United States Patent [191
`Dunn et al.
`
`[11]
`[45]
`
`Patent Number:
`Date of Patent:
`
`4,759,350
`Jul. 26, 1988
`
`[54] INSTRUMENTS FOR SHAPING DISTAL
`FEMORAL AND PROXIlVIAL TIBIAL
`SURFACES
`[76] Inventors: Harold K. Dunn, 1231 Chandler Cir.;
`Kim C. Bertin, 666 Northcliffe Cir.,
`both of Salt Lake City, Utah 84103
`[21] Appl. No.: 919,971
`[22] Filed:
`Oct. 17, 1986
`[51] Int. Cl.‘ .............................................. .. A61F 5/04
`[52] US. Cl. ............................................. .. 128/92 VW
`[58] Field of Search ....... .. 128/92 VW, 92 V, 92 VY;
`.
`623/39
`
`[56]
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`4,524,766 6/ 1985 Petersen ...................... .. 128/92 VW
`4,646,729 3/1987 Kenna et al. ............... .. 128/92 VW
`
`FOREIGN PATENT DOCUMENTS
`
`0121786 10/1984 European Pat. Off. .... .. 128/92 VW
`
`OTHER PUBLICATIONS
`Howmedica Catalog, 1984.
`A.O.R. Catalog.
`Zimmer Catalog, 1986.
`Johnson and Johnson Catalog, 1984.
`Dow Corning Wright Catalog, 1984.
`R.M.C. Catalog, 1978.
`Insall/Burstein Total Condylar Knee System, 1981.
`Primary Examiner-C. Fred Rosenbaum
`Assistant Examiner--Mark Colosimo
`Attorney, Agent, or Firm—-M. Reid Russell
`
`ABSTRACT
`[57]
`The present invention provides a system of instruments
`for shaping the distal femur and proximal tibia surfaces
`to receive components of a knee prosthesis for knee
`replacement surgery. The system references the femur
`intramedullary channel with a femoral alignment guide
`to prepare the distal femur that, in turn, is a reference
`for several cutting guides for sequential attachment to
`the femoral alignment guide and prepared bone surfaces
`whereby the prepared distal femur is prepared to a ?at
`surface that is perpendicular to the patient’s mechanical
`axis with bone surfaces adjacent thereto sectioned to
`surfaces that are at right angles to that distal femur
`surface with chamfers therebetween to receive the
`femur component of a knee prosthesis. A tibial cutting
`guide is provided for preparing the proximal tibia that
`consists of a sleeve, with a tube telescoped therein, the
`ends thereof including pin arrangements for connecting
`them into the tibia, between the ankle and near the
`proximal tibia, an open tube end of the tibial cutting
`guide to receive a rod telescoped therein that mounts a
`cutting guide platform and includes a screw arrange
`ment for releasably maintaining the rod and tube to
`gether. The cutting guide platform includes a body with
`a saw guide slot formed therethrough to receive a saw
`blade to cut across the proximal tibia to form a surface
`for accommodating a tibial component of the knee pros
`thesis, the cutting guide platform body further includ
`ing an arrangement for securing it to the tibia, slightly
`below the proximal tibia, and a tibial resection guide for
`setting a depth of cut across the proximal tibia.
`
`30 Claims, 5 Drawing Sheets
`
`4
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`-1-
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`Smith & Nephew Ex. 1036
`IPR Petition - USP 7,534,263
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`

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`US. Patent Jul. 26, 1988
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`Sheet 1 of 5
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`4,759,350
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`34
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`U.S. Patent
`Jul. 26, 1988
`US. Patent Jul. 26, 1988
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`Sheet 2 of 5
`Sheet 2 of5
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`4,759,350
`4,759,350
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`US. Patent Jul. 26, 1988
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`Sheet 3 0f 5
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`4,759,350
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`FIG.
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`53
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`FIG. I3
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`9O
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`I. 1/
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`62
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`3 5
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`FIG.
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`l2
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`U.S. Patent
`Jul. 26, 1988
`US. Patent Jul. 26, 1988
`
`Sheet 4 of5
`Sheet 4 of5
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`4,759,350
`4,759,350
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`US. Patent Jul. 26, 1988
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`Sheet 5 of5
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`4,759,350
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`4 . I /////,
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`FIG.
