations relative to ref-
`
`erence structure 30. It can then act to steady and guide
`drills, probes, and other interventional devices.
`[0038]
`In an optional embodiment, user 3 also may
`
`use a pointing device of user interface 17 to select a
`position and orientation (pose) which in asurgical instru-
`ment 4O is positioned in order to correctly insert the
`screw or pin. Design device 25 or graphics engine 21
`may have a computer model of surgical instrument 40
`pre—stored, and superimpose this model upon the imag-
`es provided on monitor 23.
`[0039] User 3 may then interactively adjust the pose
`of surgical instrument 40 by viewing its computer graph-
`ic model such that the proper pose is indicated on mon-
`itor 23. This pose may be saved and incorporated as a
`guide hole.
`[0040] The final pose of surgical instrument may be
`used to construct a guide hole 31. Guide hole 31 allows
`a shaft 41 of medical equipment, such as a surgical drill
`40, to fit through snugly with little clearance, intended to
`restrain motion of the drill 40 along in all directions ex-
`cept along an axis of guide hole 31.
`[0041] Design device 25 develops a computer model
`of reference structure 30 which may be output to an ac-
`tuator system 27. Actuator system 27 mills and drills a
`biocompatible material to form reference structure 30.
`A biocompatible material are those commonly used as
`medical implants, which are not poisonous, and do not
`cause rejections or immune—response reactions. Design
`device 25 may alternatively output the design of refer-
`ence structure 30 to actuator 27 for later off—line manu-
`facture.
`
`[0042] A collar 43 may be attached to surgical instru-
`ment 40 at the intended depth to be used as a stop when
`drilling through reference structure 30. This restrains
`motion along the axis of the guide hole at a predeter-
`mined depth.
`[0043] Alternatively, reference structure 30 may be
`constructed to a height which stops surgical instrument
`40 when instrument shaft 41 is at its proper depth.
`[0044] Reference structure 30 is intended to be held
`flush against solid structure 5, however, there are times
`that it may not mate correctly with solid structure 5. In
`an alternative embodiment, probe holes 33 are drilled
`through a body 32 of reference structure 30. A depth
`probe 35 is positioned within probe holes 33. Depth
`probe 35 is pushed inward until it contacts anchor site
`6 of solid structure 5. By markings or indication on depth
`probe 35,
`it can be discerned if reference structure 30
`is positioned flush with respect to solid structure 5. This
`also allows for readjustment and proper placements of
`image guide 30.
`
`Claims
`
`A reference structure construction system, for con-
`structing reference structure (30) for aiding in an-
`choring and guiding medical equipment at an an-
`chor site (6) of a subject (1) comprising:
`
`a) a data storage device (13) capable of storing
`
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`EP 0 908 836 A2
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`equipment, passing through the body (32) at a po-
`sition and orientation to intersect the anchor site (6)
`when the mating surface (34) is flush against the
`anchor site (6).
`
`The reference structure assembly of claim 4 further
`comprising: a collar designed to attach to a portion
`of a medical equipment intended to be received by
`the guide hole, thereby restricting the depth in which
`the surgical instrument is inserted into the guide
`hole.
`
`imaging data;
`b) medical imaging means (11) coupled to the
`data storage device (11) for acquiring medical
`imaging data of said subject (1) according to
`predetermined or user—defined imaging param-
`eters of a region including said anchor site (6)
`and for storing the data in the data storage de-
`vice (13);
`c) a segmentation device (19) coupled to the
`data storage device (13) for identifying contig-
`uous locations in the imaging data having the
`data values within a predetermined or user—de—
`fined range indicating the same tissue type, be-
`ing a segmented structure and for identifying
`surfaces between tissue types;
`d) a graphic engine (21) coupled to the data
`storage device (13) for rendering surfaces of
`the segmented structures according to prede-
`termined or user—defined imaging parameters;
`e) a design device (25) coupled to the data stor-
`age device (13) for creating a computer model
`according to predetermined or user—defined pa-
`rameters of a surgical guide (30) having a mat-
`ing surface (34) designed to fit flush with said
`subject's anchor site (6).
`
`The reference structure construction system recited
`in claim 1, further comprising:
`a user interface (17) coupled to the medical
`imaging means (11), the segmentation device (19),
`and the design device (25) for providing user—de-
`fined parameters to these elements.
`
`The reference structure construction system recited
`in claim 1, further comprising:
`an actuator device (27) coupled to design de-
`vice (25) for milling a surgical guide according tothe
`computer model constructed by the design device
`(25).
`
`A reference structure assembly for anchoring and
`guiding medical equipment at an anchor site (6) of
`a subject 1 comprising:
`
`a) a body (32) having a mating surface (34) ca-
`pable offitting flush against said anchorsite (6);
`b) at least one probe hole (33) passing through
`the body (32) intersecting the anchor site (6);
`c) at least one elongated probe (35) passing
`through the probe hole (31), and resting on the
`anchor site (6), having markings (37) measur-
`ing the depth of which the probe (35) fits into
`the body (30), indicating a separation between
`the anchor site (6) and the mating surface (34).
`
`5. The reference structure assembly of claim 4 further
`comprising: at least one guide hole (31)through the
`body (32) for receiving a portion of the medical
`
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`EP 0 908 836 A2