CA2051768C - Saggital approximator - Google Patents

Abstract

A sagittal approximator for clamping engagement with an open back hook and for urging a spinal rod into seating engagement with said hook. The sagittal approximator includes an integral fixed handle and jaw. A shiftable handle is pivotally connected to the fixed handle. A shiftable jaw is pivotally connected to the fixed handle adjacent the fixed jaw. The pivotal handle and java are pivotally interconnected such that as the pivotal handle is shifted, the pivotal jaw shifts accordingly. The fixed handle includes a threaded channel and longitudinal guide rib. A spinal rod engagement head is slidably carried by the fixed handle and jaw and includes a spinal rod seat which with contact with the spinal rod produces a balanced seating load on the rod. A threaded pusher rod is carried by the channel which when rotated longitudinally shifts the head relative to the fixed handle.

Description

~:~;~~_"~~f a~3 :»;cr r~rv~r A~wlv.or,.rMAmarr I':i,:ylc~i ~>f tlne Irzvent:ion Thi;~ <asp.i..icat:i.orc x~r~lates to ~i sagi..tr~l appl'oxlm;jt:or fc:;r sc,ating a spin<il ro<1 into an open back nook di2ring a poster~ic~r pi:~~.~) fi,~ai.ioo procedure.
Bac:k round of the Invention During a posterior ~.~pinal. fiasati.on procedure a plurality of metal rods may be connected by the surgeon to the spinal column of a pat.ieri ' by a series of open back hook > or ot_ner.
spinal f ixat:io:i clev,_' ces . The rods are connected to the opE.n bacc~ hooks and follow the curvature of the pat::ienf-'s spine.
An example of an open back hook may be had by ref erence to U.S. Patent Numbers 4,269,1'13 and 4,Fi15,453, although such hooles are not limited thereto. An open back spinal hook may be any suitable spinal hook having a slot-type opening unto the body of the hook, enabling an elongated spinal rod to pass through the slot for seating arrangement with 'the hook. The subject matter of the referenced patent numbers is provided solely to provide an understanding of the environment for the invention and in no way should be considered limiting.
Generally the rods are inserted into the open back hooks by applying pressure to the rod usiz-i~ a rod pusher as illustrated in U.S. Patent Number 4,922,425. However, it is not uncommon for additional force or stax>ility to be required to seat the x~od within the open back hook.. In such c:~,ses, a surgeon attachES a clamp to the hook and uses a mechariical ~'~ ~~_'~i~~a~
d'~vi~:e; >tlc.:a :as.; L;a:~ z and innsln~r~, l(r ;-;(:'<:rt 1_ht r(~cl.
I-t i=: c:()r:>:ic:lez'c:>(1 mo:;t noTVVC~ni~.nt if the c:l;,rnf~ ~anc', e~r,r3 ~WlSlaer' c.)t' ll~l:Y'y:~il(.'c_1' aI't=~ .111tWrC:OnI7E'CtECt. ~n eX<~Inylc-~ Ci(' .;llc:il ::1 C:C»51~>1I121i1OTl llOsC)IW:1d111t) c3nd rt:)d intr'odLlC:er' 1:>
nlanufaot'(Ire;7 L>y 3tuau ~_ , Tnc . o~: ~7r r.>ensbLZrg, Pennsylvania and sold Lunde-r ttie dc~:~:ian<~uiorls. B~W,G9 i>ulb hook holder and o460'1 rod .introduces'.
Tn iiue Stuart clevic:e the rod introduces includes a partia7.ly threaded sc:r ew shaf t leaving a swivel head connected at one end for contact.i.ng the -rod and a giving nut CoIlneCted at its oppo:~:ite end. GJhen connected to the bulb hook holder, the screw shaft with the swivel head attached is l~:terally spaced from the jaws of the holder. e'~s the screva shaft of tile rod introduces. is rotated, the 1-leacr pushes t:ne rod into the hook s tab:ilized by the clamp> or holder. In use, the offset orientation of the swivel head relative to the jaw causes a moment arm to be estat)l:ished a<> tlne spinal rod is seated into the hook. Further, even: after connection of the introduces to -the holder, -tile introduces may be rotatable about a IaterGl axis of the shaft relative to the holder. The rotation aboLlt the laterml axis o.f the shaft in combination with the offset :-screw shaft presents an awkward tool for tine surgeon.
Summary o.f the Invention The device of this invention llere.inafter referred to as a ~;agi~tta_L dpproximator eliminates the problems associated with the prior' art device described above by laterally aligning the Izead of the rod introduces with -the clamp jaws.

