CA1044979A - Surgical instrument for operation of anterior fenestrated spondylodessis in vertebral osteochondrosis - Google Patents

Abstract

SURGICAL INSTRUMENT FOR OPERATION OF ANTERIOR
FENESTRATED SPONDYLODESIS IN VERTEBRAL
OSTEOCHONDROSIS
Abstract of the Disclosure A surgical instrument for the surgical operation of anterior fenestrated spondylodesis comprising an elongated hollow body with a handle at one end, and a detachable hollow cylindrical cutter with a cutting edge, at the other. Incorpo-rated within the body is a shaft with a knife on the end situa-ted within the cavity of the cutter. The instrument has a de-vice for locking the shaft in the body in a position whereat the blades and cutting edge of the knife and the cutter lie in the same plane. The cutter is intended for excising two transplants in the shape of cylindrical segments from two adja-cent vertebrae, and the knife, for undercutting them, once they are formed by the cutter. Also situated in the cutter's cavity is a limit flange secured on the shaft, which comes in contact with the surface of the vertebral bodies and restricts the depth to which the knife descends into the intervertebral slit and, together with a stop on the rear end of the body interact-ing with the end of the shaft, ensures the right depth of the cutter's penetration into the adjacent vertebral bodies.

The instrument is reliable, does not endanger, during surgery, nearby large vessels and nerve formations, and pre-cludes the penetration of the knife into the vertebral canal.
The instrument permits the operation to be performed on any region of the spinal column.

Description

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This invention relates to medicine, and more paxticularly to orthopedics and traumatology, and is concerned wit~ the design of an ins~rument for the surgical operation o~ ant~rio~
fe~estrated spo~d~lodesis~ used ~or the treatment of ~ertebral osteochondrosis.
Yertebral ost~ochondrosis is a rather widespread disease, standing out as one o~ ~he primary causes of disability and temporary incapacity. Grave forms of osteocho~drosis xebellious to conservati~e therapy are treated by surgery~
Surgery ~or the removal o~ a diskal hernia by laminec-tomy is frequently accompanied by residual pain and relapses.
~he main causes of these reverse~ are conti~uing de~eneration and protrusion of the remaining parts of the disk (whose ~t complete removal is impossible by the posterior approach), progressive diminution o~ the height o~ the a~fected disk, which does not, however~ reach the sta~e of ~usion o~ the ~ertebrae, i.e. o~ an osseous block, whi~h leads to the compres~ion o~ nervous xoots, obstruction of blood circulation in the vertebral canal and a painful ~pathological) mobility between the vertebrae~ o~ the deforming arthrosi~ type; this damages the posterior matrix, both osseous and musculax, o~
the spinal column, resulting in its deformation and instability~
~ he most radical and patho~enetically sound surgical Gpe-ration for vertebral osteochondrosis, rather than mere remo~al o~ a diskal hernia J iS a total dis~ectomy and spondylodasis !V,' between the vertebral bodies without reducing the height between the ~ertebral bodies due to the use of a bone trans-plant. Such surgery can be perfomed only through the anterior approach. ~he positiYe results of such operations proved much better, a~d, more impoFtant still, more stable~ ~urgery per se, however, involved some negative moments~ Thus, in order to form the slot intended for the introduction of the transplant, ~ -a hammer and chisel were used, which caused concussion ~rom the blows~ a hazard ~ot only to the nearby large ~essels, but to elements of the ~ertebral canal as well. Addition injury was in~licbed when a bone transplant was removed from anot;her part o~ the body, ~or example, from the tibia or the iliac bone. ~or was -lt possible to e~ecb an accurate ~it of the transplant to the bed7 which prolonged the subsequent process of ankylosis, i.e. fusion. Diskal herniotomy through the a~terior approach was further made difficult because of the narrowne~s of the bed~ the surgical operation itself was also protracted.
5till another and more progressi~e method known in the ~rt of surgical treatment o~ ~ertebral osteochondrosis is anberior fene~trated spondylodesis and a surgical lnstrument ~or its performance.
~ he operation of anterior fenestrated spo~dylodesis rests on the following principle. The anterior surface~ of the ~er-tebrae and dis~s to be operated upon are exposed through an anterior approach. Upon the remoYal of the affected disk t. ~r ~ 79 (di~kectomy) t~Jo transplan-t~ are ~ormed by mea~s of -the a~or~mentioned înstrument i~ the shape o~ cylindrical segments from the bodies of two adjacent vertebrae, with the ~lat lateral sides o~ the transplants being parallel to the ~
intervertebral slit. Then the transplants are rotated through 90, thereby closing in the intervertebral slit7 with a~ auto-pla~tic cortical transplant placed between the autoplastic, ~erving as a spacer and also for stimulating osteogenesis~
~he prior art qurgical instrument ~or the operation o~
anterior fenestrated spondylodesis i~ essentially a hollow elongated cyli~dxical cutter with a cutting ed~ tended for simulta~eous e~cision o~ two said transplants out o~ two r adjacent ~ertebrae, and a shaft situated within the cutter coaxially therewith, with a kni~e being secured on its end for ~
introduction into the intervertebral slit and a~ecting~ ¦
through its r~tation~ the undercutting o~ the transplants after their excision by ~he cutter. ~he instrument has two detachable handles: one connected with the cutter and ensurinO
the rotation thereof, and tha other secured on th~ shaft and ensurin~ the rotation of the kni~e. A limit ring i5 secured b~
mea~s of two stop screws outside the cutter ~or restrictin~ the depth of the latterts penetration into the vertebral bodies~
a~d intended for coming in contact with the vertebral bodies and limiting the depth o~ the cutter's penetration thereinto.

