ttlllllllllllllltIlllllItIlItllllltlltIIlttlltl|||||llllllItIlltIlItllllIIl
`
`U8005871018A
`
`[19]
`United States Patent,
`
`Delp et al.
`[45] Date of Patent:
`Feb. 16, 1999
`
`[11] Patent Number:
`
`5,871,018
`
`[54] COMPUTER-ASSISTED SURGICAL
`METHOD
`
`5,305,203
`5,383,454
`
`4/1994 Raab -
`1/1995 Bucholz .
`
`[76]
`
`Inventors: Scott L. Dell), 2728 Woodbine; J.
`P91911408“, 3233 Ham-.50.” St" both 0f
`Evanston, 111‘ 602017 C1 alg-B.
`ROIEmSO“? 3307 N K611111016 Ave, Apt.
`Gar en—Front, Chicago; Ill. 60,6577
`Arthur Y' Wong, 826/2 Washington St"
`#211, Evanston, Ill. 60202; S. Davld
`gtlfigeggkfpiobgfioake Shore Dr.,
`g ’
`‘
`
`[21] Appl. NO': 870,218
`[22]
`Filed:
`Jun. 6, 1997
`
`Related US. Application Data
`
`[62] Division of Ser. No. 578,497, Dec. 26, 1995, Pat. No.
`5,682,886.
`Int. 01.6 ..................................................... A61B 19/00
`[51]
`128/898; 128/922
`[52] U:S. Cl.
`...............
`
`[58]
`Field Of 5931911
`128/898, 920,
`128/922; 600/407, 300: 425: 427; 606/97:
`99, 53, 60, 79, 96; 623/16, 20, 18, 22,
`27, 36, 39, 66; 382/131~132, 108, 190,
`195’ 153’ 285’ 287’ nggg/ggi’ 1%? 119/210;
`’
`’
`‘
`’
`
`[56]
`
`References Cited
`US. PATENT DOCUMENTS
`
`OTHER PUBLICATIONS
`Lea, 1T. M1115, A., Peshkin, M.A., Watkins, D., Kienzle 111,
`T.C., & Stulberg, 8.1)., “Registration and Immobilization for
`Robot—Assisted Orthopaedic Surgery,” Proceedings of the
`First International Symposium on Medical Robotics and
`Computer Assited Surgery, MRCAS, vol. 1., Sessions I—III,
`pp 63—68 (1994).
`Fada, M., Wang, T., Marcacci, M., Martelli, S., Dario, P.,
`Marcenaro, G. Nanetti, M., Paggetti, C., Visani, A., &
`Zaffagnini, 5., “Computer—Assisted Knee Arthroplasty at
`Rizzoli Institutes,” MRCAS, vol. 1, Sessions I~III, pp.
`36-30 (1999
`Besl, l’.J., & McKay, N.l)., “A Method of Registration of
`3—D Shapes,” IEEE Transactions on Pattern Analysis and
`Machine Intelligence, vol. 14, No. 2, pp. 2394256 (Feb.
`1992,).
`
`(”5‘ continued 0“ “6’“ Page)
`Primary Examiner—Mickey Yu
`Assistant Examiner—Kelly O’Hara
`Attorney, Agent, or Firm—«Schiff Hardin & Waite
`'
`
`ABSTRACT
`.
`[57]
`Amethod for planning surgery on abody portion is provided
`in the steps of gathering image data, storing the image data,
`reading the image data into a computer, generating a three-
`dimensional computer modellof the body portion from the
`image data, identifying anatomical features relevant to the
`surgery, and defining at
`least one desired correction to
`anatomical structures to be accomplished by the surgery.
`Also, a method for performing surgery on a body portion is
`provided in the steps of loading surgical plan data into a
`computer, registering a three-dimensional computer model
`of the body portion stored in the surgical plan data to the
`body portion, providing at least one surgical tool, position-
`ing the surgical tool relative to the body portion and per-
`forming the surgery. Further, a jig assembly is provided in
`the form of a femoral docking jig, a femoral contouring jig,
`and a tibial‘jig.
`
`,
`
`58 Claims, 19 Drawing Sheets
`
`345/424
`
`'
`
`3/1984 White .
`4,436,684
`4/1989 Cline eta].
`4,821,213
`4/1989 Walker et al. .
`4,822,365
`6/1989 Woolson.
`4,841,975
`.
`11/1989 'I‘uy et al.
`4,882,679
`.
`6/1990 Walker et a1.
`4,936,862
`4,979,949 12/1990 Matsen, III et a1.
`5,007,936
`4/1991 Woolson. ,
`5,086,401
`2/1992 Glassman et al.
`5,099,846
`3/1992 Hardy,
`5,154,717 10/1992 Matseu, III et al. .
`5,230,623
`7/1993 Guthrie et al. .
`5,236,432
`8/1993 Matsen, III et a1.
`5,299,288
`3/1994 Glassman ct al.
`.
`
`.
`
`.
`
`.
`
`(0
`
`
`POSE THREE—DIMENSIONAL
`
`
`REPRESENTATION OF THE
`
`
`PROSTHETIC COMPONENT
`
`
`ON THE THREE~DIMENSIONAL
`
`’
`COMPUTER MODELS OF THE
`
`FEMUR AND TIBIA.
`
`
`
`
`INSTRUMENTATION
`DETERMINE THE PDSES OF THE
`
`DATA
`FENORAL JIGS AND TIBIAL JIGS.
`
`
`
`
`DETERMINE THE RESECTIONS
`
`
`OF THE FEMUR AND THE TIBIA,
`
`
`
`7’10 /
`
`WMT 1004-1
`
`WMT 1004-1
`
`

