`
`WORLD INTELLECTUAL PROPERTY ORGANIZATION
`International Bureau
`
`
` (51) International Patent Classification 5 :
`
`INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT)
`(11)International Publication Number:
`~ WO 94/10928
`(43) International Publication Date:
`26 May 1994 (26.05.94)
`
`A61B 17/56
`
`(21) International Application Number: PCT/US93/10966|(81) Designated States: AU, BB, BG, BR, BY, CA, CZ, FI, HU,
`
`,
`JP, KP, KR, KZ, LK, LV, MG, MN, MW, NO, NZ,PL,
`(22) International Filing Date:
`RO, RU, SD, SK, UA, US, UZ, VN, European patent
`(AT, BE, CH, DE, DK, ES, FR, GB, GR,IE,IT, LU,
`MC,NL, PT, SE), OAPI patent (BF, BJ, CF, CG, CL
`CM, GA, GN, ML, MR, NE, SN, TD, TG).
`.
`
`12 November 1993 (12.11.93)
`
`(30) Priority data:
`92/13694
`
`.
`13 November 1992 (13.11.92) FR
`
`
`
`.
`Published
`With international search report.
`Before the expiration of the time limit for amending the
`claims and to be republished in the event of the receipt of.
`amendments.
`
`(71) Applicant (for all designated States except US): SOFAMOR }-
`DANEK GROUP,INC. [US/US]; 3092 Directors Row,
`Memphis, TN 38131 (US).
`
`(72) Inventor; and
`(75) Inventor/Applicant (for US only) : HOPF, Christoph [DE/
`DE]; Draiserstrasse 155, D-6500 Mainz 1 (DE).
`
`.
`
`(74) Agents: BECK, Michael, D. et al.; Woodard, Emhardt,
`Naughton, Moriarty & McNett, Bank One Center/Tow-
`er, Suite 3700, 111 Monument Circle, Indianapolis, IN
`46204 (US).
`
`
`
`(54) Title: PEDICULAR SCREW AND POSTERIOR SPINAL INSTRUMENTATION
`
`
`
`(57) Abstract
`
`The instrumentation comprises for each
`lumbar vertebra (L5), two pedicular screws (1)
`having two screw threads (9, 11), one (9) of the
`screw threads corresponding to the region of
`penetration of the screw in the pedicle,
`two
`rods (2) having asperitics respectively associat-
`ed with a pedicular screw and secured to the
`latter by connection elements (3) provided with
`elements for clamping the rods. Each connec-
`tion element (3) is in one piece and the screw
`thread (9) corresponding to the region of pene-
`tration of the screw in the pedicle terminates in
`an annular shoulder (16) against which the
`connection element bears which is separated
`by a smooth part (15) from the screw thread
`(11) outside the region of penetration in the
`pedicle. This instrumentation permits both re-
`turning the slipped vertebrae rearwardly and
`pivoting it in the desired direction of rotation,
`it being possible to carry out the derotation ac-
`tion slowly and by controlling the movement
`so that the surgeon achieves on the whole in
`the two movements an excellent precision in
`the repositioning of the vertebraerelative to the
`
`neighbouring vertebrae.
`
`
`
`
`
`FOR THE PURPOSES OF INFORMATION ONLY
`
`Codes used to identify States party to the PCT on the front pages of pamphlets publishing international
`applications under the PCT.
`
`Mongolia Mauritania
`
`United Kingdom
`Georgia
`Guinca
`Greece
`Hungary
`Ireland
`italy
`Japan
`Kenya
`Kyrgystan
`Democratic People’s Republic
`of Korea
`Republic of Korea
`Kazakhstan
`Liechtenstein
`Sri Lanka
`Luxembourg
`Latvia
`Monaco
`Republic of Moldova
`Madagascar
`Mali
`
`AT
`AU
`BB
`BE
`BF
`BG
`BJ
`BR
`BY
`CA
`cr
`cG
`CH
`cl
`cM
`CN
`cs
`CZ
`DE
`DK
`ES
`FI
`FR
`GA
`
`Austria
`Australia
`Barbados
`Belgium
`Burkina Faso
`Bulgaria
`Benin
`Brazil
`Belarus
`Canada
`Central African Republic
`Congo
`Switzerland
`Céte d'Ivoire
`Cameroon
`China
`Czechoslovakia
`Czech Republic
`Germany
`Denmark
`Spain
`Fintand
`France
`Gabon
`
`Malawi
`NigerNetherlands
`Norway
`New Zealand
`Poland
`Portugal
`Romania
`Russian Federation
`Sudan
`Sweden
`Slovenia
`Slovakia
`Senegal
`Chad
`Togo
`Tajikistan
`Trinidad and Tobago
`Ukraine
`United States of America
`Usbekistan
`Viet Nam
`
`°
`
`
`
`WO 94/10928
`
`.
