CA2184006A1

CA2184006A1 - Bone and tissue lengthening device

Info

Publication number: CA2184006A1
Application number: CA002184006A
Authority: CA
Inventors: Alan R. Spievack
Original assignee: Individual
Current assignee: Genesis Orthopedics
Priority date: 1994-02-22
Filing date: 1995-02-13
Publication date: 1995-08-24
Also published as: WO1995022292A1; US5536269A; AU1917295A; TW323227B; CN1119928A; KR950024744A; EP0746257A1; JPH09512717A

Abstract

A device for lengthening bone in a human or animal by incrementally extending the distance between discrete separated portions of the bone to permit continued bone growth between the separated portions comprising an intramedullary nail having distal and proximal portions both of which are secured within the medullar canal of the bone. A hydraulic cylinder is connected to the proximal portion and a piston is connected to the distal portion of the nail. An implantable supply of operating fluid communicates with the cylinder and ratcheting mechanism, between the piston and cylinder, limit their relative movement. A shock absorber mechanism permits limited lost motion between the piston and cylinder and ratcheting release means are employed to permit the piston and cylinder to reverse directions. Various interchangeable distal tips are disclosed to accommodate not only different bones but differently shaped medullar canals.

Description

Wo 95/22292 ~ J' ~
~ D 6 BO~E AND TISSUE r ~:N(~ NlN~ DEVIt'~
Backaround of the Invention This invention pertains to apparatus for extending or lengthening bones and for fracture fixation and is 5 particularly applicable to lengthening of human bones.
There are many instances where a human being has one limb, particularly a leg, which is shorter than the other which could be congenital or due to an ;~ nt.
A nllted fracture is one in which the bone is 10 broken into many small pieces, some in the form of splinters which overlap one another.
It has been found possible to lengthen the deformed or shortened limb or permit the - nllted fracture to heal by devices which extend a proximal portion of a bone 15 which has been severed or qr~ ;nt-~red from a distal portion. Such devices move the distal portion of the bone away from the proximal portion in small inCL, F~ This involves f.Yt~n~l; ng the gap between the severed bone portion~ in ;n~ of appr~Y;r-t(~ly 1/4 mm at a time.
20 When the bones are thus separated, new bone tissue grows in the ~Yt~n~ l gap as well as soft tissue ~uLL~Jul~ding the bone. It is possible to lengthen a bone such as a femur 10 or more centimeters over a period of a few months.
One such device was developed in the USSR by Gavriil 25 A. Ilizarov et al . which essentially is an ,oYtPn~l~hl e cage which fits ~Yt~rn~l l y around a limb . The distal end of the cage is in~:L~ ~l ly ~Yt~n~d from the proximal portion mechanically. One of the problems with this type of device is that a plurality of pins are inserted through 30 the muscle of the limb, and into both portions of the bone. With the proximal portion of the limb "anchored" by the pins in the cage, force is transmitted through the pins to pull the distal portion away from the ~ L.3d wo9SI22292 P~~ 'Cl~
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portion . Such a device is described in U. S . Patent s 4,615,338. One of the problems created by this type of device is that numerous incisions are created in a limb by the pins which are susceptible to infection and that the 5pins are rnnt;n~ y pulling on the flesh. Another disadvantage is that the wearing of a cage over a period of months severely limits the mobility of the patient.
Numerous other devices employ an elongated rod or nail known as an intL 11 ~ry rod or nail. Such devices 10are inserted into the marrow cavity or ~ y passage of the bone . These rods are of ten threaded and are anchored to the bone from within the r 't ~1Ar canal and are in~:L~ t~l ~ y moved by nuts or ratchet means to in~;L, ~lly rnrltimlP separating bone portions. One such 15early device is shown in U.S. Patent 3,986,504 to Avila.
The ratcheting or PYtPntl;n~ of the threaded rod is ;" l; qhPd PlrtPrn~l ly by ratcheting mechanism or wrenches. Again, this type of device lends itself to inf ection .
Other types o~ devices have been developed also in the USSR by Alexander Rl; qkllnnv and employ ratcheting devices which are implanted ;ntPrn~1 1y and are operated by the patient himself who moves portions of his body to activate the ratrhPt;nr~ n; rm One problem with this type of device is that ~rr;~ntsll VG ' or excessive v~ ' can cause too much bone separation, disturbing the growth pattern. It is to these problems that the present invention is directed. Another objective is to provide a completely; 1 ~nt~h1 e, hydraulically operated r ~h;~n; ~m with as little opportunity for infection as possible and which is subst~nt;~ly foolproof in operation .

