12 yr. fee paid 9/9/10
`
`United States Patent [19]
`DiGioia III et al.
`
`[54] APPARATUS AND METHOD FOR
`FACILITATING THE IMPLANTATION OF
`ARTIFICIAL COMPONENTS IN JOINTS
`
`[75]
`
`Inventors: Anthony M. DiGioia DI, Pittsburgh,
`Pa.; David A. Simon, Boulder, Colo.;
`Branislav Jaramaz; Michael K.
`Blackwell, both of Pittsburgh, Pa.;
`Frederick M. Morgan, Quincy; Robert
`V. O'Toole, Brookline, both of Mass.;
`Taken Kanade, Pittsburgh, Pa.
`[73] Assignee: Carnegie Mellon University,
`Pittsburgh, Pa.
`
`[21] Appl. No.: 803,993
`Feb. 21, 1997
`[22] Filed:
`Int. Cl.°
`
`[51]
`
`A61F 2/32; A61F 2/34;
`A61F 2/36
`364/578; 623/22
`364/578; 606/86,
`606/89, 90, 91; 623/11, 22, 23
`
`[52] U.S. Cl.
`[58] Field of Search
`
`[56]
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`7/1982 Perry
`4,341,220
`2/1990 Crawford
`4,905,148
`4/1991 Woolson
`5,007,936
`2/1992 Glassman et al.
`5,086,401
`9/1993 Skeens et al.
`5,242,455
`5,251,127 10/1993 Raab
`3/1994 Glassman et al.
`5,299,288
`4/1994 Raab
`5,305,203
`1/1995 Bucholz
`5,383,454
`2/1995 Heilbmn et al.
`5,389,101
`4/1995 Glassman et al.
`5,408,409
`5/1996 Kailas et al.
`5,517,990
`
`128/630
`364/413.1
`623/23
`395/94
`606/130
`364/413.13
`395/80
`364/413.13
`128/653.1
`606/130
`364/413.13
`128/653.1
`
`OTHER PUBLICATIONS
`A. M. DiGioia, M.D., D. A. Simon, B. Jaramaz, M. Black-
`well, E Morgan, R. V. O'Toole, B. Colgan, E. Kischell,
`HipNav: Pre -operative Planning and Intra -operative Navi-
`
`IIIII IIIIIIII III IIIII IIIII UI UUU6I A IIII IIIII IIIIII III IIIII IIII
`[il] Patent Number:
`[45] Date of Patent:
`
`5,880,976
`Mar. 9, 1999
`
`
`
`gational Guidance for Acetabular Implant Placement in
`Total Hip Replacement Surgery, Proceeding of Computer
`Assisted Orthopedic Surgery, Bem, Switzerland (1996).
`Robert J. Krushell, M.D., Denis W. Burke, M.D. and Wil-
`liam H. Harris, M.D., Range of Motion in Contemporary
`Total Hip Arthroplasty, pp. 97 -101, The Journal of Arthro-
`plasty, vol. 6, No. 2, Jun. 1991.
`Robert J. Krushell, M.D., Dennis w. Burke, M.D. and
`William H. Harris, M.D. , Elevated -rim Acetabular Com-
`ponents, pp. 1-6, The Journal of Arthroplasty, vol. 6, Oct.
`1991.
`
`(List continued on next page.)
`Primary Examiner Vincent N. Trans
`Assistant Examiner- Russell W. Frejd
`Attorney, Agent, or Firm-Kirkpatrick & Lockhart LLP
`ABSTRACT
`
`[57]
`Apparatuses and methods are disclosed for determining an
`implant position for at least one artificial component in a
`joint and facilitating the implantation thereof. The appara-
`tuses and methods include creating a joint model of a
`patient's joint into which an artificial component is to be
`implanted and creating a component model of the artificial
`component. The joint and artificial component models are
`used to simulate movement in the patient's joint with the
`artificial component in a test position. The component model
`and the joint model are used to calculate a range of motion
`in the joint for at least one test position based on the
`simulated motion. An implant position, including angular
`orientation, in the patient's joint is determined based on a
`predetermined range of motion and the calculated range of
`motion. In a preferred embodiment, the implant position can
`be identified in the joint model and the joint model aligned
`with the joint by registering positional data from discrete
`points on the joint with the joint model. Such registration
`also allows for tracking of the joint during surgical proce-
`dures. A current preferred application of the invention is for
`determining the implant position and sizing of an acetabular
`cup and femoral implant for use in total hip replacement
`surgery.
`
`24 Claims, 11 Drawing Sheets
`
`Mako Exhibit 1016 Page 1
`
`