`
`PCT/US93/10966
`
`PEDICULAR SCREW AND POSTERIOR SPINAL INSTRUMENTATION
`
`osteosynthesis
`lumbar
`to
`relates
`invention
`The
`instrumentation for the correction of spondylolisthesis. .
`It is known that, | substantially,
`spondyliolisthesis
`
`is
`
`the forward displacement of a vertebra relative to its lower
`
`In theory, any vertebra may be affected, but the
`neighbour.
`fifth and the fourth lumbar vertebrae are the most
`commonly
`
`10
`
`concerned.
`
`Affecting more frequently women or young girls than men,
`
`spondylolisthesis is usually classified into five
`types:
`dysplastic,
`isthmian,
`traumatic,
`degenerative
`and
`
`pathological.
`
`15
`
`Its degree of seriousness is measured
`
`by
`
`the distance
`
`travelled through by the displaced vertebra with respect
`
`to
`
`its lower neighbour.
`There are four stages:
`
`20
`
`the
`The first stage is a displacement of
`a quarter
`-
`antero-posterior diameter of the vertebral body.
`The fourth stage corresponds to a complete displacement of
`
`of
`
`the vertebral body.
`The second and third stages are the intermediate stages.
`Heretofore,
`although there
`are
`certain
`surgical -
`
`25
`
`techniques for the treatment of spondylolisthesis, either by
`
`the direct traction on
`
`the
`
`slipped vertebra,
`
`or
`
`by
`
`the
`
`screwing of the pedicles of
`
`this
`
`slipped vertebra,
`
`the
`
`
`
`WO 94/10928
`
`PCT/US93/16966
`
`reduction
`
`of
`
`the
`
`spondylolisthesis
`
`is
`
`not
`
`always
`
`satisfactory,
`
`above
`
`all
`
`in
`
`the
`
`cases
`
`of
`
`serious
`
`-2-
`
`.
`spondylolisthesis.
`long
`a
`have
`Surgery is indeed indicated for those who
`past of lumbalgia or sciatica,
`in the case of evidence of
`a
`vertebral canal stenosis, a compression of the cauda
`equina
`
`or
`a
`subjacent
`motor
`lesion,
`or
`those
`whose
`spondylolisthesis rapidly evolves toward stage 3 or stage 4,
`Generally,
`in surgery,
`an anterior
`or
`posterior
`vertebral fusion,
`-laminectomy with decompression of
`the
`
`10
`
`posterior structures and an excision of
`
`the hypertrophied
`
`mass of the fibrous tissue in the region of the lysis may be
`
`indicated.
`
`In isthmian spondylolisthesis,
`
`-the bilateral
`
`isthmian
`
`15
`
`lyses are
`
`liable to be associated with
`
`a
`
`considerable
`
`in relation with an
`pseudoarthrosis
`emerging nerve root.
`The discal state in the
`region of
`the
`spondylolisthesis
`sometimes
`requires a
`radiculographic or discographic
`assessment.
`In vertebral canal stenoses,
`the
`decompression
`
`20
`
`without fusion may be a surgical operation.
`In actual fact, an effective orthopedic surgery consists
`in returning the vertebra not only onto
`the
`axis of
`the
`
`spine but also to a position which is as correct as possible
`
`relative to the neighbouring vertebrae. Over
`
`a period of
`
`25
`
`time, or in the course of its displacement,
`
`this vertebra in
`
`fact might have been subjected to lateral thrusts which have
`
`caused it to pivot horizontally to a more
`
`or
`
`less
`
`large
`
`
`
`WO 94/10928
`
`PCT/US93/10966
`
`- 3-4
`
`extent so that a correct repositioning of
`
`the vertebra of
`
`course implies its rearward return but also a derotation.
`
`correct
`to
`made
`been
`already
`Attempts
`have
`devices
`of
`means
`by
`example
`spondylolisthesis, for
`interconnected by
`a
`consisting of
`two pedicular
`screws
`transverse plate which, by screwing a nut bearing against
`the plate,
`act
`solely by
`translation of
`the
`concerned
`
`vertebra for putting it into alignment with the neighbouring
`
`vertebrae.
`
`10.
`
`Thus,
`the device disclosed in French patent 2 615
`095
`(87 06 864) employs two rods which are longitudinally fixed
`
`in the vertebral column with the aid of pedicular screws and
`each serve as support means for two screws having a double
`
`screw thread connected to the vertebra
`
`to be corrected.
`
`15
`
`These two double thread screws are transversely connected by
`a rigid plate constituting a bipedicular base.
`It
`is
`this
`transverse plate which permits acting on the vertebra to be
`corrected owing to the provision of
`a median
`opening
`for
`
`receiving traction forceps.
`
`20
`
`acting in a
`does not permit
`“In fact, such a device
`sufficiently satisfactory manner, and experience
`has
`shown
`
`that a traction on the median part
`
`of
`
`the plate has’
`
`for
`
`effect to rearwardly return the vertebra to be corrected too
`
`it
`be derotated,
`rapidly. Further, if this vertebra must
`has been found that the presence of the plate is
`liable to
`
`25
`
`prevent the required derotation action owing
`
`to the
`
`fact
`
`that this induces at the same time a certain return: of
`
`the
`
`
`
`WO 94/10928
`
`PCT/US93/10966
`
`vertebra.