2 . _ 11~1.,,... . I, _ 2 1 ~06 At least one hydraulically operated device has been discovered by Gotz and S~~hi~l l r-nn, ~ nt; nllnll~ Lengthening of the Femur by Int~ -' ll~ry Stabilization", Archiv.
orthnr~ nhp Unfall-Chirugie 82:305-310, J.F Bergmann Publishing, Munich (1975).
S Y of the Invention A device for lengthening bone and tissue in a human or animal is disclosed for in~ lly PYt~n~;n~ the distance between discrete separated portions of the bone to permit cnnt;nllPd growth between the separated portions.
It ; nrl ~ an int~ ry nail having a distal portion and a proximal portion. The proximal portion of the nail is secured within the int~ ry canal of the bone at the proximal end thereof and the distal portion of the nail is secured within the i~ ry canal at the distal end thereof. A hydraulic cylinder is connected to the proximal portion and a piston moveable in the cylinder is connected to the distal end of the nail. There is a supply of operating fluid in ;cRti-n with the cylinder which may be; 1 ~ntahle or ~yt~rnAl and rat--hPt;n~ ch~n; rm is located between the proximal and distal portions of the nail, i . e ., the piston and cylinder, to limit their relative r ,v ~ to one direction .
An alternative ratcheting I -h~n; ~, however, permits the proximal and distal portions of the nail (i.e., piston and cylinder) to reverse directions when the pressure of the operating f luid is released .
A shock ~hlsnrhin~ member is interposed between the piston and the cylinder and cooperates with lost motion lr--h~ln; I to provide a small amount of buffered lost -Wo 95l22292 PCT/US95101798 ~4~0~

motion, creating an environment to enhance growth between the separated portions.
The pressurizable fluid is rr1nt~;nP~I in a LeseLv~,ir which may also be; l;lnt:qhl e or f~rt~rTl;ll and pumped 5 either manually or from an f~rt~rn~l 8i~n;l~ 1 in~ devicê or an; nt~rn;~l pump controlled by an i 1 ~nt~hl e battery operated mi~L~,~L~,.iessor.
The distal portion of the nail may be made as removable tips of varying conf igurations . They may be 10 secured, as by screw rol~rl;n~, directly to the distal portion of the nail or an ela8tomeric flexible rourl ;ng may be interposed between the diatal portion of the nail and the discrete tip.
The tips may be slotted as from their free end toward 15 their distal portion to give the surgeon a degree of freedom as to where he drills the bone for the screw.
The tips may be either straight or arcuate ~ p~n~;n~
upon the shape of the c~ r canal into which it is to be inserted ~ special tibulanail is disclosed. It has 20 an articulated distal tip.
There may be more than one bores or holes passing transversely through the tips to permit the use of more than one screw to secure it f irmly to the bone .
A 610t may be formed in the tip which does not extend 25 out of the tip end also to permit the surgeon a degree of freedom when drilling the hole for the securing screw.
The tip may be proYided with a pair of feet pivoted on the tip in slots. They are normally urged outwardly from the slots by compression springs such that when they 30 are inserted into the distal end of the bone the feet engage the interior of the - ' 11 ;~r canal locking the tip in place. On insertion, the feet would be held in the slot6 by a removable band.