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`Mako Exhibit 1016 Page 2
`
`

`
`U.S. Patent
`
`Mar. 9, 1999
`
`Sheet 1 of 11
`
`5,880,976
`
`13
`
`Skeletal
`Data
`Source
`
`10
`
`12
`
`16
`
`Intra -Operative
`Navigational
`Software
`
`14
`
`f 30
`
`Tracking
`Device
`
`Pre -Operative
`Geometric
`Planner
`
`Pre -Opera ive
`Kinematic
`Biomechanical
`Simulator
`
`20
`
`FIG. 1
`
`Mako Exhibit 1016 Page 3
`
`

`
`U.S. Patent
`
`Mar. 9, 1999
`
`Sheet 2 of 11
`
`5,880,976
`
`40
`
`Obtain Skeletal Structure Geometric Data Of
`A Joint In A Patient
`
`T
`
`Create Computational Models Of The Skeletal
`Structure Using The Skeletal Geometric Data And
`Computational Models Of The Implant Components
`
`50-L
`
`1
`Perform Biomechanical Simulations Of The Movement
`Of The Joint At Test Positions Using The Models
`
`Claculate A Range Of Motion Of The
`Joint Based On The Simulated Movement
`
`6
`
`4
`
`_/-
`
`42
`
`44
`
`Determine An Implant Position For The Implant
`Components Based On The Calculated Range Of Motion
`
`Identify The Implant Position In The Joint Model
`
`48
`
`52
`
`60
`
`Align The Models Of The Skeletal
`Structure With The Patient's Joint
`
`1
`Track The Position Of The Patient's
`Joint, And The Implant Components
`Using The Aligned Models.
`
`ç54
`
`56
`
`FIG. 2
`
`Mako Exhibit 1016 Page 4
`
`

`
`U.S. Patent
`
`Mar. 9,1999
`
`Sheet 3 of 11
`
`5,880,976
`
`32
`
`O\\\.Q\\\\\\-
`
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`
`
`
`Mako Exhibit 1016 Page 5
`
`

`
`U.S. Patent
`
`Mar. 9, 1999
`o rn
`
`Sheet 4 of 11
`
`5,880,976
`
`U d'
`
`o
`
`N-
`
`Mako Exhibit 1016 Page 6
`
`

`
`FIG: 5c
`
`FIG. 5b
`
`FIG. 5a
`
`92
`
`86
`
`Mako Exhibit 1016 Page 7
`
`

`
`U.S. Patent
`
`Mar. 9, 1999
`
`Sheet 6 of 11
`
`5,880,976
`
`Mako Exhibit 1016 Page 8
`
`

`
`U.S. Patent
`
`Mar. 9, 1999
`
`Sheet 7 of 11
`
`5,880,976
`
`Q)
`
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`LL
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`
`Mako Exhibit 1016 Page 9
`
`

`
`U.S. Patent
`
`Mar. 9, 1999
`
`Sheet 8 of 11
`
`5,880,976
`
`
`
`co
`P
`ii
`
`FIG. 8
`
`Mako Exhibit 1016 Page 10
`
`

`
`U.S. Patent
`
`Mar. 9, 1999
`
`Sheet 9 of 11
`
`5,880,976
`
`FIG. 9b
`
`FIG. 9a
`
`FIG.9b
`
`FIG.921
`
`Mako Exhibit 1016 Page 11
`
`

`
`U.S. Patent
`
`Mar. 9, 1999
`
`Sheet 10 of 11
`
`5,880,976
`
`FIG. 10a
`
`FIG.10a
`
`Mako Exhibit 1016 Page 12
`
`

