United States Patent [19]
`Todd
`
`USO05630820A
`[11] Patent Number:
`[45] Date of Patent:
`
`5,630,820
`May 20, 1997
`
`[54] SURGICAL BICOMPARTMENTAL
`TENSIOMETER FOR REVISION KNEE
`SURGERY
`
`[75] Inventor; Ronald C_ Todd_ Austin’ Tex
`
`[73] Assignee: Sulzer Orthopedics Inc., Austin, Tex.
`
`[21] APPL N04 349,447
`[22] Filed:
`Dec. 5, 1994
`
`6
`[51] Im, 01. ................................................... .. A6113 17/56
`[52] us. c1. ............................................. .. 606/90, 606/102
`[58] Fleld of Search ................................ .. 606/90, 88, 87,
`606/36, 96, 102, 105; 600/201, 202, 214,
`215, 219, 222
`
`[56]
`
`Refemnces Clted
`Us. PATENT DOCUMENTS
`
`X
`............................ ..
`4’938’230 7,1990 Machek et a1‘ "
`" 128/777
`5,116,338
`5/1992 Poggie a a1.
`...... .. 606/90
`5,213,112 5/1993 Niwaetal. .... ..
`128/774
`5,431,653
`7/1995 Callaway ....... ..
`606/90
`5,468,244 11/1995 Att?eld et a1. .......................... .. 606/90
`
`OTHER PUBLICATIONS
`
`“Your Partner” Protek A.G. 1991, pp. 159, 163.
`
`“FIS Modular Total Knee Replacement System” Protek
`A.G., Jan. 1991, pp. 19-21, 45, 49.
`
`Primary Examiner-Guy V. Tucker
`Attorney, Agent, or Firm—John R. Merkling
`[57]
`ABSTRACT
`
`A bicompartmemal tensiometer for use in prosthetic hm
`Surgery, and in particular for use in revision knee surgery
`Th‘; tensiometer compn'ses two parallel, independently 0pm.
`able jaws which are inserted between resected surfaces on
`the distal femur and the proximal tibia. The jaws are opened
`manually by the surgeon until the proper tension is placed on
`the collateral ligaments. Each of the jaws comprises two
`paddles which remain parallel to each other as they are
`opened. Moreover, the two jaws remain parallel to each
`other’ or in the same angular Orientation’ when adjustm to
`be laced ad'acent the cond les. Each 'aw is held 0 n b
`a pgwl whidll engages a mi
`1
`9e y
`
`13 Claims,2Drawing Sheets
`
`l6
`
`l4
`
`3220
`
`64
`
`3o
`
`4
`
`26
`
`I6
`
`12
`
`'
`
`'8
`
`,
`
`56
`
`Zéy/ 74
`_
`g-j
`é '
`"—-'_IK ‘ 'l
`I . . g ' 20
`~‘~:-:/:': / Q IF?‘
`-'
`,ll'_(@
`0’ " 68
`- lg"
`02 4
`4a
`22
`22
`26
`\
`i 70
`'3
`
`72
`
`'0
`
`4a
`
`-1-
`
`Smith & Nephew Ex. 1093
`IPR Petition - USP 7,534,263
`
`

`
`U.S. Patent
`
`May 20, 1997
`
`Sheet 1 of 2
`
`5,630,820
`
`I6
`
`8
`
`4
`
` 0M62053H7”‘NEW..,'/§l.§..1.J8I,.¢.ivulan4.4'l|.IIII.'|-Ilnuull
`
`._._s.__.__s_l_‘Enoc I
`
`I6
`
`32
`
`E, 74
`5% 9
`'1»
`2
`
`x
`
`22
`
`_
`
`_
`
`7.
`
`-2-
`
`

`
`US. Patent
`U.S. Patent
`
`May 20, 1997
`May 20, 1997
`
`Sheet 2 of 2
`Sheet 2 of 2
`
`5,630,820
`5,630,820
`
`FIG.
`
`-3-
`
`

`
`5,630,820
`
`1
`SURGICAL BICOMPARTMENTAL
`TENSIOMETER FOR REVISION KNEE
`SURGERY
`
`FIELD OF MY INVENTION
`My invention relates to surgical apparatus, and speci?
