CA1337790C - Ring currette - Google Patents

Abstract

An improved ring curette for the removal of pathological body tissues. The ring curette has an easily grasped handle connected to a flat-sided shaft that widens dramatically as it joins the ring curette. The ring curette has a sharp inner cutting surface and a blunt outer surface.
No cutting surface is provided to the rear of the ring curette to prevent accidental injury to tissue. The diameter of the opening provided by the ring curette is decreased at the central portion of the ring curette.

Description

~acksround A curette ls a surgical lnstrument consisting o~ a h~ndle, a ~aft, and ~ tip whlch l~ ~enerally cup shaped, much llke a ~mall spoon, used for the pur~ose o~ ~crapiny and scooping out various pathologlc~l (dl~ea~ed) bodily tls~ue~, such ~ a dlsc between two vertebrae ~he open space of the cup-like tip ha~ a sharPened rim to enhance its effectivensss ~or scraplng -In practice, the tip o~ the l~gtrument i~ placedinto the area o~ ti~sue to be removed and scraped agalnst the tl~aue. When the cuP 18 f~lled the ln~trument i~ removed ~rom the w~und and the tl~sue within the cup i6 then manually emptied. The in~trument i8 then returned to the wound, where the process ls perfor~ed repe~tedly untll the entlrety o~ the path~loglcal tl~sue has been removed, A rln~ curette is a particular type of curette in which the cup 18 wlthout a bottom, formln~ a rin~. Whlle ~uch a cuxette is les~ useful ln scoopin~ out a~d removing 5craped tl~es, thi~ 1~ more than o~fse~ by lt6 enhanced effectiveness in the more ~peciflc ta~k o~ 6craPin~ the tl6sue free. Slnce the bottom of the cup iB ab6ent, the scraped ti~sue pa6ses ~hrough the xin~ and doe~ not accumulate in the cup, allowing the in&trument to continue scraplng. As large amounts of tl~sue once freed can more easilY be removed wlth a ~urglcal lnstrument known a~ a ron~eur, it is more efficient to utiliZ~ the ring type curette followed by u~e of the rongeur, rather than uslng the cup type curette.
Furthermore, ~ince the rlng curette and the rongeur are more ~pecialized to their 61ngular puxpose~, t}-ey are more effectlve. Also, slnce they require less frequent passlng of the ins~rumentation in and out o~ the body, wi~h the attendant rl~k of internal tls~ue injury and wound contamination, they are ulso ~fer.

. ~

Description of the Prior Art Figures lA, B and C show a representative conventional prior art ring curette. The prior art tip has a complete uninterrupted circular scraping rim. The junction between the tip and the shaft is consisting of a relatively finely tapered distal shaft which is easily manufacturable and is relatively weak. Pressing this narrow shaft against a vertebra could result in damage to the vertebra or damage to the shaft. The prior art ring curette has no mechanism for measuring the depth of penetration of its tip in the wound.
Summary of the Invention The present invention provides a ring curette comprising a straight shaft having a first end and a second end, a handle attached to said first end and a scraping tip attached at said second end, said scraping tip in the shape of a ring, said handle being large enough so as to permit grasping of the handle by two hands, said shaft having flattened top and bottom portions in planes parallel to the plane of the ring proximate the connection of the scraping tip to the second end of said shaft, said ring extending above the planes of said flattened portions of said shaft, the circumference of said ring being sharpened, said ring having a depressed portion proximate the connection of the scraping tip to said second end`of said shaft, an edge of said depressed portion being in the plane of a flattened portion of said shaft and in which said ring has an interior opening forming side walls, said opening having a central portion which is smaller in diameter than the inside ' ~

