CA1272926A - Surgical instrument - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

A hand held surgical instrument for use in removing body tissue from a human body. It is particularly useful in arthroscopic surgery of joints such as of the knee or shoulder, but may also be used to remove tissue from the stomach, abdomen jaw or other portions of the body. An auger-like helical cutter is motor driven at speeds in excess of 1,000 rpm within a stationary outer cylindrical sheath member. The helical cutter is ground to provide a generally concave distal end which gives it a generally fish-tailed appearance and the ability to cut endwise, i.e., to effect an axial boring cut.
In addition, the cylindrical sheath member is provided with a pair of longitudinally extending, diametrically opposed tab members at its distal end. Each of the tabs has at least one longitudinally extending edge thereof ground to provide a cutting edge which co-acts with tub auger-like cutter blade to sever body tissue insertable between the tabs.

Description

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This invention relates to a hand held surgical instrument for removing body tissue from a human body and, more par~icularly, to such a surgical instrument that is particularly useful in arthroscopic surgery.

BACKGROUND OF . THE :INVENTION
~ eretofore it has been known to use coaxially mounted hollow tubes in the performance of arthroscopic knee surgery. Side cutting is effected by providing co-act~ng side edges o the tubes which diverge as cutting proceeds in the prQximal direction. The outer tube is stationary and is provided with a side port which is opened and closed on each cycle by the inner rotating tube. Vacuum is used to remove the severed body tissue which is sequentially admitted through the port in the outer tube and then withdrawn through the inner tube. U. S. patents Bonnell et al 4,203,~44 and Johnson et al 4,274,414 are examples of the previously described prior art.
These two patents are deficient in a number of respects.
First of all, because the blades are made fr~m tubular mem~ers, radial deflection is a critical problem. Bonnell et al acknow-ledges that even slight deflection, even on the order of one or two thousandths of an inch, of the rotating blade radially relative to the stationary blade can result in ~amming o~
~issues cut fr~m the knee. Secondlyv neither o~ the devices ~5 in these two patents are useful in cutting straight ahead, i.e.0 .~

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7~2~26 to give an axial bore cut. Both patents are used for side cutting only. Thirdly, because of ~he manner in which tlssue is introduced into the cutters in these patents, namely, by opening and closing a port in the'side of a tube, the speed of cutting is much too slow. In Bonnell et al 4,203,444 rotational speeds are 'limited to 200 rpm or beIow.
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SUMMA~Y OF TH~ PRESENT 'INVENTI'O~
In accordance with the' present invention the afore-mentioned difficulties and shortcomings of the kno~ prior art are effectively overcome in the'practice'of the present inven-tion. In particular, an auger-like cutter.~lade is rotated within a stationarY cylindrical sheath member which supports the cutter blade throughout its length.' ~oth'the auger-like' cutter blade and the c~lindrical sheath'are made'fr~m stainless steel and deflection.of one relative to the 'other is not a problem.
The cyl.indrical sheath mem~er. is proYided with'a pair of longitudinally extending, diametrically opposed ta~s at its distal end. A cutting edge'is providea on a longitu-dinally extending edge'of each of the ta~s whi'ch'co-acts with a helical cuttin~ edge'of the auger-like'cutter blade 'to ~ro-vide side cutting of body tissue'inserta~le.'between the'tabs.
In addition, the.au~er~ ' blade 'i~ providea with'a generall~
concave distal end ground to pro~ide'a ~enerall~ fish-tailed aopearance at its outer end te'rminatin~ in two diamet'rically - .

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opposed sharp portions capable of effecting an axial boring cut.
Finally, the surgical instrument is designed for very rapid cutting speeds. In many applica~ions, including arthroscopic knee surgery and arthroscopic shoulder surgery a rotational speed for the auger-like helical cutter blade of about 3,000 rpm is used. The surgical,instrument of the present invention is adaptable to the skill of the operating surgeon. A lower speed of 1,000 rpm is possible while upper rotational speeds of 10,000 rpm or even higher are-attainable' for delicate operations such as an operation on the human eye.
The inherent advantages and improvements of the present invention will become more readily apparent ~y refer-ence to the followlng detailed description of the invention and by reference to the drawings wherein:
Fig. 1 is a fra~mentary perspective'view illustrating the position of the surgical instrument of the present inven-tion when used in arthroscopic surger~ of a knee;' Fig. 2 is a plan view illustrating one form of a torn meniscus;
Fig. 3 is an e~ploded perspective view of the surgi-cal instrument of Fig. l;
Fig. 4 is a front elevational view,taken partially ' in vertical cross section and with'portions thereof removed ~5 of the surgical instrument oE Fig. l;

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Fig 5 is a fragmentary fronk eleva~ional view taken partially in vertical cross section showing the cutting end of the surgical instrument of Fig. 4, but drawn to an enlarged scale;
S Fig. 6 is an elevational view taken in vertical cross section along line 6-6 of Fig. 5;
~ Fig. 7 is a fragmentary top plan view of the surgical instrument of Fig. 5, but drawn to a reduced scale;
Fig. 8 is a fxagmentary front elevational view of the surgical instrument shown in Fig. 7;
Fig. 9 is an.end elevational view of the surgical instrument shown in Fig. 8;
Fig. 10 is a fragmentary, exploded, elevational view, taken in vertical cross section illustrating the assembly of the major components.of.the surgical instrument of Fig. l;
Fig. 11 is a fra~mentary, exploded perspective view, with components removed illustrating further assembly operations for the surgical instrument of Fig. l;
Fig. 12 is a fragmentary elevational view of a modified sheath member taken in vertical cross section;
Fig. 13 is an elevational .view taken in vertical cross section along line 13-13 o~.Fig. 12; and Fig. 14 is a fragmentary perspective.of another modified sheath member.with.a vertical cross section cut.