`cally to apparatus for use in knee surgery, and more spe
`ci?cally to apparatus, for placing the medial and lateral
`collateral ligaments of the knee in tension, for the purpose
`of balancing those ligaments during surgical implantation of
`a prosthetic knee.
`
`10
`
`BACKGROUND OF MY INVENTION
`
`When human joints, such as the knee, become diseased or
`otherwise are incapable of functioning, surgical intervention
`is possible. Surgeons expose the junction between the tibia
`and the femur, temporarily disconnect the patella, resect
`away parts of the femur or tibia or both, and replace the ends
`of the femur and tibia with arti?cial prostheses. Orthopedic
`implants for the human knee generally have a femoral and
`tibial component. The tibial component is usually placed on
`the resected proximal surface of the tibia and frequently has
`a metal base plate with a shaft extending into the medullar
`canal. The base plate usually carries an ultra high molecular
`weight polyethylene (UHMWPE) articulating surface. The
`articulating surface has medial and lateral condyle
`compartments, approximating the medial and lateral condyle
`compartments of a natural tibia in form and function. A
`femoral component is implanted on a resected distal end of
`the femur and presents arti?cial condyles, similar in form
`and function to the natural condyles of the femur which have
`been cut away, which articulate with the condyle compart
`ments of the tibial component. A femoral component gen
`erally comprises the condyle articulating surfaces and ?xa
`tion means, which may include an elongated stem extending
`into the medullar canal of the patient. Such prostheses are
`well known and examples can be found in US. Pat. Nos.
`4,963,152; 5,062,852; and 5,071,438.
`For patients who require an arti?cial knee prothesis,
`degeneration of the bone at either the tibia or femur or both
`may be occurring. Moreover, this degeneration may be
`proceeding unevenly with respect to the two condyles, or the
`two condyle compartments. A side effect of this degenera
`tion is that the anatomic alignment of the femur to the tibia
`may become disjointed causing an imbalance to the collat
`eral ligaments. It is known that some patients require a
`re-operation and the installation which is called a “revision”
`knee prosthesis. The revision knee prosthesis is generally
`more massive than a so-called “primary” lmee prosthesis.
`The revision femoral knee condylar parts may be thicker and
`more robust and the medullar shaft may be substantially
`longer. Moreover, in many cases, degeneration of one
`condyle may be substantially more advanced than the other.
`Whether natural or prosthetic, the knee joint is supported
`by the patella and by ligaments, including the medial and
`lateral collateral ligaments on either side of the knee, and the
`cruciate ligaments behind the knee. If present, these
`ligaments, particularly the collateral ligaments, must be
`under proper tension, and balance, both when the knee is in
`extension and when it is in ?exion, in order to maintain
`correct anatomic alignment. It is important, therefore, for a
`surgeon performing knee replacement surgery to be able to
`size the prosthesis and place resection cuts appropriately so
`that the reassembled knee will cooperate with the ligaments
`to form a stable joint. This is particularly problematic in the
`case of revision surgeries, where substantial changes in the
`
`25
`
`35
`
`45
`
`55
`
`65
`
`2
`bone structure, and also changes in the balance of the medial
`and lateral collateral ligaments may be expected.
`In the past, surgeons have placed the exposed knee joint
`under tension both in extension and ?exion either manually,
`or by use of instruments. There remains a need, however, for
`instrumentation which can enable the surgeon to spread the
`joint between the distal femur and the proximal tibia, placing
`the collateral ligaments in tension, both when the knee is in
`?exion and in extension in an effort to establish the balance
`of these ligaments with respect to the correct, or corrected,
`anatomic alignment of the knee joint. Moreover, such appa
`ratus is needed which would operate on both condyles
`simultaneously to place the medial and lateral collateral
`ligaments in tension.
`
`SUMMARY OF MY INVENTION
`
`I have invented a bicompartrnental tensiometer for use in
`prosthetic knee surgery, and in particular for use in revision
`knee surgery. The tensiometer of my invention comprises
`two parallel, independently operable jaws which are inserted
`between the distal femur resection and the proximal tibia
`resection. The jaws are placed adjacent these resected sur
`faces and opened manually by the surgeon until the proper
`tension is placed on the collateral ligaments. Each of the
`jaws comprises two paddles which remain parallel to each
`other as they are opened. Moreover, the two paddies remain
`parallel to each other, or in the same angular orientation
`when adjusted, as placed adjacent the resected surfaces.
