[19]
`United States Patent
`4,502,483
`{11] Patent Number:
`
`
`'Date of Patent:[45] Mar. 5, 1985
`Lacey
`‘
`
`[54] METHOD AND APPARATUS FOR SHAPING
`A DISTAL FEMORAL SURFACE
`
`[75]
`
`Inventor:
`
`James A. Lacey, Winter Park, Fla.
`
`[73] Assignee: Dow Corning Corporation, Midland,
`Mich.
`
`[21] Appl. No: 473,466
`
`[22] Filed:
`
`Mar. 9, 1983
`
`Int. Cl.3 ................................................ A61F 5/04
`[51]
`[52] US. Cl. .............................. 128/303 R; 128/92 E;
`128/92 H
`
`[58] Field of Search .............. 128/92 R, 92 E, 92 EA,
`128/92 EB, 92 H, 305, 317, 303; 3/19, 1.91,
`1.911
`
`[56]
`
`References Cited
`U.S. PATENT DOCUMENTS
`
` ....... 3/1911
`7/1980 Cloutier
`4,211,228
`123/92 E
`9/1982 Chambers .
`4,349,018
`4,457,307 7/1984 Stillwell .............................. 128/317
`OTHER PUBLICATIONS
`
`1981,
`
`Zimmer, “Cloutier TM Total Knee” 1979, B274 5M679.
`Howmedica, “The Howmedica Kinematic Knee Sys-
`tem”, 1981, ST3210—l 2/81 15MB.
`Howmedica, “Total Condylar Knee Prosthesis Surg.
`Tech.” C. S. Ranawat, 1978, ST2010 2/79 10MB.
`Zimmer, “Eptekhar TM II Knee Prosthesis”,
`B~281 5M281.
`Zimmer,
`“Geo—Patella TM /Geo—Tibia1 ’I‘M
`Knee” 1977, B—260-1 10M778.
`Richards, “R.C.M. TM Total Knee System” 1978, 3246,
`Rev 9—79.
`Zimmer, “The Multi—Radius TM Total Knee with Sur-
`geon—Guided Instrumentation” 1978 B271 7500 M 680.
`Howmedica Surg. Tech., “Total Condylar Prosthesis
`Surg. Tech.” J. N. Insall et 31., 1976.ST 2002 12/76
`10M.
`,
`The Howmedica® Universal TM . Total Knee Instrua
`mentation System, Brochure No. H~2026~1 1/82 15M B
`
`Total
`
`(1980); Howmedica, Inc., Rutherford, NJ 07070, espe-
`cially see pp. 19—24 and FIG. 14.
`“New Jersey Tricompartmental Total Knee Replace—
`ment Surgical Procedure by Frederick P. Buechel,
`MD”, 13 pages, issue date 1/ 1981, Form No. 1280432,
`DePuy division, Boehringer Mannheim Corp, Warsaw, ‘
`Ind., 46580.
`Dow Corning Wright Knee Instrumentation System,
`Data Sheet No. L095—0015, dated Jan. 1982; Dow Cor-
`ning Wright, Arlington, TN 38002, 6 pages.
`Dow Corning Wright Lacey Condylar Total Knee
`System, Data Sheet No. L095—0104, ©Dow Corning
`Wright 1983, Arlington, TN 38002, 8 pages.
`Primary Examiner—C. Fred Rosenbaum
`Assistant Examiner—~C. W. Shedd
`Attorney, Agent, or FirmmRichard E. Rakoczy
`
`ABSTRACT
`[57]
`The present invention provides a method and apparatus
`for preparing the distal surface of a femur to receive a
`distal femoral prosthesis employing an alignment guide
`which is used to externally locate the central long axis
`of the femur based upon certain external reference
`points on the distal femur. The alignment guide is com-
`posed of a main body, a pivotable resection guide instru-
`ment holder, a locator pin, at least one femoral surface
`modifying instrument which cooperatively engages
`with the holder and a means such as a clamp for affixing
`the main body to the femur to accomplish the shaping of
`the distal femoral surface. The central long axis of the
`main body is brought into alignment with the central
`long axis of the femur through the use of a locator pin.
`The pivotable instrument holder holds resection guide
`instruments at a preselected angle with respect to the
`main body such that the shaping instruments fixed
`thereto assume the proper alignment with respect to the
`central long axis of the femur such that the distal femo-
`ral surface is shaped relative to that axis in a simple and
`; accurate manner.
`
`.
`
`6 Claims, 17 Drawing Figures
`
`129m...
`
`
`
`,,,,,,,,,,,,,,,,,,,,,
`
`WMT 1 013-1
`
`WMT 1013-1
`
`