Wo 9~/22292 r~
2~ ~4006 It will be understood that the device, while illustrated as lengthening the femur, can with simple modification be adjusted to lengthen generally ,~1 n~s~t~d long bones.
The above and other features of the invention, ;nrlu~1;n~ various and novel detailg of construction and ;ns-tit~nR of partg will now be more particularly ~1PR~ r; hPd with ref erence to the ac~ ying drawings and pointed out in the claims. It will be underatood that the particular bone and tissue lengthening device embodying the invention ia ahown by way of illuatration only and not aa a limitation of the invention . The pr; n~ l PR and features of thia invention may be employed in varied and numerous ~ ; r R without departing f rom the scope of the invention.
~rief DeacriT:tion of thç Drawinqs Pigure 1 is a sectional view of a bone lengthening device embodying the present invention and which is located in the f emur .
Figure 2 is a detail view of an upper portion of the device ahown in Figure l.
Figure 3 ia a detailed I~Pt~t; ~n:-l view on an enlarged scale taken on the lines III-III of Figure 2 of ratchet means for limiting I ~, ~ of the device shown in Figure 1.
Figures 4, 5 and 6 are detailed enlarged views of an alternative embodiment of the ratcheting r--h~n; f-~r ; n~ 1; n~ means for reveraing the direction of the r ~~h:~n; ~.~.
Figure 7 ia a detail view of meana for supplying ~L~ asuLized operating fluid to the device.