`
`w999
`1
`t, ,
`
`U.S. Patent
`
`Mar. 9,1999
`
`Sheet 11 of 11
`
`5,880,976
`
`FIG. 10b
`
`Mako Exhibit 1016 Page 13
`
`

`
`5,880,976
`
`1
`APPARATUS AND METHOD FOR
`FACILITATING THE [MPLANTATION OF
`ARTIFICIAL COMPONENTS IN JOINTS
`
`STATEMENT REGARDING FEDERALLY
`SPONSORED RESEARCH OR DEVELOPMENT
`
`This work was supported in part by a National Challenge
`grant from the National Science Foundation Award IRI
`9422734.
`
`CROSS-REFERENCE TO RELATED
`APPLICATIONS
`
`Not Applicable
`
`BACKGROUND OF THE INVENTION
`
`The present invention is directed generally to the implan-
`tation of artificial joint components and, more particularly,
`to computer assisted surgical
`implantation of artificial
`acetabular and femoral components during total hip replace-
`ment and revision procedures.
`Total hip replacement (THR) or arthroplasty (THA)
`operations have been performed since the early 1960s to
`repair the acelabulum and_the region surrounding it and to
`replace the hip components, such as the femoral head, that
`have degenerated. Ctlrrently, approximately 200,000 THR
`operations are performed annually in the United States
`alone, of which approximately 40,000 are redo procedures,
`otherwise known as revisions. The revisions become nec-
`
`essary due to a number of problems that may arise during the
`lifetime of the implanted components, such as dislocation,
`component wear and degradation, and loosening of the
`implant from the bone.
`Dislocation of the femoral head from the acetabular
`component, or cup, is considered one of the most frequent
`early problems associated with THR, because of the sudden
`physical, and emotional, hardship brought on by the dislo-
`cation. The incidence of dislocation following the primary
`THR surgery is approximately 2-6% and the percentage is
`even higher for revisions. While dislocations can result from
`a variety of causes, such as soft tissue laxity and loosening
`of the implant, the most common cause is impingement of
`the femoral neck with either the rim of an acetabular cup
`implant, or the soft tissue or bone surrounding the implant.
`Impingement most frequently occurs as a result of the
`malposition of the acetabular cup component within the
`pelvis.
`Some clinicians and researchers have found incidence of
`impingement and dislocations can be lessened if the cup is
`oriented specifically to provide for approximately 15° of
`anteversion and 45° of abduction; however, this incidence is
`also related to the surgical approach. For example, McCo-
`llurn et al. cited a comparison of THAs reported in the
`orthopaedic literature that revealed a much higher incidence
`of dislocation in patients who had THAs with a posterolat-
`eral approach. McCollum, D. E. and W. J. Gray, “Disloca-
`tion after total hip arthroplasty (causes and prevention)”,
`Clinical Orthopaedics and Related Research, Vol. 261,
`p.159—170 (1990). McCollum’s data showed that when the
`patient is placed in the lateral position for a posterolateral
`TI-IAapproach, the lumbar lordotic curve is flattened and the
`pelvis may be flexed as much as 35°. If the cup was oriented
`at 15°—20° of fiexion with respect to the longitudinal axis of
`the body, when the patient stood up and the postoperative
`lumbar lordosis was regained, the cup could be retroverted
`as much as 10°—15° resulting in an unstable cup placement.
`
`2
`Lewinnek et al. performed a study taking into account the
`surgical approach utilized and found that the cases falling in
`the zone of 15°:l0° of anteversion and 4-0°:10° of abduc-
`tion have an instability rate of 1.5%, compared with a 6%
`instability rate for the cases falling outside this zone. Lewin-
`nek G. E., et al., “Dislocation after total hip-replacement
