GB2222953A - Microsurgery scissors - Google Patents

Description

LLICROSURGERY SCISSORS r) r) r 222953 This invention relates generally to

medical in struments and is particularly concerned with microsurgery scissors.

The invention can find application in microsurgery.

e.g., eye microsurgery,, for cutting through or off in traocular tissues, adhesions, membranes, as well as for -ianipulntion in hard-of-access body cavities, for instance, throuSh a laparoscope in the abdominal cavity.

It is rucrosurjery scissors that are frequently an iridi-spensable Dart of technical outfitting of intra ocular ophthalmosurgical procedures. juch scissors are to be introduced into the eye through a small (under 2 incision in the eybball ivall, thus inflictinG a ninimum onerative trauma. A number of constructional ve-.sions of such scissors are kno%n -in the art present ly.

One state-of-the-art microsurgery scissors of the toggle-link type (cf. Hans Geuder GmbH9 G-19980u9P.151) are known to comprise two blades having rectilinear cut tin:- edges, the movable blade traversing towards the W stationary one like one hand of a watch moves with res pect to the other. Ouch a nature of the movement per formed by the blades in conjunction -,,jith their small length and the shape of their cuttinG edges results in 1m) that lthe arl,,le of catching the tissue being cut proves to be too large, which results in expelling the tis- sues bein,-., cat fron the cutting zone when the blades are brought together which in turn leads to increased traction effect exerted on the tissue being cut and on the intraocular membranes ascociated with that tissue.

causinE; tineir rupture and hemorrhages into the intraocular.cavity.

One prior-art device for cuttinS through eye tissues (SU, A, 439,281) is knovin to comprise two coaxial members made as mutually rotatable an outer tube and an inner tube, each having a cutting edge and connected to a holder of its own. The cutting edges of the outer and inner tubes lie in a plane arrang ed at an angle to the longitudinal axis of the tubes. A disadvantage inherent in the aforesaid knovin device for cutting through eye tissues resides, as in the preceding device, in low-quality cutting concerned with expelling the tissue being dissected out of the cutting zone as a result of movement of the movable member due to too large an angle of catching of the tisGue in the device. 20 Besides, the device of such a construction falls to be applied to planar structures arranged'to an angle approximating the right angles with respect to the members of the scissors. It is an object of the invention to render surgery lestraumatic.

It is another object of the invention to provide higherquality cutting and reduce the traction effect on the tissue being cut.

It is one more object of the invention to provide hL3,her tisEue cuttin::. --peed in the course of each work- 0 c, inS cycle.

The aforesaid object is accomplished due to the fact that in the microsurgery scissors, comprising two coaxial members made as mutually rotatable outer and inner tubes, each havin: a cutting ed-e and beinconnected to a holder, according to the invention, the end of the outer tube is shEped as a cloEed helical line whose portion forming a cutting pair with the inner tube cuttin- edge, is in fact the cutting edge of C1 the outer tube, while the cutting edge of' the inner tube is situated in a plane square vjijth a long-itudinal axis of the tubes, and the inner tube is axially traversable and rotatable with respect to the outer tube which is fixed stationary.

Such a construction arrangement of the cutting edges of the outer and inner tubes enables one topr a constant angle of contact of the cutting edges, the magnitude of said angle being comparable with that of the critical angle of catch.,,,,hich makes it possible to cut through tissues without expelling them from the cutting zone practically throughout the entire length of the contact of the cuttinf, ed&es.

That iss whiy the lenEth of travel of tLhe contact puint of the cutti.nL; edFes is comparable with the cutt ini lenzth i,.,hicii in turn makes it possible to increase the cuttine, speed and quality and hence to render sur- 4 - gical procedures less traumatic.

In addition, a possibility of rotating the inner tube and its motion to meet the cutting edge of the outer tube conduces to an additional pressing of the tissue bein.,,, cat against the stationary cutting edge of the outer tube, which also adds to the cutting quality and reduces the traction effect upon the tissue being cut.

It is also expedient that in the microsurgery scis- r> sors of the invention the pitch of the helical line 1J -,-.hich for,,,,is the cutting edge of the outer tube be equal to less, than the outer tube radius.