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DEq:AILED DESCRIPTION OF THE INVENTION

Referring now to Fig. 1 of the drawings, there is illustrAted a surgical instrument indicated generally at 20 with the instrument being inserted into a small puncture site below the patella of the knee joint o a patient P.
Not shown in the figure are conventional elements including an--other small puncture site to receive a fiber optic device to light the interior of the joint from a suitable light source which return a visual image either directly to an eye piece for the surgeon or preferably with recording cameras to a visual display which is observed by the surg~on in performing the operation. Also not specifically illustrated is the external introduction of a saline solution through another small puncture site at the knee.
A vacuum line hose 22 is illustrated attached to the surgical instrument and a pneumatic drive hose 24 drives a motor within motor assemhly 78. Compressed nitrogen is usually used for this purpose. Alternatively, an electric motor can be used, although special precautions must be taken to ensure the safety of the patient, especially when saline solutions and the like are being employed.
Reference to Fig. 2 illustrates a meniscus indicated generally at 26. This meniscus is generally C-shaped in cross section and is illustrated ko have a tear at 28. Thi~ is only one of a great many different configurations that a damaged .

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-~. , . ',.,; ~ ~, - .. : ~, ~. . , ~L27Z~326 meniscus may have. In order to prevent the damaged meniscus tissue ~rom being pinched ~etween the bones comprising the knee joint, ex~raneous tissue will be removed by ma~ing a cut substantially along the dashed lines 30, 32 in order to provide a relatively smooth configuration for the tissue at the site of the meniscus.
~ FigO 3 illustrates in an ~xploded view, a number of the major elements of the surgical instrument. Thus, there is illustrated a suction housing member 34 which prior to being assembled is open at both ends as may be seen by an inspection of Figs. 4 and 10. A cylindrical sheath member 36 is illustrated which is open at both ends and terminates at its distal end in a pair of longitudinally extending, diamet-rically opposed tabs 38. A vacuum tube 40 is secured to the suction housinq member 34 at port 42 as seen in Figs. 4 and 10.
Vacuum tube 40 is provided with a series of hose barb seal members 44 in order to receive and retain the vacuum line hose 22.
As can be seen best in Figs. 4 and 10 r the cylindri-cal sheath me~ber 36 is provided with a sealing head plug member 46 inserted int~ one open end of the suction housing member 34. An auger-like helical cutter blade 48 received and supported by cutter housing member indicated generally at 50 is inserted within the cylindrical sheath member and resides in closely spaced relationship thereto. Figs. 4 :, ~

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and 10 also illustrate the use of an 0 ring on the cutter housing member SO so as to provide a seal with the interior of the suction housing member 34 on the side of port 42 that is remote from the cylindrical sheath member 36, A
C-shaped spring retainer 54 forms a longitudinal stop for an internal bearing 56. The helical cu~ter 48 is provided with a thickened end shaft 66 having hub ring members 58 thereon which straddle the bearing 56. A spacer member 60 with any required shim members are used to obtain the proper lo~gitudinal spacing for the distal end of helical cutter 48 with respect to the tab members 38. An end seal member 62 is then placed next to thie spacer and/or shim members. An additional constructional feature of the cutter blade includes a pin drive member ~4 diametrically inserted through the thickened end shaft 66.
A quick disconnect nut member 68 is carried or trapped on a cutter dxive coupling nut member 70 by virtue of a raised boss 72 (Fig. 10) on the cutter,drive coupling nut member 70. Left handed threads are provided at 74 on the cutter drive coupling nut memher 70 and threaded on the extericr left hand threads 76 of motor aissembly 78. A hose receptor 79 is provided for the motor assem~ly 78 at one end - and the motor shaft 80 extends to thP left at the other end in Figs. 4 and 10. Screw 82 secures a cutter drive coupling member 84 to the shaft 80 of the motor. The cuttar drive ''` .~ ' ' ''~ '' " ~ ' .` ',~ ` .. ''' '. "" . , ~