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~ he formatio~ of t~o transplants in the shape o~ cy~
li~drical segments by this prior art instrument is practically divided into two stages, the first o~ which is the excision o~ the cylindrical surfaces of the transplants. For this ~ -purpose, the cutter, with the sha~t and knife removed, is set agai~st the two adjacent vertebrae with the affected disk al-ready removed from bet~een them, and by :rotating the detachable handle connected with the cutter, the latter is introduced into the bodies of these vertebraeO ~he depth o~ the cutte:r's pe-netration is controlled by the external limit ring ~ixed at a preset distance ~rom the cutter~s cutti~g edge. The second stage is the undercutting o~ the transplants. ~or thi~ purpose~
the detachable handle is removed and the sha~t with the k~i~e and handle is inserbed into the cutter. In doing so, the ~nife is lowered into the intervertebral slit to the level o~ the cutter's cutting edge, which correspondæ to a mark on the upper~
part o~ the shaft. The sha~t i~ secured b~y means of a locking device. The transplants are undercut by rotating the sha~t with the kni~e by means o~ the handle set on the sha~t.
This prior art instrument allows success~ul per~ormance of the operation o~ anterior ~enestrated spondylodesis. Ho-wever, the design o~ this instrument has a num~er o~ disadvan-tages. ~hus, the e~ternal limit ring secured by two ~crews, . . .
obstruct~ the surg~on's ~ield o~ vi~ion as it occupies an ;~
e~rtra area, and~ when the cutter rotates, endangers the nearb;y t ~

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~ L~4~ 7 large vessels and nerves. The replacement of two handles (for the cutter and kni~e) during the operation prolonæs the latter.
There is no *oolproof ~uarantee against injury to the vertebral canal by the knife be~ore the ~haft with the k~ife is secured by the locking device. ~he instrument is designed for operat-ing upo~ some one region of the spinal column only, in accor-dance with the re~pecti~e dimensio~s of the particular cutt~r and kn~fe.
It is an object o~ the prese~t invention to provid9 a sur~ical i~strument for the operation of anterior fenestrated 8pondylodesis in vertebral osteochondro~is that will not endanger the nearby large vessel~ and nerve ~ormations duri~g rotating move~ents when e~cising transplants.
It is a~other object of the invention to provide an instrument that will completely rule out th~ possibilit~ of the knife for undercuttin~ the transplants penetratin~ the vertebral ca~al.
St~ll another object of khe invention is to reduce the bime re~uired ~or surgery. ,.,!
A ~urther object o~ the invention is to provide a uni-~ersal instrument that will make it possible to operate upon a~y region o~ the spi~al colllm~ (cervical, thoracic and lumbar~
It is still another object of the inventio~ to enlarge the operational observation field through reducing excessive parts of the instrument.