`

`US. Patent Mar. 5, 1985
`
`Sheet 1 of3
`
`4,502,483
`
`
`
`,,,,,,,
`
`m
`
`,
`
`.
`
`WMT1013-2 _
`
`WMT 1013-2
`
`

`

`US. Patent Mar.'s,1985
`
`Sheet20f3 ' 4,502,483
`
`
`
`AAAAAA
`
`M
`
`,
`
`WMTW1013_3 _,
`
`H
`
`WMT 1013-3
`
`

`

`US. Patent Mar. 5, 1985
`
`Sheet3of3
`
`4,502,483
`
`
`
`.WM,T101_A3_4 ,
`
`WMT 1013-4
`
`

`

`1
`
`METHOD AND APPARATUS FOR SHAPING A
`DISTAL FEMORAL SURFACE
`
`BACKGROUND OF THE INVENTION
`
`5
`
`4,502,483
`2
`serted into the fixation stud holes remaining in the
`femur after the femoral drill jig is removed.
`A method for shaping the distal femoral surface em-
`ploying the use of a relatively short femoral alignment
`rod which is positioned in the intramedullary canal is
`shown in a brochure entitled “New Jersey Tricompart-
`mental Total Knee Replacement Surgical Procedure by
`Frederick F. Buechel, MD”, 13 pages,
`issue date
`1/1981, Form. No. 1280-32, from DePuy Division, Bo-
`ehringer Mannheim Corporation, Warsaw, Ind. 46580.
`In both of the above procedures, the alignment rods
`employed may not enable a surgeon to accurately fol-
`low the central long axis of the femur because the femur
`is not exposed to visual observation along its length.
`This can especially become a problem when the femur
`possesses a deformity which may somewhat alter its
`true central long axis.
`SUMMARY OF THE INVENTION
`
`This invention relates to a method of shaping the
`distal surface of a human femur using certain alignment
`guides to guide the shaping of that surface to receive a
`distal femoral prosthesis and to certain apparatus used
`in the method.
`Various types of alignment guides and methods have
`been developed to enable a surgeon to affix a distal
`femoral knee prosthesis to the human femur. Since the
`purpose for affixing such a prosthesis is to restore the
`patient’s ability to walk after disease or other traumatic
`causes have impaired that ability, it is important that the
`prosthesis be attached to the femur in such a manner
`that it will approximate as closely as possible the natural
`condyles which the prosthesis is replacing. If the pros-
`thesis is not properly affixed with respect to the femur,
`an unnatural gait or other complications can result.
`It is common practice to use the long central axis of
`the femur as a guide in determining the manner in which
`the distal femoral surface should be shaped to receive a
`properly aligned distal femoral prosthesis. Generally, a
`pre-operative single, long anterior-posterior radiograph
`showing the shaft of the tibia and femur is made and the
`angle of the long central axis of the femur relative to the
`vertical axis of the body (physiological valgus, gener-
`ally from 5°42") is visualized. That angle is then used as
`a reference when the distal femoral surface is shaped
`using various cutting instruments and guides. In one
`such method, a long axial alignment jig (rod) is em-
`ployed which is positioned over the outside surface of
`the patient’s leg in a position which the surgeon visually
`determines to correspond to the central long axis of the
`femur and the femur is shaped relative to the alignment
`of that rod. One example of the manner in which the
`distal femoral surface is shaped to receive a prosthesis
`using an external alignment rod is shown in “The
`HOWMEDICA Universal Total Knee Instrument Sys-
`tern”, brochure no. H-2026-l 1/82 15M B (1980) from
`HOWMEDICA, Inc., Orthopaedics Division, Ruther-
`ford, NJ 07070 which is hereby incorporated by refer-
`ence.
`
`The external alignment rod has a disadvantage in that
`the surgeon is relying upon visual and tactile means for
`positioning the alignment rod and thereby the femoral
`surface resection guide since the patient’s skin covers
`the major portion of the femur and screens it froru View.
`One part of the method described in the aforemen-
`tioned Howmedica, Inc., brochure employs the use of a
`femoral drill jig having two posterior skids which align
`with the posterior surfaces of the femoral condyles and
`a drill bit which is caused to rest in the center of the
`patello~femoral (intercondylar) groove to obtain cor-
`rect medial-lateral and rotational positioning of the jig
`prior to using the jig to bore holes in the femur to re-
`ceive the fixation studs of a distal femoral prosthesis.
`Thus, reference points located directly on the distal
`femoral surface are employed to position the jig. How—
`ever, the initial reaction of the distal femoral condyles is
`made using a jig employing an external alignment rod.
`Resection of the anterior and posterior aspects of the
`distal femoral condyles is accomplished through the use
`of another jig which has locking studs which are in—
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`45
`
`50
`
`55
`
`65
`
`There appears to be a need for a method of shaping
`the distal surface of a femur to receive a distal femoral
`prosthesis which enables a surgeon to shape that surface
`as accurately as possible using certain external reference
`points associated with the surface of the distal femur.
`One object of the present invention is to provide a
`means by which certain reproducible reference points
`for the shaping of the distal femoral surface can be
`instrumentally located and fixed.
`It is another object of the present invention to pro-
`vide a fixed alignment guide upon which all femoral
`surface resection guiding instruments can be mounted
`such that the alignment of each instrument is always
`made relative to certain reference points located on the
`distal portion of the femur: the anterior surface of the
`distal portion of the femur, the intercondylar notch
`located between the medial and lateral distal femoral
`condyles, and the posterior aspects of the distal femoral
`condyles.
`It is another object of the present invention to pro—
`vide a method for overcoming the difficulties involved
`in attempting to externally locate the central long axis
`of the femur, particularly when the femur contains a
`deformity, and to enable a surgeon to more accurately
`shape the distal surface of a femur relative to that axis
`for the purpose of receiving a distal femoral prosthesis
`in a relatively simple manner.
`These and other objects of the present invention are
`provided by a method which comprises placing a main
`body of an alignment guide having a resection guide
`instrument holder affixed thereto on the anterior surface
`of the femur wherein the holder is adjusted to hold a
`pivotable resection guide instrument at a preselected
`angle with respect to the central long axis of the main
`body and of the femur; inserting a locator pin through
`the pivot point of the holder; advancing the main body
`along the anterior surface of the femur until the locator
`pin contacts the center of the intercondylar notch of the
`distal femoral condyles; rotating the main body to prop-
`erly align the central axis of the locator pin transversely
`with respect to the posterior aspects of the femoral
`condyles; affixing the main body to the femur; attaching
`a distal femoral surface shaping guide instrument to the
`instrument holder; modifying the distal femoral surface
`through the use of that instrument; attaching other
`guide instruments as needed and further modifying the
`distal femoral surface; removing the alignment guide;
`and completing any further shaping of the distal femoral
`surface.
`
`'WIVIT 1013.5-...........................
`
`WMT 1013-5
`
`

