WO2006090380A2

WO2006090380A2 - Device and method for vertebral column distraction and oscillation

Info

Publication number: WO2006090380A2
Application number: PCT/IL2006/000240
Authority: WO
Inventors: Mordechay Ilovich; Yona Kosashvili; Elik Chen
Original assignee: Orthogon Technologies 2003 Ltd.
Priority date: 2005-02-22
Filing date: 2006-02-22
Publication date: 2006-08-31
Also published as: WO2006090380A3

Abstract

The present invention is generally directed to a device for manipulating the spinal vertebrae of a subject. Said device comprises at least one activator having a moveable element which is capable of being displaced in response to externally induced energizing signals, wherein said activator is affixed to at least one vertebra, and coupled to at least one other vertebra, such that said activator is capable of moving the vertebra(e) to which it is coupled in an axial direction, wherein said movement can be unidirectional, resulting in either distraction or compression of the vertebrae, or bidirectional, resulting in an oscillatory movement of the vertebrae.

Description

Device and method for vertebral column distraction and oscillation

Field of the Invention

The present invention relates to methods and devices for manipulating spinal vertebrae. More particularly, the invention relates to methods and devices for distracting, compressing, and/or oscillating, spinal vertebrae.

Background of the Invention

Some orthopedic treatments, in particular treatments of spinal deformities, involve the straightening and/or lengthening of the spinal cord, and/or enhancing spinal fusion. Patients suffering from spinal deformities such as scoliosis are prone to loss of height following spinal fixation. The expected lost height for each vertebra is 0.07 cm per year of growth remaining until skeletal maturity. These patients would potentially benefit from the controlled distraction of their vertebral column, as a means of regaining lost height.

Patien-ts suffering with pain resulting from spinal instability (for example, following surgical procedures such as dissectomy and laminectomy) often find relief following spinal fusion of the affected region. In many of these procedures spinal fusion is performed by using pedicular screws and rods in addition to bone graft in the form of bone chips between the corresponding transverse processes of the vertebrae. However, in many cases - particularly where the local blood supply to the vertebrae is less than ideal - the prior art procedures that utilize the implantation of bone chips along with rigid spinal fixation are unsuccessful due to lack of fusion of said chips resulting in a failure rate of the above said fusion of 10-30%, especially when more than one segment is fused and in case the patient is a smoker. There thus exists a need for an improved method for obtaining spinal fusion.

In addition, in cases of spinal stenosis, one of the main etiologies is loss of disc height which starts a vicious circle of spinal instability and production of bony spurs (osteophytes) leading to the spinal canal stenosis and to stenosis of the spinal foramina. It would be advantageous to perform controlled elongation of the stenotic spinal segments in order to restore the height of the spinal segment and thus decrease the pressure both in the spinal canal and at the spinal foramina.

Moreover, the technique of bone grafting is a cornerstone of many spinal fusion operations, including but not limited to scoliosis. In that situation, patients need to wear cumbersome braces for long periods of up to one year in order to allow the fusion process to take place without risking hardware failure of the instrumentation. These patients would be highly satisfied if this period could be considerably shortened.

U.S. Patent application serial No. 2005/261682 (to Bret A. Ferree) describes a vertebral shock absorber constructed from telescopic members. In this shock absorber a compressible resilient component, such as a spring, elastomeric material, liquid, gel, or hydrogel, is disposed in the cavity of the telescopic members. The ends of the shock absorber are fastened to an upper vertebra and a lower vertebra by pedicle screws or by way of ball-and-socket joints for enhanced range of motion.

Heretofore known prior art devices for treating the spinal cord have not provided suitable means for applying controlled retraction, compression and/or oscillation of adjacent vertebrae, and of stimulating bone union in the spinal cord.

The primary aim of the present invention is to provide a device that may be implanted in close relation to the desired region of the vertebral column and which may be used for either controlled vertebral distraction or for stimulating bone union by means of causing mechanical oscillation, compression, and/or tension.

Another aim of the present invention is to provide a surgical procedure for causing controlled distraction that may be followed, if required, by mechanical vibrations (oscillations), of the spinal column, said procedure being suitable for use in the management of spinal deformities such as scoliosis and stenosis.

A further aim of the present invention is to provide a surgical method for causing stimulating bone union in clinical situations by compression and/or vibration (oscillation) in which it is desirable to initiate and/or enhance spinal fusion-.

It is a further object of the present invention to provide a device capable of applying distraction, compression, oscillation (vibration) , and/or tension, between spinal vertebrae for stimulating bone union.

Summary of the Invention

The present invention describes a device for manipulating spinal vertebrae of a subject, wherein said device may be implanted by means of screws onto at least two vertebrae of said subject. The device generally comprises at least one activator comprising a moveable element which is capable of being displaced in response to externally induced energizing signals, wherein said activator is affixed to at least one vertebra, and coupled to at least one other vertebra, such that said activator is capable of moving the vertebra (e) to which it is coupled in an axial direction, wherein said movement can be unidirectional, resulting in either distraction or compression of the vertebrae, or bidirectional, resulting in an oscillatory movement of the vertebrae.

The phrase "manipulating spinal vertebrae" and phrases related thereto refer to manipulations whereby the vertebrae are caused to move axially, in any desired direction (i.e. distractive, compressive and/or oscillatory movements) .

The phrase "energizing signals" in the context of the present disclosure refers to signals (e.g. a magnetic field) capable of remotely and wirelessly actuating mechanical displacement means attached to the spinal column, which react in the presen-ce of said signal. These "energizing signals" may be applied according to a predetermined pattern of signals, or they may be determined according to a feedback signal received from the device that monitors the obtained movements.

The device preferably comprises one or more elongated platforms, each of which is horizontally affixed to one of the vertebrae of said subject, wherein said elongated platforms are used for affixing said at least one activator, and/or for attaching coupling means, to the respective vertebra. The device may further comprise linear guidance means slidably attached to the sides of said two or more vertebrae. Alternatively or additionally, the device may comprise stabilizing and synchronizing arms rotatably attached to the sides of some of said at least two vertebrae and/or to elongated platforms horizontally affixed thereto. The coupling means may be implemented by lever arms and/or ramp surfaces attached to one or more of said elongated platforms.

The activator may be configured to be energized by an externally induced magnetic field. In one specific embodiment of the invention the activator comprises at least one pair of ferromagnetic/magnetic elements, wherein each pair of ferromagnetic/magnetic elements comprises a stationary ferromagnetic/magnetic element affixed to the internal wall of said activator and a movable ferromagnetic/magnetic element affixed in proximity to said stationary ferromagnetic/magnetic element to a shaft coaxially and slidably supported therein, such that magnetic attraction forces are evolved between said ferromagnetic/magnetic elements in the presence of a magnetic field, and wherein said magnetic attraction forces may affect axial movements of said shaft. The activator may further comprise a gear unit coupled to said shaft by means of a clutch and motion conversion units. The activator may further comprise a feedback monitoring assembly for indicating obtained movements and outputting the same to the user, to an external device, or to a controlled feedback system.