`Each jaw is held open by a pawl which engages a rack. With
`both sides of the knee joint simultaneously under appropri
`ate tension, a more accurate evaluation of the anatomic
`alignment of the joint, due to the proper balancing of the
`collateral ligaments, can be made. It is at this point, also, that
`cutting jigs or blocks, such as a femoral anterior/posterior
`chamfer cutting block available from Intermedics
`Orthopedics, Inc., the Assignee of my invention, can be
`properly aligned with the knee joint while in ?exion. This
`block may be drilled and pinned into place while the
`tensiometer is in operation. The tensiometer can then be
`removed prior to the use of a saggital saw with the cutting
`block.
`With the foregoing in mind, it is a principle object of my
`invention to provide a tensiometer for knee surgery which
`operates simultaneously on both the medial and lateral
`compartments of the knee joint.
`It is a further object of my invention to provide such a
`tensiometer which can be used with either the right or left
`knee.
`It is an object of my invention to provide a tensiometer in
`which two paddles, comprising a jaw, remain parallel when
`moved.
`Another object of my invention is to provide a bicondylar
`tensiometer which operates independently on each condyle,
`and in which both jaws and paddies forming the jaws move
`in parallel fashion with respect to their co-operating parts.
`These and other objects and features of my invention will
`be apparent from the following detailed description taken
`with respect to the accompanying drawings.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 is a perspective view of a bicompartmental tensi
`ometer in accordance with my invention.
`FIG. 2 is an exploded perspective view of the tensiometer
`of FIG. 1.
`
`-4-
`
`

`
`3
`DETAILED DESCRIPTION OF MY PREFERRED
`EMBODIMENT
`
`5,630,820
`
`I will now describe my invention with respect to the
`accompanying drawings. Like numerals will refer to like
`parts throughout all the drawings. A bicompartmental
`tensiometer, generally designated 10, for use in knee surgery
`is illustrated in perspective view in FIG. 1. The tensiometer
`10 can be used on either a patient’s right knee or on the left
`knee. I will, therefore, describe my invention from the
`perspective of the surgeon utilizing the apparatus, such that
`“right” refers to the right hand side of the surgeon manipu
`lating the apparatus, while “left” refers to the left hand side
`of the surgeon.
`The tensiometer 10 comprises two jaws, a right jaw 12
`and a left jaw 14. The jaws are initially closed and are slid
`between a resected surface on the distal end of the patient’s
`femur and a resected surface on the proximal end of the
`patient’s tibia, usually at the medial and lateral ends of these
`resected surfaces. The jaws 12, 14 are ?rst adjusted to be
`accurately placed into these positions and then opened
`independently to place the collateral ligaments of the knee in
`tension. The patient’s knee may be either in extension or
`?exion, and it is usual for a surgeon to observe the action of
`the knee joint in both positions. Each jaw 12, 14, comprises
`an upper paddle 16 and a lower paddle 18. Preferably, the
`paddles 16, 18, are ?at with rounded or chamfered comers.
`The upper paddles 16 are each connected to a shaft 20 at a
`right angle. Each lower paddle 18 is connected to a body 22.
`Each body 22 has its longest dimension parallel to the shaft
`20 of its associated upper paddle 16, and has a through bore
`forming a bearing 24 for the shaft 20. Each shaft 20 rides in
`its associated bearing 24, so that the upper and lower paddles
`16, 18 can be displaced with respect to each other. The upper
`and lower paddles 16, 18 have a speci?c angular orientation
`with respect to each other. In my preferred embodiment, the
`two paddles are parallel, but other angular orientations could
`be chosen. When the two paddles are displaced with respect
`to each other, however, they retain the same angular orien
`tation. That is, each part of the upper paddles in contact with
`bone would move the same distance with respect to a
`corresponding part of the lower paddle. I call this motion
`“parallel motion”.