2.

~~ ~~r,~~.)~f Tlte~ cl;-tnti, i,~x~t r,r liolraer of tlm invention inc~lude~ :-a i-ira~cl j:~w anci handle t~>y r:ombinat-:ic>n and a shiftablc: java conrmc:te~d tcs the fixed hai~dlo icy a double ltinc~e, A pusher rod i:-tlreada>;~ly accommodated by a channel formed along the top of the rear port.i.on of the fixed haandlc.. A thumb wheel is connected at orz~> enci of the f,usPzer rod. The rod terminates at its oppos.ito end in a bulbous tip. A T-sHaped -rib is formed along the top o.f 'the fixed handle ar,d extends from the end Of the Ch:~I1t1e1 -i.oward the tip end of the fixed jaw. A rod engaging mead is removably connec.:ted tc> the bulbous tip of pusher rod and includes a T-shaped channel for slidabiy accommodating the T-shaped rib. As the pusher rod is rotated in one dire ction within the threaded channel, -the head is slid along the top of the fixed jaw guided by -the rib toward the jaws of the sagittal approximator. The head includes a rod engaging member which contacts the spinal rod and forces it into seating arrangement with an open back hook. Since thze head sand pusher rod is laterally aligned with the clamp, the Load on the spinal rod is balanced at the cent=Pr of the hook.
rr~urther the direct connection of the pusher rod and head to the clamp provides a one piece clamp and rod introduces eliminating a great deal of awkwardness ass~r.iated with prior art two piece de~rices.
Accordingly, it is an abject of this invention to provide for a novel sagittal approximator.

~~3 a~.'~f~~3 Anotht~r ulojt~c~ c>~ t_lnis inv~.,utiors :iet:o f~t~ovi.c3.e, fc~r ~z novel open b~~cl;. lnuuh holder .
Another obje~cR of this invc:nt:ion i~> to provide far a novel open back hook balder having a rod introduces connected Hereto in lateral alignment with the balder.
Another object of this invention is to provide far a sagittal app:roximator whex~ein the force exerted on a rod is centered relative to the open baclz hook.
Other objects o.f this invention will become apparent upon a reading of the follawing descripti0I1 taken with the accompanying drawings.
Brief Description of the Drawings Fig. 1 is a perspective view of the invention with a hook and rod shaven in broken lines fox illustrative purposes only.
Fig. 2 is a reverse perspective view of the invention.
Fig. 3 is a top elevational view of the invention.
Fig. 4 is a side elevational view of tine invention.
Fig. 5 is a front end elevational view of the invention.
Fig. 6 is a fragmented perspective view of the invention having an alternative embodiment of the rod engaging head with a rod and hoolz shown in brolzcn lines far illustrative purposes.
Fig. 7 is a front end elevational view of Fig. 6.
Fig. 8 is a perspective view of the alternative embodiment of the rod engaging head shown in use in Fig. 6.