`

`4,502,483
`
`3
`This invention also relates to a distal femoral align-
`ment guide which is a combination of a main body, an
`instrument holder, a locator pin, a distal femoral surface
`shaping guide and a means for affixing the main body to
`the femur.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`The above and other objects, features and advantages
`of the present invention will become apparent to those
`skilled” in the art upon an examination of the following
`description and drawings which are merely illustrative
`of the present invention.
`,
`In the Drawings:
`FIG. 1 is a plan view of the main body of the align—
`ment guide of the present invention.
`FIG. 2 is a side view of FIG. 1.
`FIG. 3 is a front view of FIG. 1.
`FIG. 4 is a plan view of a resection guide instrument
`holder.
`'
`FIG; 5 is a side view of FIG. 4.
`FIG. 6 is a front View of FIG. 4.
`FIG. 7 is a front view of a distal femoral condyle
`resection guide instrument.
`FIG. 8 is a plan view of FIG. 7,.
`FIG. 9 is a side view of FIG. 7.
`FIG. 10 is a rear view of an anterior-posterior distal
`femoral condyle resection guide.
`FIG. 11 is a side view of FIG. 10.
`FIG. 12 is a front View of FIG. 10.
`FIG. 13 is a perspective View of a human knee with
`the distal femur and proximal tibia exposed, further
`showing the main body of FIG. 1 in place, the resecting
`guide instrument holder of FIG. 4 in placeand a locator
`pin.
`.
`FIG. 14 is a perspective View as in FIG. 13 further
`having the distal femoral condyle resection guide in-
`strument of FIG. 7 in place.
`.
`FIG. 15 is a perspective View as in FIG. 13 further
`having the anterior—posterior distal femoral condyle
`resection guide instrument of FIG. 10 in place.
`FIG. 16 is a side perspective view of the last step in
`shaping a distal femoral surface in accordance with the
`- method of the present invention.
`FIG. 17 is a side perspective view of a distal femoral
`surface fully shaped in accordance with the method of
`the present invention.
`
`DETAILED DESCRIPTION OF THE
`INVENTION
`
`Referring to the drawings, FIGS. 1—3 show the pre-
`ferred form for the main body 10 of the alignment guide
`of the present invention. Main body 10 contains a pair of
`positioning fins 11 and 12 which are adapted to rest on
`the anterior surface of the shaft of the distal femur and
`in the embodiment shown are 0.5" (12.7 mm)—the sym-
`bol- means inches and mm means millimeters—in width
`at edge 21 appearing in the side view of FIG. 2. Arm 13
`connects fins 11 and ,12 to transverse positioning plate
`14. In the preferred embodiment of FIG. 2, the distance
`along the upper surface of arm 13 from plate 14 to the
`point where fin 12 angles downward is 2” (50.8 mm),
`the distance from plate 14 to the distal end of fin 12 is 3”
`(76.2 mm), the distance between the outer edges 21 and
`22 of fins 11 and 12 as shown in FIG. 1 is about 1.4" (36
`mm) and the angle 8 between an extension of the upper
`surface of fin 12 and surface 13 'is 30°. In FIG. 2, plate
`14 is 1.47" (37.3 mm) high and 0.25” (6.4 mm) thick
`having a distance of 0.69” (17.5 mm) between the upper
`
`4
`surface of plate 15 and the upper surface of arm 13. Arm
`13 is 0.28” (7.1 mm) in thickness. In FIG. 3, plate 14 is
`1.87” (47.5 mm) in width. Cylindrical guideplate holder
`16 extends upward from plateau 15 and is designed to .
`cooperatively engage with the hereinafter described
`resection instrument guide holder and in the preferred