`
`revealed “that
`has
`experience
`surgical
`Now,
`is
`desirable to act slowly on the vertebra by
`acting on
`each
`one of the double thread screws independently, so
`that’
`the
`surgeon can gradually adjust for each particular case his
`
`it
`
`vertebra derotation and/or return action.
`Moreover, such a device is relatively complex and costly
`
`owing to the number of its component parts which
`
`further
`
`increases
`
`the mounting difficulties
`
`encountered by
`
`the
`
`in
`concerns
`As
`surgical operation.
`surgeon during the
`fact
`particular the double thread screw,
`in addition to the
`that it is long and costly to produce, its
`implantation in
`
`the pedicles is not at all convenient.
`
`Further,
`this double
`thread screw is
`subjected to
`extremely high shear stresses, mainly in the region of
`the
`junction with the instrumentation appliances or in the upper
`part of the screw thread.
`An object of
`the
`invention is
`osteosynthesis
`instrumentation for
`
`lumbar
`a
`to provide
`the
`correction
`of
`
`10
`
`15
`
`20
`
`spondylolisthesis, which permits both returning the vertebra
`
`to the rear and pivoting it
`
`in the desired direction of
`
`rotation. Another object of the invention is to provide
`
`a
`
`double thread pedicular screw so arranged as to overcome the
`
`aforementioned drawbacks while permitting mass production
`
`25
`
`which is cheaper than in the case of screws known in the art
`
`which can only be produced on a small scale.
`
`The osteosynthesis
`
`instrumentation according
`
`to the
`
`
`
`WO 94/10928
`
`PCT/US93/10966
`
`~5 2
`
`invention comprises, for each lumbar vertebra,
`
`two pedicular
`
`double thread screws, one thread of which corresponds to the
`region of penetration of the screw in the pedicle,
`two
`rods
`having surface asperities
`respectively associated with
`a
`pedicular screw and connected to the
`latter
`by
`connection
`
`elements provided with elements for clamping the rods.
`
`is
`According to the invention, each connection element
`in one piece and the
`screw . thread corresponding.
`to the
`region of penetration of the screw in the pedicle terminates
`
`10
`
`on an annular
`
`shoulder
`
`on which
`
`the
`
`connection element
`
`bears.
`
`The derotation action exerted by means
`of
`this
`instrumentation has the advantage that it can be carried out
`
`slowly and with a
`
`certain amount of
`
`control. over
`
`the
`
`15
`
`movements,
`
`thereby affording on the whole
`
`in the
`
`two
`
`movements an excellent precision in the repositioning of the
`
`vertebra relative to its neighbouring vertebrae.
`Further,
`the arrangement ofa transverse shoulder
`
`into
`
`which tangentially fades the screw thread of the part of the
`
`20
`
`screw serving to penetrate
`the
`pedicle,
`provides
`a
`reinforcement or strengthening resisting the shear
`stresses
`
`in this region.
`
`The continuous peripheral shoulder may also
`
`act as a support for an added part.
`
`According to a particular feature of the invention,
`
`the
`
`25
`
`end of the screw thread outside
`
`the part
`
`of
`
`the
`
`screw
`
`serving to penetrate the pedicle
`
`is
`
`extended
`
`by
`
`a
`
`screw
`
`threaded rod adapted to cooperate with an ancillary screwing
`
`
`
`WO 94/10928
`
`PCT/US93/10966
`
`device.
`
`The instrumentation according to the invention comprises
`
`an ancillary device for screwing the pedicular double thread
`screw,
`this device bearing against
`the
`screw threaded
`extension of said screw. This ancillary device comprises
`a
`
`rod provided with an end grip and
`
`includes
`
`a
`
`tubular
`
`end
`
`the
`insertion of
`the
`arranged to permit
`part which is
`operating part of the double thread screw,
`has
`a
`conical
`
`free end part remote from the grip tapering toward the grip
`
`10
`
`and is provided with at least one longitudinal
`
`slot.
`
`This
`
`ancillary device further comprises a tube freely slidable on
`
`the rod for the purpose of
`surrounding and gripping the
`conical end part of its tubular end part for the purpose
`of
`
`clamping it on the operating part of the pedicular screw.
`
`With this ancillary device,
`
`the length of the operating
`
`tubular
`in -the
`screw thread is almost completely enclosed
`end part and clamped owing to the action of the second tube
`when the latter
`surrounds
`the conical
`end part
`of
`the
`tubular end part. After having provided a prior bore in the
`pedicle,
`the surgeon can in this way easily screw the double
`
`thread screw in position.
`
`Further features and advantages of the invention will be
`
`apparent from the following description with
`
`reference
`
`to
`
`the accompanying drawings which illustrate two
`embodiments
`of the invention by way of non-limitative examples,
`
`In the drawings:
`
`Fig.