`Each body 22 has a handle 26 extending therefrom A slot
`28 extends partially through the handle adjacent the body 22
`and into the body 22, opening into the bearing 24. This slot
`28 receives a pawl 30. Each pawl 30 engages a rack 32 on
`its respective shaft 20. Each pawl comprises a pivot 34
`through which is passed a pin 36. Each pin 36 also engages
`a pivot bore 38 in its respective handle. A tooth 40 engages
`the rack 32 to prevent the jaws 12, 14 from closing. A trigger
`42 permits the surgeon to disengage the pawl 30 from the
`rack 32 and close the respective jaw. A spring 44 is placed
`within each pawl slot 28 under the respective trigger 42 to
`urge the pawl against the rack.
`Distally from its respective upper paddle 16, each shaft 20
`has a threaded stopped bore 46. A grip lever 48 is inserted
`into each threaded stopped bore 46 such that a threaded shaft
`50 thereon can be screwed into the stopped bore 46. When
`assembled, the upper paddle on the right will be over and
`parallel to the lower paddle on the right and will be parallel
`both to the upper paddle on the left and to the lower paddle
`on the left. The handle 26 on the right side will be parallel
`to its associated grip lever 48 and the handle of the left side
`will be parallel to its associated grip lever. Preferably, the
`two jaws 12, 14 are parallel to one another, but the right and
`left handles will diverge from their respective bodies away
`
`50
`
`55
`
`65
`
`10
`
`25
`
`30
`
`35
`
`4
`from each other. This provides greater room for the physi
`cian to manipulate the jaws simultaneously.
`The right and left jaws 12, 14 are held parallel to one
`another by a stabilizer assembly 52. The stabilizer assembly
`52 comprises an upper support rod 54 and a lower support
`rod 56. These support rods 54, 56 pass through bores 58, 60
`in each body 22. The two rods 54, 56 are held in rigid planar
`relationship to each other by a brace 62 into which the rods
`54, 56 are inserted and then secured by welding. Caps 64, 66
`may be placed on the ends of one or both support rods to
`prevent the bodies 22 from sliding completely off the rods.
`As an additional feature, the bodies 22 may be provided with
`sterilization slots, such as slot 68, both to reduce the weight
`of the tensiometer 10 and to provide better sterilization for
`the instrument.
`In use, the jaws 12, 14 are closed by opening the pawl 30
`and moving the respective grip lever 48 away from its
`associated handle 26. The handle 26 and grip lever 48 on the
`right side form a grip assembly 70 for manipulating the right
`jaw 12, while the handle 26 and grip lever 48 on the left side
`form a left grip assembly 72 for manipulating the left jaw 14.
`With the jaws 12, 14 closed, the paddles 16, 18 may be
`inserted between a resected surface on the distal end of the
`femur and aresected surface on the proximal end of the tibia.
`The jaws 12, 14 can then be positioned optimally under their
`respective condyles by sliding them outwardly or inwardly
`along the rods 54, 56 of the stabilizer assembly 52.
`With the jaws 12, 14 in appropriate position between the
`patient’s femur and tibia. the surgeon can then indepen
`dently open the jaws by squeezing the right grip assembly 70
`and the left grip assembly 72. As the grip assemblies 70, 72
`close, their associated jaws 12, 14 open. The surgeon will be
`able to manually detect the resistance. When the appropriate
`tension has been achieved, the associated pawl 30 will
`automatically engage the rack 32, due to the spring tension
`on each pawl 30. supplied by spring 44, and hold the knee
`open at the selected tension. The pawl 30 need not be
`depressed while operating the grip assemblies 70, 72. While
`the grip assemblies are in operation, the pawl 30 will pivot,
`at point 34 such that the pawl 30 tip will be forced open, due
`to the shape of teeth on the rack 32, and act as a ratchet type
`mechanism for the full length of engagement with the teeth
`on the rack. Because the spring 44 loads the pawl 30 in the
`forward direction into the teeth on the rack 32 the pawl tip
`can continually engage the rack teeth. With the collateral
`ligaments under the surgeon’s selected tension, appropriate
`measurements can be made to select the size of the pros
`thesis to be implanted and to place and make the necessary
`resecting cuts. Depending on the type of prosthesis selected
`by the surgeon, other measurement instruments may be
`employed. However, a scale 74 may also be provided along
`each shaft 20 so that the amount by which each condyle has
`been spread by the tensiometer 10 can be measured directly.
