,
`
`United States Patent [191
`Chapman et a1.
`
`US005190544A
`
`[11] Patent Number:
`[45] Date of Patent:
`
`5,190,544
`Mar. 2, 1993
`
`[54] MODULAR FEMORAL FIXATION SYSTEM
`
`FOREIGN PATENT DOCUMENTS
`
`[75] Inventors: Michael W. Chapman, Sacramento,
`Calif.; Charles C. Edwards,
`32111111255: ’ 1:‘: d‘; Dan C’ Mm’
`’
`'
`P?ze H -tal Prod ts G ’ In _
`:
`73 A -
`[
`1
`sslgnee Newryog?iy. “c
`mup c ’
`
`[21] Appl. No.: 670,839
`
`[22] Filed;
`
`Mar, 18, 1991
`
`[62]
`
`_
`_
`Related U's' Apphcahon Data
`Division of Ser. No. 232,188, Aug. 15, 1988, Pat. No.
`5,041,114, which is a division of Ser. No. 877,626, Jun.
`23, 1936, Pat- NO- 4,776,330-
`
`[51] Int. Cl.5 ............................................ .. A61B 17/58
`[52] [1.5. Cl. . . . . . . . . . . . . . . . .
`. . . . . . . . . .. 606/69; 606/ 71
`[58] Field of Search ..................... ,. 606/53, 60, 62, 63,
`606/65’ 66’ 69’ 70’ 71’ 72’ 73’ 86’ 105
`
`[56]
`
`References Cited
`US. PATENT DOCUMENTS
`2,801,631 8/1957 Charnley ............................. .. 606/65
`3,463,143 3/1969 Tfeacg ___________ u
`3,996,931 12/1976 Callender, Jr. ..
`4,621,629 11/1986 Koeneman .......................... .. 606/65
`
`2405705 5/1979 France ................................ .. 606/69
`2406429 5/1979 France ................................ .. 606/69
`Primary Examiner-Robert A. Hafer
`Assistant Examiner-Sam Rimell
`Attorney, Agent, or Firm-Peter C. Richardson;
`Lawrence C. Akers; Elizabeth 0. Slade
`[57]
`ABSTRACT
`.
`.
`.
`A modular femoral internal implant system for use in
`the treatment of femoral disorders resulting from injury,
`disease or congenital defect includes at least three inter
`connectable components: 1) an elongated epiphyseaV
`metaphyseal implant, 2) an intramedullary rod and 3) an
`angled side plate having an elongated plate portion
`adapted to be secured to the outer cortical wall and a
`hollow sleeve adapted to extend into the femur. The
`epiphyseal/metaphyseal implant can be connected to
`either the angled side plate or the pimmmedullary rod_
`The System may also include an elongated bone plate
`connectable to the angled side plate, one or more addi
`tional epiphyseal/metaphyseal implants of variable
`length, an additional angled side plate, a distal buttress
`plate connectable to the elongated bone plate, and a
`plurality of bone screws of a universal design. Prefera
`my’ many "I an °f the °°mPonems °f ‘he Sysmm are
`made of an inert, resilient titanium-base alloy.
`
`6 Claims, 6 Drawing Sheets
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`MODULAR FEMORAL FIXATION SYSTEM
`
`This is a division of application Ser. No. 232,188, ?led
`on Aug. 15, 1988, now U.S. Pat. No. 5,041,114, which in
`turn is a division of application Ser. No. 877,626, ?led
`on Jun. 23, 1986, now US Pat. No. 4,776,330.
`
`BACKGROUND OF THE INVENTION
`'Internal ?xation of femoral fractures is one of the
`most common orthopedic surgical procedures. Many
`different types of femoral fractures are encountered in
`practice, including fractures in the femoral neck, inter
`trochanteric, mid-shaft and distal condylar regions. The
`femoral bone will sometimes fracture cleanly into two
`large fragments along a well-de?ned fracture line, and
`on other occasions fracture into many smaller frag
`ments. Often, more than one type of fracture will exist
`concurrently in different regions of the femur of an
`injured patient.