WO 95/22292 P~
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Figure 8 is an alternative ' _'; ~ of the means for supplying pressurized operating fluid.
Figure 9 is a threaded coupler for r~lP~hly joining selected distal tips to the piston.
Figures lO through 13 are alternative distal tips for use with the device.
Figure 14 is a view of the tip of Figure 10 j oined by the coupler to the piston.
Figure 15 is another alternative distal tip.
Figure 16 i5 still another alternative distal tip.
Figure 17 is an articulated tibial nail.
~etailed Descri~tion of the Invention A device for lengthening bone and soft tissue in a human or other animal by in~ ly f~Yt~n-l;ns the ~ t~nl~e between discrete separated portions of the bone or tissue to permit ct nt inll~od growth between the portions will be seen in Figure 1. The device is shown inserted into a human f emur 2, although it could be another bone in a human or animal. Initially, a surgeon removes the soft, pulpy material in the I ' l l ~ canal to produce an elongate opening. He then cuts the bone tLw~ veLflely as at 3 to receive an intL ' l l~ry nail or rod generally n ~ t ~ 4 -The rod includes a distal portion 6 and a proximal portion 8. The proximal portion has formed in it a central bore 10 which leads to a cylinder 12 having an upper, domed shaped, fluid chamber 14~ The proximal portion terminates at a point designated 16. A plate 18 is securable by screws 20 to the femur. A one-way valve 22 is threaded into the plate 18 and/or portion 8 and is secured by a nut 24 at the proximal end of the f emur . A
flexible conduit 26 leads from the one-wa~ valve 22 to an Wo 95l22292 P~
21~84Oo6 implantable reservoir 30 (Figure 1) which, in turn, is actuated by a pump 32, both elements to be described in greater detail hereinafter. The proximal portion 8 of the L ~ lary nail is secured to the femur by screws 34.
5 The distal portion 6 of the intL ~1111 Ary nail is secured by 6crews 36 within the distal portion of the ~ 1 l Ar canal and on its upper end is formed a piston 9. Ratchet teeth 40 are formed in a line 42 in the piston 9.
A collar 44 i8 secured to the piston 9 by screws 48 10 and is received within an annular groove 46 in the cylinder 12. A dog 46 is received within a slot 49 in the sleeve 44 for ~,~ inwardly and outwardly radially with regard to the piston and has teeth 50 ~n~A~Ahl e with the mating teeth 42 formed in the piston 9. A fluid tight 15 gasket 51 is f itted in a groove in the piston 9 and engages the wall of the cylinder 12. An annular, elastomeric shock absorbing element 52 is f~n~A~Ahl e with the sleeve 44 on the top 55 of the slot 49.
Lost motion between the piston 12 and the cylinder 4 20 occurs to the extent of the gap 54 between the sleeve 44 and the slot 49 as the patient~ 9 lower leg is moved, thus causing the lower cut portion of the femur to move or vibrate slightly relative to the upper cut portion. In other words, the piston is permitted a small amount of 25 lost motion relative to the cylinder, buffered by the shock ~h~ h~r 52, which motion or vibration i8 b~n~f;
to bone growth.
The dog 46 is urged to the left as seen in Figure 3 by a compression spring 56 which is received within the 30 sleeve 44. nhen the piston 9 and, hence, the distal portion of the bone, is urged ~ ly by pressurized f luid entering the chamber 14, the dog 4 6 is moved slightly to the right as viewed in Figure 3 by the teeth Wo 9sl22292 ~ .,. I, ~1 s~ao6 --8-- ,~
44. Each tooth moves downwardly engaging the next adj acent tooth . This limits the motion of the distal end of the nail relative to the proximal portion to one direction. Thus, the piston can only move out of the 5 cylinder upon admission of pressurized fluid to the chamher 14 above the piston head and not reverse direction. This will be done by the surgeon when the bone growth is completed.
An elastomeric piston cap 60 (Figure 2) is secured by 10 a screw 62 to the top of the piston member 9. The edges of the cap 62 ~--int~;n a seal against the inner walls 64 of the cylinder 12 which in conjunction with the annular seal 51 assures that there is no leakage of the saline operating f luid ~
Whereas the invention c~-lnt ~ tPq both either an external supply of operating fluid aRd either an PYtPrn--l or ;ntPrn-l pump, the ~ nt~hle version is the preferred pmhorl i r ~ .
Ref erring next to Figure 7, there will be seen an 20 _lAntAhle supply of galine operatiRg fluid 70 ~ ,nt_;n~l within an elastomeric diaphragm reservoir 72,; l;~ntPd and secured by sutures 74 on an inner portion of the skin and muscle of the patient generally ;n~ tPd 76. A
f~LL -~nPtiC disk 78 is secured in an upper domed portion 25 73 of the diaphragm reservoir. The implanted conduit 26 which leads to the one-way valve 22 of the cylinder communicates with an opening 80 in the f luid reservoir 72 .
An PYtPrn_l pump PY~-;t;nj member 82 is Pn~AJ~iAhle with the skin adjacent the feLL, _ -ti c disk 78 . It comprises 30 an ele~LL _ -t 84, a battery 86 and a trigger 88 such that a surgeon or even a patient can trigger the exciting memher to cause the feLl, _ et; ~- disk 78 to pulse toward and away from the electL _ -t 84 to , ~ess and relax Wo 95/22292 21 ~4006 g the diaphragm reservoir to cause the saline fluid to pass through the conduit 26 through the one-way valve 22 and into the domed reservoir 14 at the top of the piston.
An alterative pumping r - -h~n; r-~ is shown in Figure 8 .
5 The reservoir 72 is connected by a flexible conduit 88 to a pump 90 operated from a reversible geared motor 92. A
le microprocegsor 94, through batteries 96, supplies signal to the motor 92 to pump fluid from the reservoir through the conduit 26 into the upper domed 10 portion 14 of the cylinder 4. The motor 90, being reversible, may also pump fluid back to the reservoir 72.
With reference to Figures 4, S and 6,, -hAn;l for reversing the direction of the piston 9 within the cylinder 12 will now be described. At the top of the 15 piston, an inverted, bell shaped seal 100 is provided which is mounted for flexure between a pair of hinged r~t~-h~t;n~ wings 102, 104, having teeth 106 which are .nsA!rs~hl e with mating teeth 108 on the interior of the cylinder wall. The wings 102, 104 are pivoted on a rod 20 112 received within bores in the top of the piston 9. The piston is cut away at 114 to A~ Ate the lower ends of the wings which pivot inwardly and outwardly under the control of a coiled spring 116.
When it is de5ired to in.:L Al ly separate the 25 proximal and distal portions of the bone, the; ~ 1 AntAhl e reservoir 72 is yL~s~ULiZed either ~Yt~rnAl ly by the electL ,..et 82 or, preferably, by the mi~Lv~Lv~:essor operated pump 9o because the system is reversible. This causes fluid to flow through the flexible tube 26 through 30 the pA~sa~ 10 into the upper domed portion 14 of the cylinder. The pressurized fluid acts against the seal 100 ~Anrl; n~ it8 upper annular portion 101 to expand against the cylinder walls as shown in Figures 4 and 5. The W0 9~122292 :) pressure urges the wings 102, 104 apart against the force of its spring 116. The teeth 106 engage the teeth 108 in the cylinder walls, one by one. ~nt;n~ pressurization urges the piston 9 downwardly causing the bones to 5 separate and permit new growth to take place.
If, for some reason, the bone portions have been separated too much or it is desired to terminate the bone growth, de~ es~uLization of the fluid above the piston permits the coiled spring 116 to squeeze the seal 100 10 together as shown in Figure 6 with the pLe~juLized saline fluid reversing direction in the pA'ql3S~ - y 10 and retl-rn;n~ to the reservoir 72. The reversible pump 90 controls the fluid reversal.
Without using the pump 90, with the teeth 106 on the 15 wings 102, 104 withdrawn from the teeth 108 on the inner cylinder walls, pLe~uLe on the distal end of the bone, as for example, by the orth-~p~ t applying counter pressure, can cause the piston 9 and the distal end of the bone to rise slightly, closing the gap 3 between it and the 20 proximal portion of the bone.
A plurality of distal tips and adaptors will now be described .
Whereas the distal portion or tip 6 of the ;nt~ -' ll~ry nail or rod 4 has been shown as one piece, 25 the distal end may be removable and to include alternative distal tips.
Figure 14 shows the distal portion 6 having a female threaded portion 120 which receives the male threaded portion 122 of a coupler 124 which is also shown in Figure 30 9 Axially opposite the male threaded portion 122 is a female threaded portion 126.