diameter of said ring at either the top or bottom of said ring~
the inside walls of said ring sloping towards the center of said opening.
The flattened portions of the shaft permits using the ring curette in the manner of a lever, having its fulcrum on the vertebra. This makes scraping easier, while avoiding damage to the vertebra. This levering action is also assisted by having the handle of the curette sufficiently large so as to enable the handle to be grasped fully by both hands at the same time.
The ring tip has a discontinuous scraping rim surface so that scraping action is achieved only by the forward interior portion of the ring tip. This is in contrast to the prior art conventional ring tip structure which has a scraping rim surface around the entire inner portion of the ring tip. Since the rear portion of the ring tip of the present invention is depressed, when the ring tip is pushed back and forth to scrape the tissue, tissue cannot catch on the rear portion of the ring tip.
These and other features of the present invention will be apparent from a review of the following specification and accompanying drawings, wherein:-Figure lA is a perspective view of a conventionalprior art ring curette.
Figure lB is an end view of the prior art ring curette of Figure lA.
Figure lC is a side view of the prior art ring curette of Figure lA.
Figure lD is a side view of a prior art ring curette B

in a vertebral interspace.
Figure 2 is a perspective view of the present invention.
Figure 2A is a top view of the ring curette of Figure 2.
Figure 3 is an end view of the ring curette of Figure 2.
Figure 4 is a side view of the ring curette of Figure 2.
Figure 5 is a side view of the present invention shown in a vertebral interespace.
Figure 6 is a side view of an alternative embodiment of the present invention.

~D
0 4a fc ~

Flgures lA-lC show ~ conventional prior art rln~ curette con~i~tln~ Or a handle "~". 6ha~t "s", and a tip "T"
essentially rin~ llke in ~hape. There i~ extreme tapering o~
the shaft at the ~unctlon to the rin~ tip. The scr~ping rim o~ the Fin~ tip i6 uniform acros~ its entire ci~cumference and hAs a unlfoxm interior wall suxface. Figure lD ls a side view of the prior art ~in~ curette in a lumbar intersp~ce and parall~l to the end plate con~istent with its method of u8e.
Pi~urè 2 i8 a perspective view of the pre~ent inventlon 1~ consl~ting of handle 11, shaft 12, and rin~ tip 13. The distal end Or the shaft 14 ha~ opposed broad ~lat surfaces 15 and 16 and blunted edge~ 17, 18, 19 and 20. The ~ha~t 12 is su~ficiently lon~ ,to ~llow the handle 11 to be ~rasped by both hands of th~ u~er. T~e dl~tal end of the shaft 14 has circumferentlal ~cribe marks 21, 22, and 23 correRp~ndlng to lengths from the mo~t dlstal extremlty o~ the tip 13. ~he 6crlbe mark~ 21, 22 ~nd 23 are separated by 2~, 25 and 30 ' milllmeters, allowin~ the surgeon to asse~s the depth o~
pen~tr~tion of the ring tip 13 even when the ring tip of the instrument cannot be vlsualized. Slnce the ideal depth o~
penetratlon of the rlng tiP 13 in the lu~`oax sp1ne, for example, is between 20 and 30 1~1.1 ~ter~, lt 1~ possible to achleve that ideal without the dan~er o~ over ~ehetratlon despite the fact that the tip m~y not be vi~lble. The marking~ may be color coded se~men~ instead of, or ln additlon to, the scrlbe marks 21, ~2 and 23.
The ring tip 13 haG an outside ma~or diameter which i8 wlder than the neck o~ the shaft. ~he top ~nd bottom ~craping rlm ~urface of the rln~ tlp i3 extend8 above and below the broad flat surface 15 a~d 16 of the sha$t 12. The upper and lower scr~pln~ rim~ of the ring tlp each have a depre~6ed portion 2S and 2~ ~t the poxtion of the rlng tip proximate the junctlon of the shaft and xing tlp. ~he bottom of the depression~ are level wlth the flat ~urface 15 and 16 of ~he shaft 12. The lnner portlon of the scra~lns rlms ure exceedin~ly sharp across their inner ed~e~ 26 and 27 and are qulte dull at their outer edges 28. The inside walls o~ the rlm are tapered inwardly ~o as to create a funnel into sre~
29. The meetlng o~ the upper and lower tapers i~ referred to a~ the equator, In ~he preferred embodiment, the handle 11 ha~ a diameter of approximately 1 1/4 inches and i8 8 1/2 lnches long. ~he shaft 12 i8 a~proxlma~ely 5 1/2 inches long and h~ a dlameter of 3/8 lnches, The ring tip ha~ ~n outslde diameter at the scrapin~ rim~ of ~bout 5/~ lnches and about 7/16 inche~ a~
the narrow equator. ~he ~crapin~ rims of the rin~ tip have an overall height of 5~16 inches and extend approximately 1/32 inche~ above the Plane of the ~l~t portlon o~ the shaft. The ~ha~ h~ a Width at the ~lat portlon o~ 1/4 ln~hes ahd tapers smoothly to the glde walls of the ring tip, The depresæed portions extend around 90 degrees o~ ths circum~erence o~ the ring tlp, Pigure 5 is side view of the pre~ent invention in a lumbar disc space showlng the placement o~ the dl~tal shaft 14 with depth markin~s 21, 22. and 23 ag~lnst the vertebral endplate bodY ~unction J. The orlentatlon of the instrument l~ shown being utilized with the scraplng rim of rin~ 24 8craping the disc material M, facllitatlng i~g removal.
Slnce the rlng-tiP 13 is open ~cro~s lt6 wldQ~t area the tls6ue 18 essentlally funneled by the sloplng ihterlor walls into a trap~ed posltlon where it is easlly sheared by the advanclng sharpened inner edge.
Since the scraplng rlm o~ the rlng tlp is dull on it~
outer edge and of~ers a clo~ed ring most dlstally, it ~anhot accidentally penetrate too deeply and will cut tis~ue only on the upstroke, since the more proximal end of the rihg tlp does not have a sharpened and Protrudi~g scrapin~ rim. a~ the ~lp i8 brou~ht ~rom deep to superflclal on the cutting stroke, the more superfici~l tl~sues lncludin~ the spi~al sac: and nerve root~ will not be accidentally cut by the ring tlp.