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`FIG. I7
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`I29
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`FIG. l8
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`FIG. 20
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`-6-
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`1
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`INSTRUMENTS FOR SHAPING DISTAL
`FEMORAL AND PROXIMAL TIBIAL SURFACES
`
`5
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`4,759,350
`2
`ferent from those taught by the present invention, and,
`of course, the Lacey patent does not involve a length
`adjustable tibial cutting guide as does the present inven
`tion.
`The present invention provides a set of alignment and
`cutting guides and method for their use that is easier and
`more reliable for a surgeon to operate with as compared
`with earlier arrangements and provides a system that
`even a surgeon who has limited experience in total knee
`reconstruction surgery can use. The present invention
`provides a surgeon with the capability to simply and
`accurately prepare distal femur and proximal tibial bone
`ends to receive a preferred knee prosthesis ?xed thereto
`within a time frame that is reasonable for the perfor
`mance of the surgical procedure.
`
`BACKGROUND OF THE INVENTION
`1. Field Of The Invention
`The present invention relates to medical instruments
`and a method for their use and pertains particularly to
`an improved instrument system for accurately prepar
`ing and shaping distal femur and proximal tibia end
`surfaces to receive a knee prosthesis secured thereto.
`2. Prior Art
`In recent times knee surgery for the repair and/or
`replacement of knee joints has become increasingly
`common. Such total knee implant, when properly in
`stalled, will closely approximate or mimic natural knee
`movement. Even with such improvement in total knee
`structures, however, there still exists the problem of
`properly ?tting and installing such prosthesis. Hereto
`fore, with the surgical instruments available, a surgeon
`installing such implant must have had a high degree of
`skill in order to achieve optimum ?t and alignment. It
`has therefore been recognized that it is desirable to
`provide an effective system of instruments and method
`for their use to insure a high degree of success in the
`preparation of the distal femur and proximal tibial ends
`to receive a prosthesis secured thereto.
`Even prior to the present invention the need to pro
`vide such a system suitable for use by even a less skilled
`surgeon to reliably and efficiently prepare distal femur
`and proximal tibia ends for receiving a knee prosthesis
`has resulted in the development of several systems. One
`such system is shown in a patent by Petersen, U.S. Pat.
`No. 4,524,766 that involves a surgical knee alignment
`and cutting guide system and method. This system ref
`erences a patient’s mechanical axis and from that deter
`mination provides cutting guides for selective attach
`ment for shaping the patient’s proximal tibia to receive
`the tibia portion of the knee prosthesis and mounts cut
`ting guides from the tibia components for appropriately
`shaping the distal femoral end to receive the femur
`portion of that knee prosthesis. Where the present in
`vention is intended to accomplish the same result, the
`structure thereof and its use are decidedly distinct from
`this device. Particularly, for shaping the tibia proximal
`end, the present invention involves an elongate extensi
`ble support frame that, unlike the Petersen system, pro
`vides for a close calibration of length adjustment capa~
`bility. Additionally, unlike this earlier Petersen patent
`that references from the tibia, the present invention
`references from the patient’s distal femur and provides
`for locating the patient’s mechanical axis from their
`anatomical axis, and after referencing that mechanical
`axis, employs an alignment guide and cutting guides
`that are distinct from those of the Petersen patent.
`Another system for shaping the distal femur is shown
`in a patent by Lacey, US. Pat. No. 4,502,483. This
`patent, like the present invention, provides for locating
`a patient’s mechanical axis relative to their anatomical
`axis and accordingly then locates and secures a femoral
`distal cutting guide to that bone end to form a ?rst cut
`across the femoral condyle. From this ?rst cut, the
`distal femur end is cut at a right angle to the patient’s
`mechanical axis. Like the Lacey patent, the present
`invention references the patient’s mechanical axis and
`provides for establishing a desired angle to their femur
`anatomical axis to calculate that mechanical axis. The
`cutting guides of Lacey, however, are structurally dif
`
`SUMMARY OF THE INVENTION
`The principal object of the present invention is to
`provide an apparatus and system for accurately shaping
`distal femur and proximal tibia end surfaces to receive
`components of a knee joint prosthesis attached thereto
`such that the attached prosthesis will be aligned to func
`tion so as to approximate the functioning of a natural
`knee joint.