`embodiment shown is 0.497” (12.6 mm) in diameter,
`0.63” (16 mm) high and has a concentric passage 17
`through its center which is transverse to and passes
`through plateau 15. Passage 17 is adapted to coopera-
`tively engage a locator pin as will be described infra. In
`the embodiment shown in FIG. 1, passage 17 is 0.257"
`(6.5 mm) in diameter and the center (central long axis)
`of passage 17 is 0.38" (9.7 mm) from edge 23 of plateau
`15. The preferred main body .10 shown in FIG. 1 is
`5.63” (143 mm) in length from a vertical plane defined
`by the distal edgesof fins 11 and 12 to the edge 23 of
`plateau 15, i.e., along its central long axis.
`In the preferred embodiment shown in FIG. 1, four
`threaded passages 18 and corresponding threaded pas-
`sages 19 pass through the surface of plateau 15 with the
`centers of passages 18 and 19 which are closest
`to
`holder 16 being a horizontal distance of 1" (24.4 mm)
`from the central long axis (center) of holder 16, the
`measurement being taken along the horizontal central
`long axis of main body 10, and, the remainder of pas-
`sages 18 and 19 are situated a horizontal distance of
`1.25”, 1.50” and 1.75” (31.8 mm, 38.1 mm and 44.4 mm),
`respectively, from that axis. Each passage is placed on
`plateau 15 such that when the hereinafter described .
`resection guide instrument holder is affixed to the main
`body, the holder can be adjusted to hold a resection '
`guide instrument at a fixed angle with respect to the
`horizontal central long axis of the upper portion of main
`body 10 and thereby tovthe central long axis of the
`femur which is caused to run through the horizontal
`central long axis of the upper portion of the main body
`10 by means of the hereinafter described manner in
`which it is affixed to the distal femur. In the preferred
`embodiment shown, the centers of the closest of pas-
`- sages 18 and 19 to passage 17 are each typically situated
`0.0435” (1.10 mm) from the horizontal central long axis
`of main body 10 while the remaining passages are situ-
`ated 0.0765", 0.119” and 0.170” (1.94 mm, 3.02 mm and
`4.32 mm), respectively, away from the central long axis
`(center) of holder 16. As shown in FIG. 2, a reinforcing
`means shown as rib 20 may be fitted between position—
`ing plate 14 and plateau 15 to strengthen and rigidify
`plateau 15. All measurements specified herein are nomi-
`nal.
`FIG. 3 shows main body 10 from the front showing
`the recess 24 in positioning plate 14 which as a configu-
`- ration similar to fins 11 and 12 and is likewise adapted to
`rest on the anterior surface of the distal femur to se-
`curely affix main body 10 to that surface. In the pre—
`ferred embodiment shown, the‘recess 24 extends 0.5”
`(12.7 mm) upward in the center and the sides are set at
`a 45° angle with respect to a plane running across recess
`24 along the bottom edge of positioning plate 14.
`FIGS. 4~6 show the preferred form for the resection
`guide instrument holder 40 which cooperates with the
`previously described main body 10 in forming the align-
`ment guide of the present invention. Holder 40 is com-
`posed of a locator plate 41 having a raised portion 42
`which cooperatively engages guideplate holder 16 of
`main body 10 by means of passage 44. Passage 44 fits
`over guideplate holder 16 and allows plate 41 to pivot
`about the central long axis of guideplate holder 16 to
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`45
`
`50
`
`55
`
`65
`
`
`
`WMT» 1013-6
`
`WMT 1013-6
`
`