. .. .
Also, conventional rln~ curette reqUire the operator ~o u~e conslderable force to re~ist the tendencY of the full rlng tlp to be pushed away by the rear tlaaue. Ther0 1B an ever presesl~ ~nd real dan~er that the grasp on the rear ti~sue will glve way, or that ~he rlng tip will slide off, and plunge through the front of the disc rupturln~ the aorta, venae cava, or o~her vlt~l ~tructure~ ~nd possibly causing the dea~h o~
the patlent. Also, for the very s~me reasons lt 16 po~qlble ~or the conventional rln~ tip curette to lose en~a~ement on the ups~roke and ~o force~ùlly escape the dlsc space poseerlorly ~from behlnd) rUpturih~ the dural 8ac and po~lbly causlng paralysi~.
~ he present inventlon i8 more effectlve in engagin~ the tl~sue because ~he depres~ed rear portlon prevents lt from catchln~ on the tl~6ue. Purther, the depre~sed portion o~ the scraping ri~ of the ring tip become~ fully visible prlor to the cutting ed~e arriving, thereb~ allowlng the operator to avoid accidental presentation.
A ~u~ther safe~y desi~n feature i~ that the ring ~lp is clo8ed to sllghtly beyond the eqùator of the rin~ tip so that by rot~ting the ring tiP. movlng the shaft ~rom the vert~cal to a more horlzontal position, lt is then possible to extract the rlng tip wi~hout having the cuttlng ed~e of the protruded rlm enga~e the surroundin~ tl~sues, therebY avoidln~ d~mage those tis~uea.
The relatively lar~e mass of the 6haft tlP junction without a narrow n~ck, allows the lnstrument to be sa~ely utillzed wlthou~ mechanlcal fallure. The broad and ~lattened ~urfaces parallel to the open faces o~ the rin~ tip and to the vertebral endplates, comblned wlth the blunted ed~es, 1~
de~i~ned to ~roteC~ the ver~ebrae themselve~ by ~roviding a lar~e ~urface area without any sharp edges. The prlor ~rt rlng cu~ette cannot be u~ed ln thls manner (leverased off the fulcrum of the vertebral body endplate ~unctlont because they are not ~uf$1clently stron~ and are delicately necked at the rin~ and shaEt ~unc~ion. Such leverlng with a slender and rou~ded shaft would result in too small an area for such a magnitude of load and would result ln elther a fracturin~ o~ ;
the vertebra or a failure of the instrument.
Finally, the prior art ~haft wlth lts tapered neck offers no reslstance to the movement of the lnstrument in and out of the wound. ~hus, a~ the operator attempts to in6ert the r~ng tip through the small opening of the interspace, there 1G an lncreaslng resistance as the ma~or di~me~e~ of the rlng tlp iB approached, and then a sudden Plunging, and ~lving way.
SlmllarlY~ on attemptin~ to remove the instrument, there i~
an increasing res~stance as the ma~or dlameter of the ring tip 18 approached, and then a ~udden release and "fly~n~ away"
of the instrument.
I~ contrast, the present invention has a con~luent ~unction o~ tip and shaft which allows for the 6mooth introduction and removal of the ring ~ip.
Pl~ure lD demonstrates the method of u~e of the prlor-art ring curette, whlle Flgure 5 demonstrates the method o~
use of the present inventlon. The present invention takes advantage of the avallable vertebra and employs the very s~rong cor~ical bone at the vertebral body endplate ~unction a8 a fulcrum polnt 91nce the distance from the fulcrum to the tip ls considerablY shorter than the di~tance from the ~ulcrum to the handle, a mechanical ad~antage 1~ produced whlch increases the ef fectiveness of the ln5trument and greatly reduces the amoun~ of force needed to be a~Plied to the handle to obtaln effectlve tlsEue cutting. The lar~e diameter ~nd long h~ndle permlts the instrument to be held by both of the surgeon~ hand~, thereby permi~tlng better control of the in~trument durln~ the scraping actlvlty.
Flgure 6 is an al~er~ative embodiment of the present lnvention wlth the dlstal ~haft angled to ~acilitate the removal o~ disc tis~ue in a more angul~ted lnter~pAce.
While the examPles of~ered refer to the use o~ the .;