`Another object of the present invention is to provide
`a system for determining a patient’s mechanical axis
`with reference to their anatomical axis with an align
`ment guide of the invention that is arranged for ?tting
`into a hole drilling into the distal femur end that inter
`sects the femoral intramedullary channel, and further
`includes cutting guides that are sequentially attached to
`that alignment guide and shaped bone surfaces used in
`shaping that distal femur end to receive the femur por
`tion of the knee prosthetic.
`Still another object of the present invention is to
`provide a tibial cutting guide for attachment to a tibia
`between the patient’s ankle and below their proximal
`tibial end, which guide is for alignment with the pa
`tient’s mechanical axis and provides a cutting guide
`arrangement that is adjustable for controlling the depth
`of cut thereacross for forming the tibia proximal end to
`receive a tibia portion of the knee prosthesis.
`Still another object of the present invention is to
`provide a system for accurately preparing the distal
`femur and proximal tibial ends such that the plane of
`each of said cuts across the bone ends will be appropri
`ate to receive the portions of a knee prosthesis selected
`to re?ect the spacing distance and size of the respective
`bone ends such that, the installed prosthesis will func
`tion as a total knee system, approximating the mechani
`cal functioning of a normal knee.
`In accordance with the above objects, the present
`invention is in a system of surgical instruments and a
`method for their use for preparing distal femur and
`proximal tibia ends to receive a knee prosthesis secured
`thereto that replace a natural knee. The distal femur end
`preparation portion of the system includes: a femoral
`alignment guide; anterior femoral cutting guide with
`locator; a distal femoral cutting guide; an A/P measur
`ing guide; a femoral ?nishing guide; and the system for
`preparing the proximal tibia end includes; a tibial cut
`ting guide with a cutting platform and a tibial depth
`resection guide. In practice, a surgeon, after opening the
`damaged knee area sequentially utilizes these instru
`ments to prepare a patient’s distal femur and proximal
`tibia ends to receive knee components of a select pros
`thesis secured thereto.
`
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`Use of the system of the present invention requires
`ing an equal angular chamfer that extends from the
`?rst a determination of the angle between a patient’s
`parallel surfaces and intersects the distal femur end. The
`anatomical axis and their mechanical axis to reproduce
`distal femur end is thereby equaled or squared off to
`a use of the system of the present invention, which
`receive a femur portion of the select knee prosthesis
`anatomical axis is determined by reference to the femur
`?tted thereto.
`intramedullary channel. To verify this reference a hole
`With the distal femur end prepared, as set out'above,
`is drilled into the distal femur that is parallel to the shaft
`the opposing proximal tibia end is shaped to compli
`of the femur to intersect the intramedullary channel.
`ment that distal femur end preparation utilizing a tibial
`Whereafter the femoral alignment guide is secured to
`cutting guide. The tibial cutting guide of the present
`that distal femur surface so as to be perpendicular to the
`invention is arranged for attachment to the tibia to ex
`posterior femoral condyles. In such positioning, approx-:
`tend between the center of the patient’s ankle and proxi
`imately equal amounts of medial and lateral femoral
`mal to the tibial tubercle. The tibial cutting guide is set
`condyle are exposed posterior to or behind the guide.
`to be parallel to the tibia mechanical axis and is con
`To the femoral alignment guide is attached an anterior
`structed to be telescoped between its two tibia connec
`femoral cutting guide that includes a locator that ex
`tion points. The tibial cutting guide additionally in
`tends therefrom so as to just touch the interior cortex of
`volves a cutting platform that is arranged to be indepen
`that femur, proximal to the anterior condyles. So posi
`dently telescoped and includes a cutting guide slot
`tioned, a saw or like cutting device is ?tted through a
`formed thereacross that is to receive a reciprocating
`cutting guide slot of that anterior femoral cutting guide
`saw blade ?tted therethrough to cut across the tibia.
`and is reciprocated to cut across the femoral condyles.
`The plane of which tibia cut, to accommodate the se
`The depth of which cut is to be suf?cient to accommo
`lected tibia prosthesis component, is at a ten degree
`date the ?tting a distal femoral cutting guide to that
`(10°) angle below a perpendicular plane to that patient’s
`bone surface after removal of the anterior femoral cut
`mechanical axis. The cutting platform further includes a
`ting guide.
`tibial depth resection guide that is positionable across
`The distal femoral cutting guide is for pivotal mount
`the proximal tibia end to set a desired depth of tibial
`ing to the femoral alignment guide so as to be angularly
`resection. Appropriately setting the depth of cut ena
`adjustable thereto. The angular adjustability is around a
`bles the surgeon to compensate for bone defects in that
`transverse axis across the distal femur to position a
`proximal tibial surface.