`20
`A wide variety of implants have been developed over
`the years for use in the internal ?xation of femoral frac
`tures. Although numerous excellent design achieve
`ments have been realized, several general problem areas
`remain. First, almost all of the currently available im
`plants have a highly specialized application limited to
`only one speci?c anatomical location in the femur.
`Thus, a hospital must maintain at great expense a very
`large and variegated inventory of different implants to
`handle all expected contingencies. These implants are
`generally not compatible, i.e. they cannot be intercon
`nected together in case of a complicated fracture pat
`tern extending into different anatomical regions of the
`femur. Second, each implant has its own peculiar attri
`butes and de?ciencies, and the use of many of the
`known implants involves the use of a surgical technique
`that is unique to that implant and sometimes compli
`cated and difficult as well. Consequently, the opportu
`nities for improper implant selection and surgeon error
`during, implantation are inevitably increased. Finally,
`tissue reactions with implants made of stainless steel and
`certain other surgical implant alloys tend to reduce the
`useful lifetime of the implants and require premature
`removal from the patient’s body.
`One very commonly utilized femoral internal ?xation
`device is an elongated implant (nail, screw, pin, etc.)
`adapted to be positioned along the longitudinal axis of
`the femoral neck with its leading end portion in the
`femoral head so as to stabilize a fracture of the femoral
`neck. The elongated implant may be implanted by itself
`or connected to another implant such as a side plate or
`intramedullary rod. The leading end portion of the
`implant typically includes means to positively grip the
`femoral head bone (external threads, expanding arms,
`etc.), but the inclusion of such gripping means can intro
`duce several signi?cant problems. First, implants with
`sharp edges on the leading end portion, such as the
`externally threaded implants, exhibit a tendency to mi
`grate proximally towards the hip joint bearing surface
`after implantation. Such proximal migration under
`60
`physiological loading, which is also referred to as femo
`ral head cut-out, can lead to signi?cant damage to the
`adjacent hip joint. Also, the externally threaded im
`plants can generate large stress concentrations in the
`vicinal bone during implantation which can lead to
`stripping of the threads formed in the bone and thus
`obviously a weakened grip. The movable arms of
`known expanding arm devices are usually free at one
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`end and attached at the other end to the main body of
`the leading end portion of the implant. As a result, all
`fatigue loading is concentrated at the attached ends of
`the arms and undesirably large bending moments are
`realized at the points of attachment.
`As stated above, known elongated implants used to
`stabilize fractures of the femoral neck are often con
`nected in use to a side plate which in turn is secured to
`the outer cortical wall of the adjacent femoral shaft, for
`example with bone screws. This type of assembly is
`often selected when a femoral neck fracture is a part of
`a more complicated fracture pattern including also one
`or more fractures in the metaphyseal and/or diaphyseal
`regions of the femur. Clearly, the surgeon desires to be
`able to select the appropriate length of the side plate
`depending upon the particular traumatic condition of
`the patient’s femur. However, the surgeon’s flexibility
`in this regard typically requires the hospital to maintain
`a costly inventory of implants.
`
`SUMMARY OF THE INVENTION
`It is an object of the present invention to provide a
`modular system of femoral internal implants, and instru
`mentation therefor, that can be employed to treat a
`number of different fracture patterns and other disor
`ders with a minimal number of interconnectable system
`components involving simple uncomplicated opera
`tional procedures in which surgical invasiveness and
`operation times are minimized.
`This and other objects of the invention are achieved
`with a novel kit for use in the amelioration of a number
`of different types of femoral disorders resulting from
`injury, disease or congenital defect with a minimal num
`ber of interconnectable components. The kit comprises
`at least the following components: 1) an elongated epi
`physeal/metaphyseal implant having a leading end por
`tion and a trailing end portion and adapted to grip bone
`at its leading end portion; 2) an intramedullary rod
`having a distal end and a proximal end; 3) an angled side
`plate comprising an elongated plate portion adapted to
`be secured to the outer cortical wall of the femoral shaft
`and an integral hollow sleeve extending at an angle
`from one end of the plate portion so that said hollow
`sleeve extends into the femur when the plate portion is
`secured to said cortical wall; and 4) means for connect
`ing the epiphyseal/metaphyseal implant to the intra
`medullary rod adjacent to one of the ends of the rod
`with the epiphyseal/metaphyseal implant at an angle
`with respect to the intramedullary rod.