~~J~ ~d~J~°~
F:ig. 9 i:=~ an rrxplodecl fragmEnted view of they invmution of Fic;s, 1._.,.
Desc:rir~lion of the Pre:Pe~~red Embodiments The preferred embodiments herein disclosed are nat W tended to be exhaustive or to limit the invention t:a the precise forms disclosed. Rather, they are chosen and desc:r:ibed so that others skilled in the art may utilize its teachings.
Referring now to the drawings, sagittal approximator 10 includes a fixed handle 12 1-aaving an integral f fixed upper jaw 14. A generally C-shaped channel 16 is formed in the upper surface of handle 12. Channel 16 extends from end 18 of handle 12 toward jaw 14 and terminates abruptly forming arr abutment 20. Channel 16 in the preferred embodiment is~
partially threaded as shown. A T-shaped guide 22 extends along the top surface of handle 12 from abutment 20 toward jaw part 14 and terrn:inates in a sloped end spaced from the jaw end 24. A pair of spaced legs 26 extend downwardly from the underside of f fixed handle 12 adjacent end 18. Each leg 2G
includes a bore formed therethrough with one of the bores including threads. A leaf spring 28 is connected to the underside of fixed handle 12 by a fastener 29. The free end 2~ of spring 28 extends between legs 26. A rack 30 is shiftably connected to legs 2f by a fastener 31 and includes a generally squared end 34. Square end 34 of rack 30 in combination with leaf spring 28 imparts a positive snap feel ~~ a~.'~~:~~K~
to racar. 30 wt~~~n ~,iwc» eri toward the position of Pig. 4. Rack 30 may ht: coll<~p:;t~u !o lie acljacEnl: the under<~ide of handle, 12 as shown in b'ig:>. 2 :and 2. R<~ck 30 includes a plur~~lity of teeth 32.. A flange 35 extends downwardly from the underSlds' of handle 22. and includes a bore formed therethrougii (see Pig. 4). A pair of spacecZ legs 38 efa end downwardly .from the underside of handle i2 as illustrated and each include a through bore therethrough in alignment with one another. Legs 38 are longitudinally spaced from flange 35. One of the bores formed in one leg 38 :includes ttureads for ac;commodating a fastener 42. Fixed jaw i4 includes a transverse abutment 44 extending downwardly from the jaw and a 'tooth 46 adjar_ent end 24 of the jaw 14.
A lower' handle 48 is provided and includes a pair of spaced legs 50 (only cne shown) each including a bore 52 therethrough for accommodating a fastening device. One of the bores 52 include threads. Each leg includes a second bore 54 adjacent 'the end of the leg with one of the bores 54 including threads. The opposite end of handle 48 includes a single tooth 55 inset relative the handle end 49 for engagement vaith the teeth 32 of rack 30. A fastener 58 is threadably accommodated by bores 52 of legs 50 and extends through bore of flange 35 to pivotally CUIIIIeCt handle 48 to fixed handle 12.