`

`5,871,018
`Page 2
`
`OTHER PUBLICATIONS
`
`Kass, M., Witkin, A., & Terzopoulos, D., “Active Contour
`Models,” International Journal of Computer Vision, pp.
`321—331 (1988).
`Canny, l, “A Computational Approach to Edge Detection”
`IEEE Transactions on Pattern Analysis and Machine Intel-
`ligence, V01. PAMI 8, No. 6, pp. 679—698 (Sep. 1986).
`ISO Technologies Inc., 6509 Airport Road, Toronto, Ontario
`Canada, 14V 157 14161, “Technical Specifications: The
`Viewing Wand”.
`'
`Integrated Surgical Systems, Inc., 829 West Stadium Lane,
`Sacramento, California, 95834, “Robodoc” Surgical Assis—
`tant System.
`'
`Picker International, Inc. World Headquarters, 595 Miner
`Road, Cleveland, Ohio, 44143, “ViewPoint” Workstation for
`Image—Guided Surgery: Product Data.
`Caponetti, L. & Fanelli, A., “Computer—Aided Simulation
`for Bone surgery,” I'EEE Computer Graphics and Applica—
`tions 13, No. 6, pp. 86—91 (Nov. 1993).
`Kienzle, T., Stulherg, 3., Peshkin, M. Quiad, A., Lea, J.,
`Goswami, A. & Wu, C, “Total Knee Replacement,” I.E.E.E.
`Engineering in Medicine & Biology 14, No. 3, pp. 301—306
`(May/Jun. 1995).
`
`Finlay, P.A., “OIthoSista'm An Active Surgical Localiser for
`Assisting Orthopaedic Fracture Fixation,” Proceeding from
`the Second Annual International Symposium on Medical
`Robotics and Computer Assisted Surgery, pp. 203—207
`(Nov. 4'7, 1995).
`'
`
`Potaminos, P., Davies, BL, & Hibberd, R.D., “Intra~Op-
`erative Imaging Guidance for Keyhole Surgery Methodol-
`ogy and Calibration,” Proceedings of the International Sym—
`posium on Medical Robotics
`and Computer~Assisted
`Surgery, Pittsburgh, Pennsylvania, pp. 98—104(Sep. 1994).
`
`Santos—Munne, J.J., Peshkin, M.A., Mirkovic, IS., Stulberg,
`S.D., & Kiezle III, TC, “AStereotactic/Robotic System for
`Pedicle Screw Placement,” Interactive Technology and the
`New Paradigm for Healrhcm‘e—Proceedings of Medicine
`Meets Virtual Reality III, San Diego, CA, pp. 326—333 (Jan.
`1995).
`
`Phillips, 11., Viant, W.J., Mohsen,A.M.M.A., Griffiths, J.G.,
`Bell, M.A.,_ Cain, T.J., Sherman, K.P., & Karpinski, M.R.K.,
`“Image Guided Orthopaedic Surgery Design and Analysis,”
`accepted for publication, IEE Transactions on Robotics
`Control (Mar. 1996).
`I
`'
`
`WM-T .1 004-2»»»»»»
`
`WMT 1004-2
`
`

`

`
`
`WMT 1004-3
`
`WMT 1004-3
`
`

`

`US. Patent
`
`Feb. 16,1999
`
`Sheet 2 of 19
`
`5,871,018
`
`130
`
`200
`A
`'
`,,//////
`FW(5.1+
`
`
`FIRST
`MEMORY
`
`220
`
`MEANS
`
`
`
`
`
`
`
`COMPUTER
`
`
`
`MEMORY
`
`SECOND
`
`MEANS
`
`210
`
`VISUAL DISPLAY
`MEANS
`
`23°
`
`WMT 1004-4
`
`WMT 1004-4
`
`

`

`US. Patent
`
`Feb. 16,1999
`
`Sheet 3 of 19
`
`5,871,018
`
`FIG. 5
`
`START
`
`
`
`250
`
`, , ~ ~260
`
`240
`
`
`
`
`CT
`IMAGE ,
`
`SLICES
`
`LOAD MEDICAL IMAGE DATA .
`
`,
`_
`_
`I
`I
`-
`265 /—-\I\
`I
`I
`I
`
`DISPLAY NEXT IMAGE SLICE ON
`VISUAL DISPLAY MEANS
`
`‘
`
`.
`
`I
`270 rl~m
`I
`'
`'
`230 -~I—~——
`I
`I
`325 mi
`I\
`I
`
`,
`
`APPLY EANNY FILTER
`\‘T TO OUTLINE EDGES
`
`_
`
`APPLY SNAKE T0
`OUTLINE EDGES
`
`
`MANUALLY ADJUST CONTOURS
`IF NECESSARY
`
`/ /
`4* WWW]
`3D
`i
`RECONSTRUCTION ,
`‘
`I
`I
`
`.
`
`,
`
`_
`
`
`
`NO
`
`1
`1
`‘
`'
`I
`ALL SLICES
`320 ””TW‘T\
`OUTLINED?
`I
`.
`l
`YES
`I
`APPLY SURFACE PATCHES TO .
`330 {Ir
`CONTOUR CONTROL POINTS
`I
`,
`'
`L TESSELATE SURFACE PATCHES TO
`35° / ‘
`CREATE 3D POLYGONAL MODEL ,
`
`L __________
`_
`_
`
`.
`
`I
`I
`‘
`I
`I
`|
`I
`I
`I
`
`I
`
`I
`3
`I
`‘
`I
`:
`I
`I
`I
`I
`I
`l
`.J
`
`A, WMrT-w1004-5
`
`WMT 1004-5
`
`