`According to the invention, the components of the
`novel kit are dimensioned such that the elongated epi
`physeal/metaphyseal implant is capable of being con
`nected to the angled side plate by the insertion of the
`trailing end portion of the epiphyseal/metaphyseal im
`plant into the hollow sleeve of the angled side plate and
`the elongated epiphyseal/metaphyseal implant is also
`capable of being connected to the intramedullary rod
`with the use of said connecting means. Thus the same
`epiphyseal/metaphyseal implant can be either con
`nected to the intramedullary rod, to form for example a
`Y-nail type of assembly to treat an unstable subtrochan
`teric fracture pattern, or connected to the angled side
`plate, to form for example a side plate-pin assembly to
`treat a different fracture pattern. The intramedullary
`rod may be either connected to the elongated epi
`physeal/metaphyseal implant or implanted indepen
`dently of said implant and the angled side plate.
`
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`3
`The novel kit can be used to treat a variety of trauma
`conditions as well as to ameliorate other types of femo
`ral disorders including non-unions, congenital deformi
`ties and pathological deformities (e.g. Paget’s disease),
`and can also be utilized in the prophylactic ?xation of
`weakened bone, bone defects, etc., and in the perfor
`mance of osteotomies. Simple and uncomplicated surgi
`cal techniques can be employed and operating times and
`' implant inventories kept at a low level.
`As used herein the term “elongated epiphyseal/meta
`physeal implant” refers to an elongated implant adapted
`to be usedvin such a manner that it extends after implan
`tation from the epiphyseal region of the proximal femur
`into the adjacent metaphyseal region, or from the lateral
`to the medial epiphyseal region of the distal femur. In
`general, the elongated epiphyseal/metaphyseal implant
`can be a pin, nail, screw, etc. Preferably, the intramedul
`lary rod is axially cannulated and is provided with at
`least one through bore adjacent its distal end for recep
`tion of a locking screw.
`The modular femoral implant system advantageously
`includes components additional to the essential epi
`physeal/metaphyseal implant, intramedullary rod, an
`gled side plate and epiphyseal/metaphyseal implant
`intramedullary rod connection means. Thus, the kit
`preferably includes an elongated bone plate adapted to
`be secured to the outer cortical wall of the femoral
`shaft. The elongated bone plate and angled side plate
`are dimensioned such that the elongated bone plate can
`be connected to the plate portion of the angled side
`30
`plate to provide an extension of the effective length of
`said plate portion without having to inventory two
`complete angled side plates. The elongated bone plate
`can of course be utilized by itself in a conventional
`manner, if desired. Most preferably, several elongated
`bone plates of variable length are included in the kit.
`In a further preferred embodiment of the invention
`the kit includes a_ distal buttress plate including a rela
`tively?at elongated proximal portion adapted to be
`secured to the lateral distal femoral shaft and a rela
`- tively curved distal portion adapted to be secured to the
`lateral distal femoral condyle. In this embodiment the
`kit includes at least one elongated bone plate that is
`capable of being connected to each of the plate portion
`of the angled side plate and the proximal portion of the
`distal buttress plate for effective length extension pur
`poses, as desired.
`The novel kit of the present invention preferably
`includes a plurality of threaded self-tapping cortical
`bone screws for use in securing the elongated plate
`portion of the one or more angled side plates to the
`outer cortical wall of the femoral shaft and, when the
`kit includes an intramedullary rod with a distal through
`bore and one or more elongated bone plates, securing
`the distal end of the intramedullary rod to the distal
`femur, securing said bone plate(s) to the outer cortical
`wall of the femoral shaft, and connecting said plate
`portion(s) and bone plate(s) together in axial alignment.