In one specific embodiment of the invention the device comprises at least one parallel pair of activators affixed to the lateral sides of at least one vertebra and coupled to another vertebra. The at least one pair of activators, and/or coupling means coupled thereto, may be affixed to at least one vertebra by means of elongated platforms horizontally affixed to said vertebra. In another aspect, the present invention is directed to a method for regaining lost height in a subject having already undergone a spinal fixation procedure comprising the steps of: a) Removing one of the fixation rods previously implanted for the purpose of reducing a spinal deformity; b) Connecting a first device of the present invention as disclosed hereinabove to the same side of the spinal column from which the previously implanted fixation rod was removed in step (a) ; c) Removing the second fixation rod; d) Connecting a second device of the present invention as disclosed hereinabove to the same side of the spinal column from which the second fixation rod was removed in step (c) ; e) Optionally interconnecting the two devices by means of one or more interconnecting elements (as described hereinabove) ; f) Applying a magnetic field induced by an externally placed coil to the region of the spinal column in which the devices were implanted, such that the activators of said devices respond by applying distracting forces to the vertebrae to which they are coupled in order to increase the distance between the said vertebrae and the vertebrae to which the other ends of said activators are affixed; g) Optionally applying, at the end of the distraction phase, a magnetic field induced by an externally placed coil to the region of the spinal column in which the devices were implanted, such that the activators of said devices respond by oscillating the vertebrae to which they are coupled in order to increase the healing process and reduce the healing time.

In one preferred embodiment of the above-disclosed method, the subject is a patient being treated for scoliosis.

In one preferred embodiment of the method, the magnetic field is applied at least once per day between 1 second to 30 minutes for a total period of between 1 and 30 days, preferably for a period of one week.

The magnetic field may be applied in several sessions per day where in each session the obtained distraction length may range between few micro-millimeters and up to few tenths of a millimeter. The magnetic field may be applied within time intervals of 0.5 to 30 seconds, where in each of said time intervals the magnetic field is applied for a period of time ranging between 0.1 to 1.5 sec.

Optionally, the magnetic field may be applied in pulses, wherein, the width of said magnetic pulse is in the range of 0.001 second to 10 seconds and the frequency of said pulses is in the range of 0.01 Hz to 500 Hz.

The present invention also provides a method for causing spinal fusion comprising the steps of:

a) connecting a first device of the present invention as disclosed hereinabove to one side of the spinal column and a second said device to the other side of the spinal column; b) optionally interconnecting the two devices by means of one or more interconnecting elements (as described hereinabove) ; c) applying a magnetic field induced by an externally placed coil to the region of the spinal column in which the devices were implanted, such that the activators of said devices respond by applying compressive forces to the vertebrae to which they are coupled in order to reduce the distance between the said vertebrae and the vertebrae to which the other ends of said activators are affixed.

In a preferred embodiment of this method, the compressive force is applied between once and fifty times per day, each time for a period of between 1 milisecond and 120 minutes.

Preferably, the compressive force is applied once per day for a period of 20 minutes.

The present invention also provides a method for causing spinal fusion comprising the steps of: a) connecting a first device of the present invention as disclosed hereinabove to one side of the spinal column and a second said device to the other side of the spinal column; b) optionally interconnecting the two devices by means of one or more interconnecting elements (as described hereinabove) ; c) applying a magnetic field induced by an externally placed coil to the region of the spinal column in which the devices were implanted, such that the activators of said devices respond by applying axially-directed oscillatory forces to the vertebrae to which they are coupled thereby causing axial oscillation of said vertebrae.

In one preferred embodiment of this method, the frequency of the axial oscillation is between 0.01 and 50 Hz, preferably 0.5 Hz: This oscillatory motion may be induced between 1 and 8 times per day, preferably once a day for a period of 20 minutes .

In the above-defined methods of treatment, the first and second devices are preferably connected to the vertebral column using pedicular screws.

Brief Description of the Drawings

The present invention is illustrated by way of example in the accompanying drawings, in which similar references consistently indicate similar elements and in which:

Fig. IA is a block diagram generally demonstrating an axial activator of the invention; Fig. IB schematically illustrates a preferred embodiment of an axial activator of the invention based on a magnetic driving source;

Fig. 1C schematically illustrates another implementation of the magnetic activator of the invention wherein the driving force is delivered to the activator by an arm- lever transferring means/

Fig. ID is a block diagram generally demonstrating a rotary output activator of the invention;

Fig. IE schematically illustrates a preferred embodiment of a rotary output activator of the invention based on a magnetic driving source;

Fig. IF schematically illustrates a preferred embodiment of an axial magnetic activator of the invention in which the axis of rotations is perpendicular to the activator; Fig. IG schematically illustrates a preferred embodiment of a rotary output magnetic activator of the invention based on a linear ratchet mechanism;

Fig. 2A schematically illustrates a magnetic activation scheme wherein the windings of an electromagnet enclose an axial/rotary magnetic activator;

Fig. 2B schematically illustrates a magnetic activation scheme wherein the windings of an electromagnet are positioned in the proximity of an axial/rotary magnetic activator;

Fig. 3A schematically illustrates a device of the invention operating with a pair of parallel axial activators;

Fig. 3B schematically illustrates a device of the invention operating with a single axial activator and linear guidance means;

Fig. 3C schematically illustrates a device of the invention operating with a single axial activator and with stabilizing and synchronizing arms; Fig . 3D is a variation of the device illustrated in Fig.

3C, wherein the activator is not centered;

Fig. 3E schematically illustrates a device of the invention operating with a single axial activator and with two pairs of stabilizing and synchronizing arms;

Fig. 3F schematically illustrates a device of the invention operating with a single axial activator and a lever arm;

Fig. 3G schematically illustrates a device of the invention operating with a pair of axial activators and respective lever arms linked thereto;

Fig. 3H schematically illustrates a device of the invention operating with a pair of horizontally disposed axial activators and respective ramp surfaces;

Fig. 4A schematically illustrates a device of the invention operating with a single rotary activator and ramped surfaces;

Fig. 4B schematically illustrates a device of the invention operating with a single horizontally disposed rotary activator and an eccenter;

Fig. 4C is a variation of the device illustrated in Fig.

4B, operating with linear guidance means;

Fig. 4D is a variation of the device illustrated in Fig.

4B, operating with stabilizing and synchronizing arms;

Fig. 4E is a variation of the device illustrated in Fig.

4B, operating with two pairs of stabilizing and synchronizing arms;

Fig. 5A illustrates a portion of a typical vertebral column;

Fig. 5B shows a top view of a typical spinal vertebra;

Fig. 6A schematically illustrates a device of the invention comprising a pair of rotary activators and designed to concurrently operate on a number of vertebrae;

Fig. 6B schematically illustrates a device of the invention comprising a pair of axial activators and designed to concurrently operate on a number of vertebrae;

Fig. 6C schematically illustrates a device of the invention comprising a pair of axial activators and designed to concurrently push a number of vertebrae throughout a pin to pin coupling;

Fig. 6D schematically illustrates a device of the invention comprising a number of rotary activator and designed to concurrently operate on a number of vertebrae with linear guidance means; and

Fig. 6E schematically illustrates a device of the invention comprising a number of axial activators and designed to concurrently operate on a number of vertebrae with linear guidance means.