`

`US. Patent
`
`Feb. 16,1999
`
`Sheet 4 0f 19
`
`5,871,018
`
`FIG. 6 ,
`
`
`
`WMT 1004-6
`
`WMT 1004-6
`
`

`

`US. Patent
`
`Feb. 16,1999
`
`Sheet 5 0f 19
`
`5,871,018
`
`FIG. 8
`
`I
`i
`T
`,
`l
`I
`I
`I
`
`I l I I I
`
`
`
`_ _
`_
`_.
`_
`FIND
`mp
`[ENTER
`
`
`
`A00 \\
`
`
`H
`I
`IDENTIFY FOUR POINTS ON
`1.10 ,WLLW
`T \ THE PERIMETER OF THE
`
`
`FEMORAL HEAD IN THE '
`I
`l
`IMAGE DATA.
`I
`
`
`I
`'
`I
`o xx.
`I \ DEFINE A SPHERE FROM
`
`
`
`52
`
`'
`
`- THE FOUR POINTS.
`
`
`
`
`
`
`
`
`
`447
`
`-
`
`I
`
`I
`
`|
`
`
`I
`LOCATE THE MIDPOINT 0F
`.
`
`THE LINE CONNECTING THE
`4,3 I
`EPICDNDYLAR POINTS.
`
`‘
`.. — __
`FIND
`
`I
`CENTER I
`I
`l
`:
`.
`I
`I
`' 1,450
`I“
`
`}
`
`I I I
`
`ANKLE
`CENTER
`
`
`
`“57
`
`
`
`I
`LOCATE THE NIDPOINT OF
`H
`,
`
`
`;
`#53 j“ \ THE LINE CONNECTING THE
`I
`ALLEOL P MS.
`,
`
`L_..._._..~__________.
`___. __________ J
`
`
`
`,W WMT 1004-7
`
`,,,,,,,
`
`WMT 1004-7
`
`

`

`U.S. Patent
`
`Feb. 16,1999
`
`Sheet 6 of 19
`
`5,871,018
`
`FIG. 9
`
`
`
`390
`
`(x—ar-o
`
`WMT 1004-8»-
`
`WMT 1004-8
`
`

`

`US. Patent
`
`Feb.16,1999
`
`Sheet 7 of 19
`
`5,871,018
`
`FIG. 10
`
`0
`
`COO
`
`
`
`
`
`IDENTIFY THE CONDYLE UPON WHICH
`
`THE SURGERY WILL BE PERFORMED.
`
`
`
`1/ 490
`
`THE
`
`LIMB
`
`’
`
`I,__.__.~, __,.____.__ L- ,_ mw___ww_1..___»
`
`POSITION
`POSITION THE KNEE CENTER AT THE ORIGIN
`
`
`
`OF THE GRAPHICS COORDINATE SYSTEM.
`
`
`
`
`ROTATE THE MODEL SO THAT THE
`HIP CENTER LIES ON THE Y—AXIS.
`
`
`
`
`ROTATE THE MODEL SO THAT THE
`
`L
`
`
`EPICONDYLARPOINTS AND THE
`HIP CENTER LIE IN THE Y—Z PLANE,
`
`OF THE GRAPHICS COORDINATE SYSTEM.
`
`
`
`520 '
`
`
`
`FIND THE MODEL VERTEX WITH THE
`MINIMUM Y VALUE OPPOSITE THE
`
`«
`
`INVOLVED FEMORAL CONDYLE.
`
`
`
`
`
`
`
`530
`
`SAO
`
`
`
`DEFINE THE ROTATION AXIS AS A LINE
`PERPENDICULAR TO THE Y—Z PLANE
`
`PASSING THROUGH THE MINIMUM Y VERTEX.
`
`
`
` ROTATE THE‘3O TIBIAL MODEL
`
`
`
`
`ABOUT THE ROTATION AXIS
`
`TO ACHIEVE DESIRED ALIGNMENT.
`
`WMT 1004-9
`
`WMT 1004-9
`
`

`

`US. Patent
`
`Feb. 16,1999 »
`
`SheetSof 19
`
`5,871,018
`
`FIG. 11
`
`
`
`
`
`WMT 1004-10
`
`