`The kit preferably includes a plurality of such screws
`each having a head and a threaded shank, with said
`screws being identical except for variations in the
`length of the threaded shanks. Although not every one
`of these screws can be used in all of the capacities set
`forth above (for example short cortical screws cannot
`be used to secure the distal end of the intramedullary
`rod), the provision of a plurality of threaded self-tap
`ping cortical bone screws of universal screw head and
`screw shank design (except for variations in screw
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`5,190,544
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`shank length) provides substantial opportunities for
`interchangeability in use and reduced inventory levels,
`and requires the surgeon to be familiar with only one set
`of cortical screw characteristics, attributes and tech
`niques of use. Furthermore, said bone screws can be
`used independently as bone fixation screws to hold
`fragments of bone together during healing of a fracture.
`Most preferably, the heads of the cortical screws and
`the apertures in the plate portion(s) and bone plate(s)
`intended to receive them are con?gured in such a man
`ner that the screws are capable of a universal rotation
`with respect to the plate portion or bone plate within a
`cone having an apex angle of at least about 20° when the
`screw head is fully advanced into the aperture receiving
`it. Thus, for example, the underside of the universal
`screw head may be spherically rounded (convex
`towards the bone) and the abutting surfaces of the
`screw-receiving apertures complimentary thereto (and
`of course concave away from the bone).
`Preferably, the components of the novel kit of the
`invention are made of a resilient, physiologically inert
`titanium-base alloy such as Ti-ll.5Mo-6Zr-4.5Sn, Ti
`6Al-4V or Ti-3Al-2.5V. The physiological inertness of
`such alloys reduces the potential for adverse tissue reac
`tions (as compared to e.g. stainless steel) and thus will
`serve to increase product lifetime in vivo after implanta
`tion. Also, most of the currently available implants for
`the internal fixation or amelioration of femoral fractures
`or other disorders are made of highly rigid materials,
`thus leading in many circumstances to excessive “stress
`shielding” in which too much of the stresses applied to
`the femur are borne by the implant rather than the heal
`ing bone in the fracture region. Stress shielding may
`delay fracture healing and weaken the surrounding
`bone. This problem of stress shielding is greatly allevi
`ated by making the components of the kit out of a resil
`ient titanium-base alloy.
`In a preferred distribution of components, the kit
`comprises: 1) two epiphyseal/metaphyseal implants of
`different length, 2) an angled side plate in which the
`hollow sleeve and plate portion are mutually oriented at
`an oblique angle so that the hollow sleeve is adapted to
`extend into the intertrochanteric region when the plate
`portion is secured to the outer cortical wall of the adja
`cent femoral shaft, 3) an angled side plate in which the
`hollow sleeve and plate portion are substantially per
`pendicular so that the hollow sleeve is adapted to ex
`tend into the distal condylar region of the femur when
`the plate portion is secured to the outer cortical wall of
`the adjacent distal femoral shaft, 4) an intramedullary
`rod (preferably having a through bore adjacent its distal
`end), 5) means for connecting the shorter of the two
`epiphyseal/metaphyseal implants to the intramedullary
`rod adjacent to the proximal end of the rod to form a
`Y-nail type of assembly, 6) a plurality of cancellous and
`cortical bone screws, and 7) at least one elongated bone
`plate capable of being connected in axial alignment to
`the plate portion of each of the angled side plates for
`effective length extension purposes. The shorter epi
`physeal/metaphyseal implant is also capable of being
`connected to the substantially perpendicularly-angled
`side plate, while the longer epiphyseal/metaphyseal
`implant is capable of being connected to the obliquely
`angled side plate. With this highly preferred distribu
`tion of components, the components of the kit can be
`assembled together in different ways or used indepen
`dently to treat or ameliorate most of the femoral frac
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`more evenly distributed along the strip. The actuation
`ture conditions and other femoral disorders commonly
`encountered by orthopedic surgeons.
`mechanism of this novel expansion sleeve implant is
`simple and foolproof and includes no complicated mov
`In addition to the overall modular concept of the
`ing parts that might malfunction during implantation.