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~ hese and other objects are achieved by that an instru-ment is proposed for the surgical operation of anterior fenestrated spondylodesis in ~ertebral osteochondrosis ~hich, in accordance with the inventio~, comprises a hollo~ elonga-ted c~lindrical body with a handle secured tran~ersally thereto at it~ rear end, and a detachable hollow cylindrical c~tter with a cu~ti~g edge, secured coaxially therewith on the ~rontal end of the body and i~tended for the simultaneous excision of two transplants in the shape o~ cylindrical segme~ts ~rom the ~odies of two adjacent vertebrae. ~ituated in the body coaxial-ly therewith i s a ~reel~ rotatable and longitudinally movable shaft, secured on whose end i8 a detachable kni~e situated within the cavity o~ the cutter. The knife's blade~ lie i~ a plane parallel to that of the cutting edge o~ the cutter, and the size of the knife is so selected as to enable it~ intro-duction into the intervertebral slit following the removal of ~-the in~ervertebral dis~ and complete undercutting o~ said transplants following their exci~ion by the cutter, by subse-quent rotation of the knife. The instrument also contains a device ~or locking the shaft relative to the bod~ in a posi-tion whereat the cutbing edge and the blades of the cutter and the knife lie in the same plane, and prevènting, at the same time~ the shaft~s rotation relative to the body, a limit flange fastened o~ the shaft and situated in the inner cavity of the cutter at a dista~ce from the blades of the ~nife, equal .