A lcaw~~r jezw GO i:pivotally connected to fixed h~anc7le 1?
at_ lf~gs 38 by a fastener 42 extending through 'core 68 of .,1,.=.
lower jaw 60 and bores 40 of le=cis 8c~~ . Lower jaw 60 includes an upwardly extending trans~rerse abutment 62 and a tooth 64.
Jaw 60 is c.onnE:c:t:ed to handle 12 such that its toc>th 64 is aligned with tooth 46 of fixed jaw 24 and its abutment 62 f:;
aligned with abutmeznt 44 of jaw 14 vahen the jaws are substantially parallel {see Fig. 4) . A slotted bore ?0 is formed through jaw 60 neax~ end 61. A fastener ?1 extends through bores 54 of handle legs 50 and slotted bore ?0 of jaw 60 to pivotally connect pivotable handle 48 to pivotal jaw 60.
Due to the pivotal connection of lower hand y 48 and of lower jaw 60 to .fixed handle 12, as well as their pivotal interconnection by fastener ?7. three pivot points are established about :fasteners 58, 42 and ?1 -respectively. The use of three pivot points provide a tool wherein the top jaw 14 arid handle 12 are stationary and the lower jaw 60 pivots about fastener 42 responsive to pivotal movement of handle 48.
As the handle 48 and jaw 60 pivot, fastener ?1 slides within slotted bore ?0 of jaw 60.
An introduc:er rod or pusher rod ?2 is threadably accommodated by channel 16 and includes a threaded portion ?4 and bulbous end ?6. A thumb wheel ?3 is connected to rod ?2 adjacent threaded portion ?4. A portion of the shaft of rod ?2 along with the bulbous end ?6 extends outwardly from channel 16 toward jaw 14. Bulbous end ?6 of rod ?2 is ~~Ji~'~~~~'~
laterally aligned wit:1 T-shaper_i guide 22 being .paced parallel and above l:hc: clu:ide <~s shown. A5 rod ?2 is rotatEd vaithin c:luanntl 16 tlrN rod is longitudin.311y shii: led along tile channel Lay thf:~ thrE.mcle~d engagement between the rod and c:hannE~1.
A :spinal rod engaging head 80 is provided and includes a body 82 having a T-shaped channel 83 formed in the bottc;rn of thc> head (.see rig. 5} . A slot 84 having a bulbed end is formed in the upper surface of head 80 and extends rearwardly as shown. Head 80 further includes a transverse body part 85.
A leg 86 extends downwax~diy from each end of part 85 as illustrated. Each lea includes a recessed spinal rod seat 88.
In use, a head 80 is connected to sagittal approxirnator such that T-shaped guide 22 slides within channel 83 of the head. End Z6 of rod Z2 is seated within slot 84. The bulbed end of push x~od Z2 permits rotation Of the rod relative to head 80 but prevents the head from shifting longitudinally relative to the push rod Z2. Thumb wheel Z3 is turned by the surgeon in one direction to draw rod Z2 and head 80 rearwardiy or turned in the opposite direction to shift the rod and head forwardly. Abutment 20 defines the fully rearward position of head 80.
The surgeon seats tooth 40 o.f fixed jaw 14 into alignment bore of the body of the spinal hook 2 shown in broken lines in Fig. 1. End 49 of handle 48 is dx~awn towax~d fixed Yrandle 12 to pivot jaw 60 'toward fixed jaw 14 until tooth 64 of the pivotal ja~a seats within a second aligmnent bore of the body :~3~'~'~~~~j of thr Book. Sliglot manipulatiun may tae r~q~.iired to ~~eW the.
jaw t:ec~ih properly. Once tlve teeth axve seated, the ::urgeun squeegees handle 48 to further draw erAu 49 toward handle i2 to clamp the hook hetwc.en the jaws. If desirable, rack 30 may be extended prior to seating of the teeth within the hoole, such that as end 49 of handle 48 is pivoted tovaard handle 12, tooth 56 engages with the rack teeth to temporarily fix handle 48 relative to handle 12 when sufficient clamping pressure is exerted on the hook by the jaws.
When the jaws 14 and 60 are c1 amped to the hook 2 , as described, a spinal rod or section of a spinal rod 3 used in the procedure is positioned between the jaws. Fig. 1 illustrates the positioning of spinal rod 3 relative to jaws 14 and 60 wherein spinal rod 3 is illustrated in broken lines only. The head 80 is positioned such that spinal rod 3 is between the hook 2 and head 80 (see Fig. 1).
To seat spinal rod 3 within the open back hook 2, the user rotates thumb wheel Z3 to shift pusher rod Z2 longitudinally along handle 12 toward jaw 14. Rod '12 slides head 80 along T-shaped guide 22. As head 80 is slid tovaard hook 2 by pusher rod ~2, legs 86 of the head contact spinal rod 3 at seats 88 of the legs to urge the spinal rod toward the hook. Continued rotation of thumb wheel Z3 pushes the head and spinal rod toward the hook, When the spinal rod reaches the hook, additional rotation of the thumb wheel forces the spinal rod through the opening in the hook 2 and ?~.w~e~r~~~~J~'~
iluto seating mx~ran~~=:~mewt w:ittl the hook. Since ,:~ leg 86 E'xtEl1(~" dUVdIlWar~Cily Url t:eil:h S:lde of 'tht' JclV7 the Sp:i['1d1 rod is ellgagt~d on e>~ac:ll :;icae of hook 2, and thus the legs 86 of head 80 straddle the tloolz. 'The load on the spinal rod is balanced or centered relative to the hook 2 to cause an even seating of the s~=final rod anc-1 prevent a moment arrn from developing on the spinal rod.
An alternative embodiment of the spinal rod contacting head is illustrated in Figs. 6-8. Spinal rod contacting head 90 includes a body 92 having a T-shaped channel 94 and a bulbous Slot 96 similar to head 80. A pair of legs 98 extend at a downward angle from body 92 and are integral with an interconnecting end wall 100. A protrusion 101 extends longitudinally from wall 100 and includes an arcuate seat 102 for engaging the spinal rod. As illustrated in Figs. & and T when head 90 i~; connected to sagittal approximator 10 previously described, end wall 100 and protrusion 101 are positioned between jaws 14 and 50. In use, protrusion 101 contacts a spinal rod and seats the spinal rod into the hook as the thumb wheel '13 is rotated. Protrusion 101 is centrally aligned with 'the jaws which aligns the force on the rod with the center of the body of the hook to balance the load on the spinal rod to evenly seat the spinal rod within the hook.
The choice of which head 80 or 90 to be used during the procedure is primarily one of surgeon's preference. However, it may be especially useful t:o use head 90 when an ~~; ~~C."~~.~~~3 insnffici~>nt l~~r~cJtln cW rod Eaxtcru:3,> f~~:~om one end of the hoof:
a:> may be commcwu.ly exper:ienc:ed near Ni lher the eiid of i:hE-, patient:' spine. The lue<~c3s o0 or 90 may be cormenic~ntly ixW:erclnange~~hly connected tee the sagittal approxirnator instrument.
It should be under.srood that the invention is not to Le limited to the preci.~e forms disclosed but may be modified within the scope of the appended claims.