`femoral implant system, the present invention is also
`Preferably, the plunger includes a raised annular rib
`directed to the particular design of various of the com
`adjacent the trailing end of the plunger body portion,
`ponents of the system. Thus, included within the con
`cept of the present invention is a novel bone implant for
`which rib is adapted to ?t into a corresponding groove
`provided in the inner wall of the circular ring of the
`use in the stabilization of a bone fracture comprising an
`integral substantially cylindrical expansion sleeve hav
`expansion sleeve when the plunger is fully advanced
`ing a smoothly rounded circumferentially-closed dome
`within the sleeve. This rib and groove combination
`serves to lock the plunger and sleeve against undesired
`at one end, a circumferentially-closed circular ring at its
`relative axial displacement after implantation.
`other end, and a plurality of thin elongated strips ex
`It is highly preferred that the expansion sleeve be
`tending between, and connected at their opposed ends
`to, the circumferentially-closed dome and ring, said
`made of a resilient material such as a titanium-base al
`strips being of varying radial thickness along their
`loy. In this case, the resilient strips of the expansion
`sleeve will expand radially outwardly in elastic defor
`length and having textured outer surfaces; and an elon
`mation when the plunger is advanced into the sleeve
`gated plunger having at one end thereof a substantially
`cylindrical body portion having a diameter essentially
`and will revert to their original shape (to facilitate re
`equal to the inner diameter of the circumferentially
`moval of the sleeve, if desired) when the plunger is
`closed circular ring of the expansion sleeve. When the
`withdrawn. Also, whether or not the sleeve is made of
`expansion sleeve is held in a cavity in a bone fragment
`a resilient material, it is desirable to design it so that
`openings are provided in the sleeve in its rest position.
`on one side of a fracture and the plunger is advanced
`through said circular ring and into the interior of the
`An extrudable material such as a bone cement for en
`sleeve with its substantially cylindrical body portion in
`hancement of the bone implant ?xation can be placed‘
`the leading position, the plurality of thin elongated
`into the sleeve and then extruded through these open
`ings to the bone-implant interface as the plunger is ad
`strips in the sleeve are caused to expand radially out
`wardly and thereby securely grip the bone fragment.
`vanced. The desired openings in the sleeve can be dis
`tinct gaps between the strips in the rest position of the
`The novel bone implant of this aspect of the invention
`sleeve, or some other type of opening.
`can be, but is not necessarily, an epiphyseal/meta
`physeal implant.
`In a preferred surgical implantation technique, a
`guide wire is placed into the patient’s bone at the de
`As used herein the topographical term “circumferen
`sired location, a substantially cylindrical cavity to re
`tially-closed” means that a path can be traced entirely
`around the circumference of a hollow structure having
`ceive the implant is formed with a drill or reamer can
`nulated to fit over the guide wire, the expansion sleeve
`an axis while avoiding any break or gap or other inter
`is secured (preferably releasably) at its smoothly
`ruption in the solid material of the structure. Thus, for
`example, a split ring would not be circumferentially
`rounded dome to an elongated cannulated rod (carrying
`the plunger) which extends within the expansion sleeve
`closed, while a closed ring would be. The uninterrupted
`and through the circumferentially-closed circular ring
`path may be irregular in contour but must be continuous
`thereof, the expansion sleeve is inserted into and held in
`for a full 360° with respect to the axis of the structure in
`question.
`place within the prepared cavity in the bone by means
`Because the expansion sleeve of the bone implant of
`of the elongated rod (which ?ts over the guide wire),
`and the plunger is advanced along said insertion rod
`this aspect of the invention has a smoothly rounded
`into the interior of the expansion sleeve. More prefera
`circumferentially-closed dome at its leading end, the
`likelihood of signi?cant proximal implant migration or
`bly, the insertion rod is externally threaded at one end
`and the dome of the expansion sleeve is provided with
`“cut-out” in the femoral head is greatly reduced (as
`45
`a centrally-disposed threaded axial through bore for the
`compared, for example, to an externally-threaded bone
`releasable attachment of the externally threaded end of
`screw or tri-flanged nail). This is a very important fea
`ture giving rise to substantially improved product life
`the insertion rod.