Detailed Description of Preferred Embodiments

The present invention aims to provide devices and methods for treating spinal deformities. More particularly, the present invention aims to provide devices and methods for straightening and/or lengthening the spinal cord, and/or enhancing spinal fusion.

Fig. 5A schematically illustrates a portion of a typical vertebral column comprising series of vertebrae 50a, 50b, and 50c. As seen in the top view shown in Fig. 5B, each vertebrae 50 is composed of a disk (anterior body) 100 and a (posterior) neural arch 107. The neural arch 107 comprises two transverse processes 101 protruding transversely, a spinous process 104 protruding posteriorly, and superior articular facets 103 protruding upwardly.

The device of the present invention comprises an activator configured to generate axial or rotary motion which may be used to cause increased or decreased separation between pairs of adjacent vertebrae. A typical axial activator is composed of at least one pair of mutually-contacting elongate members which are arranged such that the overall end-to-end length thereof may be altered by causing each member of the at least one pair to move axially in relation to each other. The cross section of said members can be circular, elliptic, rectangular, square or any other shape. The members may be solid, hollow or a combination of the two, and are manufactured by the use of the standard machining processes that are well known in the art. Said members may be constructed from any suitable biocompatible material including (but not limited to) titanium alloys and a biocompatible stainless steel alloy such as 316LVM. The overall end-to-end length of a device activator of the invention (i.e. comprising one or more pairs of elongate members) is usually in the range of 2 cm to 40 cm. The precise length will, of course, be determined by the length of the vertebral column that requires to be treated. Each elongate member will typically have, but not be limited to, an external diameter of between 1 and 25 mm.

Connected to each of said members is at least one connecting element, the purpose of which is to connect said member with a pedicular screw inserted into a vertebra 50. The pedicular screws will generally have a diameter of between 1 mm and 16 mm, preferably 3.5 mm, and can be fully or half threaded, the screws may be uncoated or coated either with hydroxyapatite or with other materials improving their lasting purchase of bone. The pedicular screws are typically screwed into the transverse processes 101 and/or the into disk 100 section of the vertebra .

Preferably, each activator is linked with two connecting elements. However, any suitable larger number of connecting elements (in accordance with the overall length of the elongate member in question) may be used, as required, without exceeding the bounds of the present invention.

Optionally, one or more of said members may also have connected thereto a longer interconnecting element, the purpose of which is to provide a connection with the corresponding member of a similar device located on the contralateral side of the vertebral column.

Standard connectors for use in spinal surgery (such as the De Puy and Aesculap connectors, both of which are well-known in the art) may be used to construct both the aforementioned connecting elements and the aforementioned optional interconnecting elements.

The mutual contact and interaction of each pair of members may be arranged in one of the two following ways:

1) Each pair of members (i.e., activator) may consist of two mutually-telescoping members, such that the overall change in end-to-end length of said member pair is caused by the axial telescopic movement of one member within the other member. One of the pair of members is hollow, that is, it comprises an internal cavity in which the second member may engage in its axial movement. 2) Each pair of members (i.e., activator) may consist of two members arranged so that they may be caused to slide axially in relation to each other, such that the overall change in end-to-end length of said member pair is caused by the axial sliding of one member over the other member.

In both cases (i.e. the case of a pair of sliding members and the case of telescopic pair) , one or both of said members may comprise guide means (e.g., linear guidance) for ensuring the accurate, controlled axial movement of the other member along its length. The guide means may consist of a guide-track having lateral lips that prevent sideways slipping of the second member or guiding pin(s) (e.g., guided pin comprising rollers to minimize friction) that is inserted therein, without impeding the desired axial movement. In another embodiment, the guide means comprises a semi-circular channel into which the second member (having a circular or semicircular cross-section) is able to move in an axial (but not lateral or rotary) direction. In a further embodiment, the guide means may be provided in the form of a "tongue-and- groove" structure, whereby an axially-directed tongue (or ridge)- located on one member may move freely in an axial direction within a complementarily-shaped groove or slot in the second member. Clearly, many other types of guide means are possible, all of which fall within the scope of the present invention.

Both members of the activator are constructed of a nonmagnetic material. However, one of said members comprises a ferromagnetic and/or magnetic material (present either in the form of one unit or in the form of several discrete units) that are capable of being actuated by an external magnetic field, such that the member with the ferromagnetic/magnetic unit(s) and/or the member without the ferromagnetic/magnetic parts move axially in relation to each other. By way of example, the aforementioned magnetic material may be provided in the form of a series of pairs of cylindrical (or other shape, such as square) ferromagnets (and/or magnets) , each ferromagnet (or magnet) having, for example, a diameter of 3- 12 mm and a length of up to 2-40mm (or any other suitable length according to the device dimensions), with a spacing of up to 6 mm between each pair to minimize attraction forces between moveable Ferromagnets and stationary Ferromagnets of adjacent pairs. The gap between the moving and the stationary Ferromagnets/magnets in each pair is preferably up to 1.5mm.

Typically, this arrangement would consist of a series of up to 8 pairs of ferromagnets. It should be emphasized that this configuration is given by way of example only, and is not intended to be limiting in any way.

The axial movement in one direction is caused by the magnetic forces induced by the external magnetic field acting on the member comprising the ferromagnetic/magnetic material, as described hereinabove. In cases where it is required that said moving member will be capable of moving in a second, reverse direction, this axial returning movement in the other direction is caused either by said magnetic forces or by means of a spring and/or other return mechanism, for example a ratchet together with appropriate screws or bolts and nuts (e.g., lead screw). In the case that the activator is formed as a telescoping pair, said spring and/or other return mechanism is located in the internal space of the hollow section. A similar arrangement will also be present when a pair of sliding members is employed.

The above-described axial movements of the elongate members may be used to cause the two sections of the activator to distract from each other in one embodiment (thereby increasing the total end-to-end length of the device) , or cause compression in a second embodiment (thereby reducing the total end-to-end length of the device) , or to oscillate in a third embodiment .

Progressive spinal distraction (which is most typically used in cases in which height restoration is required) can be achieved by uni-directional magnetically-induced distraction (as described hereinabove) combined with a ratchet or/and unidirectional clutch mechanism or a transmission mechanism pushing an internal and/or external screw or a slider in order to prevent backward motion.