`cutting surface of the guide to a plane that is perpendic=
`The above sets out the apparatus and system of the
`ular to the patient’s mechanical axis. The angular posi
`present invention for preparing the distal femur and
`tioning, once set, is initially maintained by a pivot pin
`proximal tibia ends. To fully prepare a patient’s knee to
`arrangement and is later secured by ?tting two or three
`receive a knee prosthesis additionally involves prepar
`pins through appropriate openings in the guide that are
`ing their patella to receive a certain thickness of patella
`turned into the femur. Thereafter, the femoral align
`component of that knee prosthesis secured thereto.
`ment guide can be left in place or removed as a saw
`35
`Patella preparation in the system of the present inven
`blade is ?tted through the slot in the distal femoral
`tion preferably involves well known tools and a system
`cutting guide and is reciprocated to cut across the face
`for the use for longitudinally cutting the patella at the
`of the distal femur. This cut is thereby made across the
`level of the quadriceps tendon and preparing it to re
`distal femur end at a right or normal angle to the pa
`ceive a selected patellar implant.
`tient’s mechanical axis. It is from this cut surface that
`With the distal femur and proximal tibia ends appro
`the other cuts to be made in the distal femur are refer
`priately formed, as set out above, and after the prepara
`enced.
`tion of the patella, a trial reduction and ?xation of the
`After removal of the distal femoral cutting guide, and
`knee prosthesis is attempted. This trial involves ?tting
`the femoral alignment guide, if such had been left in
`the prosthesis components to the prepared surfaces and
`place, a measuring guide is fitted across that distal femur
`45
`checking the patient’s range of motion and the ligament
`?at surface. The measuring guide includes spaced apart
`stability that will be afforded by the prosthesis attach
`parallel feet on the bone engaging surface that are set on
`ment. This check may include performing necessary
`the cartilage of the posterior condyles and further in
`tissue release to effect the desired range of motion.
`cludes a mobile gauge portion thereof that extends from
`After that trial, the proximal tibial end is preferably ?rst
`the measuring guide body to rest on the cut anterior
`?tted with the tibial base plate followed by ?tting the
`femoral surface. The measuring guide provides for siz~
`femur portion of the prosthesis to the prepared distal
`ing a femur portion of a knee prosthesis, which size can
`femur end and securing the patella prosthesis to the
`be read directly from a scale thereon. Thereafter, the
`patella. The result is tested and thereafter the incision
`measuring guide is removed and a femur ?nishing guide
`into the kneecap is appropriately closed and dressed.
`is ?tted over that prepared ?at femur distal end surface
`such that a top ledge adjacent to the bone engaging
`The above sets out a brief summary of the compo
`nents of the system along with their use in preparing the
`surface thereof will rest on the cut surface of the ante
`opposing distal femur and proximal tibial ends and the
`rior femur. This guide, after careful ?tting to the pre
`pared distal femur, receives a drill ?tted through holes
`patella to receive a selected knee prosthesis ?tted
`thereto that will, after healing, mimic or approximate
`formed therethrough that is turned into the bone end.
`To securely hold that ?nishing guide in place fasteners
`the range of motion of a natural knee.
`are turned into the drilled holes. So positioned, a recipa
`rocating saw blade, or like cutting instrument, can be
`?tted through appropriate slots formed in that femur
`?nishing guide to cut, in turn, the femur posterior con
`dyles, posterior chamfers. anterior condyles and ante
`rior chamfers. The posterior and anterior distal femur
`sides are thereby cut parallel to one another, each hav
`
`THE DRAWINGS
`These and other objects will be apparent from the
`following detailed description in which preferred em
`bodiment and method for its use of the present inven
`tion has been described in detail in conjunction with the
`accompanying drawings.