`My invention may be embodied in other specific forms
`without departing from the teachings thereof. The foregoing
`description is to be considered in all respects to be illustra
`tive and not restrictive. The scope of my invention is de?ned
`by the following claims, and all changes which come within
`the scope of equivalency of the claims are intended to be
`encompassed therein.
`I claim as my invention:
`1. A surgical apparatus for spreading a distal end of a
`femur away from a proximal end of a tibia at a lmee joint of
`a patient thereby placing adjacent collateral ligaments in
`tension, said apparatus comprising
`means for spreading a medial side of said knee,
`
`-5-
`
`

`
`5
`means for spreading a lateral side of said knee, and
`a pair of parallel rods connecting said means for spreading
`said medial side and said means for spreading said
`lateral side for holding said means for spreading in
`selectable non-rotatable spaced relation with respect to
`each other, each rod slidingly received in at least one of
`said means for spreading.
`2. The surgical apparatus according to claim 1 wherein at
`least one of said means for spreading comprise
`an upper paddle,
`a lower paddle,
`means for adjusting the position of said paddles relative to
`each other, and
`means for locking said adjusting means to retain said
`upper and lower paddles in a selected position relative
`to each other.
`3. The apparatus according to claim 2 wherein said means
`for adjusting comprise
`a shaft attached to said upper paddle, and
`body means attached to said lower paddle, said body
`means having a bore, said shaft being slidingly
`received in said bore, and wherein said means for
`locking comprise
`a rack a?ixed to said shaft, and
`a pawl attached to said body means, said pawl selectively
`engaging said rack.
`4. The apparatus according to claim 1 wherein at least one
`of said means for spreading a side of a lmee comprises
`an upper paddle,
`a lower paddle, and
`means for adjusting the position of said paddles relative to
`each other while permitting only parallel motion of said
`paddles.
`5. The apparatus according to claim 4 wherein said means
`for adjusting comprise
`a shaft attached to said upper paddle, and
`body means attached to said lower paddle, said body
`means having a bore, said shaft being slidingly
`received in said bore.
`6. The apparatus according to claim 5 further comprising
`means for measuring displacement of said upper paddle with
`respect to said lower paddle.
`7. The apparatus according to claim 6 wherein said means
`for measuring comprises a scale on said shaft.
`
`6
`8. A surgical apparatus for spreading a distal end of a
`femur away from a proximal end of a tibia at a knee joint of
`a patient thereby placing adjacent collateral ligaments in
`tension, said apparatus comprising
`means for spreading a medial side of said knee,
`said means for spreading said medial side of said knee
`having
`a medial upper paddle, and
`a medial lower paddle, and
`means for adjusting the position of said medial paddles
`relative to each other while permitting only parallel
`motion of said paddles, means for spreading a lateral
`side of said knee,
`said means for spreading said lateral side of said knee
`having
`a lateral upper paddle, and
`a lateral lower paddle, and
`means for adjusting the position of said lateral paddles
`relative to each other while permitting only parallel
`motion of said paddles, and
`means for non-rotatably translating in the medial-lateral
`direction said means for spreading said medial side of
`said lmee away from or towards said means for spread
`ing said lateral side of said knee.
`9. The apparatus according to claim 8 further comprising
`means for locking said adjusting means to retain said upper
`and lower paddles in a selected position relative to each
`other.
`10. The apparatus according to claim 9 wherein said
`means for locking comprise
`a rack affixed to said shaft, and
`a pawl attached to said body means, said pawl selectively
`engaging said rack.
`11. The apparatus according to claim 8 wherein said
`means for adjusting comprise
`a shaft attached to said upper paddle, and
`body means attached to said lower paddle, said body
`means having a bore, said shaft being slidingly
`received in said bore.
`12. The apparatus according to claim 11 further compris
`ing means for measuring displacement of said upper paddle
`with respect to said lower paddle.
`13. The apparatus according to claim 12 wherein said
`means for measuring comprises a scale on said shaft.
`
`* * * * *
`
`5,630,820
`
`10
`
`15
`
`20
`
`35
`
`45
`
`-6-