`
`1
`
`is
`
`a perspective
`
`view from above
`
`of
`
`one
`
`15
`
`20
`
`25
`
`
`
`WO 94/10928
`
`PCT/US93/10966
`
`-7-
`lumbar osteosynthesis
`the
`of
`embodiment
`according to the invention, mounted
`on
`the
`
`instrumentation
`first
`lumbar
`
`vertebra and on the sacrum.
`perspective
`Fig.
`2
`is a partial
`instrumentation shown in Fig. 1.
`
`view
`
`of
`
`the
`
`|
`
`Fig.
`
`3
`
`is
`
`an elevational
`
`view in the
`
`transverse
`
`direction, partly in section, of the
`in Figs.
`1 and 2.
`Pig.
`4 is an elevational view to a
`
`instrumentation shown
`|
`a
`
`scale of
`
`larger
`
`10
`
`pedicular double
`
`thread screw which
`
`is part
`
`of
`
`the
`
`instrumentation shown in Figs.
`1
`to 3.
`Fig. 5 is a perspective view of
`an
`
`embodiment
`
`of
`
`the
`
`ancillary device for mounting the pedicular screw shown
`Fig. 4.
`
`in
`
`15
`
`Fig.
`
`6 is a perspective view to a
`
`larger
`
`scale of
`
`an
`
`alternative embodiment of the. connection element between the
`
`osteosynthesis rod and the screw.
`Fig.
`7 is a sectional view taken on line 7-7 of Fig. 6.
`
`The lumbar osteosynthesis instrumentation shown in Figs.
`
`20
`
`1
`
`to 3
`
`is
`
`adapted
`
`to correct
`
`spondylolisthesis
`
`by
`
`the
`
`posterior approach.
`
`it comprises, for each lumbar vertebra to be
`
`corrected,
`
`for example the vertebra L5,
`
`two pedicular screws
`
`1
`
`having
`
`two screw threads,
`two cylindrical rods
`2, preferably two
`rods of the so-called Cotrel type having surface asperities
`
`25
`
`or knurling extending longitudinally along
`
`the
`
`concerned
`
`lumbar segment
`
`(vertebrae L5,
`
`L4
`
`and
`
`sacrum S
`
`in the
`
`
`
`WO 94/10928
`
`PCT/US93/ 10966
`
`-8-
`
`assembly shown in Fig. 1), connection elements 3
`
`connecting >
`
`each pedicular screw 1
`
`to the
`
`adjacent
`
`rod
`
`2,
`
`pedicular
`
`screws 4 for securing the rods 2 to the vertebra L4
`
`and
`
`to
`
`the
`
`sacrum S,
`
`and devices
`
`5
`
`providing
`
`a
`
`transverse
`
`connection between the rods. All these elements except
`
`the
`
`pedicular screws 1 and the connection elements 3
`
`are
`
`known
`
`per _se and therefore need no special description.
`Each connection element
`3 has, when
`viewed
`
`in the
`
`transverse direction,
`
`a
`
`substantially L-shaped
`
`profile
`
`10
`
`consisting of an enlarged base 3a in which
`is provided a
`through passage 10
`receiving the rod 2 and having an
`axis
`
`X=-X. This portion 3a has on one side a cylindrical
`
`surface
`
`and on the other side a planar surface and is extended by
`
`a
`
`thin portion 3b.
`
`The
`
`latter has
`
`two parallel planar
`
`15
`
`surfaces and is provided with an opening 7 for
`the
`passage
`of the pedicular screw 1.
`The opening 7
`consists of
`a
`
`cylindrical central part having an axis Z-2Z extended on each
`side by two conical parts 7b, 7c
`opening onto the planar
`
`surfaces.
`
`The taper of these conical parts is such that
`
`it
`
`20.
`
`permits an inclination of the axis of the screw 11
`
`relative
`
`to the axis Z-Z of about + 15°,
`
`the angular limits
`
`of
`
`this
`
`‘axis corresponding to the axes Y-Y and y'-y'
`
`(Fig.
`
`7).
`
`A
`
`tapped opening 6
`
`transversely opens onto the bore or passage
`
`10 and receives a screw 20 for radially clamping the rod
`
`2.
`
`25
`
`The surface 3c of the element 3 remote from the passage
`
`10
`
`is completely planar.
`
`The element
`
`3 constitutes the means for securing the rod
`
`
`
`WO 94/10928
`
`PCT/US93/10966
`
`-9-
`
`2 and the means for screwing the
`
`screw 1.
`
`The distance
`
`between the axes of the screw 1 and
`rod
`2
`vary with the
`subject so that the surgeon can choose the most
`appropriate
`
`element 3.
`Each screw 1 comprises from its point 8
`
`a
`
`first
`
`screw
`
`threaded part 9 extending to the length of penetration of
`
`the screw 1
`
`in the pedicular and
`
`a
`
`second
`
`screw threaded
`
`part 11 which is outside the region of penetration in the
`‘pedicle and is termed the "operating" part.