Claims (7)

1. A surgical device, for clamping engagement with a spinal fixation hook and for urging a spinal rod into seating engagement with the clamped hook, said hook including a body having a slot therein for accommodating said rod, said device including a clamp having a fixed handle with integral fixed jaw, a shiftable jaw and a shiftable handle being pivotally connected to said fixed handle and jaw, wherein as said shiftable handle pivots toward said fixed handle said pivotal jaw pivots toward said fixed jaw for clamping engagement with said body of the hook positioned between the jaws, said device further including an engagement means slidably carried by said fixed handle for engagement with said spinal rod to urge said spinal rod through said slot and into seating engagement with said body of the hook, said engagement means being longitudinally shiftable along an upper surface of said fixed handle and jaw between a retracted position and an extended position relative to said fixed jaw, and a shifting means connected to said engagement means and carried by said fixed handle for longitudinally shifting said engagement means.

2. The surgical device of Claim 1 further including a longitudinal guide formed along a portion of said upper surface, said engagement means including a body slidably accommodating said guide to shiftably connect said engagement means to said fixed handle and jaw, a pair of legs extend from said body on opposite side edges of said fixed jaw, seat means carried by said legs for contacting said spinal rod as said engagement means is shifted from said retracted position toward said extended position.

3. The surgical device of Claim 2 wherein said seat means is vertically aligned between said fixed jaw and said pivotal jaw such that contact with said spinal rod causes a load on said spinal rod to be laterally aligned with a longitudinal axis of said surgical device.

4. The surgical device of Claim 1 further including a threaded channel formed in said fixed handle, said shifting means including a shaft threadably accommodated by said channel, wherein as said shaft is rotated within said channel said shaft longitudinally shifts relative to said channel, said shaft including an end rotatably connected to said engagement means, wherein rotation of said shaft in one direction causes said shaft to longitudinally shift relative to said fixed handle to shift said engagement means toward said extended position.

5. A surgical device for clamping to an open back hook and seating a spinal rod within said hook, said device comprising a clamp having an integral stationary first handle part and stationary first jaw part, a second jaw part pivotally connected at its proximal end to said first jaw part, a second handle part pivotally connected at its proximal end to said first handle part, said proximal end of second jaw part and said proximal end of second handle part being pivotally interconnected, said second jaw part having a distal end, said second handle part having a distal end, wherein as said distal end of said second handle part is pivoted toward said stationary first handle part said distal end of second jaw part is pivoted toward said stationary first jaw part.

6. A spinal rod engaging head for a sagittal approximator, said sagittal approximator including an integral fixed handle and jaw part having a guide rib formed on its upper surface, said head including a body having a channel being formed therein for slidable accommodation of said guide rib, a pair of legs extend downwardly from said body on opposite sides of said channel, said legs carrying seat means for engagement with said spinal rod.

7. The spinal rod engaging head of Claim 6 wherein said seat means includes a wall extending between said legs, a protrusion extends outwardly from said wall in a direction away from said body, said protrusion includes an arcuate end.