In one embodiment, the device of the present invention may comprise a single pair of mutually-contacting elongate members, as described hereinabove. In other embodiments, however, the device may comprise a plurality of pairs of elongate members, such that upon application of the external magnetic field, the members comprising the magnetic/ferromagnetic material will move in an axial or rotatronal direction, thereby altering the end-to-end length of the entire device. Various possibilities exist for the forms which the plurality of pairs may take. In one embodiment, for example, each member is a hollow member, capable of accommodating the telescope-like axial movement of another hollow member within its internal cavity. In this embodiment, the device will comprise an assembly of three or more hollow members, each of said members having a larger outer diameter than its neighbor (on one side) , in order to accommodate said neighbor within its internal cavity. In a further embodiment, the device of the invention comprises an assembly of three or more members, arranged such that a hollow member alternates with a piston-like member that is capable of moving axially within the internal space of said hollow member. In this case, the middle (i.e. non-terminal) hollow members have either an internal space running through their entire length or two separate internal spaces extending inwards from each end of the member, in order to allow telescopic interaction of piston-like members on both sides of said hollow member. In this embodiment (unlike in the previously described embodiment) the outer diameter of each of the hollow members will be the same. In a further embodiment, the device comprises a plurality of pairs of members, each having the same diameter, said members being connected in series, the end-to-end distance of each pair being elongated by the magnetic field

The spinal vertebra manipulator of the invention may utilize a multi vertebral linear guiding mechanism such as bushings and guide rods or linkage mechanism. As will be described and exemplified herein below, in such implementations a single activator may be effectively used to manipulate a relevant spinal section.

Fig. IA is a block diagram generally demonstrating an axial activator 18 of the invention. In this example the activator 18 comprises a driving source 1 that is preferably adapted for generating axial movements to a movement transformation unit 2 capable of transforming said axial movements into angular movements,, i.e., rotary motion. Said angular movements are received by a gear and unidirectional clutch unit 4 via a ratchet mechanism 3, wherein said gear is configured to allow the actuation of the vertebra manipulation device of the invention with reduced moments. The rotary movements outputted by gear device 4 are then transformed into axial movements by the transformation unit 5. Fig. IB schematically illustrates an implementation of an axial activator 18a, constructed according to the scheme described above with reference to Fig. IA, and in which the driving source (1) is based on magnetic force actuation. Axial activator 18a comprises an elongated hollow body 9 used for housing the units and devices (1, 2, 3, 4 and 5) utilized in axial activator 18a. In a preferred embodiment of the invention the driving source (1) is implemented by one or more pairs of stationary magnetic (or ferromagnetic) elements 11 and movable magnetic elements 10, wherein magnetic elements 11a, lib,..., Hn, are affixed to the inner wall of body 9, and movable magnetic elements 10a, 10b,..., 1On, are affixed to shaft 122 slidably centered thereinside.

Stationary magnetic elements 11 are configured to provide a concentric passage suitable to slidably comprise shaft 122. Each stationary magnetic element 11 preferably occupies a circumferential cross-sectional area of hollow body 9 while providing a passage thereinside, where the passage of the adjacent stationary magnetic elements 11 are centered about the longitudinal axis of elongated body 9.

Stationary magnetic elements 11 are preferably distributed over a longitudinal section of body 9 in equal distances therebetween, and movable magnetic elements 10 are preferably distributed along shaft 122 in corresponding distances therebetween, such that corresponding pairs of stationary and movable magnetic elements ({10a, Ha}, {10b, lib},...) are obtained. In this way shaft 122 may be moved horizontally, as exemplified by arrow 7, by applying a magnetic field along the longitudinal axis of elongated body 9, which in turn cause attraction forces to develop between each pair of stationary and movable magnetic elements 11 and 10. Elongated body 9 is preferably a hollow cylindrical body manufactured from a non-magnetic material such as S.S316LVM or Titanium alloy. Its length is generally in range of 30 mm to 400 mm, preferably about 100 mm. The outer diameter of body 9 is generally in the range of 6 mm to 12 mm, preferably about 10 mm, and its inner diameter in the range of 4 mm to 8 mm, preferably about 7 mm. Stationary magnetic elements 11 are preferably toroid shape elements manufactured form ferromagnetic or magnetic material, such as carbon steel or industial Ferromagnetic alloy, preferably from VACCOFLUX 50, SAElOlO, SAE1018, or SAE1020, Carbon steel. The diameter of stationary magnetic elements 11 is determined to allow fitting thereof in the hollow interior of elongated body 9. Stationary magnetic elements 11 preferably comprise a hollow bore, aligned with the longitudinal axis of elongated body 9, wherein said bore is configured to allow shaft 122 to move therethrough, for example, said bore may be in the range of 1.5 mm to 3.5 mm, preferably about 2.4 mm.

Shaft 122 may be manufactured from Stainless steel or Titanium alloy, preferably from S . S316LVM. The length of shaft 122 is generally in range of 20 mm to 80 mm, preferably about 30 mm, and its diameter is generally in range of 1 mm to 3 mm, preferably about 2 mm. The distance between pairs of magnetic elements (e.g., the distance between magnetic element 10a and 10b) along the longitudinal axis of elongated hollow body 9 is generally in range of 6 mm to 20 mm, preferably about 11 mm. The gap between a stationary magnetic elements 11 and a movable magnetic elements 10 is generally in range of 0.4 mm to 2 mm, preferably about 1.2 mm, and the magnetic force applied during operation of the activator may bring said elements to come into contact. As exemplified in Fig. IB, one end tip of shaft 122 contacts the base 12a of plunger 12. Plunger 12 is slidably centered in elongated body 9 by means of collar 17 and bearing (or roller) 14 which are affixed to the inner wall of elongated body 9. Collar 17 is engaged with the body section 12c of plunger 12, wherein said body section 12c comprises a returning spring 13 disposed thereover and between said collar 17 and said base 12a. Bearing 14 engaged in a horizontal groove 12b provided on the outer surface of base 12a, prevents rotational movements thereof and utilized provide linear guidance thereto. This assembly of plunger 12 and spring 13 is efficiently used in the motion transformer (2) to transfer the axial movements of shaft 122, and to return shaft 12 backwards to its initial position when the applied magnetic force is reduced or zeroed, thereby restoring the gap between the stationary and movable magnetic elements 10 and 11.

One end of body section 12c is attached to base 12a of plunger 12 while its other end is slidably engaged in the hollow interior of base section 18a of motion converter 18. One or more rollers 16 provided on body section 12c are engaged in corresponding helical grooves 18d provided on the inside wall of the hollow interior of base section 18a. Alternatively, grooves 18d may be implemented as helical slits passing from the outer surface of base section 18a into its hollow interior.

Hollow interior of base section 18a of motion converter 18 should be respectively configured to allow body section 12c of plunger 12 perform the entire axial movements forwarded thereto by shaft 122. An annular groove 18b is provided over the outer surface of motion converter 18 for rotatably centering it in the internal space of elongated hollow body 9 by means of bearings (or rollers) 8 affixed to the inner side wall of elongated hollow body 9. This linkage between plunger

12 and converter 18 by means of said rollers 16 and helical groove 18d translates the axial motion of plunger 12 into an angular motion of converter 18.

Alternatively, bearing 8 may be implemented without a corresponding groove 18b, but with one or more concentric ball bearings arranged in tandem, wherein the axes of said bearings coincides with the axis of converter 18.