`

`US. Patent
`
`'
`
`Feb. 16,1999
`
`Sheet90f 19
`
`5,871,018
`
`660
`
`
`
`
`_
`.
`IDENTIFY BOUNDINO POINTS
`WITH MIN. AND MAX.
`x COORDINATE VALUES
`ONINVOLVEDCONDYLE
`
`
`
`
`
`I
`I
`I
`I
`I
`I
`I
`I
`I
`I
`
`
`
`
`
`
`
`flfigfigfigf
`EOMPAREBOUNmNGPONnS
`
`
`
`DATABASE -
`TO PROSTHESIS SIZE DATA.
`
`
`
`r ~~~~~~~~~~~~
`|
`SIZE AND SELECT
`I
`COMPONENTS
`I
`I
`l
`|
`I
`I_
`
`'
`
`I
`
`FIG. 16
`
`700 ’4
`
`POSE THREE-DIMENSIONAL
`REPRESENTATION OF THE
`
`
`
`
`
`
`
`.
`
`PROSTHETIE COMPONENT
`735
`ON THE THREE~DIMENSIONAL
`
`COMPUTER MODELS OF THE
`
`FEMUR AND TIBIA.
`
`
`
`
`
`
`INSTRUMENTATION
`DETERMINE THE POSES OF THE
`DATA
`FEMORAL JIGS AND TIBIAL JIGS.
`
`
`
`
`
`
`DETERMINE THE RESECTIONS :
`
`
`OF THE FEMUR AND THE TIBIA.
`i
`
`7M) /”\
`
`WMT 1004-11
`
`

`

`US. Patent
`760 \
`
`
`
`Sheet 10 0f 19
`
`5,871,018
`
`770
`
`Feb. 16, 1999
`FIG. 17
`780
`
`
`
`
`COMPUTER
`
`REGISTRATION»
`
`MEANS/
`
`[MM
`
`
`
`
`VISUAL DISPLAY
`” MEANS
`
`
`
`
`WMT 1004-12
`
`WMT 1004-12
`
`

`

`US. Patent
`
`Feb. 16,1999
`
`’ Sheet 11 of 19
`
`5,871,018
`
`
`
`V
`
`
`REVIEW THE PLAN TO
`DETERMINE ACCURACY.
`
`
`
`
`
`
`
`
`
`MAKE INCISION 0N
`PATIENT'S LEG, FLEX KNEE T0
`APPROXIMATELY 90
`DEGREES, AND FIX LEG IN
`PLACE.
`
`
`
`
`WMT 1004-13-
`
`WMT 1004-13
`
`

`

`US. Patent
`
`Feb. 16, 1999
`
`Sheet 12 0f 19
`
`5,871,018
`
`FIG. 21
`
`DISPLAY IMAGE 0F
`
`SUGGESTED CMM POSE
`
`RELATIVE TO FEMUR.
`
`FEMORAL
`
`SUGGESTED
`
`POSE
`
`
`IS CMM BUTTON
`
`DOWN?
`
`910
`
`
`
`
`ALIGN CMM WITH THE
`>
`POSE DISPLAYED
`
`
`
`
`
`(SUGGESTED POSE)
`
`
`
`
`
`FEMORAL REGISTRATION
`
`
`FEMORAL REGISTRATION _
`,
`TRANSFORM u.
`INVERSE (CURRENT POSE)
`, x
`
`CURSOR TRANSFORM =
`
`TRANSFORM
`
`,,,,,
`
`. WMTW’I 004-14%,“
`
`,9
`
`WMT 1004-14
`
`

`

`U.S._ Patent
`
`Feb. 16, 1999
`
`Sheet 13 0f 19
`
`5,871,018
`
`FIG. 22
`
`6
`
`
`— “'" * * — " “1
`
`FEMORAL
`
`MULTI-POINT
`omeaAmN
`REGISTRATION
`
`WMTM’I 004-159,,“
`
`I
`
`1
`
`I
`970 ”T\
`
`,
`
`
`
`
`
`
`DISPLAY IMAGE 0F FEMUR
`AND CMM CURSOR.
`
`
`
`
`
`
`
`
`
`PATIENT‘S FEMUR.
`
`SAMPLE POINTS 0N .
`
`
`
`
`
`
`
`SMALL.
`
`WMT 1004-15
`
`

`

`US. Patent
`
`Feb.16, 1999
`
`Sheet 14 01'19
`
`5,871,018
`
`FIG. 23
`
`.
`1030 \ .1
`
`/ 1010
`
`101+0
`
`1020
`
`1050
`
`
`
`WMT~ ,1 004-1 6
`
`WMT 1004-16
`
`

`

`US. Patent
`
`Feb. 16,1999
`
`,
`
`Sheet 15 0f 19
`
`5,871,018
`
`
`
`FIG. 28
`
`
`
`
`Ci)
`
`FEMORALJIGTI
`
`‘
`
`
`
`
`
`DISPLAY FEMUR, PLANNED JIG POSITION. ANO
`REPRESENTATION 0F JIGS IN THEIR ACTUAL POSITION.
`
`
`PLACEMENT I
`
`
`
`
`
`
`APPLY CURRENT [MM POSE TRANSFORM AND FEMORAL
`REGISTRATION TRANSFORM TO 3D JIG REPRESENTATION.
`
`
`
`
`
`
`1200
`
`~ \- \\
`
`'
`'
`\» PROVIDE VISUAL FEEDBACK.
`
`I I I I I I I I I I I I I I I I I I II I II
`
`
`
`
`
`1210 M T‘.‘\
`I
`I
`
`\
`
`UPD
`
`,
`
`|I +
`
`1215 i
`1
`L
`
`M\
`
`\
`
`ATE ARROW AND STOP
`SIGN INDICATORS.
`
`
`
`
`DONE
`POSITIONING JIG?
`
`
`_I
`
`-----
`
`WMT 1004-9-17
`
`WMT 1004-17
`
`