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to tke rsquired neight of the transplants being excised, a~d intended for coming in contact with the ~ur~ace of the bedies of said adjacant vertebrae and thereby limiting the depth to which the knife is lowered into the intervertebral slit~ and a stop situated on the rear end of the body interacting with the end o~ the shaft during the latterqs longitudinal mo~ement towards the rear end of the body and thereby ensuringp together with the limit flange, the preset depth of cutter pe~etration i~to the bodies of ad;acent vertebrae.
A lim~t flange allowing the cylindrical cutter to penebrate into the bodies of adjacr~t vertebrae to a definite depth and preventin~ the shaft wibh the ~nife from descending below the cutting edge o~ the cutter, makes it possible to do away with the external limit ring with t~o screws~ As a re-sult, the danger of injuring nearb~ large vessels and nerve G
~ormations, and of the penetration of the cutter or the knife into the vertebral canal is removed. The ~bservation field of the sur~ical wound a~d of the anberior ~ur~ace area of the spinal column is at the same -time increased. The new instrument has but one handle fitted with a locking de~ice for securing bhe sha~t with the knife relative to the body, which allows to combine two processes: the excision o~ the tra`nsplants and their severing from the spinal column. The time o~ the opera-tion is thereby reduced. The cutter and knife being detachable allows to have them in 3ets of dif~erent sizes, so thab the _ 9 _ ~ 9 same instrument complete with a set of cutters ~d knives can be used for surgery on any region o~ the spinal column ~cer~i~
c~l, thoracic and lum~ar). -~
It i8 preferable that the limit ~lange be secured on the shaft so that its distance from the blades o~ the kni~e is adjustable, thereby allowing to control ~he height of the transplants bei~g e~cised.
~ he limit ~lange can be made on a sleeve set on the shaft rotatably a~d movably there along, and having a lug engaging with one of the annuIar grooves made on the shaft at some ;`
distance one from another, thus permitting adiustment of the distancs between the limit flange and the blades of the k~ife.
Ib is preferable to so arrange the device locking the ~hàft relative to the bod~ as to ensure that, in the lockea f position, the knive secured on the sha~t and the handle secured on the body are in the same longitudinal plane, which allow~
the surgeon during surgery to see the positio~ of the kni~e by that of the handle.
~ e proposed instrument has bee~ used ~or performing the operation of anterior ~enestrated spondylodesi~ in 283 patients with grave ~orms of vertebral osteochondrosis, 98 of them in bhe cervical region, 6 in the thoracic and 179 in the lumbar region. All the aforemenbio~ed advantages of the instrument were confirmed i~ practice. During surgery, there were no complications associated with the use of the instrumentO ;
s Good follow-up results were ascertained in 85 per c~nt of the patients.
~ he i~ention will now be described in greater detail with re~erence to preferred embodiments thereof, taken in conjunction ~ith the accompanyi~g drawings9 wherein:
~ ig. 1 is a longitudinal section view of a surgical instrument for the operation o~ anterior ~enestrated spondylo-de~is in vertebral osteochondrosis, in accordance with the invention;
~ ig. 2 is a section ~iew along line II-II o~ Fig. 1;
Fig. 3 is a section view aloDg line III-III of Fig. 1;
~ ig. 4 i8 a section view along line IV-I~ of b'ig. 1;
Fig. 5 is a longitudinal 9ection view o~ the instrument's t~
handle with the sha~t~s locking device in the position ~i.th J.
the shaft released, in accordance wi~h the. i~ventionj . ~ig. 6 is a section vie~ along line VI-VI of ~ig. 5; ~.
Fig~ 7 is a partially cut ~iew along arrow 7 towards the cuttert in accordance with the invention;
Figs. 8 to 22 show consecu-tive steps of the operation of diskectomy with a~terior fenestxated spondylodesis per~ormed with the aid of a~ instrument embodied in accordance with the invention~ ~
~ ig~ 23 is a section view alo~g line XXIII-XXIII o~ ~ig.
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i ~ Jl 7~ -The sur~ical instrument for the operation of anterior fen~strated spo~dylodesis in vertebral osteochondrosis com-prises a hollow elongated cylindrical body 1 (~ig. 1 ) with a ha~dle 2 rigidly secured transversely thereto on t~e rear end of the body 1. Detachably secured on the frontal end of the 1 by means of a union nut 3 is a hollow cylindrical cutter 4 ~ith a cutting edge 5. intended for simultaneous excision of two transplants in the shape o~ cylindrical segments from the bodies of two adjacent vertebrae. Situated i~ the body 1 and coaxially thereto is a shaft 6 with a knife 7 secured on ib~ end (~igs~ 1 and 2). ~he kni~e 7 is ~ecured by mean~ of a spr~ng plate 8 (~ig~. ~ and 3), ~astened by a screw 9 to the shaft 6, its lug entering a respective depression on the shank 10 of the knife 7. ~he knife 7, however, may be secured on the sha~t 6 also by means of a thread (not shown).
~ he blade~ 11 (Fig. 1) o~ the knife 7 lie i~ a plane pa-rallel to tha-t in which the cutting edge ~5 of the cutter 4 is s~tuated.
~ he size of the knife 7 is so selected that it can be întroduced into the intervertebral slit aftex the removal of the intervertebral disk and provides, upon its subsequent ro-tation, for complete undercuttin~ of the transplants once they ~
are excised ~y the cutter 4. . ~`
The shaft 6 is ~reely rotatable and longi-tudinally mo~able relative to the body 1. In a position of the shaft 6 whereat ,~,, c~ ~