`

`4,502,483
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`6
`, position which is transverse to the central long axis of
`main body 10 (not shown).
`Since the central long axis of passage 44 is adapted to
`be concentric with the central long axis of passage 17 in
`main body 10, the position of the guide surfaces 77 and
`78 of guideplates 75 and 76 which are distal to recessed
`portion 71 and which are used to guide a resection
`means such as a saw blade are situated along the distal
`femoral condyles relative to the position of the central
`long axis of passage 17. As can be seen in FIG. 13, a
`locator pin 129 having handle I31 and having a posi-
`tioning portion 130 which is adapted to cooperatively
`engage with passage 17 is passed through passage 17
`and main body 10 is moved toward the proximal end, of
`the femur until the rear surface of portion 130 rests in
`the middle of and against the distal intercondylar notch
`135 of distal femur 134. As a result, the guide surfaces 77
`and 78 are spaced away from notch 135 a distance equal
`to the distance between a plane formed by guide sur-
`faces 77 and 78 of guideplates 7S and 76 and the central
`long axisof passage 17 plus an amount equal to the
`radius of portion 130 (0.250" (6.35 mm) in diameter
`when passagetl'l is 0.257“ (6.53 mm) in diameter) be-
`cause the central long axis of portion 130 is adapted to
`be concentric with passage 17. The actual distance se-
`lected is dependent upon the configuration of the distal
`femoral prosthesis for which the distal femoral surface
`is being shaped to receive. Instrument 70 enables a sur~
`geon to easily and reproducibly resect the distal femoral
`condyles of both the right and left femur using the same
`guide instrument 70 and the resection is always made
`relative to the distal intercondylar notch and transverse
`to and at a preselected angle with respect to the central .
`long axis of the femur. Another advantage is that the
`alignment guide is noninvasive, i.e., it is not affixed to
`the femur by boring holes or by using other fixation
`means which extend through the surface of the femur.
`FIGS. 10-12 show a preferred embodiment of an
`anterior~posterior condyle resection guide instrument
`100 which contains a recessed portion 101 which is
`adapted to cooperatively engage the front surface 49
`and sides of guideplate 43 of FIG. 6. A locking bolt or
`other means is passed through slot 102 to holder 40 as
`shown in FIG. 15. Recessed portion 101 functions in the
`same manner as does the previously described recessed
`portion 71 of instrument 70. However, portion 101 fur-
`ther includes passage 103 which is also adapted to coop-
`eratively engage a locator pin 129 having positioning
`portion 130 as shown in FIG. 15 such that the rear
`portion of positioning portion 130 is inserted through
`passage 103 up to handle 131 and instrument 100 is
`lowered until the rear surface of portion 130 contacts
`the anterior surface of the femur 150 located in the
`intercondylar notch between the anterior aspects of the
`lateral and medial femoral condyles. The distance be-
`tween the lower surface of portion 103 and the upper
`surface of guideplate 104 is selected to suit the require-
`ments of the distal femoral prosthesis for which the
`distal femoral surface is being shaped to receive because
`the upper surfaces of guideplate 104 located on either
`side of portion 101 are employed as resection guide
`surfaces upon which a resection means such as a saw
`blade is placed to accomplish resection of the anterior
`aspects of the medial and lateral femoral condyles. The
`lower surface 'of guideplate 104 is likewise ldcated at a
`preselected distance from the lower surface of position-
`ing portion 130 which suits the requirements of the
`distal femoral prosthesis selected and those'lower sure