`

`US. Patent
`
`Feb. 16, 1999
`
`Sheet 16 '0f19
`
`5,871,018
`
`1250’"
`
`FIG. 30
`1220\ 1
`mm a
`
`IZAO
`
`FIG. 31
`
`
`
`I
`I
`I
`I
`
`I I
`
`I I
`
`I
`
`}I I
`
`»
`TIBIAL
`RESECTION
`
`FEMORAL
`RESECTION
`
`
`'
`DISPLAY TIBIA MODEL AND
`TIBIAL JIGS 0N MODEL.
`
`,
`
`
`
`WMT 1004-18
`
`WMT 1004-18
`
`

`

`US. Patent
`
`Feb. 16,1999
`
`Sheet 17 0f 19
`
`5,871,018
`
`FIG. 32
`
` 1295 \
`
`SAMPLE CHARACTERISTIC
`
`CORNERS OF THE
`
`RESECTIONS USING THE
`
`
`
`
`
`
`
`CMM.
`
`
`
`1300
`
`
`
`
`
`CONSTRUCT A 3D MODEL
`
`OF THE RESECTIONS USING
`
`THE CORNER DATA.
`
`
`
`
`131° T"
`
`
`
`COMPARE INTENDED:
`
`
`RESECTION WITH THE
`
`
`ACTUAL RESECTIONS.
`
`
`
`
`
`
`DETERMINE VARIATIONS
`
`BETWEEN THE ACTUAL
`
`RESECTION POSE AND THE
`INTENDED RESECTION POSE.
`
`
`
`
`
`
`4
`
`MEANS.
`
`1330
`
`DISPLAY THE VARIATIONS
`
`ONITHE VISUAL DISPLAY
`
`WMT 1004-19
`
`WMT 1004-19
`
`

`

`US. Patent
`
`Feb. 16,1999 I
`
`Sheet 18 0f 19
`
`5,871,018 ’
`
`FIG. 33
`
`1340
`
`
`NSTALL TRIAL COMPONENTS.
`
`1350 x
`
`,
`
`~
`
`SAMPLE KNOWN POINTS.
`
`
`
`
`
`
`
`
`
`
`
`
`136°
`
`' 1370
`
`CALCULATE CURRENT
`COMPONENT POSE.
`
`
`
`COMPARE CURRENT
`
`COMPONENT POSE TO
`PLANNED COMPONENT POSE
`AND DISPLAY VARIATIONS.
`
`
`
`,,,,,
`
`WMT 14004-20“.
`
`WMT 1004-20
`
`

`

`US. Patent
`
`Feb. 16,1999
`
`Sheet 19 of 19
`
`(
`
`5,871,018
`
`FTI3.231+
`
`1375\\I
`
`\
`
`L
`
`TRIAL
`
`REDUCTION
`
`
`
`
` SELECT AND INSERT
`PROSTHETIC COMPONENTS.
`
`
`
`MOVE KNEE THROUGH ENTIRE
`RANGE OF MOTION AND TEST
`
`
`STABILITY AND TENSION IN'
`
`THE LIGAMENTS.
`
`
`
`
`
`
`
`
`
`
`CEMENT PROSTHETIC
`COMPONENTS INTO PLACE
`AND CLOSE INCISION.
`
`‘
`
`1400
`
`
`
`DISPLAY, ON VISUAL
`DISPLAY MEANS, THE
`AMOUNT OF TIME THE
`
`V1410
`
`SURGEON TOOK TO COMPLETE
`EACH STEP, AND PROVIDE
`INVENTORY CONTROL FOR
`
`
`
`
`DEVICES USE IN SURGERY.
`
`
`
`
`,,,,,,,,,,,
`
`__
`
`I,
`
`_.
`
`I
`
`,9 W-MT 1004-21
`
`WMT 1004-21
`
`