Plunger 12 may be manufactured by lathing or mold casting in a cylindrical shape from a stainless steel or Titanium alloy, preferably from S.S316LVM. The diameter of the base 12a of plunger 12 is generally in the range of 4 mm to 8 mm, preferably about 7.5 mm, and the diameter of its body section 12c is generally in the range of 2.5 mm to 6.5 mm, preferably about 6 mm.

Converter 18 is coupled to gear and unidirectional clutch unit (4) via ratchet mechanism (3) implemented by the coupling of a driving ratchet element 18c, attached to (or formed on) a cross—sectional surface of motion converter 18, and a driven ratchet element 19a attached to (or formed on) the base of ratchet 19. For example, said ratchet elements, 18c and 19a, may be implemented by a circular saw tooth arrangement (not shown) provided on opposing faces of said elements, and configured such that rotations of converter 18 resulting from movements forwarded by shaft 122 establish coupling therebetween, while the rotations in the opposite direction, caused by the return of plunger 12 due to spring 20, breaks said coupling due to the sliding of the saw tooth ramps. Said sliding of the saw tooth ramps results in axial motions of ratchet 19, the body section 19b of which is received in a coupling element 20. Motion converter 18 may be manufactured by lathing, milling, EDM (Electro Erosion) , or mold casting, in a cylindrical shape, from stainless steel or Titanium alloy, preferably from S.S316LVM. The length of motion converter 18 is generally in the range of 6 mm to 8mm, preferably about 7 mm, its diameter is generally in the range of 6 mm to 8 mm, preferably about 7.5 mm, and the angular motions it performs are generally in the range of 4° to 12° , preferably about 6.4°.

As illustrated in Fig. IB, the cross section of body section 19b of ratchet 19 is smaller than the cross section area of the driven ratchet element 19a, which defines an annular recess between driven ratchet . element 19a and coupling element 20, wherein returning spring 27 resides. The hollow base 20a of coupling element 20 is configured to receive an end portion of body section 19b of ratchet 19 thereinto and any axial movements thereof during the sliding of the saw tooth ramps. Returning spring 27 retract portion of said body section 19b from the interior of hollow base of coupling element 20, thereby restoring the coupling between ratchet elements, 18c and 19a.

Backwards angular motion of ratchet 19 is prevented by means of friction like O-ring seal , the shape of the interacted teeth's profile angle (moderate) and the unidirectional clutch. A sliding pin 19c, provided on body section 19b of ratchet 19, transfers the angular displacements of driven ratchet element 19a to coupling element 20. The hollow interior of coupling element 20 receives body section 19b of ratchet 19 and sliding pin 19σ provided thereon is received in horizontal groove 20b, thus allowing ratchet 19 to move back and forth, linearly guided, while the ratchet teeth of ratchet elements, 18c and 19a, are being engaged/disengaged during their rotation.

Ratchet 19 may be manufactured by lathing, milling, EDM (Electro Erosion) , or mold casting, in a cylindrical shape from stainless steel or Titanium alloy, preferably from S.S316LVM. The diameter of driven ratchet element 19a of ratchet 19 is generally in the range of 6 mm to 8 mm, preferably about 7.5 mm, and its length is preferably about 2 mm. The diameter of body section 19b of ratchet 19 is generally in the range of 4.5 mm to 6.5 mm, preferably about 5.5 mm, and its length if preferably about 5 mm.

Linear guidance means 20 may be manufactured by lathing or mold casing in a cylindrical shape from stainless steel or Titanium alloy, preferably from S.S316LVM. The outer diameter of hollow base 20a is generally in the range of 6 mm to 8 mm, preferably about 7.5 mm, and its length is preferably about 6 mm. The inner diameter of hollow base 20a is generally in the range of 5 mm to 7 mm, preferably about 6 mm, and its length is preferably about 6 mm. The diameter of coupling portion 20c of linear guidance means 20 is generally in the range of 2 mm to 8 mm, preferably about 5 to 7.5 mm, and its length is preferably about 7 mm.

The rotations transferred by linear guidance means 20 are received via coupling portion 20c thereof in gear 21. The chassis 21a of gear and unidirectional clutch 21 is affixed to inner wall of elongated hollow body 9, and a stationary part 22a of thrust bearing element 22 is affixed on its cross section surface. The rotating part 22b of said thrust bearing element 22 is affixed to the base 23a of rotating shaft 23. Thrust bearing element is designed to absorb external shocks and payload axial force which may be delivered via rotating shaft 23. A cross sectional portion area of said base 23a is coupled to the output shaft 21b of gear 21, where said output shaft 21b outputs rotational movements received via coupling portion 20σ and which are transformed by transmission elements (not shown) of gear 21. An annular groove may be formed on the circumference of said base 23a in which O-ring 23b may be mounted for sealing elongated hollow body 9. O-ring 23a may be implemented by a single, or a pair of, silicone 0-rings mounted in grooves provided in base 23a of rotating shaft 23.

Gear and unidirectional clutch 21 may be a type of planetary gear head (e.g., 16/1 of Faulhaber group), its diameter is generally in the range of 6 mm to 8 mm, preferably about 7.5 mm, and its length is preferably about 6 mm. The unidirectional clutch is preferably an "of the shelve" unidirectional clutch, such as manufactured by INA integrated in a gear and unidirectional clutch 21. Thrust bearing element 22 may be implemented by F3-8M manufactured by SAPPORO PRECISION INC.

Rotating pivot 23 comprises a threaded section 23c for transl-ating the rotational motions received via gear 21 into linear movements outputted via moving arm 24 slidably centered inside elongated hollow body 9. Some portion of moving arm 24 is made hollow and its internal space can be accessed via an opening provided by the bore of nut 24a mounted at the base of moving arm 24. Moving arm 24 may further comprise horizontal grooves for receiving linear guiding means such as rollers, keys, pins, and the like. Affixed to respective locations on the inner wall of elongated hollow body 9.

Rotating pivot 23 may be manufactured from stainless steel or Ti alloy, preferably from S.S316LVM, its diameter is generally in the range of 5 mm to 7.5 mm, preferably about 7 mm, and its length is preferably about 50 mm. Moving arm 24 may be manufactured by lathing and milling from stainless steel or Titanium alloy, preferably from S.S316LVM, its diameter is generally in the range of 8 mm to 7 mm, preferably about 7.5 mm, and its length is preferably about 90 mm. The diameter of the hollow interior of moving arm 24 is generally in the range of 2.4 mm to 4.4 mm, preferably about 3.4 mm, and its length is preferably about 50 mm.

The axial motion output of magnetic activator 18a is provided by axial movements of moving arm 24 which protrudes outwardly via opening 28 of elongated hollow body 9. Said axial motion is obtained from the angular motion outputted by gear 21 which is translated by the threaded section 23c of rotating pivot 23 and the nut 24a affixed to the opening to the hollow interior of moving arm 24 into corresponding axial movements.