`
`5
`enable resection guide instruments which cooperatively
`engage with guideplate 43 to be pivoted about the same
`axis. {Guideplate 43 is affixed to and forms a part of
`raised portion 42 and locator plate 41. When holder 40
`is affixed to main body 10 as shown in FIGS. 13—15 and
`locator plate 41 is pivoted about the central axis of
`holder 16, passages 47 which are marked with numerals
`48 are brought into alignment with passages 18 (for the
`right femur) and passages 19 (for the left femur as indi-
`cated by reference numeral 46). A locking bolt or other
`position fixing means can then be placed through the
`preselected passage 47 and corresponding appropriate
`passage 18 or 19 to cause the front surface 49 of guide-
`plate 43 to assume a specific angle (5°, 7°, 9", 11° or
`some other preselected angle) with respect to the hori~
`zontal central long axis of the main body 10 and thus
`with respect to the central long axis of the femur to
`shape the femur to the preselected degree of physiolog-
`ical valgus. As will be described infra, guideplate 43 is
`of a suitable configuration which enables a distal femo-
`ral surface resection guide to be cooperatively engaged
`with it such that the distal femoral surface is resected »
`relative to the position of holder 40 to the horizontal
`central long axis of main body 10. To this end, guide-
`plate 43 contains passages 45 and 50 which are threaded
`or contain some other means therein to receive a means
`for fixedly securing a resection guide instrument to
`guideplate 43.
`,
`In the preferred embodiment shown in FIGS. 4—6,
`passage 44 has a 0.500" (12.7 mm) inner diameter when
`main body 10 having holder 16 of 0.497” (12.6 mm)
`outer diameter is employed. The centers of passages 47
`are located 0.004”, 1.259", 1.519" and 1.783” (25.50 mm,
`31.98 mm, 38.58 mm and 45.29 mm), respectively, from
`the center of passage 44. In the preferred embodiment
`shown, the planar surface 49 of guideplate 43 facing
`shown in FIGS. 5 and 6 is vertically (FIG. 5) parallel to
`the central long axis of passage 44 and horizontally
`transverse (FIG. 6) to the plane of the lower surface of
`locator plate 41 and, thus, is transverse to the central
`long axis of main body 15. In the preferred embodiment
`shown, the distance between the center of passage 44
`and planar surface 49 of FIG. 4 is 0.812” (20.6 mm). In
`the preferred embodiment shown in FIG. 4, holder 40 is
`3.06” (77.7 mm) in its longest dimension and 0.76” (19.3
`mm) in its shortest dimension. In the preferred embodi-
`ment shown in FIG. 5, locator plate 41 is 0.25" (6.4 mm)
`in thickness and is 0.375” (9.5 mm) above the lower
`edge of guideplate 43, raised portion 42 is 0.63” (16 mm)
`in height and guideplate 43 is 0.38” (9.7 mm) in thick-
`ness. In FIG. 6, the preferred embodiment of guideplate
`43 shown is 1.5” (38.1 mm) in height and 0.75" (19.1
`mm) in width with passages 45 and 50 being 0.25” (6.4
`mm) in diameter and are spaced 1" (25.4 mm) apart.
`FIGS. 7—9 show a preferred embodiment of a distal
`femoral condyle resection guide instrument 70. Instru-
`ment 70 has a recessed portion 71 which is adapted to
`cooperatively engage the front surface 49 and sides of
`guideplate 43 shown in FIG. 6. A locking bolt or other
`means is passed through slot 72 in portion 71 to secure
`instrument 70 to holder 40 as shown in FIG. 14. Portion
`71 has resection guides 75 and 76 attached to it by
`means of arms 74 and 73, respectively. Arms 74 and 73
`hold the guide surfaces 77 and 78, respectively of resec-
`tion guides 75 and 76 at a fixed and preselected distance
`from and parallel to the central long axis of passage 44.
`At the same time, guide surfaces 77 and 78 are held in a
`
`50
`
`55
`
`60
`
`65
`
`............WMT~ 1 013-7
`
`WMT 1013-7
`
`