~ Q4~79 the cutti~g edge 5 o~ t.he cutter 4 and the blades 11 o~ the knife 7 lie approximately in the same plane9 the shaft ~ may be secured by means of the loc~in~ device 12, which at the - ~ame time prevents the rotation of the shaft 6 in the bod~
The locking device 12 has a head 13 with lugs 14 (~`igs. 1 and 4)~ entering a correspondin~ slot on a stop bush 15~ ~astened - on the handle 2 (Fig. 1). Rigidly secured on the head 13 is a rod 16 loaded by a spring 17 retained b~ the stop bush 150 W~th the shaft 6 in the locked position, the rod 16 enters a hole 18 in the shaft 6. To release the ~ha~t 6, the head ~3 is drawn away ~rom the stop bush 15 and turned so that the lugs 14 of the head 13 are withdrawn ~rom the slot in the stop , ~ush 15, as shown in P`igs. 5 and 6, and brought to rest agai~st_.
ths striking face o~ the stop bush 15. Thereupon9 the rod 16 is withdrawn from the hole 18 o~ the shaft 6. ~he arrangement of the lock~ng device 12 on the handle 2 is such that with the sha~t 6 locked, the knife 7 (~ig. 1) and the handle 2 are se-. cured in the same longitudinal plane, so that during surgery the surgeon can see the direction of the kni~e 7 by that o~
~he handle 2~ P`or preventing the cutter 4 and the knife 7 from penetrating the vertebral canal, the instrument is fitted with ~a limit ~lange 19 situated inside the cutter 4 at a distance ~rom the the blade~ 11 o~ the knife 7 equal to the required height of the transplants bei~g e~cised. The limit ~lange 11 is made on a sleeve 20 set o~ the shaft 6 mo~ably along the 1~4~
shaf~ 6 and is rotatable thereon. Three grooves 21 are made on the sha~t 6 at some distance one from another for securing the sleeve 20 whose lug 22 can engage with each of them. Each o~
the grooves 21 has a slightly dif~erent width so that the lug 22 goe~ easily into the wider part of a groove 21J and, upon the rotation of the sleeve 20, gets wdgecl in the groove 21, thereby ~aste~ing the sleeve 20 on the shaft 6. ,~
The limit flange 19 is intended for coming in contact with the sur~ace of the bodies of two adjacent vertebrae, thereby limiting the depth to which the kni~e 7 can be lowered into the intervertebral slit. By selectin~ a particular groove 21 it is pos~ible to control the distance between the limit flange 19 a~d the blades 11 of the kni~e 7, to ensure the `~
necessary height o~ the transplants being excised.
There is a stop 23 at the rear end o~ the body 1 inter-acting with the end 24 (Fig~ 5) o~ the shaft 6 during the latter's longibudin~l movement towards the rear end o~ the bod~ 10 Jointl~ ~ith the limit ~lange 19, ~he stop 23 (~ig. 1) ensures the preset depth o~ introduction of the cutter 6 i~to the bodies of the adjacenb ~ertebrae.
The instrument is supplied with a set of cutters 4 9 knives 7 and limit flanges 19 to enable the perfo~mance of surgery on different regions of the spinal column: cervical, thoracic and lumbar. -~^
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Lugs 25 (Fi~. ~ on ~e cutter 4s enteri~g corresponding slots on the body 1, serve to prevent rotation o~ the cutter 4 relative to the body 1 ~ or the sterilisation of the instrument its working parts, namely, the cutter~ kni~e, limit flange and sha~t, are removed.
Be~ore surger~, the size of the vertebrae to be operated upon is determined by X-ray picture6 ~direct and lateral), and the cutter 4, limit flange 19 (~ig. 1) and ~nife 7 of appropria-te size are picked ~rom the setO `
~ he se~uence o~ the intrument's assembl~ is as follows:
1. ~ecuring the limit ~lange 19 o~ the shaft 6. ~or thispurpose, the lug 22 o~ the sleeve 20 o~ the limit flange 19 is inserted in a groo~e 21~ and by rotating the limit ~lange 19 through 90 it i5 secured on the shaft 6. Naturall~, for the deep penetration of the cutter 4, that is, ~or obtaining a f large transplant, the limit ~lange is engaged with the upper groove 21, and vice versa

2. Securing the knife 7 on the sha~t 6. This is effected by inserting the shank 10 of the knife 7 i~to a respecbive slot on the sh~ft 6 as ~ar a~ it goes, at which point the ~prinO plate 8 presses it to the sha~t 6.