`

`5,871,018
`
`1
`COMPU’I‘ER~ASSISTED SURGICAL
`METHOD
`
`This is a divisional of application Ser. No. 08/578,497
`filed on Dec. 26, 1995 now US. Pat. No. 5,682,886.
`BACKGROUND OF THE INVENTION
`
`This invention relates generally to computer-assisted sur-
`gical systems, and in particular to a computer~assisted knee
`replacement system used to achieve accurate limb alignment
`with minimal surgical invasiveness.
`One application for computer-assisted surgical systems is
`in the field 'of knee arthroplasty. Knee arthroplasty is a
`surgical procedure in which the articular surfaces of the
`femur and tibia (and the patella, in the case of tricomparb
`mental knee arthroplasty)‘ are cut away and replaced by
`metal and/or plastic prosthetic components. The goals of
`knee arthroplasty are to resurface the bones in the knee joint
`and to reposition the joint center on the mechanical axis of
`the leg. Knee arthroplasty is performed to relieve pain and
`stitfness in patients suffering from joint damage caused by
`osteo—, rheumatoid, or post—traumatic arthritis.
`In 11.993,
`approximately 189,000 knee arthroplasties were performed
`in the United States, and this number is expected to increase
`over the next decade as the US. population ages.
`More than 95% of knee arthroplasties performed in the
`US. are tricompartmental. Tricompartmental knee arthro-
`plasty (“TKA”) involves the replacement of all the articular
`surfaces of the knee joint, and is performed when arthritis is
`present in two or more of the three compartments of the
`knee: medial (toward the body’s central axis), lateral (away
`from the body’s central axis), and patello—femoral (frontal).
`The remaining knee arthroplasties are unicompartrnental
`knee arthroplasties (“UKA”). UKAs involve the replace—
`ment of the articular surfaces of only one knee compartment,
`usually the medial. UKAs are indicated when arthritis is
`present in only one compartment and when the patellar
`surface appears healthy.
`UKAs have several advantages over TKAs. These include
`the preservation of more patient anatomy, increased knee
`stability, less complicated revision surgery, and the potential
`for installation through a smaller incision, as compared with
`a TKA. A TKA requires the resection of the entire tibial
`plateau, both condyles of the femur, and the posterior side of
`the patella, because all compartments of the knee are
`replaced. As a result,
`in TKAs,
`the anterior cruciate
`ligament, which is attached to the front of the tibial plateau,
`usually is removed, severely reducing the stability of the
`knee after the operation. In contrast, during UKAs, only one
`compartment is replaced, and thus only one side of the tibial
`plateau is removed. As a result, the anterior cruciate liga—
`ment may be preserved, allowing for increased knee stabil—
`ity. In addition, if a revision surgery is required, more natural
`bone stock is present on which to place the revision com—
`ponents. Finally, since the resections and components used
`in UKAs are smaller, minimally—invasive surgical proce~
`dures may be applied.
`'
`In the late 19705, there were reports of high failure rates
`for UKAs due to problems such as improper alignment. One
`study, for example, reported that 10% of UKA patients
`needed revision surgery because one or both of the other
`knee compartments degenerated due to the presence of
`polyethylene particles that flaked off the prosthetic compo-
`nents. Overcorrection of the varus/valgus deformity, which
`is the angle between the mechanical axis of the femur and
`the mechanical axis of the tibia in the anterior/posterior
`
`10
`
`215
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`_
`
`2
`(“A/P”) plane, was one suspected cause of the excessive
`component wear.
`In contrast, many recent studies have indicated high
`success rates for UKAs. These studies report that the inci-
`dence of failure for UKAs is comparable to or less than that
`for TKAs. The higher success rates for UKAs are likely due
`to the use of thicker tibial components than used in earlier
`UKAs, the use of component materials that are less suscep-
`tible to wear than earlier materials, and better alignment of
`the components by the surgeon so as to not overcorrect
`varus/valgus deformity.
`Despite these recent studies, in many cases where UKAs
`are indicated, orthopaedic surgeons in the US. still perform
`TKAs. This conservative attitude towards UKAs is believed
`to be the result of several factors, such as the use of poor
`instrumentation to install the implants, concern over arthritis
`spreading to other compartments, and the early mixed
`reviews of UKA outcomes in the literature. Because of this
`conservative attitude, the benefits of UKAs are not realized
`by many patients.
`Although UKA success rates are higher than they were 20
`years 'ago, there are still important problems in UKA and
`TKA performance. For example, alignment of the femoral
`and tibial prosthetic components with respect to the bones
`and to each other currently involves the use of purely
`mechanical instrumentation systems. Typical femoral instru-
`mentation consists of an intramedullary rod (a metal rod that
`is aligned with the femoral shaft via insertion into the
`medullary canal of the femur) and several slotted cutting jigs
`for guidinga saw blade used to resect the bone. The surgeon
`aligns the jigs first by drilling a hole through the center of the
`distal end of the femur into the medullary canal, which runs
`the length of the femoral shaft, and then inserts the intramed-
`ullary rod into the canal. Thereafter, the surgeon removes the
`rod from the femur, and slides a cutting guide onto the rod.
`The surgeon next reintroduces the rod into the medullary
`canal, and positions thevculting guide against the distal end
`of the femur. To account for the fact that the rod is oriented
`along the femoral shaft, which does not correspond to the
`mechanical axis of the femur, the cutting guide is usually
`offset by a predetermined and fixed distance from the rod in
`the AIP plane, The oifset is provided to allow a distal cut to
`be made that is perpendicular to the mechanical axis of the
`femur,
`thus correcting any varus/valgus deformity. The
`depth of the distal cut is usually adjustable in discrete
`intervals: some systems have cutting blocks with slots at
`multiple depths, while others have cutting blocks with pin
`holes at multiple depths allowing the entire block to be
`moved up or down on a set of parallel pins. The remaining
`cuts vary depending on the geometry of the implant being
`installed. The depth and: orientation of all
`these cuts,
`however, are determined by the cuts already made and/or by
`visual means.
`
`Tibial instrumentation consists of an extramedullary rod
`(a metal rod that the surgeon aligns with the tibial shaft via
`external anatomical landmarks) and a slotted cutting guide.
`The mechanical axis of the tibia is assumed to run along the
`tibial shaft. The surgeon places the cutting jig at the top of
`the rod, with the cutting surface perpendicular to the rod.
`The depth of the cut is adjusted by moving the jig along the
`rod. The surgeon clamps the bottom of the rod around the
`ankle, just proximal to the malleoli (which form the distal
`portion of the tibia and fibula).
`The instrumentation systems just described suifer from
`certain problems. Femoral varus/valgus alignment,
`for
`example, is determined by a discrete and predefined offset
`
`WMT 1004-22
`
`WMT 1004-22
`
`