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coupling member 84 is slotted at 86 and provided with a widely tapering end so as to self-seat the pin drive member 64 of the helical cutter blade 48. Spring 88 is retained within ~he cutter drive coupling member 84 ~y means of recess 90 in the cutter drive coupling member 84 and engages the end of the thickened end shaft 66 so as to urge the auger-like helical cutter blade 48 constantly toward its dis~al end eliminating any positional change caused by any backlash in the geared drive motor.
In order to effect a quick disconnect for the sur-gical instrument and to gain access to the cutting blade, the quick disconnect nut member 68 is provided with internal threads 92 engageable with external threads 94 of the suction housing member 34. By simply unscrewing this connection, the end of the cutter housing member 50, w~ich i8 knurled at 95 as illustrated in Fig. 3~ is simply pulled away fr~m the cylindrical sheath member whereby any jammed tissue may be removed. Alternatively, a dîfferent size of helical cutter 48 and cylindrical sheath 36 may be inserted.
Certain measures may be taken to minimize lodging of the tissue within the surgical instrument and these are shown in Figs. 12 - 14 to include the application of ~traight grooves such as that shown in Figs. 12 and 13 within the cylindrical sheath member 36 or the use o~ spiral grooves 96a within cylindrical sheath member 36a in Fig. 14. The direction ~

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of spiralling of the spiral grooves 96a is pre~erably opposite to that of the spiralling of the helix on ~he cutter blade 48.
Further details of the distal end of the auger-like helical cutting blade 48 and cylindrical sheath member 36 may be see~ in Figs. 5 - 9. In particular, one longitudinally extending edge of each of the tabs 38 is ground to provide a cutting edge 100. The edge of the helical spiral on the helical cutter blades 48 cooperate with these cutting edges 100 to provide lateral ~hearing of tissue which is inserted lat-erally between the tabs 38. The tabs 38 are undercut at 102 to provide a protective outer stop shoulder for the blade 48.
With the aid of spacer member 60 and any required shims, the outer edge of the cutter blade 48 is positioned from about two to about four thousandths of an.inch away fr~m thP hook-like undercut portion of ~he tab members 38.
In addition, the auger-like helical cutting blade 48 is provided with a generally concave distal end at 104 that is ground to provide a generall~ fish~tailed appearance at its outer end terminating in two di~metrically opposed sharp portions 106 so that.the surgical.instrument is.capable of making what is called a plunge cut or an axial boring cut.
To increase the sti~fness of the surgical instrument, it is possible to provide increased thickness at the region of the tab members such as is shown at 108 in Figs. 5 and 8.

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It is possible to vary the details of the blade cutter to suit the skill of the surgeon as well as to vary it to accommodate different tissues that are inserted between the tab members 38. For example, the back angle or sharp edge at 106 on the helical cutter blade 48 may be varied from about 35 degrees minimum to an angle approaching 90 degrees.
If this angle is too blunt, no cutting will be effected and if it is too steep, the cutting edge becomes fragile. It is also possible to vary the width of the tab memb~rs 38 of the sheath. As the width is made narrower, it is possi~le to cut faster. Tnis width may be either less than the di~metex of the Dlade or grPater than the diameter of the blade. Once again the width is varied dependent upon the skill of the surgeon.
As far as the amount of suction is concerned, 27 inches of mercury is deemed to ba high suction and will work very satisfactorily with the surgical instrument of the pres-ent invention. Twelve to 16 inches of mercury is considered to be marginal and if'the suction is less than that, the chances of clogging the spiral groove in the auger-like ~0 helical cutter blade 48 becomes much greater. The auger-like blade with its helical groove serve as a conduit for severed tissue under the influence of the ~acuum connected to vacuum tube 40.

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While presently preferred embodiment3 of the invention have been illustrated and described, it will be recognizPd that ~he in~ention may he otherwise variously embodied and practiced within the scope of the claims which follow.
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Claims (3)

WE CLAIM:

1. A hand held surgical instrument for removing tissue from a human body which comprises a. a suction housing member having a port therein to receive a suction line, said suction housing being open at opposite longitudinal ends, b. a cylindrical sheath member having its proximate end received in external sealing relation-ship with one open end of said suction housing member, (1) said cylindrical sheath member being open at both ends and terminating at its distal end in a pair of longitudinally extending, dia-metrically opposed tabs, (a) one longitudinally extending edge of each of said tabs being ground to provide a cutting edge, c. a cutter housing member being inserted into the other open end of said suction housing member, d. a helical cutter received within said cutter housing member and supported thereby, (1) said helical cutter extending within said cylindrical sheath member in closely spaced rela-tionship and said helical cutter cooperating with said cutting edge on each of said tabs to sever tissue inserted between said tabs upon rotation of said helical cutter, (2) said helical cutter having a helical groove extending for substantially the entire length thereof with said groove functioning as a conduit for severed tissue, (3) said cylindrical sheath member having an open distal end whereby body tissue may be in-serted axially between said diametrically opposed tabs to be severed by said helical cutter in effecting an axial boring cut, e. motor means to turn said helical cutter at a rotational speed of at least 1000 rpm, f. means for coupling said motor means to said helical cutter, g. and vacuum means connected to said port in said suction housing to remove severed tissue.

2. A hand held surgical instrument as defined in claim 1 wherein each of said tab members is undercut to provide a protective stop shoulder for said helical cutter.

3. A hand held surgical instrument as defined in claim 2 wherein said means for coupling said motor means to said helical cutter includes a spring member to urge said helical cutter toward said protective stop shoulder.