`arthroplasties”, Journal of Bone and Joint Surgery, Vol.
`60-A, No.2, p, 217-220 (March 1978). The Lewinnek work
`essentially verifies that dislocations can be correlated with
`the extent of malpositioning, as would be expected. The
`study does not address other variables, such as implant
`design and the anatomy of the individual, both of which are
`known to greatly affect the performance of the implant.
`The design of the implant significantly atfects stability as
`well. A number of researchers have found that the head-to-
`neek ratio of the femoral component is the key factor of the
`implant impingement, see Amstutz H. C., et al., “Range of
`Motion Studies for Total Hip Replacements", Clinical
`Orthopaedics and Related Research Vol. 111, p. 124-130
`(September 1975). Krushell et al. additionally found that
`certain long and extra long neck designs of modular
`implants can have an adverse effect on the range of motion.
`Krushell, R. J., Burke D. W., and Hanis W. H., “Range of
`motion in contemporary total hip arthroplasty (the impact of
`modular head-neck components)”, The Journal of
`Arthroplasty, Vol. 6, p. 97-101 (February 1991). Krushell ct
`al. also found that an optimally oriented elevated-rim liner
`in an acetabular cup implant may improve the joint stability
`with respect to implant impingement. Krushell, R. J., Burke
`D. W., and Harris W. H., “Elevated-rim acetabular compo-
`nents: Etfect on range of motion and stability in total hip
`arthroplasty”, The Journal of Arthroplasty, Vol. 6
`Supplement, p. 1-6, (October 1991). Cobb et al. have shown
`a statistically significant reduction of dislocations in the case
`of elevated—rim liners, compared to standard liners. Cobb T.
`K., Morrey B. F., Ilstrup D. M., “The elevated-rim acetabu-
`lar tiner in total hip arthroplasty: Relationship to postopera-
`tive dislocation", Journal of Bone and Joint Surgery, .Vol
`78-A, No. 1, p. 80-86, (January 1996). The two-year prob-
`ability of dislocation was 2.19% for the elevated liner,
`compared with 3.85% for standard liner. Initial studies by
`Maxian et al. using a finite element model indicate that the
`contact stresses and therefore the polyethylene wear are not
`significantly increased for elevated rim liners; however,
`points of impingement and subsequent angles of dislocation
`for dill'erent liner designs are dilferent as would be expected.
`Maxian T. A., et al. “Femoral head containment in total hip
`arthroplasty: Standard vs. extended Lip liners", 42nd Annual
`meeting, Orthopaedic Research society, p. 420, Atlanta, Ga.
`(Feb. 19-22, 1996); and Maxian T. A., et al. “Finite element
`modeling of dislocation propensity in total hip arthroplasty”,
`42nd Annual meeting, Orthopaedic Research society, p.
`259-64, Atlanta, Ga. (Feb. 19-22, 1996).
`An equally important concern in evaluating the disloca-
`tion propensity of an implant are variations in individual
`anatomies. As a result of anatomical variations, there is no
`single optimal design and orientation of hip replacement
`components and surgical procedure to minimize the dislo-
`cation propensity of the implant. For example, the pelvis can
`assume different positions and orientations depending or
`whether an individual is lying supine (as during a CT-scan
`or routine X-rays), in the lateral decubitis position (as during
`surgery) or in critical positions during activities of normal
`daily living (like bending over to tie shoes or during normal
`gait). The relative position of the pelvis and leg when
`defining a “neutral” plane from which the angles of
`movement, anteversion, abduction, elc., are calculated will
`
`5
`
`I0
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`Mako Exhibit 1016 Page 14
`
`