`On
`the
`side
`
`remote from the screw threaded part 9 the operating part
`
`11
`
`is extended by a profiled end portion 12,
`constituted for
`example by two flats 13 adapted to permit both the gripping
`
`of the double thread screw 1 and
`
`the
`
`screwing
`
`thereof
`
`means of an ancillary device
`
`14
`
`(Fig.
`
`5) which will
`
`by
`
`be
`
`15
`
`described hereinafter.
`
`At the end remote from the profiled end portion 12,
`
`the
`
`
`screw threaded operating part 11 a=shortis extended by
`
`
`
`smooth region 15
`terminating in a continuous peripheral
`shoulder 16 constituting the end of the screw threaded part
`
`20
`
`9. This shoulder 16 bears against the planar surface of the
`element 3 which is the most remote from the
`screw threaded
`
`part 11, consequently the screw 1 cannot pass
`
`through the
`
`element 3.
`
`.
`
`The screw thread 18
`
`of
`
`this screw threaded part
`
`is
`
`25
`
`adjacent the shoulder 16 and the depth of
`
`the
`
`thread 21
`
`close to the
`
`shoulder
`
`16 gradually diminishes until it
`
`tangentially merges with or fades onto a cylindrical
`
`sector
`
`
`
`WO 94/10928
`
`PCT/US93/10966
`
`- 10 -
`
`22 bordered by the shoulder 16 which
`
`thus
`
`forms
`
`a
`
`screw
`
`reinforcing region in this position.
`act as a support fora device or
`an
`element 3.
`|
`
`The
`shoulder
`16 may
`associated connection
`
`The operating part 11 of the screw 1
`
`is constituted by a
`
`metal screw thread of small pitch, for example
`
`between
`
`0.5
`
`and 2 mm and preferably between 0.8 and
`1
`mm,
`adapted
`receive a nut 23
`for
`clamping
`the
`connection element
`
`to
`3
`
`against the shoulder 16.
`
`10
`
`This instrumentation has the following advantages:
`The fact that the connection element
`3
`is made
`single piece not only makes
`this
`element
`cheaper
`
`in a
`to
`
`Manufacture but
`
`also simplifies
`
`the positioning of
`
`the
`
`element by the surgeon, and above all improves the
`
`strength
`
`15
`
`of the connection between the rod 2 having asperities
`
`and
`
`the pedicular screw 1.
`
`As previously explained,
`
`the pedicular- double
`
`thread
`
`screw 1
`
`is subjected to high mechanical stresses of multiple
`
`origins;
`
`it must
`
`resist
`
`these various
`
`stresses
`
`for
`
`‘a
`
`20
`
`relatively long period of time the duration of which depends
`
`on each patient.
`
`The screw 1 must therefore be as simple as
`
`possible to mount during the surgical operations,
`
`but must
`
`also have sufficient strength to withstand all
`
`the
`
`forces
`
`during and after the operation.
`
`Now, with
`
`the pedicular
`
`25
`
`screws employed heretofore, it has been found that fractures
`
`generally occur in the region between the two screw threads.
`
`The invention remedies this
`
`situation by
`
`terminating the
`
`
`
`WO 94/10928
`
`,
`
`PCT/US93/10966
`
`screw thread 18
`
`for
`
`-~ It
`-—
`anchoring in the pedicle
`
`in ‘the
`
`the screw
`substantially tangential region 22. Consequently,
`16
`thread 18 does not “open out"
`onto
`the
`shoulder
`for
`supporting the connection element 3 and consequently ensures
`that this shoulder 16 has
`a peripheral
`continuity and
`a
`sufficient supporting thickness. This supporting thickness
`
`thus affords the maximum mechanical resistance to the forces
`transmitted to the
`connection element
`3
`and therefore
`
`exerted by the latter.
`
`10
`
`Another advantage afforded by this
`arrangement
`of
`anchoring screw thread 18 resides in the fact that, when
`
`the
`it
`
`is desired to effect a bicortical anchorage by reaching the
`
`opposite cortical part of the vertebra and with the
`
`screw
`
`thread length corresponding to the
`
`length of
`
`the passage
`
`15
`
`through the vertebra,
`the surgeon is informed of the desired
`final position of the screw thread.
`The
`stoppage of
`the
`
`latter in its upper part indeed constitutes
`a warning
`that the surgeon must suddenly exert a higher | torque.
`
`in
`He
`
`20
`
`must therefore stop his screwing effort.
`Owing to the provision of the profiled end portion 12,
`the engagement of the pedicular screw 1
`by
`the ancillary
`
`device 14 no longer occurs in the central
`region of
`screw, as described in said patent 2 615
`095, but at
`free end of the screw. This end region may be in the
`
`the
`the
`form.
`
`25
`
`of two flats 13 provided on a smooth,
`
`or optionally screw
`
`threaded, end part to permit the ancillary device 14 to act
`
`on the screw.