Provision olr-- such a helical line pitch as described above makes it possible to decrease the angle of catch while retaining an adequate space between the cut- C.) C-- -ing o."' the tissue beint; cut tin.-- edt-es, for free put-IU therebetween.

Given'below are some sDecific embod.-Lments of the present invention aimed at promoting its understanding and to be read with reference to the accompanying draw- ings, villnerein:

FIG. 1 is a general view of the:Acrosurgery scis sors, according to the invention; FIG. 2 is a viem of the outer tube end with a cutt ing edge, according to the invention; FIG. 3 shows the position of the outer and inner tubes at the instant when their cutting edges start contacting each other, according to the invention; and FIG. 4 shows the osition of said tubes at the end 1 of cutting, according. to the invention.

The microsurgery scissors of the invention comprise two coaxial me=bers made as mutually rotatable an outer tube 1 and an inner tube 2 (FIG. 1), both tubes being connected to a holder 3. The outer tube 1 is connected fixedly to the holder 3. while the inner tube 2 is axially traversable and rotatable with respect to the outer tube 1 by means of a drive 4 located in the holder 3. Used aS the drive 4 can be an electric motor 10,-,hich is connected to a pedal switch 6 through a cable5. the outer tube 1 is shaped as a helical The e.-.d o.L line 7 (FIG. 2) whose portion for=ing a cuttin. pair vii;k. h a cuttinj edge 8 (FIG. 3) of the inner tube 2, is in fact a cuttin,-: edge 9 of the outer tube 1. The cuttin& edge 8 of the inner tube 2 is situated in a plane square with a longitudinal axis 10 of the tubes 1 and 2.

The end of the outer tube 1 shaped as the helical line 7 (FIG. 2) is composed oil conjugate lines KP, PN9 NEM, L2. s,.,1i-llch converge to meet at an apical point K Of the cuttin.. . ed,.e 9, while a contour WNEL.1K of the end of the outer tube 1 is made up of the arcs KP and NEL1 of two cylin..rical helical lines AMPC and DMENF interconnected by'conjugate lines EIZ and LW, and the helical lines ABEPC and DIENF feature the same angle of helix r and pitch h between said helical lines, the value of the pitch h being not in excesz of the radius of the^ outer tube 1. The cutting edge 9 (FIG.3) of the outer tube 1 and the cutting edge 8 of the inner tube 2 establish a- cutting pair at the instant when said cutting edges start contacting each other, an angle of catch confined between se-id ed-es being designated as C> 011.

The microsurgery scissors of the invention operate as follows.

The workin- end of the microsurgery scissors in C> the loDen' position (FIG. 1) when the cutting edge 8 of the inner tube 2 runs short of the end contour of t_kie outer tube 1, is introduced into the operative field, e.g., into the eyeball interior. The surgeon.while keeping the instrument by the holder 3, brings the outtin edge of the outer tube 1 under the ocular struc- ture to be cut -.hrough, then the surgeon actuates the drive 4 by pressin, ,, the pedal switch 6, vinereby the inner lube 2 starts movine towards the apical point h 0.1A the cutting edge 9 alonE, the axis 10, at the same time rotating the inner tube 2 to a certain ang le abothe w.is 10 against the cutting edge 9 of the outer 20 ut tube 1, thus cutting the tissue caught between the cutting edi--es 9 and 8. The beginning of the contact of the C- cu-t.ting edges 9 and 8 with the tissues being cut through is illustrated in FIG. 3. Once the cutting edge 8 of the inner tube 2 has passed by the apical point K of the cutting edge 9 of the outer tube 1, as can be seen in FIG. 4, the inner tube 2 is stopped. Then the 1 inner tube 2 is actuated by the drive 4 to return to the initial position (FIG. 1) beyond the end contour of the outer tube 1.

The surgeon is in a position of repeating the entire working cycle as many times as required. Simultaneously with the cutting process the surgeon can maintain a required intraocular pressure by feeding the substitutinj solution into the eyeball interior through the bore of the inner tube 2. Whenever necessary aqueous humor can be aspirated frorr, the eyeball through the same bore.