The magnetic actuation scheme described hereinabove may be used to implement a reciprocating motion device (e.g., for oscillation purposes) operating with lower force magnitudes (e.g., up to 10Kg pushing/pulling force). Such reciprocating motion^* device may be implemented using pairs of Ferromagnets and/or magnetic elements ({10a, lla}, {10b, lib}... {10n, lln}) and a shaft (122) and returning spring (13) , as described above. The motion converters, ratchet mechanism and gear and clutch devices are not needed in such implementation. Furthermore, the magnetic actuation may be implemented in various Ferromagnetic and/or magnetic elements arrangement using 3 such element in tandem, for instance 2 moving ferromagnetic/magnetic elements and one stationary. Such reciprocating motion implementation may be useful in cases wherein pushing two bone's fracture to each other stimulates and improves fusion at the fracture zone. The activator may also comprise a monitoring feedback device for measuring directly or indirectly the axial/rotary movements of the activator and output corresponding indications. For example, the monitoring feedback device may be implemented by one of the following options:

1. RF Transmission - A standard miniature RF transmitter may be located inside the activator. Said RF transmitter may be energized via a small battery and transmit system displacement (rotary or linear) to an external monitor. A RF antenna can be located external to the activator.

The rotary or linear displacement measuring may be carried out using a rotary chopper disc (disc with many slots) passing through an opto-coupler device (Infra red solid state diode illuminating a receiver) capable of counting the received pulses. Similarly, a capacitance proximitter, a Hall Effect proximitter, a mechanical switch, or a rotary or linear encoder, may be used in such implementation to provide a readout of the measured movements.

2. An internal Buzzer alert may be used to provide indication relating to the measured movements. The buzzer may be located inside the activator, such that whenever it is indicated that the required elongation was accomplished the buzzer is energized and generates an audible signal that may be sensed by an external microphone located outside the body of the treated subject.

3. A mechanical internal feedback scheme may utilized to lock the Ferromagnets/magnets actuation system whenever a complete elongation cycle (e.g., 0.25mm) is accomplished. In this way, an external microphone may be used to sense that no internal impact noise is created and stop the elongation. An additional electro-magnetic field or internal mechanism may be used to actuate the locking index into a disable position in which it is ready for the next elongation treatment. Fig. 1C schematically illustrates another possible embodiment of a magnetically-actuated linear activator 18b of the invention wherein the driving force is delivered from a driving source (1) by an arm-lever transferring means 33. In this example the driving source (1) is produced by a driving unit comprising a single pair (or several pairs) of ferromagnetic/magnetic elements, movable ferromagnetic/magnetic element 31 attached to shaft 122b which passes through stationary ferromagnetic/magnetic element 32 affixed to the inner wall of the driving unit. The axial movements produced by this driving unit in the presence of an alternating magnetic field are transferred by an arm-lever transferring means 33 to a parallel unit comprising axial to rotary motion transformation means (2) , ratchet mechanism (3) , gear and unidirectional clutch unit (4) , and rotary to axial motion transformation means (5) , similar to those which were previously described hereinabove. As demonstrated in Fig. 1C, such implementation can effectively provide a magnetic activator having a shorter longitudinal length. The arm-lever means 33 may be encapsulated inside the activator hollow body, for example where the plunger (12 in Fig. IB) and return spring (13 in Fig. IB) to prevent backlash. The rotary arm of arm-lever means 33 may be implemented by a pivoted rod rotatably supported at the center of its length to assure pure rotational displacement.

Fig. ID is a block diagram demonstrating construction of an activator 30 of the invention which outputs rotary movements. Activator 30 is substantially similar to activator 18, which was described hereinabove with reference to Fig. IA. Activator 30 comprises driving source 1, axial to rotary motion transformer 2, a ratchet mechanism 3, and a gear and unidirectional clutch device 4. As demonstrated in Fig. IE, a rotary motion magnetic activator 30a may be constructed with similar components as in the axial magnetic activator which was described hereinabove with reference to Fig. IB. In this implementation rotary magnetic activator 30a outputs rotary motion directly via rotating pivot 23, the end tip of which may protrude outwardly via opening 28a of elongated hollow body 9a.

Fig. IF schematically illustrates a magnetic rotary activator 30b of the invention in which the axis 36 of the outputted rotary motions is perpendicular to the axis of the elongated hollow body of the activator 30b. Activator 30b may comprise a driving source (1), axial to rotary motion transformer (2), ratchet mechanism (3), and gear and unidirectional device (4), similar to those described herein above with reference to Fig. IB. In this implementation the rotary motions outputted by gear device 21 are transferred to rotating shaft 35 via bevel gear 34 comprised of conical transmission wheels 34a and 34b. In this case elongated hollow body 9b is preferably formed in a "L" shape having an opening 28b perpendicular to the axis of elongated hollow housing 30b. The base of transmission wheel 34a is^* coupled to output shaft 21b of gear 21, and its tapered end is coupled to the tapering end of transmission wheel 34b. Rotating shaft is concentrically affixed in transmission wheel 34b and is rotatably affixed to the inner wall of elongated hollow body 9b via supports 26a and 26b.

Bevel gear 34 may be a type of straight, spiral or hypoid shape gear, manufactured by milling from stainless steel or Titanium alloy, preferably from S.S316LVM. Of course, the rotary motion may be transferred perpendicularly using other gear means, such as a worm gear. Fig. IG schematically illustrates a rotary magnetic activator

30c of the invention based on a standard linear ratchet mechanism. In this example, elongated hollow body 9c comprises a pair of actuating magnetic elements, movable magnetic element 41 attached to shaft 122c which passes through stationary magnetic element 42 affixed to the inner wall of elongated hollow body 9c via supports 43. The axial movements produced by this driving unit in the presence of an alternating magnetic field are transferred via shaft 122c to a linear ratchet 45 coupled to driven rotary ratchet 47. Return spring 44, which returns shaft 122c to its initial position, after each magnetic activation, is mounted between inner end wall of elongated hollow body 9c and linear ratchet 45. Pawl mechanism 46 may used to prevent angular backward motion of driven rotary ratchet 47 during the return cycles of shaft 122c. Gear head 48, outputting angular motions via output shaft affixed thereto, may be concentrically affixed to driven rotary ratchet 47.

Linear ratchet 45 is guided linearly via rolling or friction means to maintain consistent coupling with the rotary driven ratchet 47. Linear ratchet 45 may be manufactured by milling or mold casting from stainless steel or titanium alloy, preferably from S.S316LVM. Driven rotary ratchet 47 is designed to output a desired angular motion, it may be manufactured by milling, EDM, or mold casting from a stainless steel or Titanium alloy, preferably from S.S316LVM. Gear head 48 is preferably a type of planetary gear head, manufactured by milling or mold casting from a stainless steel or Ti alloy, preferably from S.S316LVM.