`
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`cutting platform for positioning relative to the proximal
`tibia such that a saw guide slot portion thereof will be
`positioned to receive a saw blade therethrough to cut
`across that proximal tibia;
`FIG. 15 shows a side elevation view the of the tibial
`cutting guide of FIG. 14, with the cutting platform
`thereof and includes a tibial depth resection guide with
`an arm for extending across the proximal tibia end to set
`a desired thickness of the proximal tibia end section to
`be cut;
`FIG. 15A shows an enlarged view of the end of the
`tibial cutting guide secured at one end to the tibial tu
`bercle with the cutting platform telescoped therefrom
`and the tibial depth resection guide ?tted thereto;
`FIG. 16 shows a side elevation view of a saw blade
`?tted through the guide slot of the cutting platform of
`the tibial cutting guide shown operated to cut a flat
`surface across that proximal tibia at an angle of ten
`degrees (10°) below a plane across the distal tibia, which
`plane is perpendicular to the patient’s mechanical axis;
`FIG. 17 shows the proximal tibia end with a section
`shown separated therefrom;
`FIG. 18 shows a patella of the patient’s knee main
`tained in a patellar cutting guide and shows a saw blade
`cutting longitudinally through that patella;
`FIG. 19 is a side elevation view of the patellar cutting
`guide of FIG. 18 that includes a saw guide for setting
`the depth of cut thereacross; and
`FIG. 20 shows the patella with a hole guide ?tted
`over the cut surface thereof and shows a drill aligned to
`drill holes in that patella to receive a patella portion of
`a knee portion of a prosthesis ?tted thereto.
`
`20
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`25
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`5
`FIG. 1 is a view of a femur and tibia bones of a human
`leg showing, with broken lines, the patient’s anatomic
`and mechanical axes;
`FIG. 2 is a sectional taken within the line 2 of FIG. 1
`showing an expanded view of the distal femur end, with
`the respective anatomic and mechanical axes de?ned in
`broken lines;
`FIG. 3 is an end sectional view taken along the line
`3-3 of FIG. 2 showing in broken lines the position of a
`hole to be drilled therein to intersect the femur intra
`medullary channel;
`FIG. 4 is a pro?le perspective view and a femoral
`alignment guide that includes an intramedullary rod
`aligned for ?tting into the hole shown located in broken
`lines in FIG. 3 and shows in broken lines the proximal
`tibia end with the patient’s leg bent at the knee;
`FIG. 5 shows the femoral alignment guide of FIG. 4
`installed in the femur, whereto a femoral cutting guide
`is attached that is shown to include a U-shape platform,
`the legs thereof extending from that femoral alignment
`guide, and includes a locator to contact the anterior
`cortex and shows a saw blade resting on that anterior
`femoral cutting guide platform that is reciprocated to
`cut the anterior femoral condyles from the distal femur;
`FIG. 6 is a pro?le view of the femur distal end show
`ing the anterior femoral condyles separated therefrom;
`FIG. 7 shows a distal femoral cutting guide that has
`been ?tted to the femoral alignment guide that is shown
`resting on the ?at surface of the distal femoral end that
`was formed by the removal of the femoral condyles, as
`shown in FIG. 6, the distal femoral cutting guide shown
`secured to the alignment guide by ?tting a pin through
`a selected hole, one of a number of holes that are identi
`?ed with ascending numbers from 3 to 8 which numbers
`represent angles from a right angle that is the angular
`difference between the patient’W’s anatomic and me
`chanical axes;
`FIG. 8 shows the distal femur end after the femoral
`alignment guide of FIG. 7 has been removed, and shows
`40
`a saw blade ?tted through a slot in the femoral distal
`cutting guide, the distal femur end shown being cut
`thereacross to leave a ?at transverse surface that is
`perpendicular to the femur mechanical axis;
`FIG. 9 shows the distal femur end having a portion of
`the distal femur end separated therefrom;
`45
`FIG. 10 is a pro?le perspective view of measuring
`guide that has been ?tted onto the distal femur end as
`shown prepared in FIG. 9, showing the feet of that
`measuring guide resting on the cartilage of the posterior
`condyles with a mobile gauge portion thereof shown
`resting on the cut anterior femoral surface, that mobile
`gauge shown to preferably include calibrations thereon
`for use in selecting a proper size of a femur portion of a
`knee prosthesis for attachment thereto;
`FIG. 11 is a pro?le perspective view of the distal
`femur end shown ?tted with a femoral ?nishing guide
`with a pin shown aligned to turn into a hole for holding
`that guide to the prepared ?at distal femur end;
`FIG. 12 is a cross-sectional view taken along the line
`12-42 of FIG. 11, the femoral ?nishing guide as includ
`ing guide slots with a saw blade shown ?tted through
`one guide slot;
`FIG. 13 shows the femur distal end having bone
`portions separated therefrom;
`FIG. 14 is a front elevation view of a patient’s lower
`leg from knee to foot, showing a tibia cutting guide
`attached at points at their ankle and proximal to the tibia
`tubercle, the tibia cutting guide shown as including a
`
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`DETAILED DESCRIPTION
`Rational and Pre-Operative Planning
`The present invention is in a system of the instru
`ments and a procedure for their use for performing a
`total knee arthroplasty. The success of this procedure is
`directly dependent on the re-establishment to the pa
`tient of a normal lower extremity alignment, proper
`component design and orientation, secure component,
`?xation, and adequate soft tissue stability. The present
`invention and the system for its use has been developed
`to satisfy these objectives.