`and substantially reduced bone damage. The feature
`The present invention also includes a preferred in
`that the expandable strips in the expansion sleeve extend
`strument for use in inserting a surgical implant (e.g. the
`novel expansion sleeve-containing bone implant of the
`between, and are connected at their opposed ends to,
`two circumferentially-closed structures (i.e. the
`invention discussed above) into a cavity in a patient’s
`bone. This novel insertion instrument comprises an
`smoothly rounded dome at the leading end of the ex
`elongated axially cannulated rod having an externally
`pansion sleeve and the circular ring at the trailing end)
`is also signi?cant since it means that these thin strips
`threaded portion adjacent one of its ends and an exter
`nally smooth portion extending from the externally
`have no free ends that can contribute to cut-out or catch
`threaded portion towards the other end of the rod; a
`on the wall of a prepared cavity in the patient’s bone
`structure during implantation. No signi?cant torque
`hollow sleeve receiving the elongated rod, which
`sleeve is capable of sliding movement upon the exter
`(which can cause rotation of the femoral head during
`nally smooth portion of the rod; and means for advanc
`insertion or stripping of the bone material) has to be
`60
`applied to the implant during its implantation, and the
`ing the hollow sleeve along the externally smooth por
`tion of the elongated rod towards the externally
`radial expansion of the textured strips provides a highly
`threaded portion of the rod. The sleeve advancing
`effective and secure bone gripping action distributed
`along the surface of the sleeve without generating ex
`means is preferably structured in such a way that it
`positively prevents movement of the hollow sleeve
`cessive stress concentrations in the bone adjacent the
`implant. Additionally, because the expandable strips are
`along the rod in a direction away from the externally
`threaded portion of the rod while it is engaged with the
`anchored at both ends fatigue loading is not concen
`sleeve. Suitable sleeve advancing means include a
`trated at one end of the strip and bending moments are
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`be, for example, another bone plate, an angled side
`knurled knob threaded upon a second externally
`threaded portion of the elongated rod on the opposite
`plate, a distal buttress plate, or the like. Thus, a further
`advantage of the novel elongated bone plate of the
`side of the externally smooth portion than the afore
`mentioned ?rst externally threaded portion, or a
`invention is that it can be readily connected to a surgical
`implant having an elongated plate portion adapted to be
`spreader tool which interacts with ratchets provided on
`the elongated rod on said opposite side of its externally
`secured to a patient’s bone by means of bone fasteners
`smooth portion.
`received in apertures in the elongated plate portion,
`By using the preferred implantation technique and
`which plate portion has upper and lower surfaces, with
`a cavity being formed in the lower surface of the plate
`insertion instrument described above, with the hollow
`portion at a free end thereof, said cavity extending lon
`sleeve of the instrument positioned behind and forcing
`the plunger of the implant into the expansion sleeve, the
`gitudinally from said free end to a shoulder defming an
`novel expansion sleeve and plunger-containing bone
`end of the cavity and said cavity having a transverse
`cross-section complementary to that of the elongated
`. implant of the invention can be readily inserted into the
`bone plate of the invention. An important consequence
`‘ prepared cavity in the patient’s bone in a simple surgical
`procedure involving low consumption of time and mini
`of the complementary designs of the transverse cross
`sections, including downwardly-inwardly tapered side
`mal risk of surgical error or equipment malfunction and
`walls, of the surgical implant cavity and elongated bone
`having highly reproducible results from case to case.
`plate is that the bone plate “dovetails” with the surgical
`The same insertion instrument can be used withbone
`implants of different length. The feature that the sleeve
`implant so that it can enter and be removed from the
`cavity in the surgical implant only by relative axial
`advancing means positively prevents rearward move
`movement through the cavity opening at the free end of
`‘ment of the sleeve along the rod is signi?cant because it
`the elongated plate portion of the surgical implant.
`permits the surgeon to readily stop advancement of the
`plunger during its insertion into the expansion sleeve
`Also, no relative rotation is permitted between the sur
`without releasing the compressive force being placed
`gical implant and bone plate. When the end of the bone
`plate abuts the shoulder at the other end of the cavity,
`upon the plunger by the hollow sleeve of the insertion
`instrument.