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The coupler of Figure 9 is ahown as being an elastomeric material for flP~;h;l;ty and i8 made of any ely~Lu~Liate bio-~ ,-t;hle material.
Figures 10 -13 show a plurality of r~rl Ac~Ahle distal 5 tips 128 to 134. Tip 128 iB cylindrical and has an n~Ated alot 136 f~yt~nrl; n~ axially. Tip 130 is also cylindrical having a spherical nose 138 and an elongate slot 140 running axially tf~rm;nAt;n~ short of the noae 138. Tip 132 ia cylindrical having a ~L~iVl:~e bore 142.
lO Tip 134 is arcuate but having a cylindrical cross-section and a cylindrical transverse bore 144.
The purposes of the slots 136 and 140 are to permit the hole in the bone at its distal end to be drilled ~L~ vl:Lsely to receive the pin 36 (Figure 1) without 15 precise locAt;nrl lengthwise of thia bone. The ~ n~Ate alota 136 and 138 being able to A: J-te the screw or the pin 36 at a point along their lengths.
The additional purposes of the slotted tips as in Figures 10 and 11 are such that when the piston is being 20 urged toward the distal portion of the bone, i.e. away from the proximal portion, the pin 36 (Figure 1) abuts the upper ends 142 of either of the slots 136, 140. Lost motion provided by the element 51 then comes into play.
The slot 10 readily P~C~ ~,datea the reverae motion by 25 cauaing the end of the slot 142 to move away from the pin 36 which is fixed in the bone. In addition, the slotted tip 128 can be removed without removal of the pin 36. By use of the tips of the ~ of Figures lo and 11, the vibratory effect or the shock-absorbing effect of the 30 element 51 is negated. Whereas, with the tips of Figures 12 and 13, the pin 36 fits directly and firmly into the bores 143 or 144 would cause the tip to reciprocate.