`The present invention is in a system of instruments for
`use by a surgeon to provide for a restoration of normal
`lower extremity alignment of knee prosthesis compo
`nents that are aligned relative to the patient’s mechani
`cal axis. The patient’s mechanical axis is established by
`drawing a line on an appropriate x-ray from the pa
`tient’s hip to ankle when the patient is in a stable, erect
`attitude. In practice, this mechanical axis is generally a
`line or axis drawn through the longitudinal center of the
`patient’s tibia that intersects the center of the femur
`head. This axis must be measured for each particular
`patient, and, for the purposes of this invention, is gener
`ally then referenced from the patient’s anatomic axis,
`which is the axis through an intramedullary channel in
`the femur bone. This angular difference from the verti
`cal of the mechanical to anatomic axis has been found in
`practice to be usually ?ve degrees (5") and, in a few
`women it has been found to be six degrees (6°). Occa
`sionally, in patients who have had total hip arthroplasty
`with a femoral component that has more valgus in the
`shaft angle then usual, or in the patient with coxa valga,
`this angular difference will be four degrees (4°) or even
`three degrees (3°). In a very rare patient who has signi?
`cant coxa valga or a broad pelvis with a long femoral
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`neck the angular difference may be seven degrees (7°)
`trated also in FIG. 3, is the point on the bone end that
`or eight degrees (8°). Accordingly, the present inven
`will be immediately opposite to and on line with the
`femur intramedullary channel and is therefore the point
`tion provides for sitting a range of angles of a cutting
`guide relative to the anatomic axis, as will be discussed
`where an end of a drill is positioned to drill into the
`later herein, between zero degrees (0°) and eight de
`bone to intersect that channel. After locating this point
`grees (8°).
`35 a surgeon drills a hole into the distal femur that inter
`With the angular difference between the patient’s
`sects and enters that intramedullary channel. The hole
`mechanical and anatomical axis, in a normal patient
`formed at 35 should have an appropriate diameter to
`their femur channel, that is also known as the intramed
`receive an intramedullary rod 41 portion of an femoral
`intramedullary alignment guide 40, shown in FIG. 4,
`ullary channel, will duplicate their anatomic axis. A
`most accurate method of femoral component alignment
`whose function will be described in detail hereinbelow.
`is therefore provided by using that intramedullary chan
`The above sets out the procedure for determining and
`nel as a reference. In this procedure, a pre-operative
`utilizing a patient’s anatomic axis as a reference for
`sequentially attaching cutting guide components for
`x-ray ?lm is ?rst taken with an intramedullary rod in~
`stalled therein to clearly show the channel. In the pre
`surgically shaping the distal femur end to receive a
`operative planning, the x-ray is preferably a standing
`femur component of a Miller/Galante prosthesis. No
`radiograph made showing the center of the femoral
`calculations are necessary to provide for locating the
`mechanical axis of the proximal tibia, as the patient’s
`head, the knee and as much as the tibia as possible,
`preferably to include the ankle. Alternatively, a single
`mechanical axis is de?ned visually as the longitudinal
`A/P radiograph of the entire femur will allow for cor
`center of the tibia and a tibial cutting guide is to be
`rect calculation. On the developed radiograph, as illus
`secured between the proximal tibia and the center of the
`ankle. The tibia cutting guide is secured in the tibia at
`trated in FIG. 1, a line is drawn from the center of the
`femoral head to the center of the distal femur at the
`the two points and mounts a cutting platform to extend
`knee with a second line drawn down the middle of the
`from the end thereof closest to the proximal tibia to
`distal femoral shaft in the area where an intramedullary
`provide a guide arrangement for receiving a saw to cut
`25
`alignment rod is ?tted to reproduce the anatomic axis of
`that proximal tibia thereacross.