`
`5,880,976
`
`3
`significantly influence the measured amount of motion per-
`mitted before impingement and dislocation occurs.
`Therefore, it is necessary to uniquely define both the neutral
`orientation of the femur relative to the pelvis for relevant
`positions and activities, and the relations between the femur
`with respect to the pelvis of the patient during each segment
`of leg motion.
`Currently, most planning for acetabular implant place-
`ment and size selection is performed using acetate templates
`and a single anterior-posterior x-ray of the pelvis. Acctabular
`templating is most useful for determining the approximate
`size of the acetabular component; however, it is only of
`limited utility for positioning of the implant because the
`x-rays provide only a two dimensional image of tl1e pelvis.
`Also, the variations in pelvic orientation can not be more
`fully considered as discussed above.
`Intra-operative positioning devices currently used by sur-
`geons attempt
`to align the acetabular component with
`respect to the sagittai and coronal planes of the patient. B. F.
`Morrey, editor, “Reconstructive Surgery of the Joints”,
`chapter Joint Replacement Arthroplasty, pages 605-608,
`Churchill Livingston, 1996. These devices assume that the
`patient’s pelvis and trunk are aligned in a known orientation,
`and do not
`take into account
`individual variations in a
`patient’s anatomy or pelvic position on the operating room
`table. These types of positioners can lead to a wide discrep-
`ancy between the desired and actual implant placement,
`possibly resulting in reduced range of motion, impingement
`and subsequent dislocation.
`Several attempts have been made to more precisely pre-
`pare the acetabular region for the implant components. U.S.
`Pat. No. 5,007,936 issued to Woolson is directed to estab-
`lishing a reference plane through which the acetabulum can
`be reamed and generally prepared to receive the acetabular
`cup implant. The method provides for establishing the
`reference plane based on selecting three reference points,
`preferably the 12 o’clock position on the superior rim of the
`acetabulum and two other reference points, such as a point
`in the posterior rim and the inner wall, that are a known
`distance from the superior rim. The location of the superior
`rim is determined by performing a series of computed
`tomography (CT) scans that are concentrated near the supe-
`rior rim and other reference locations in the acetabular
`region.
`In the Woolson method, calculations are then performed
`to determine a plane in which the rim of the acetabular cup
`should be positioned to allow for a predetermined rotation of
`the femoral head in the cup. The distances between the
`points and the plane are calculated and an orientation jig is
`calibrated to define the plane when thejig is mounted on the
`reference points. During the surgical procedure, the surgeon
`must identify the 12 o’clocl< orientation of the superior rim
`and the reference points. .In the preferred mode, the jig is
`fixed to the acetabulum by drilling a hole through the
`reference point on the inner wall of the acetahulum and
`afiixing the jig to the acetabulum. The jig incorporates a drill
`guide to provide for reaming of the acetabulum in the
`selected plane.
`A number of ditficulties exist with the Woolson method.
`For example, the preferred method requires drilling a hole in
`the acetabulum. Also, visual recognition of the reference
`points must be required and precision placement on the jig
`on reference points is performed in a surgical setting. In
`addition, proper alignment of the reaming device does not
`ensure that the implant will be properly positioned, thereby
`establishing a more lengthy and costly procedure with no
`
`5
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`45
`
`50
`
`55
`
`60
`
`65
`
`4
`guarantees of better results. These problems may be a reason
`why the Woolson method has not gained widespread accep-
`tance in the medical community.
`In U.S. Pat. Nos. 5,251,127 and 5,305,203 issued to Raah,
`a computer-aided surgery apparatus is disclosed in which a
`reference jig is attached to a double self indexing screw,
`previously attached to the patient, to provide for a more
`consistent alignment of the cutting instruments similar to
`that of Woolson. However, unlike Woolson, Raab et al.
`employ a digitizer and a computer to determine and relate
`the orientation of the reference jig and the patient during
`surgery with the skeletal shapes determined by tomography.
`Similarly, U.S. Pat. Nos. 5,086,401, 5,299,288 and 5,408,
`409 issued to Glassman et al. disclose an image directed
`surgical robotic system for reaming a human femur to accept
`a femoral stem and head implant using a robot cutter system.
`In the system, at least three locating pins are inserted in the
`femur and CTscans of the femur in the region containing the
`locating pins are performed. During the implanting
`procedure, the locating pins are identified on the patient, as
`discussed in col. 9, lines 19-68 of Glassman’s ’401 patent.
`The location of the pins during the surgery are used by a
`computer to transform CT scan coordinates into the robot
`cutter coordinates, which are used to guide the robot cutter
`during reaming operations.
`While the Woolson, Raab and Glassman patents provide
`methods and apparatuses that further offer the potential for
`increased accuracy and consistency in the preparation of the
`acetabular region to receive implant components,
`there
`remain a number of difficulties with the procedures. A
`significant shortcoming of the methods and apparatuses is
`that when used for implanting components in a joint there
`are underlying assumptions that the proper position for the
`placement of the components in the joints has been deter-
`mined and provided as input to the methods and apparatuses
`that are used to prepare the site. As such, the utility and
`benefit of the methods and apparatuses are based upon the
`correctness and quality of the implant position provided as
`input to the methods.
`In addition, both the Raab and Glassman methods and
`apparatuses require that fiducial markers be attached to the
`patient prior to performing tomography of the patients.
`Following the tomography, the markers must either remain
`attached to the patient until the surgical procedure is per-
`formed or the markers must he reattached at the precise
`locations to allow the transformation of the tomographic
`data to the robotic coordinate system, either of which is
`undesirable and/or diflicult in practice.
`Thus, the need exists for apparatuses and methods which
`overcome, among others, the above-discussed problems so
`as to provide for the proper placement and implantation of
`the joint components to provide an improved range of
`motion and usage of the joint following joint reconstruction,
`replacement and revision surgery.
`BRIEF SUMMARY OF THE INVENTION
`
`The above objectives and others are accomplished by
`methods and apparatuses in accordance with the present
`invention. The apparatuses and methods include creating a
`joint model of a patient’s joint into which an artificial
`component is to be implanted and creating a component
`model of the artificial component. The joint and artificial
`component models are used to simulate movement of the
`patient’s joint with the artificial component in a test position.
`The component model and the joint model are used to
`calculate a range of motion of the joint for at least one test
`
`Mako Exhibit 1016 Page 15
`
`