wo 95l22292 Pc~/USg5/01798 The arcuate conf iguration of the tip shown in Figure 13 is to fit within the enlarged int, :L, ' 11 ;Iry cavity in the bone shown at the lower portion of Figure 1.
The axial passageways 135 are located in the tipa to 5 aid the surgeon in removing the tips should they become inadvertently lodged in the bond by the use of a ~ f ishing wire. "
Figure 15 discloses a somewhat longer tip 137 having two tLe~ v~L~e bores 146 and 148 for receiving two pins or 10 screws 36.
Figure 16 discloses yet another ` '; ~ of another removable tip 140 which does not require the bone to be drilled to receive the locking pin 36. A pair of feet 150, 152 are pivoted at 154 and 156 in slots 162. They 15 are urged outwardly f rom the slots by compression springs 164, 166 such that when they are inserted into the distal end of the bone the f eet engage the interior of the r 11l11 Ar canal locking the tip in place. On inserting the tip 140, the feet are held in place by a removable band 20 168 which may be either removed or slid upwardly by the surgeon to permit the f eet to be biased into the locking position .
Figure 17 discloses a device which is usable in f;Y~tin~ or ~ytpn~l;n~ the length of the tibia. As with 25 the Figure 1 device, the tibial nail includes a piston 9, screws 20 and 34, flexible conduit 26, ratrh~t;n~
; rn~ 42, all functioning as in the Figure 1 embodiment. The lower end 170 of the piston is removable as is the coupling device ~ s~od in Figure 9. The 30 distal tip 172 is articulable relative to the piston 9 by way of a ball and socket joint 174 joining the tip 172 to the lower end 170 of the piston. This is to f~t~;lit~te .

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entry of the nail into the tibia because of its unique shape .

Claims

29. A device for lengthening bone and tissue and for fracture fixation in a human or animal by incrementally extending the distance between discrete separated portions of the bone to permit continued growth between the separated portions comprising:
an intramedullary nail (4) having a distal portion (6) and a proximal portion (8);
the proximal portion (8) of the nail (4) being securable within the medullar canal of the bone at the proximal end of the bone;
the distal portion (6) of the nail being securable within the medullar canal of the bone at the distal end of the bone;
a hydraulic cylinder (12) connected to the proximal portion (8) of the nail (4);
a piston (9) connected to the distal portion (6) of the nail (4) and movable in the cylinder (12);
a supply of implantable operating fluid (70) in communication with the cylinder (12);
a shock absorbing element (52) operatively engagable with both the piston (9) and the cylinder (12); and means (54, 44, 49) to permit limited lost motion between the piston (9) and the cylinder (12) against the shock absorbing element (52) in the direction of movement of the piston to stimulate bone growth between the separated portions of the bone.

30. A device according to Claim 29 wherein the supply of operating fluid (70) has a pump (32) and external means (82) for exciting said pump.
31. A device according to Claim 29 wherein the distal portion (6) of the nail (4) securable within the bone is a removable tip.
32. A device according to Claim 31 wherein a flexible coupling (124) joins the removable tip to the nail.
33. A device according to Claim 29 wherein the distal portion of the nail securable within the bone is a removable slotted tip (128-130).
34. A device according to claim 29 wherein the distal portion (6) of the nail is securable in a removable tip (140) having spring based fingers (160-162) for engaging the medullar canal.
35. A device according to Claim 29 wherein there is mechanism (100, 102, 104) to permit the piston to reverse directions relative to the cylinder when the pressure of the operating fluid is released.
36. A device according to Claim 29 wherein the releasable securing means (124) is articulable.
37. A device according to Claim 29 wherein the supply (70) of operating fluid is implantable.