l 33179 .. .
present lnvention in the splne, ~ch lnstruments would be usQ~ul ln many other area~ of thQ body. Also, while the tip and shaft of the present inventlon may be made of an approprlate lur~ical quality metal, lt 1~ recognized that the ~ . . .
t~p and ~haft as well as ~he handle mlght be made ~rom non-metallic but equivalent materials. ~uch as plaetic6, ceramic~, compo~ites, or other.
Also, while the ring curette o~ thls present invention has been described in relatlon to a ring curette havlng 8harP
scraping rim surf~ces on both the upper and lower surfaces of the rlng tip, it can b~ employed on;only one of the surfAce~.
', ' ' . " ' ".'''';.

Claims (3)

1. A ring curette comprising a straight shaft having a first end and a second end , a handle attached to said first end and a scraping tip attached at said second end, said scraping tip in the shape of a ring, said handle being large enough so as to permit grasping of the handle by two hands, said shaft having flattened top and bottom portions in planes parallel to the plane of the ring proximate the connection of the scraping tip to the second end of said shaft, said ring extending above the planes of said flattened portions of said shaft, the circumference of said ring being sharpened, said ring having a depressed portion proximate the connection of the scraping tip to said second end of said shaft, an edge of said depressed portion being in the plane of a flattened portion of said shaft and in which said ring has an interior opening forming side walls, said opening having a central portion which is smaller in diameter than the inside diameter of said ring at either the top or bottom of said ring, the inside walls of said ring sloping towards the center of said opening.

2. The ring curette of claim 1 in which said handle has a diameter greater than 1 inch and a length of at least 5 inches.

3. The ring curette of claim 1 in which the ring curette is symmetrical about its central axis in the plane of said ring.