`
`
`
`WO 94/10928
`
`PCT/US93/10966
`
`This ancillary device comprises a red 24 provided with a.
`
`-12-
`
`tubular end part 25 and, at its opposite end, a manual grip
`26.
`The tubular part 25 is so dimensioned as to permit
`the
`insertion therein of the operating part 11 of the
`screw 1,
`and the ancillary device 14 is completed by a tube or sleeve
`27 coaxial with the rod
`24
`and
`slidably mounted
`on
`the
`‘latter so as to be capable of surrounding the
`tubular part
`25 at the end of its travel.
`
`The tubular part 25 is provided with longitudinal
`
`slots
`
`10
`
`28 starting at its free end,
`
`for
`
`example
`
`three slots as
`
`illustrated, extending along a part of
`
`the
`
`length of
`
`the
`
`The free end portion 29 of the latter is conical
`region 25.
`and tapers in the direction toward the grip 26. Beyond
`the
`
`slots 28, at a certain distance from the
`
`latter,
`
`there
`
`is
`
`15
`
`provided a hollow profile matching the profiled end portion
`12 of the screw, for. example, as shown in Fig. 5,
`two
`flats
`31 whose longitudinal surfaces are parallel.
`The two
`fiats
`of
`31 are adapted to receive
`corresponding flats 13
`the
`screw 1 and thus lock the latter against rotation after
`the
`
`20
`
`insertion of the operating part 11
`in the tubular part 25.
`In the direction toward the conical end part 29,
`the
`flats
`31 are extended by longitudinal recesses
`32
`for
`receiving
`
`the operating part 11 of the screw 1. Lastly,
`
`in order
`
`to
`
`permit a visual checking of the position of the profiled end
`
`25
`
`portion 12 on the flats 31,
`
`the tubular part 25 is provided
`
`with a transverse opening 33 in the region of the flats.
`
`When
`
`the operating part 11
`
`is inserted in the tubular
`
`
`
`WO 94/10928
`
`PCT/US93/10966
`
`~13-
`
`part 25 with its end portion 12
`
`locked
`
`against
`
`rotation -
`
`between the flats 31,
`
`the surgeon slides the tube
`
`27
`
`along
`
`the tubular part 25 until the conical end portion 29 is made
`to grip round the operating part 11,
`the tapered portion 29
`thus constituting a holding chuck for the screw i. The
`two
`
`flats constitute additional means for preventing a
`
`reverse
`
`rotation of the pedicular screw 1
`in the ancillary device
`14.
`The ancillary device 14 also serves to screw the nut 23
`clamping the screw 1
`in the connection element
`3.
`It
`is
`
`10
`
`provided in its end
`
`29 with a
`
`corresponding recess
`
`for
`
`engaging this nut 23.
`The
`instrumentation just described is
`
`used
`
`in the
`
`following manner.
`
`Before placing in position the support rods 2, which are
`
`15
`
`for example the known Cotrel
`rods
`(Registered Trademark),
`the surgeon suitably anchors with his ancillary device
`14
`the double thread screws 1
`in each of the pedicles
`of
`the
`vertebra L5 to correct. Then he secures the support reds
`2
`
`to the neighbouring vertebrae, or,
`
`as
`
`in ‘the
`
`embodiment
`
`20
`
`shown in Fig. 1,
`
`to the sacrum S and vertebra L4.
`
`Then
`
`firmly fixes the connection elements 3
`
`to the
`
`rods
`
`2
`
`means of a radial clamping screw 20 (Fig. 1}.
`At this stage,
`the two transverse connection rods 5
`
`he
`
`by
`
`are
`
`not yet installed.
`
`In order to correct
`
`the vertebra L5,
`
`- 25
`
`i.e. to return it
`
`rearwardly
`
`(spondylolisthesis) and/or
`
`derotate it, the surgeon acts on the nuts
`
`23
`
`clamping
`
`the
`
`connection elements 3 by means of an ancillary device
`
`and
`
`
`
`WO 94/10928
`
`.
`
`PCT/US93/10966
`
`-14-
`
`preferably two ancillary devices, each being disposed onone
`
`of the nuts 23 of the two screws 1.
`
`He is now free to act,
`
`as desired, more on the screwing of one of the nuts 23
`
`than
`
`- on the screwing of the other, depending on the movement
`
`he -
`
`wishes to impart to the vertebra L5, as he is free to act in
`an identical manner on the two nuts 23.
`23,
`the nuts
`Each time the surgeon acts on one of
`exerts by the bearing of the screw thread-nut system on
`
`he
`the
`
`connection element 3 firmly connected to the support rod
`
`2,
`
`a traction on the vertebra L5
`
`in. a direction toward
`
`the
`
`connection element 3. When he acts on a single one
`
`of
`
`the
`
`nuts 23, he also produces a slight rotation of the vertebra
`
`L5 about itself. When he acts equally on both nuts
`
`23,
`
`he
`
`produces a rearward return of the vertebra L5.