`

`4
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`45
`
`55
`
`60
`
`65
`
`7
`faces are used to guide a resection means in resecting
`the posterior aspects of the medial and lateral femoral
`condyles. The rear surface of guideplate 104- is parallel
`to the central long axis of passage .17 of main body 10
`and is thus transverse to the central long axis of the main
`body 10 and of the femur. Bevel cutting guides 105 and
`106 are located in guideplate 104 in such a manner that
`the anterior distal femoral aspects of the femoral con-
`dyles are resected at an angle 9 as shown in FIG. 11. In
`the embodiment shown, angle 9 is 45" with respect: to an
`extension of slot 106 and the rear surface of guideplate
`104; The location of slots 105 and 106 relative to the
`lower surface (contacting the femur) of positioning
`portion 130 as well as the angle 9 will be dictated by the
`type of distal femoral prosthesis selected to be affixed to
`the distal femoral surface.
`Passages 107 and 108 act as guides for the boring of
`holes in the distal femoral surface to receive distal femo-
`ral prosthesis fixation studs which are used to hold the
`selected distal femoral prosthesis to the femur and their
`location on guideplate 104 is likewise dictated by the
`prosthesis selected. It is another advantage of the pres-
`ent invention that instrument 100 and the other appara-
`tus described herein. can be used to shape the distal
`femoral surface of both the left andthe right femur.
`Distal femoral prostheses are well known to those
`skilled in the art as shown in the previously noted How— '
`medica, Inc. brochure and no specific details as to their
`design are included herein. It is well within the ability
`of those skilled in the art to construct guide instruments
`in accordance with the aforementioned description
`which meet the specific design requirements to produce
`a shaped distal femoral surface for a particular distal
`femoral prosthesis.
`The above described main body, locator plate, resec~
`tion instruments and components thereof are all prefera-
`bly manufactured from a suitable surgical grade of stain-
`less steel of the type commonly employed by those
`skilled in the art to construct surgical tools for use in
`contact with the body. The exact composition of the
`metal from which the above are constructed forms no
`part of the present invention and other metals suitable
`for use within the body and for the intended uses of the
`instruments may be used without altering the nature of
`the invention.
`The manner in which the method of the present in-
`vention may be carried out will now be described. The
`pro-operative procedures for radiographically deter-
`mining the central long axis of the femur and the angle _
`50
`at which resection of the distal femoral surface is to be
`made with reSpect to that axis (physiological valgus)
`using this method is the same as is typically employed in
`other methods known to those skilled in the art. Defor-
`mities in the femur are also noted during this procedure.
`Operatively, the extremity is prepared and draped in
`the usual manner. An anterior 5" to 6" (127 mm to 152
`mm) midline incision is made with the knee flexed to 90
`degrees. The knee is then placed in extension and dissec-
`tion is carried out in line with the skin incision down
`through the medial retinaculum. Subperiosteal flaps are
`developed medially and laterally about the metaphyseal
`flares. The patella is reflected laterally and the knee is
`flexed to 90 degrees. The anterior portion of the menisci
`are excised and the anterior cruciate ligament is incised.
`If a proximal tibial prosthesis is to also be implanted
`as’in total knee implant surgery, the proximal tibial.
`~ surface may preferablynow ‘be shaped to receive that
`proximal tibial prosthesis in the manner typically em-
`
`4,502,483
`
`8
`ployed for such a prosthesis. The tibial surface should
`be prepared such that the tibial prosthesis will properly
`align and cooperate with the distal femoral prosthesis