`

`5,871,018
`
`3
`from the femoral shaft, which may not result in the desired
`angular correction. The amount of bone resected is
`adjustable, but only through slots positioned at discrete
`intervals of about two millimeters. Other parameters, such as
`rotation around the axis of the limb, must be determined
`visually. The tibial jig is aligned almost entirely by the
`surgeon’s visual judgment.
`Discretely adjustable alignment systems can introduce
`inaccuracies when an optimal resection falls between or
`outside of the range of predefined alternatives. The surgeon
`in such circumstances must decide which of the available
`alternatives is closest to the optimal resection. Moreover, the
`accuracy of visual alignment is primarily the product of the
`surgeon’s experience in performing TKAs and UKAs. The
`accuracy needed in alignment of the prosthetic components
`with respect: to the bones is still being debated, but it has
`been shown that misalignment of the components can cause
`excessive component wear. As a result, revision surgery
`often is necessary.
`4
`Moreover, because current UKA instrumentation systems
`are, for the most part, modified TKA instrumentation
`systems, some of the possible benefits unique to UKAs have
`not been realized. For example, because UKA components
`are less than half the size of TKA components, they can be
`implanted using a smaller surgical incision. However, many
`of the instrumentation sets for UKAs still require full
`exposure of the knee, and the use of an intramedullary rod,
`which can be a source of complications. Thus, the benefits
`of limited exposure, such as shorter operating room (“OR”)
`time, decreased healing time, and less morbidity, have not
`been realized with current UKA techniques.
`New technologies, in addition, reveal that existing pro~
`cedures may be improved. Recent advances in medical
`imaging technology, such as computed tomography (“CT”)
`and magnetic resonance (“MR”) imaging, have made it
`possible to display and manipulate realistic computer-
`generated images of anatomical structures. These advances
`have had immediate practical applications to surgery
`simulation, i.e., computer—modeled surgical procedures used
`to plan, teach, or aid surgery. Many of the early simulations
`are related to planning and evaluating neurosurgery. More
`recently,
`three—dimensional reconstructions from CT data
`have been used to plan total hip reconstructions, osteotomies
`(a removal of a piece of bone to correct a deformity), and
`allograft procedures (tissue graft), and to design custom
`prostheses. Such surgical planning systems can be used to
`develop three-dimensional models, which help surgeons
`properly size and “pose” surgical tools and prosthetic com-
`ponents in the body. (As used herein, “pose” refers to the
`position and the orientation of a structure, and may be used
`as a noun or as a verb.) Most systems, however, have no way
`of transferring this information into the operating room. The
`computer assists in the planning, but not
`in the
`implementation, of the procedure. For the computer to assist
`in the implementation of the surgical plan, the models used
`in the surgical planning procedure must be “registered” to
`the patient intraoperatively. Registration is the process of
`defining a geometric transform between the physical world
`and a computer model. In this way, the computer can direct
`the placement of the tools and prosthetic components rela—
`tive to the patient.
`Some computer—assisted surgery systems combine surgi-
`cal planning software with a registration method to imple-
`ment surgical plans. These systems have been applied to the
`planning and implementation of orthopaedic procedures. For
`example, the “Robodoc” hip replacement system from Inte~
`grated Surgical Systems (Sacramento, Calif.) uses a
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`4o
`
`45
`
`50
`
`55
`
`6O
`
`65
`
`4
`computer-based surgical plan with a robotic manipulator to
`perform intraoperative registration and some of the bone
`resections needed for hip replacement. The Robodoc system
`has been tested in the operating room and has produced
`accurate bone resections, but the system has several impor-
`tant limitations. It is expensive, for example, and must be
`operated by a specially—trained technician.
`It also adds
`substantially to OR time, increasing the cost of using the
`system. Another problem is that the Robodoc system uses a
`pin-based registration method. The pins, called “fiducials,”
`are inserted into the patient’s bones prior to imaging. Reg— ‘
`istration is achieved by aligning the fiducials in the image
`data with the fiducials on the patient. Pin-based registration
`requires an additional surgical procedure to insert the. pins,
`causing additional pain to the patient, and lengthening the
`patient’s rehabilitation time.
`The present invention is intended to overcome the disad-
`vantages associated with current knee arthroplasty
`procedures, surgical planning systems, and computer—
`assisted surgery systems. The present invention determines
`optimal alignment of resections preoperatively, and uses
`computer modeling techniques to help the surgeon achieve
`that alignment. Moreover, smaller jigs are used in the
`present invention, and therefore, smaller incisions are made
`in the patient’s leg. The present invention also plans the
`surgical procedure preoperatively, and assists in implement—
`ing the plan. Further, the present invention is less expensive
`than many prior art systems, and makes it possible to use
`pinless registration methods. Thus,
`the present invention
`represents a significant solution to many problems experi-
`enced in the field.
`
`SUMMARY OF THE INVENTION
`
`The invention is embodied in a method for planning
`surgery on a portion of a body with the goals of improving
`the accuracy of the surgery and reducing the risks associated
`with surgery. This method comprises the steps of gathering
`image data of the portion of a body using a radiant energy
`means for gathering image data. The image data is stored in
`a memory means. The stored image data then is read into a
`computer having a visual display for displaying images
`generated in at least one process step. The system uses the
`image data to generate a three—dimensional computer model
`of the body portion using a modeling means, and/identifies
`anatomical features relevant to the surgery on the three-
`dimensional computer model. Finally, the system defines at
`least one desired correction to the anatomical structures to
`be accomplished by the surgery. In one embodiment of the
`invention, the method for planning surgery is used to plan
`unicompartmental knee arthroplasty surgery.
`The invention further is embodied in a method of per~
`forming surgery on a portion of a body with the goals of,
`improving the accuracy of the surgery and reducing the risks
`associated with surgery. The method comprises the steps of
`loading surgical plan data stored in a memory means into a
`computer having a visual display for. displaying images
`generated in at least one process step. The surgical plan data
`comprises a three—dimensional computer model of a body
`portion, and data relating to at least one prosthesis of defined
`size and position relative to the body portion. The system
`then registers the three—dimensional computer model of the
`body portion to the actual body portion using a registration
`means. The system next provides at least one surgical tool
`that has a defined relationship relative to the prosthesis
`defined in the surgical plan data, the relationship defining a
`desired pose for the surgical tool relative to the body portion.
`Finally, the system allows the user to pose the surgical tool
`
`WMT 1004-23,.
`
`...............................................
`
`.
`
`WMT 1004-23
`
`