`
`pre-determined ROM is described in Col. 5 In. 1-16
`
`5,880,976
`
`5
`position based on the simulated movement. An implant
`position,
`including angular orientation,
`for the artificial
`component is determined based on a predetermined range of
`motion and the calculated range of motion. A goal of the
`simulation process is to find the implant position which
`optimizes the calculated range of motion using the prede-
`termined range of motion as a basis for optimization. In
`practice, the predetermined range of motion is determined
`based on desired functional motions selected by a medical
`practitioner on a patient specific basis (c.g. sitting requires
`fiexion of 90°). In a preferred embodiment,
`the implant
`position can be identified in the joint model. During surgery
`the joint model can be aligned with the joint by registering
`positional data from discrete points on the joint with the joint
`model. Such registration also aliows for tracking of the joint
`during the surgical procedures.
`A current preferred application of the invention is for
`determining the implant position and sizing of an acetabular
`cup and femoral implant for use in total hip replacement
`surgery. Also in a preferred embodiment, alignment of the
`joint model with the patient’s joint
`is performed using
`surface based registration techniques. The tracking of the
`pelvis,
`the acetabular cup, femoral
`implant, and surgical
`instrument is preferably performed using an emitter/detector
`optical tracking system.
`The present invention provides the medical practitioner a
`tool to precisely determine an optimal size and position of
`artificial components in a joint to provide a desired range of
`motion of the joint following surggry and to substantially
`lessen the possibility of subsequent dislocation.
`Accordingly,
`the present
`invention provides an elIective
`solution to problems heretofore encountered with precisely
`determining the proper sizing and placement of an artificial
`component
`to be implanted in a joint. In addition,
`the
`practitioner is afiorded a less invasive method for executing
`the surgical procedure in accordance with the present inven-
`tion. These advantages and others will become apparent
`from the following detailed description.
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`A preferred embodiment of the invention will now be
`described, by way of example only, with reference to the
`accompanying figures wherein like members bear like ref-
`erence numerals and wherein:
`
`FIG. 1 is a system overview of a preferred embodiment of
`the present invention;
`FIG. 2 is a flow chart illustrating the method of the present
`invention;
`FIG. 3 is a schematic layout of the apparatus of the present
`invention being used in a hip replacement procedure;
`FIGS. 4((I—c) show the creation of the pelvic model using
`two dimensional scans of the pelvis ((1), from which skeietal
`geometric data is extracted as shown in (b) and used to
`create the pelvic model (c);
`FIGS. 5(a—c) show the creation of the femur model using
`two dimensional scans of the femur (a), from which skeletal
`geometric data is extracted as shown in (b) and used to
`create the femur model (c);
`FIG. 6 shows the sizing of the acctabular cup in the pelvic
`model;
`FIGS. 7(n—e) show the creation of different sized femoral
`implant models (:1) and the fitting of the femoral implant
`model into a cut femur (b—e);
`FIG. 8 is a schematic drawing showing the range of
`motion of a femoral shaft and the impingement (in dotted
`lines) of a femoral shaft on an acetabular cup;
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`ab
`
`65
`
`6
`FIGS. 9(a—b) shows the range of motion results from
`biomcchanical simulation of two respective acetabular cup
`orientations; and
`FIGS. 10 (a) and (b) show the registration of the pelvis
`and femur.
`
`DETAILED DESCRIPTION OF THE
`INVENTION
`
`invention will be
`The apparatus 10 of the present
`described generally with reference to the drawings for the
`purpose of illustrating the present preferred embodiments of
`the invention only and not for purposes of limiting the same.
`A system overview is provided in FIG. 1 and general