Figs. 2A and 2B demonstrates magnetic activation schemes which may be possibly used in actuating the spinal column manipulator of the invention. As exemplified in Fig. 2A the windings of electromagnet 112 may enclose the magnetic activator 18/30 (18 - axial activator; 30 - rotary activator) of the invention. In this way the magnetic activator can be actuated by magnetic flux 111 emanating from electromagnet 112 and passing therethrough, when connected to an electrical current source 113. Alternatively, as exemplified in Fig. 2B electromagnet 112 may be located adjacent to activator 18/30 such that magnetic flux 111 surrounding it can actuate it. Of course, other magnetic field sources may be similarly used, such as a permanent magnet.

The magnetic field induced by the electromagnet 112 is in the range of 0.01 Tesla to 2 Tesla. The magnetic forces induced by electromagnet 112 are generally in the range of 0.1Kg to 20Kg. Electromagnet 112 may be helmholtz type such as manufactured by TESLA. The electrical currents driven by current source 113 are sinusoidal alternating currents or DC currents, generally in the range of 1 to 500 Amper, preferably about 50 Amper, and their frequency is generally in the range of 0.01 to 50 Hz, preferably about 1 Hz.

Electromagnet 112 may comprise 1 or 2 serially connected coils, wherein said coils are encapsulated, or partially encapsulated, in a suitable Ferromagnetic shielding such as carbon steel to minimize environmental electro magnetic field interferences, and to concentrate the electro magnetic flux within an active area.

Although it is possible to utilize a device of the present invention on only one side of the vertebral column in order to achieve the desired results, in a particularly preferred embodiment, one device is situated on each side of the vertebral column. In this case, the two devices are of equal end-to-end length. Coordination of the end-to-end length changes between the two devices is achieved, in part, by the use of the interconnecting elements described hereinabove.

The following examples describes with reference to Figs. 3A to 3H and Figs. 4A to 4E, a particular solution of the invention which may be utilized in cases wherein manipulation of two neighboring vertebrae is required (e.g., spinal stenosis).

In general, the devices used in these examples are comprised of the following elements:

A. Platform (53) - hooked up to the spinal column (vertebrae 50) by two tightening screws (51) , which may be used to support linear guidance means (85 and 86, Fig. 3B), activators 18/30, and additional means, if needed.

B. Tightening screws (51) - the screw heads may be circular or rectangular or any other suitable shape. Using rectangular shapes heads accompanied by two respective open slots at the platform front side enables easy insertion of the platform onto the two rectangular screw heads and then clamping or securing the platform to the screws.

C. The magnetic activator (18/30) may activate a linearly bushing guided telescopic arm (Figs. 3B, 3G, 4C), or a mechanical cantilever leverage mechanism (Figs. 3F, 3G) or a rotational axial cam shaft (Fig. 4A) (Figs. 4B-4E) , or a cam shaft mechanism (Figs. 4B, 4C, 4D, 4E) or arms kinematics mechanism with 3-10 arms etc (Fig. 3C, 3D, 3E, 4D, 4E) .

Fig. 3A schematically illustrates a device of the invention operating with a pair of parallel axial activators 18. Two platforms, 53a and 53b, are attached to the manipulated vertebrae 50a (lower) and 50b (upper) , respectively, by means of screws 51a and 51b, respectively. The screws 51 may be threaded into the disc (100, Figs. 5A and 5B), and/or the transverse processes (101, Figs. 5A and 5B) bony portions of the vertebrae 50. The body part of axial activators 18 may be affixed (e.g., by screws 51a) to the lower platform 53a, and the moving arm thereof may be similarly affixed to the upper platform 53b, or the other way around.

Platforms 53a and 53b may be manufactured form a S.S316LVM or Ti alloy type of material, preferably from S.S316LVM, and their geometrical dimensions should be determined according to the dimensions of the manipulated vertebrae. For example, the horizontal length of the platforms may be in general in range of 30 mm to 60 mm, preferably about 40 mm, their width in range of 10 mm to 30 mm, preferably about 15 mm, and their thickness in the range of 4 mm to 10 mm. Screws 51a and 51b may be any type of suitable screws, such as pedicular screws.

Fig. 3B schematically illustrates a device of the invention operating with a single axial activator 18 and with linear guidance means, 85 and 86. Axial activator is preferably attached to the centers of platforms 53a and 53b by means of clamping or tightening screws on one side where in the other floating/rigid coupling such as surface to surface contact, ball ^'and socket mechanism, clevis mechanism, round edge against conical shape slot or cavity. Linear guidance means may be constructed from shafts 85b and 86b, affixed (e.g., by screws 51a) to the lower platform 53a and telescopically engaged in respective bushings and 85b, which are affixed (e.g., by screws 51b) to the upper platform 53b.

Shafts 85b and 86b may be manufactured by lathing from a stainless steel or Titanium alloy type of material, preferably from S.S316LVM, their diameter is generally in range of 2 mm to 6 mm, preferably about 3 mm. Bushings 85a and 86a may be manufactured by lathing from stainless steel or Titanium alloy, preferably from S.S316LVM, their outer diameter is generally in range of 5 mm to 10 mm, their inner diameter is generally in range of 3 mm to 8. The length of said shafts and bushings should be determined in each specific case according the distance between the vertebrae.

It should be noted that a bio-compatible low friction polymeric bushing may be implemented into the metallic bushing inner diameter spacing to be in-contact with the shaft in order to reduce friction.

Fig. 3C schematically illustrates a device of the invention operating with a single axial activator and with stabilizing and synchronizing arms 56a and 56b. As in the device described above with reference to Fig. 3B, activator 18 is affixed to the centers of platforms 53a and 53b. Arms 56a and 56b are rotatably attached to respective supporting means, 55b and 55a, which are welded or machined at one lateral side to the lower side of platform 53b and to the upper side of platform 53a, respectively. Mutual rotational axis 59 attached the centers of arms 56a and 56b, and their other end is rotatably attached to wheels 52a and 52b, respectively. Wheels 52a and 52b are slidably enclosed in compartments 58a and 58b, respectively, wherein said wheels are free to horizontally slide in said compartments thereby permitting the vertical manipulation of vertebrae 53a and 53b by the device.

Arms 56a and 56b are preferably made from stainless steel or Titanium alloy, preferably from S.S316LVM, their width may be in the range of 3 mm to 8 mm, their thickness in the range 0.5 mm to 4 mm, and their length should be determined in each specific case according to the distance between the vertebrae. Compartments 58a and 58b are attached to the upper side of the lower platform 53a and to the lower side of the upper platform 53b, at the lateral side opposing supports 55a and 55b. Compartments 58a and 58b may be manufactured from the same material of platforms 53b and 53a, and their geometrical dimensions are determined according to the wheels 52a and 52b which are used. Wheels 52a and 52b may be manufactured from a stainless steel, Titanium alloy or Bio-compatible polymer, preferably from S.S316LVM, and their diameter is generally in the range of 3 mm to 8 mm.