`
`the fine pitch of
`In all cases,
`the
`screw thread 11
`correction nut
`supporting the
`23 permits
`acting
`very
`progressively on the vertebra. When the vertebra is finally
`in the position requiredby the surgeon,
`the
`latter
`severs
`the double thread screw 1 above the nut 23.
`The severing of
`the rod deforms the screw thread 11
`and
`this
`subsequently
`prevents the unscrewing of the nut 23.
`
`It is only at this moment that
`
`the
`
`transverse
`
`rods
`
`5
`
`interconnecting the rods 2 can be mounted,
`
`thereby achieving
`
`a rectangulation of the whole final instrumentation.
`
`The instrumentation according to the invention is easier
`
`to place in position by the surgeon than that disclosed in
`
`said French patent
`
`2
`
`615
`
`095,
`
`cheaper
`
`as
`
`concerns
`
`the
`
`10
`
`15
`
`20
`
`25
`
`
`
`WO 94/10928
`
`PCT/US93/ 10966
`
`- 15 -
`
`fabrication of the screw, and more reliable in use;
`
`it
`
`no
`
`longer requires a transverse handling plate in the region of
`the connection elements 3. “The screwing of
`the pedicular
`screws 1 by their profiled end portions 12
`rather
`than by
`their central
`regions
`as in the
`aforementioned
`prior
`
`instrumentation,
`
`is also more convenient for the surgeon.
`
`it must be understood that the scope of the invention is
`not intended to be limited to. the described embodiments
`and
`
`various modifications may
`
`be made.
`
`For
`
`example,
`
`it
`
`is
`
`10
`
`obvious that the
`
`end portion 12 may
`
`have
`
`any suitable
`
`true of
`being
`the same
`profile other than that described,
`the corresponding two flats 31 of the ancillary device 14.
`Likewise,
`in the alternative embodiment shown in Fig. 6,
`
`the connection element 3 may
`
`be
`
`constructed to have,
`
`as
`
`15
`
`viewed in the transverse direction, a substantially L-shaped
`profile and be disposed in such manner
`that
`its - planar
`surface 3c (in contact with the nut
`23
`in Fig.
`3)
`is
`inverted, by turning the element round, so as to be
`closer
`
`to the adjacent vertebra.
`
`
`
`WO 94/10928
`
`PCF/US93/10966
`
`WHAT IS CLAIHED IS:
`
`1.
`
`Lumbar osteosynthesis
`
`instrumentation for
`
`the
`
`correction of spondylolisthesis
`comprising in combination
`for
`
`by
`each
`
`a posterior
`approach,
`lumbar vertebra,
`two
`
`pedicular screws each having a
`first
`screw thread and
`a
`second screw thread, said first screw thread corresponding
`
`to a region of penetration of said pedicular
`pedicle
`of
`the vertebra,
`two
`cylindrical
`associated with a
`respective pedicular
`screw,
`
`the
`screw in
`‘each
`rods
`connection
`
`elements each interconnecting each rod and_the associated
`
`
`10
`pedicular
`screw,
`an
`annular bearing shoulder
`for
`the
`
`connection element interposed between said first and
`
`second
`
`srew threads on each pedicular screw, clamping elements each
`
`associated with a respective connecting element for clamping
`
`15
`
`the
`
`respective
`
`rod,
`
`said first screw thread of
`
`each
`
`
`
`pedicular . screw terminating on and_saidsaid shoulder
`
`
`
`shoulder being separated by a smooth part from said second
`screw thread outside said region of penetration of
`said
`
`first screw thread in said pedicle.
`
`20
`
`2.
`
`Instrumentation according to claim 1, wherein
`
`each
`
`connection element has a substantially L-shaped profile and
`
`a planar surface and is disposed, when
`
`the
`
`instrumentation
`
`is placed in position,
`
`in such manner
`
`that
`
`said planar
`
`surface is placed as
`vertebra.
`
`25
`
`close
`
`as possible
`
`to the
`
`adjacent
`
`3.
`
`Instrumentation according to claim 1, wherein each
`
`connection element has a substantially L-shaped profile and
`
`
`
`WO 94/10928
`
`.
`
` PCT/US93/10966
`
`- 17 _
`
`a planar surface and is disposed, when
`
`the
`
`instrumentation
`
`is placed in position,
`in
`such manner
`that said planar
`surface is spaced away from the adjacent vertebra.
`4.
`Instrumentation according to claim 1, wherein each
`connection element has two opposed planar
`surfaces
`and -is
`provided with an opening
`for
`receiving the
`respective
`
`central
`pedicular screw, said opening having a cylindrical
`part extended at both ends by conical parts each opening out
`
`onto a respective one of
`
`said planar
`
`surfaces
`
`of
`
`said
`
`10
`
`connection element.
`
`5.
`
`Instrumentation according to claim 1,
`
`comprising a
`
`profiled end portion at an end of said second
`
`screw thread
`
`remote from said shoulder of
`
`each pedicular
`
`screw for
`
`cooperation with an ancillary screwing device.