3. Mounting the cu-tter 4. For this the lugs 25 (Fig. 7) o~ the outter 4 are placed in the slots o~ the~body 1 and the connection is made rigid b~ means of the union nu~ 3.

4. 8ecuring the sha~t 6 (~ig. 1)o The latter, i~ as~embly with the limit ~lange 19 and the kni~e 7, i~ inserted into the ~ d, _ 15 -body 1 to the stop~ The knife 7 is set parallel to the handle 2~ while the sha~t 6 is locked in position b~ the loc~ing de-~ice 12.
The operation o~ diskectomy with anteriox ~enestrated spondylodesis is carried out with the aid of the proposed instrument in the following manner.
~ he anterior sur~ace o~ the spinal column 26 (Fig~ 8) is exposed, and an H-like incision o~ the a~fected disk 28 (Figs.
9 and 10) i~ made with a scalpel, i.e. two parallel incisions are made at the borders of the disk 28 with the bodies o~ the ad~acenb vertebrae 29 and 30 and one incision connecting them.
Two ~laps 31 (~ig. 10) are ~ormed ~ro~ the outer layers of the fibrous ring. ~he ~laps 31 are pulled apart on both sides with sutures. ~he degenerated dis~ 28 is scraped out with a scalpel and the scoop 32, which leaves in its place a narrow opening, the intervertebral slit 33 (~ig. 11).
~ he assembled instrument is rested p~rpendicularly on the spinal column 26 (Fig. 12) over the intervertebral slit 33~ so that it co~ers equal areas of the adiace~t vertebral bodies 29 and 30. The handle 2 a~d the knife 7 are situated parallel to the intervertebral slit 33 (Fig. 12 and subsequent Figures conditionally depict the ha~dle 2 as rotated through 90 f~r clearer prese~tation). f~
The shaft 6 is released (Figo 13). For this purpose,the head 13 o~ the loc~ing device 12 is pulled so that the rod 16 ~. ~

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9L 91 ri;J~3 relea~es th~ shaft 6~ This pe~mits the kni~e 7, secured on th~ ~haft 6, to drop into the i~ter~ertebral slit 33 until the limit ~lange 19 stops against the anterior surface o~ the adjacent ~ertebral bodies 29 and 30. This contact lasts till the end of the instrument's performance. ~he knife 7, suspended at the level determined by the limit flange 19, remains passive æubsequent locking o~ the shaft 6.
B~ light rotati~g mo~ements o~ the handle 2 accompanied b~ slight pressure the cutter 4 ~ig. 14) is worked into the bodie~ o~ the adjacent ~ertebrae 29 and 30. In the process of thi~ penetration~ the di~tance bebween the stop 23 and the upper end 24 of th~ shaft 6 diminishes. ~1he advance of the cutter 4 ceases altogether ab the moment when the ~,top 23 touches the upper end 24 o~ the sha~t 6 (~ig. 15) and from now on any pressure is conveyed to the limit flange 19 only.
~t this,point, the surgeon clearly feels that further depre~- I
sion o~ the cu~ter 4 is obstructed~ !
- The shaft 6 is locked in position with the locking device 12~ and the knife 7 is set in the working position, whereby it i~ linked with the handle 2. B~ a single rotation of the handle 2 through 180C the transplants 34 and 35 (~ig. 16), excised by the cutter 4, are undercut from their base b~ the knife 7 An additional tu~n o~ the handle 2 through a~other 90 .
will retain the transplants 34 and 35 by means of the ~nife 7 withi~ the cutter 4, and the instrument, together with the - 17 - , ;:

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transplants 34 and 35, as shown ~l ~ig. 17, is withdrawn ~rom the wound. .
~ he obtained autoplastic transplants 34 and 35 in the shape of cylindrical segments ~Fig. 18) a.re taken out of the i~strument a~ter releasing the sha~t 6 (not shown).
The subseguent steps o~ the operatio~ are the concluding one~ and are carried out ~ow ~Jithout the instrument.
~ ell ~isible through the circular bed ~ormed by ~he remo-val of the transplants 34 and 35 are the posterior portions c~
the disk~ including the hernial protrusions 36 (~ig. 19), which can be now easily removed with the ~coop 32. After additional treatment ~clearing from so~t tissues) the semicircular auto-plastic transplants 34 and 35 (~lg. 20), turned through 90 relati~e to their former position i~ the vertebrae 29 and 30, are introduced once again into the ~ormed circular bed so that the slit formed between the transplants 34 and 35 is perpendi-- cular to the intervertebral sl~.t 28~ A homoplastic cortical transplant 36 (~ig. 21) is tightly packed as a spacer be~ween the transplants 34 and 35, thereby achieving an ideal adapta-tion between the tr~nsplants 34 and 35 and the bodies o~ the adjacent vertebrae 29 and 30. ~he ~laps 31 (Fig. 22) o~ the ~ibrous ring are ~utured up like a strap over -~he transplants 349 35 and 36.
~ ig. 23 shows the depth o~ penetration of the homoplastic transplant 36, which correspond6 to the depth of penetratio~

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o~ the transplanl;s 34 and 35 towards the end OI the operation, and not vi~ible in ~ig. 23.
The wound is sutured up in a conventi.onal wa~.

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Claims (4)

1. THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
   PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
   
   10. A surgical instrument for the operation of anterior fenestral spondylodesis in vertebral osteochondrosis, compris-ing: a hollow elongated cylindrical body; a handle secured on the rear end of said body transversally thereto; a detachable hollow cylindrical cutter with a cutting edge, secured on the front end of said body coaxially therewith and intended for the simultaneous excision of two transplants in the shape of cylindrical segments from the bodies of two adjacent verte-brae; a shaft situated in said body coaxially therewith and freely rotatable and movable longitudinally; a detachable knife situated in the cavity of said cutter and secured on the end of said shaft for movement jointly therewith, whose blades lie in a plane parallel to the plane of the cutting edge of the cutter, and whose size is so selected as to ensure the introduction of the knife into the intervertebral slit following the removal of an intervertebral disk and the comple-te undercutting of said transplants after their excision by said cutter, upon subsequent rotation of the knife; a device for locking said shaft relative to the aforementioned body in a position whereby the cutting edge of the cutter and the blades of the knife lie in approximately the same plane, while preventing the shaft's rotation relative to the body; a limit flange, secured on said shaft and situated within the cavity of said cutter at a distance from the blades of said knife, equal to the required height of the transplants being excised and intended for coming in contact with the surface of said adjacent vertebral bodies and thereby restricting the depth of the knife's descent into the intervertebral slit;
   a stop situated on the rear end of said body, interacting with the end of said shaft during its longitudinal movement towards the rear end of the body and ensuring thereby, together with said limit flange, a preset depth of penetration of the cutter into the adjacent vertebral bodies.
2. 2. A surgical instrument as claimed in Claim 1, in which said limit flange is secured on said shaft so as to enable the adjustment of its distance from the blades of the knife in order to control the height of the transplants being excised.
3. 3. A surgical instrument as claimed in Claim 2, compris-ing: a sleeve, fastened on which is said limit flange, set on said shaft, movable and rotatable thereon; a lug on said sleeve; several annular grooves on said shaft, situated at some distance one from another, each of them being adapted for engagement with the aforementioned lug and for securing the position of said sleeve.
4. 4. A surgical instrument as claimed in Claims 1 to 3, in which said locking device, locking the shaft relative to the body, is so situated as to secure, when in the locked po-sition, the position of said knife, fastened on the shaft, and said handle, fastened on the body, in one and the same longitudinal plane.