`no relative translational movement is possible between
`the surgical implant and bone plate except for axial
`Another aspect of the present invention is a novel
`elongated bone plate having an upper surface intended
`separation. By insuring that at least one bone fastener
`receiving aperture in the elongated plate portion of the
`to face away from the patient’s bone that is wider than
`surgical implant overlies a bone fastener-receiving aper
`a lower surface intended to face towards the patient’s
`ture in the bone plate when the plate is inserted into said
`bone, and two side surfaces connecting the upper and
`cavity in the surgical implant and abuts the shoulder at
`lower surfaces which are tapered inwardly toward one
`the end of the cavity, a stable and secure assembly of
`another in the direction from the upper surface to the
`surgical implant and bone plate, in which the length of
`lower surface. The bone plate has a substantially con
`the elongated plate portion of the surgical implant is
`stant thickness between the two side surfaces and is
`35
`effectively extended by the elongated bone plate, can be
`adapted to be secured to a patient’s bone by means of
`realized when the assembled surgical implant and bone
`bone fasteners received in apertures in the bone plate.
`plate are secured together. to the patient’s bone.
`Because the lower surface adjacent the bone is thinner
`The present invention comprises additionally a novel
`(preferably 70% to 90% in width) than the upper sur
`distal buttress plate adapted to be secured to the outer
`face at which stresses from physiological bending mo
`cortical wall of the lateral distal femur by means of bone
`ments applied to the plate tend to be at a maximum, the
`necessary periosteal tissue stripping adjacent the bone
`fasteners received in apertures in the plate. The plate
`includes a relatively ?at elongated proximal portion
`for implantation purposes can be reduced without ex
`cessively sacri?cing the strength of the bone plate under
`adapted to be secured to the lateral distal femoral shaft
`and a relatively curved distal portion, curved out of the
`bending. In one preferred embodiment said upper and
`plane of the proximal portion, adapted to be secured to
`lower surfaces are de?ned in transverse bone plate
`the lateral distal femoral condyle.
`cross-sections by arcs of two concentric circles, while
`For injuries including a sagital fracture through the
`the two side surfaces are de?ned therein by two straight
`radial lines passing through the common center of said
`distal epiphyseal bone, it is highly desirable to use a
`distal buttress plate in conjunction with at least two lag
`concentric circles.
`It is also preferred that an elongated bone plate of this
`screws used for fracture reduction in the distal condylar
`aspect of the invention comprise two parallel integral
`region, with these lag screws being positioned in close
`proximity to, but not passing through, the distal portion
`downwardly-extending rails located at opposite sides of
`the lower surface and extending along substantially the
`of the buttress plate. Thus, in accordance with this
`entire length of the bone plate. These two rails serve to
`aspect of the invention, two spaces for the accommoda
`tion of a pair of lag screws are left adjacent the sides of
`lift the lower surface of the bone plate away from the
`a thin neck connecting a wider, generally rounded head
`‘ surface of the patient’s bone so as to permit enhanced
`vascularization of the bone directly beneath the lower
`at the distal end of said distal portion and a still wider
`distal portion body having a greater maximum width
`surface and thus avoid any excessive weakening of that
`than the elongated proximal portion of the buttress
`bone tissue.
`_
`plate. Preferably, at least one elongated aperture capa
`As has been discussed above in connection with the
`ble of receiving two bone fasteners is provided in the
`modular femoral implant kit or system of the invention,
`distal portion head and a pair of such elongated aper
`it is highly advantageous to provide an elongated bone '
`plate that can be readily connected to the elongated
`tures, one on each side of the body, are provided in the
`plate portion of another surgical implant in a simple,
`distal portion body. It is also preferred that the rela
`tively ?at proximal portion of the buttress plate be pro
`foolproof, non-time consuming surgical method so as to
`effectively provide an extension of the length of said
`vided with an appropriately dimensioned cavity for a
`elongated plate portion. The other surgical implant may
`"dovetailed” connection to the novel bone plate of the
`
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`
`