`the femur. The angle between these two lines is the
`.
`Surgical Approach
`angle that is reproduced during surgery using the instru
`In a practice of the system of the present invention
`ments of the present invention.
`for preparing a patient’s knee to receive the components
`The above sets out a preferred practice for determin
`of a knee prosthesis, a standard medial parapatellar
`ing the patient’s mechanical axis in relation to their
`arthrotomy is ?rst made through a slightly curved or
`anatomic axis. Once the anatomic axis is established, the
`direct anterior skin incision at the knee area. If it is
`amount of distal femur removal can be calculated, pro
`anticipated that a lateral retinacular release will be nec
`viding for cutting that bone end to form a plane surface
`essary this is done at this time. Thereafter, the patella is
`that is perpendicular to the mechanical axis using the
`everted and the knee is ?exed and is maintained in that
`?exed attitude. The soft tissue of the suprapatellar
`system of the present invention as set hereinbelow. In
`the vein of locating the patient’s mechanical axis and
`pouch proximal to the cartilage surface is then removed
`therefrom making perpendicular cuts across the distal
`so as to expose the distal femur. If a signi?cant pre-oper
`femur and proximal tibia, for a preferred Miller/
`ative soft tissue contracture exists, a preliminary soft
`Galante tibial component the proximal tibia is to be cut
`tissue release can be made at this time to facilitate expo
`at an angle of ten degrees (10°) to a plane perpendicular
`sure of the distal femur and proximal tibia, which re
`to that mechanical axis. To prepare the proximal tibia,
`lease also lessens the amount of soft tissue release that
`the present invention utilizes a guide that is used inde
`will be needed later. The femur and tibia ends are pre
`pendently from the distal femur preparation instrument
`pared independently and either one can be prepared
`?rst. However, in practice the distal femur is routinely
`and is ?tted and secured between the center of the
`upper tibia and the ankle. This guide, once installed,
`prepared ?rst as the resection of the posterior femoral
`provides a cutting guide platform for cutting across the
`condyles will offer greater exposure of the proximal
`tibia, thereby facilitating its preparation.
`proximal tibia at the desired angle of ten degrees (10°)
`The Surgical Procedure
`below a plane that is perpendicular to the patient’s me
`chanical axis.
`With the patient’s knee opened appropriately and
`FIG. 1, as set out above, illustrates the relationship
`?exed, as illustrated in FIG. 4, the site or location for
`between a patient’s femur and tibia bones as would be
`inserting a femoral alignment guide 40 is selected on the
`shown in an A/P radiograph, therein the tibia is shown
`distal femur. This location is shown in FIG. 3 as a hole
`at 30 and the femur is shown at 31. F IG. 1 identi?es the
`35 that is drilled into the distal femur. Hole 35 will be
`patient’s mechanical and anatomic axis and a transverse
`anterior to the intercondylar notch in that distal femur.
`axis that is perpendicular to the mechanical axis of the
`In the drilling process, approximately an eight millime
`respective opposing faces identi?ed at 33 and 32 of the
`ter hole is preferably formed into that bone mass. In that
`distal femur and proximal tibia. The mechanical axis is
`hole formation it is important that this hole be parallel
`shown as a line drawn from approximately the center of
`to the shaft of the femur in both the A/P and lateral
`projections. In practice, only the cancellous bone of
`the distal femur end to the femur head 34. In FIG. 1
`therefore the angle between the mechanical axis and the
`that distal femur needs to be drilled as the femur hollow
`anatomic is established by measuring the angle differ
`diaphysis will provide no resistance to the insertion of
`the intramedullary rod. The drilled hole, it should be
`ence of the two axis as shown in the x-ray, which angle,
`understood, is important only for alignment and is not
`as set out above, is usually ?ve degrees (5°) or six de
`grees (6°). FIG. 2 is an expanded sectional view taken
`for component positioning on that distal femur.
`within the line 2-2 of FIG. 1 that shows the distal
`Shown in FIG. 4, a femoral intramedullary alignment
`guide 40, hereinafter referred to as alignment guide 40,
`femur 33 with the mechanical and anatomic axis con
`verging at a point 35. The convergent point 35, as illus
`is shown as including an intramedullary rod 41 that
`
`45
`
`30
`
`40
`
`55
`
`-10-
`
`

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