`description of the method of the present invention is pre-
`sented in flow chart form in FIG. 2. The apparatus 10
`includes a geometric pre-operative planner 12 that is used to
`create geometric models of the joint and the components to
`be implanted based on geometric data received from a
`skeletal structure data source 13. The pre-operative planner
`12 is interfaced with a pre-operative kinematic biomechani-
`cal simulator 14 that simulates movement of the joint using
`the geometric models for use in determining implant
`positions, including angular orientations, for the compo-
`nents. The implant positions are used in conjunction with the
`geometric models in intra-operative navigational software
`16 to guide a medical practitioner in the placement of the
`implant components at the implant positions.
`The pre-operative geometric planner 12, the pre-operative
`kinematic biornechanical simulator 14 and the intra-
`operative navigational software are implemented using a
`computer System 20 having at least one display monitor 22,
`as shown in FIG. 3. For example, applicants have found that
`a Silicon Graphics 02 workstation (Mountain View, Calif.)
`can be suitably employed as the computer system 20;
`however, the choice of computer system 20 will necessarily
`depend upon the resolution and calculational detail sought in
`practice. During the prc-operative stages of the method, the
`display monitor 22 is used for viewing and interactively
`creating andlor generating models in the pre-operative plan-
`ner 12 and displaying the results of the biomechanical
`simulator 14. The pre-operative stages of the method may be
`carried out on a computer (not shovm) remote from the
`surgical theater.
`the
`During the intra-operative stages of the method,
`computer system 20 is used to display the relative locations
`of the objects being tracked with a tracking device 30. The
`medical practitioner preferably can control the operation of
`the computer system 20 during the procedure, such as
`through the use of a foot pedal controller 24 connected to the
`computer system 20. ‘The tracking device 30 can employ any
`type of tracking method as may be known in the art, for
`example, emitter/detector systems including optic, acoustic
`or other wave forms, shape based recognition track.ing
`algorithms, or video-based, mechanical, electro-magnetic
`and radio frequency (RF) systems.
`In a preferred
`embodiment, schematically shown in FIG. 3, the tracking
`device 30 is an optical tracking system that includes at least
`one camera 32 that is attached to the computer system 20
`and positioned to detect light emitted from a number of
`special light emitting diodes, or targets 34. The targets 34
`can be attached to bones, tools, and other objects in the
`operating room equipment to provide precision tracking of
`the objects. One such device that has been found to be
`suitable for performing the tracking function is the
`Optotrakm 3020 system from Northern Digital Inc.,
`Ontario, Canada, which is advertised as capable of achieving
`
`Mako Exhibit 1016 Page 16
`
`

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`Mako Exhibit 1016 Page 17
`
`

`
`5,880,976
`
`9
`including orientation, of the joint, as discussed
`position,
`above in the Simon et al. references. The goal of the
`registration process is to determine a “registration transfor-
`mation” which best aligns the discrete points that provide
`the spatial position and orientation ofthe joint with the joint
`models. Preferably, an initial estimate of this transformation
`is first detennined using manually specified anatomical
`landmarks to perform corresponding point
`registration.
`Once this initial estimate is determined, the surface-based
`registration algorithm uses the pre- and intra-operative data
`to refine the initial transformation estimate.
`Alternatively, step 54 can be implemented using registra-
`tion systems that employ fiducial markers,
`to align the
`pre-operative data with the intra-operative position of the
`patient’s joint. In those methods, the fiducial markers must
`be surgically implanted into the skeletal structure before
`prc-operative images are acquired in step 40. The intr