`
`15
`
`6.
`second
`
`Instrumentation according to claim 1, wherein each
`screw thread has a pitch of
`substantially 0.5 to
`
`2 mm.
`
`7.
`
`Instrumentation according to claim 1, wherein each
`
`second screw thread has a pitch of 0.8 to 1 mm
`
`20
`
`8.
`
`Instrumentation according to claim 5 in combination
`
`with an ancillary device for screwing each pedicular
`
`screw
`
`by a part
`
`thereof,
`
`termed operating part,
`
`outside
`
`said
`
`region of penetration of
`
`said pedicular
`
`screw in said
`
`25
`
`pedicle, said ancillary device
`comprising a
`rod provided
`with an end grip and a tubular end part which is arranged to
`permit the insertion therein of said operating part
`of
`the
`
`respective pedicular screw, has a conical free
`
`end portion
`
`
`
`WO 94/10928
`
`PCT/US93/10966
`
`- 18 -
`
`remote from said grip and tapering in a direction toward
`
`said grip, and defines at least one longitudinal slot,
`
`and
`
`a tube freely slidably mounted on said rod of said device so
`as to be capable of surrounding and gripping said conical
`
`free end portion of said tubular end part for causing it
`
`to
`
`grip said operating part of said pedicular screw.
`
`Instrumentation according to claim 5 in combination
`9.
`with an ancillary device for screwing each pedicular
`screw
`by a part
`thereof,
`termed operating part, outside
`said
`
`10
`
`said pedicular
`region of penetration of
`pedicle, said ancillary device
`comprising
`
`screw in said
`rod provided
`
`a
`
`with an end grip and a tubular end part which is arranged to
`
`‘permit the insertion therein of said operating part
`
`of
`
`the
`
`respective pedicular screw, has a conical free end portion
`
`15
`
`remote from said grip and tapering in a direction toward
`
`said grip, and defines at least one longitudinal slot,
`and
`a tube freely slidably mounted on said rod of Said device so
`as to be capable of surrounding and gripping said conical
`
`free end portion of said tubular end part for gripping and
`
`20
`
`tightening a nut.
`
`10.
`
`Instrumentation according to claim 9, wherein
`
`said
`
`ancillary device comprises,
`in said tubular
`beyond said conical
`free end portion,
`a
`
`end part
`and
`hollow profile
`
`matching said profiled end portion of said pedicular
`
`screw
`
`25
`
`so as to prevent rotation of said pedicular
`
`screw relative
`
`to said tubular end part.
`
`11.
`
`Instrumentation according to claim 10, wherein said
`
`
`
`WO 94/10928
`
`PCT/US93/10966
`
`- 19 —
`hollow profile defines two flats
`
`having parallel
`
`surfaces
`
`screw
`said pedicular
`and said profiled end portion of
`defines two flats having parallel surfaces cooperative with
`said two flats of said hollow profile.
`
`12..
`
`Instrumentation according to claim 10, wherein said
`
`hollow profile is
`
`extended in a direction toward
`
`said
`
`conical
`
`free
`
`end portion by
`
`longitudinal
`
`recesses
`
`for
`
`receiving said second screw thread of said pedicular screw.
`
`10
`
`13.
`Instrumentation according to claim 10, comprising a
`transverse opening in said tubular end part in the region of
`said hollow profile for a visual checking of the engagement
`of
`said pedicular
`screw with said hollow profile for
`
`preventing relative rotation.
`
`14.
`
`Pedicular
`
`screw for use
`
`in an osteosynthesis
`
`15
`
`instrumentation, said pedicular screw comprising a
`
`first
`
`screw thread and a second
`screw thread and
`a
`transverse
`‘shoulder interposed between
`said two
`screw threads
`for
`supporting a
`connection element
`forming part
`of
`said
`instrumentation, said first screw thread being for
`screwing
`
`20
`
`into the pedicle of a vertebra and having
`
`an
`
`end
`
`thread
`
`helix which fades tangentially on a cylindrical
`
`sector
`
`of
`
`said transverse shoulder.
`
`15. Ancillary device
`intended
`for
`an osteosynthesis
`instrumentation for screwing a pedicular screw which
`forms
`
`25
`
`part of said instrumentation and comprises
`
`a
`
`first
`
`screw
`
`for screwing into the pedicle of a vertebra
`
`and
`
`a_
`
`second
`
`screw constituting an operating part, said ancillary device
`
`
`
`WO 94/10928
`
`PCT/US93/10966
`
`-~ 20 +
`comprising a rod which has a tubular end part and terminates
`
`in an end grip, said tubular end part being
`so dimensioned
`as to permit the insertion therein of said operating part of
`said pedicular screw, said tubular end part having a conical
`free end portion remote from said grip which
`tapers
`in a
`
`direction toward said grip, and at
`
`least
`
`one
`
`longitudinal
`
`slot, said ancillary device further comprising a tube freely
`
`slid
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