The present microsurgery scissors have been tested experimentally on five isolated eyes and on the eyes of four test rabbits, whereupon they have been tri- alled in a clinic in 12 surgical procedures for cuttinG through intraocular adhesions and excision of preretinal me:'.ibranes.

ting edge 9 of the outer tube 1 Provision of the cutt as the arc KP of the cylindrical helical line 7 en- sures a longer length of the edge 9 and hence a higher tissue cutting speed, which influences positively on the cutting quality.

Furthermore, formation of the cutting edge 6 of the inner tube 2'by a section square with the longi- tudinal axis 10 of the tubes 1 and 2 enables one to provide a constant an&le of contact of the cutting edges 9 and 8. The magnitude of said angle is comparable with that of the critical angle of catch C for intraocular tissues, whereby such tissues can be cut through without beinj expelled practically throughout the entire length of contact of the cutting edges 9 and 8. That is why the length of travel of the point E of contact of the cutting edges 9 and 8 is comparable with the cutting lenCth which in turn makes it possible to add to the cutting speed and quality.

In addition, a possibility of moving the inner tube 2 along the axis 10 and rotating said tube about 10 said axis enables one, from the standpoint of blade cuttin,- theory, to classify the present microsurgery scissors to instruments ol' curvilinear-oscillating slidin cutting, which are featured by high cuttinS proper- t the axis 10 hies. Besides, oscillating motion about t provides f,i- participation of a greater 1=-n,,th of' the cuttinz edze 8 in the cut-ci-19 processs, v., hereby said cut- C> tinj:- edge g ets dull with a lesser intensity. Rotation of the inner tube 2 against the cut. ting edge 9 of the outer tube 1 contributes to an additional pressing of the tissue being cut against the stationary cutting edge 9, thereby reducing the force with which said tissue is expelled from the cuttinG zone.

Provision of the contour of the outer tube 1 as conjuSate lines donverging to meet the apical point X 25 of the cutting edge 9 renders the present microsurgery G scissors less trauMatic. The fact that the end contour of the outer tube 1 is for;-.ied by the arcs of tivo cylindrical helical lines having different helix angles and 9 - interconnected by conjujate lines makes the manufacture of such scissors more nroductioneered end enables one to provide high accuracy of the geometric parameters of the cuttinZ. edges 8 and 9. The fact that the pitch of C> tIhe helical line 7 is not in excess of the radius of the outer tube 1 makes it possible to diminish the magnitude of the -,-in,,,,le '^< of catch, while retaining an adequate space between the cutting ed&es for free putting of the tissue beinj cut betmeen said cuttinl edges.

Thus, the r:,Jcrosure.ei-y scissors described above rer-de,- intraocular sur,ical procedures less traumetic.

k - 10

Claims (3)

1,7111AT WE CLAIM IS:

1. Microsurgery --cissorsq comprising tWO coaxial mernbers made as mutually rotatable an outer tube and an inner tube, each having a cutting edge and being connected to a holder. the outer tube end is shaped as a closed helical line whose portion forminE a cutting pair with the inner tube cutting edge is in fact outer tube cutting ed---e, the in-laer tube cutting edge is situ- ated in a plane substantially square with a lorgitudinal axis of the in,.-.,er tube, and the inner tube is ax.ially traversable and rotatablc- with respect to the outer tube, which is stationary relative thereto.

2. liiicrosur,--ery scissors as claimed in Claim 1, tlle pitch of the helical line fori-iiini, the out- er tube cutting edGe is equal to or less than the ra- C-11 dius of theouter tube.

3. 11icrosurgery scissors substantially as describ- ed hereinabove with reference to, and as illustrated in tile accompanying drawings.

Published 1990 atThePateritOffice,State House, 6671 High Holborn, LondonWClR4TP. Further copies maybe obtainedfrom The Patent Office. Sales Branch, St Mary Cray. Orpington. Kent BR5 3RD. Printed by Multiplex techniques ltd, St Mary Cray, Kent, Con. 1/87