`

`5,871,018
`
`5
`relative to the body portion in the desired pose, and the
`surgery is performed. In one embodiment of the invention,
`the method for performing surgery is used to perform
`unicompartmental knee arthroplasty. In another embodiment
`of the invention, the method for performing surgery further
`comprises the step of performing at least one resection on
`the body portion, wherein the resection is performed using
`a burring device.
`The invention also is found in a jig assembly for guiding
`a device used to resect a femur and a tibia. The jig assembly
`comprises a femoral docking jig having a body, and a first
`aperture for receiving a positioning device. The jig assembly
`also comprises a femoral contouring jig that has a second
`aperture for receiving the femoral docking jig and at least
`one surface for guiding a device used to resect the femur and
`the tibia. Finally, the jig assembly comprises a tibial jig
`having a horizontal cutting guide surface and a vertical
`cutting guide surface to guide the device used to resect the
`femur and the tibia, and a docking hole for receiving a
`positioning device. In another embodiment where the tibial
`prosthesis employs a fixation post, a tibial post hole jig also
`is positioned.
`It is an object of the invention to provide a computer-
`assisted surgical system that costs substantially less than
`current systems.
`It is another object of the invention to provide a computer—
`assisted surgical system that requires shorter OR time than
`current systems.
`,.
`Another object of the invention is to provide a computer—
`assisted surgical system method that decreases patient com—
`plications.
`It
`is another object of this invention to provide a
`computer—assisted surgical system that decreases the length
`of a patient’s hospital stay.
`Another object of the invention is to provide a computer—
`assisted surgical system that decreases a patient’s rehabili-
`tation time.
`
`Another object of the invention to provide a computer-
`assisted surgical system that allows surgeons to install
`unicompartmental knee implants more accurately and less
`invasively than is possible with current systems, thereby
`increasing implant longevity and improving knee function.
`Still another object of the invention is to provide a method
`of performing knee arthroplasty that allows for more accu—
`rate alignment of the prosthetic components with respect to
`the bones than is currently available using mechanical
`instruments with slots distanced at discrete intervals.
`
`Another object of the invention is to provide a method of
`performing knee arthroplasty that does not require the use of
`an intramedullary rod in the femur.
`‘ Another obj eet of the invention is to provide a method for
`implanting unicompartmental knee arthroplasty components
`using a smaller surgical incision than is used by current
`methods.
`
`Another object of the invention is to provide a method of
`registering a computer model and surgical plan to a patient’s
`body using a coordinate measuring machine.
`Another object of the invention is to provide a method of
`registering a computer model and surgical plan to a patient
`without the need for an additional surgical procedure.
`Still another object of the invention is to provide cutting
`jigs that are smaller than current cutting jigs, thereby requir-
`ing smaller incisions for placement.
`Another object of the invention is to provide cutting jigs
`each of which can guide multiple bone resections necessary
`
`6
`thereby reducing the number of cutting jigs
`for UKAs,
`required to perform UKAs.
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 is a front plan View of a femur.
`FIG, 2 is a front plan View of a tibia.
`FIG. 3 is a front elevational view of the knee joint,
`showing the bottom of a femur, with the patella deleted to
`expose the femur, tibia, and ligaments.
`FIG. 4 is a functional block diagram of the planning
`computer and associated hardware used in the invention.
`FIG. 5 is a flow chart illustrating one sequence of steps
`that
`is useful
`in the invention to generate a three-
`dimensional computer model of a patient’s anatomy.
`FIG. 6 is a top plan View of a CT image slice outlined by
`an active contour.
`FIG. 7 is a side view of a three—dimensional computer
`model, based in part on the active contour shown in FIG. 6,
`of the top of a femur lying horizontally.
`FIG. 8 is a flow chart illustrating one sequence of steps
`that is useful in the invention to find a hip center, a knee
`center, and an ankle center.
`FIG. 9 is a plan view of a femur and a tibia, and their
`mechanical axes.
`
`FIG. 10 is a flow chart illustrating one sequence of steps