`which is attached to the distal femoral surface being
`shaped in accordance with the method of the present
`invention.
`
`After the proximal tibial surface has been shaped the
`kneeis placed1n extension and a “T” incisionis made'1n
`the synovial recess off the anterior femur A plane is
`developed between the soft areolar tissue and the peri—
`osteum. Care should be taken not to strip the periosteum
`from the anterior portion of the femur.
`The aforementioned surgical procedure is not illus-
`trated. The following operations can be followed by
`referring to FIG. 13 which illustrates the end result of
`' these operations. Locator 40 is cooperatively engaged
`with main body 10 by inserting holder 16 through pas—
`sage 44 and locking bolt 133 is passed through the ap~
`propriate passage in locator plate 41 corresponding to
`the desired degree of valgus radiographically deter-
`mined to be needed for the patient. Typically, an angle
`of 5°, 7°, 9°, or 11° will suffice with 9" being the most
`commonly used degree of valgus. Locator plate 41 is
`rotated about holder 16 until the correct passage, (18 for
`the right and 19 for the left femur) in main body 10 lines
`up with passage 44 and locking bolt 133 is passed into
`passage 18 or 19 to fix locator 40 to main body 10.
`Positioning portion 130 of locator pin 129 is placed
`through passage 17 in main body 10 and main body 10
`is then inserted along the anterior shaft of the femur
`with fins 11 and 12 resting along that shaft until posio
`tioning» portion 130 contacts the distal intracondylar
`notch 135 and main body 10 cannot be inserted any
`further.
`long axis of positioning portion 130
`The central
`should then be aligned perpendicular to a plane defined
`by the posterior aspects of the medial and lateral femo-
`ral condyles by moving main body 10 from side to side
`until it is aligned as above. Generally, if there is no
`angular deformity in the distal femoral surface,
`the
`central long axis of positioning portion 130 will point
`down the shaft of the tibia. The alignment may be
`checked by placing a straight edge transversely along
`the posterior surfaces of the femoral condyles to insure
`that the central long axis of positioning portion 130 is
`perpendicular to the plane defined by the posterior
`surfaces of the femoral condyles. This positioning deter-
`mines the proper rotational alignment for the distal
`femoral prosthesis to be attached.
`Main body 10 with locator 40 attached theretois then
`securely fixed to the distal femur 134 by some suitable
`means such as clamp 136. In FIG. 13, locator pin 129 is
`shown above passage 17 for the purposes of clarity.
`Locking bolt 132 which is employed to secure resection
`guide instruments to guideplate 43 is shown in exploded
`fashion set away from passage 50. For SOme distal femo-
`ral surfaces, it may be more desirable to place locking
`bolt 132 in passage 45 instead of passage 50.
`The positioning pin is removed and distal femoral
`condyle resection guide instrument 70 is cooperatively
`engaged'with guideplate 43 of locator 40 and lOWered
`until the arms 73 and ’74 rest on the anterior surfaces of
`the distal femoral condyies and secured to guideplate 43
`by means of locking bolt 132. A resection means such as
`an oscillating saw (not shown) is placed against the
`distal surface 78 of guide 76 and the saw is brought
`across the guide 76 in the direction of the arrows shown
`on surface 78 to transversely resect the distal femoral
`
`-
`
`.
`
`~~WMT 1013-8
`
`
`
`WMT 1013-8
`
`

`

`4,502,483
`
`9
`condyle. The same procedure is repeated for the oppo-
`site distal condylar surface using guide 75 to guide a
`resection means in the direction of arrows 142. Instru-
`ment 70 is then removed and the resection of each distal
`condylar surface is completed if it could not be com~ 5
`pleted with instrument 70 in place. The resulting re~
`sect'ed distal femoral surface is transverse to the central
`long axis of the femur and offset from that axis by the
`pres