In this embodiment arms 56a and 56b enhance the stability of the device and maintains parallelism and synchronization of the applied manipulations. Fig. 3D is a variation of the device illustrated in Fig. 3C, wherein axial activator 18 mounted near one of the lateral sides of the device (off center positioning) . In this example axial activator 18 is mounted at the same side with compartments 58a and 58b, and its moving arm 24 is attached to the lower part of compartment 58b (or to arm 56b) .

Fig. 3E schematically illustrates a device of the invention operating with a single axial activator 18 and with two pairs of stabilizing and synchronizing arms 63 and 64. Two lateral supports with rotational axes 55c and 55d are welded or machined with to the upper side of the lower platform 53a. First arms, 63c and 63d, are rotatably attached at one end thereof to respective supports 55c and 55d, and second arms 64c and 64d, are rotatably attached at one end thereof to the other end of said first arms. Gear wheels 62c and 62d are rotatably attached to the other end of said second arms 64c and 64d, where said gear wheels are slidably enclosed in respective compartments 58c and 58d, which are attached to the lower side of upper platform 53b.

A rack and pinion mechanism may be provided to couple wheels 62c and 62d to respective racks 65c and 65d attached to the lower side of upper platform 53b. Said rack and pinion mechanism synchronizes the movements applied to platforms 53a and 53b by activator 18. Arms 63a, 63b, 64a, and 64b are preferably made from a stainless steel or Ti alloy, preferably from S.S316LVM, their width may be in the range of 3 mm to 8 mm, their thickness is in the range 0.5 mm to 4 mm, and their length should be determined in each specific case according to the distance between the vertebrae.

Fig. 3F schematically illustrates a device of the invention operating with a single axial 18 activator and a lever arm 68. Lever arm 68 may be rotatably attached to supporting means 66 affixed to the upper side of lower platform 53a. In this example the body of activator 18 is affixed to the upper platform 53b and its moving arm is linked to the actuated part 68b of arm 68. Wheel 67 may be rotatably attached to the manipulating part 68a of arm 68, where said wheel 67 is slidably engaged with the lower side of platform 53b, such that it may slide horizontally thereon according to the movements of arm 68. The ratio between the lengths of the manipulating part 68a and the actuated part 68b of arm 68 may be utilized to amplify the applied movements or applied pushing force.

Arm 68 is preferably made from stainless steel or Titanium alloy, preferably from S.S316LVM, its width may be in the range of 3 mm to 8 mm, and its thickness in the range 0.5 mm to 6 mm. Fig. 3G schematically illustrates a device of the invention operating with a pair of axial activators 18 and respective lever arms 68 and 70 linked thereto.

Fig. 3H schematically illustrates a device of the invention operating with a pair of horizontally disposed axial activators 18 and respective ramp surfaces 74a and 74b. Axial activators 18 are horizontally affixed to support members 72a and 72b, attached to the upper side of platform 53a and to the lower side of platform 53b, respectively. Wheels 73a and 73b are rotatably attached to the moving arms of said activators 18, wherein each of said wheels is sandwiched between a respective ramp surface, 74a and 74b, and the horizontal surface a support member, 72b and 72a, respectively. The elevation force applied in this embodiment is proportional to 1/tgα, where α is the angle of the ramps. For example, if the angle of ramps 74a and 74b is α=20° the output force applied would be 2.7 times higher.

Ramps 74a and 74b are preferably made from a stainless steel or Titanium alloy, preferably from S.S316LVM, their horizontal widths may be in the range of 4 mm to 15 mm, their thickness in the range 1 mm to 6 mm, and their ramp angle may be in the range of 15° to 45°. Support members 72a and 72b are preferably made from a stainless steel or Ti alloy, preferably from S.S316LVM, their horizontal widths may be in the range of 5 mm to 15 mm, their thickness in the range 1 mm to 7 mm.

Fig. 4^"7A schematically illustrates a device of the invention operating with a single rotary activator 30 and ramped surfaces 76 and 77, or additional ramp surfaces used to improve stability. In this example rotary activator 30 is centrically affixed to lower platform 53a and its rotating shaft is attached to the bottom side of the ramp surfaces 76 and 77. Said ramp surfaces are rotatably attached to the upper side of platform 53a via bearings (or rollers, or low friction bio-compatible polymeric material) 66. The upper side of ramp surfaces 76 and 77 is coupled with the lower side of upper platform 53b via wheels 75 rotatably attached thereto. Ramps 76 and 77 are preferably made from stainless steel or

Titanium alloy, preferably from S.S316LVM, their horizontal widths may be in the range of 5 mm to 30 mm, their thickness in the range 1 mm to 6 mm, and their ramp angle may be in the range of 15° to 45°.

Fig. 4B schematically illustrates a device of the invention operating with a single horizontally disposed rotary activator 30 and an eccenter 79 mounted on its rotating shaft. Activator 30 is horizontally affixed to support means 78 that is attached to the upper side of lower platform 53a. Eccenter 79 is mounted on the rotating arm of rotary activator 30, and it is coupled with cam follower 80 that is rotatably mounted on the lower side of upper platform 53b via a clevids affixed thereto. Eccenter 79 is preferably made from stainless steel or Titanium alloy, preferably from S.S316LVM, its thickness may be in the range of 1 mm to 5 mm, and its diameter in the range 6 mm to 25 mm. Cam follower 80 is preferably made from the same material exxenter 79i made from, its thickness may be in the range of 1 mm to 5 mm, and its diameter in the range 3 mm to 10 mm.

Figs. 4C, 4D and 4E, exemplifies implementations of the device described above wherein vertical manipulations are affected by a horizontally disposed rotary activator 30 having an eccenter 79 mounted on its rotating shaft, which eccenter is coupled with a cam follower 80, and wherein the devices utilizes linear guidance means 85 and 86, stabilizing and synchronizing arms 56a and 56b, and two pairs of stabilizing and synchronizing arms 63c, 64c, 63d, and 64d. The use of linear guidance means and stabilizing and synchronizing arms exemplified in Figs. 4C, 4D and 4E, is substantially as was described hereinabove with reference to figs. 3B, 3C-3D, and 3E, and for the sake of brevity will not be further discussed in detail.

Obviously, the rotary activator 30 used in the device demonstrated in Figs. 4A to 4E may be a type of rotary activator in which the axis of rotation is aligned with axis of the elongated hollow housing (e.g., 30a in Fig. IE), or a type of rotary activator in which the axis of rotation is perpendicular to the axis of the elongated hollow housing (e.g., 30b and 30c in Figs. IF and IG), mutatis mutandis.

The following examples relate to the case where several vertebrae are evolved (e.g., in scoliosis). In this case various versions of the above described concepts may be used. For example, said concepts may be implemented as follows:

A. One activator is actuating all of the selected vertebra, each of which is equipped with two bushings (or other linear guidance measures) which allows them to slide linearly during distraction on mutual or/and separate linear guidance rods.

B. Each two neighbor vertebrae are equipped with guiding measures and single activator.

C. Mutual activator for all participating vertebrae while using rack and pinion mechanism capable of rotating several eccentric cams located in tandem, or any other mechanism as mentioned before, where each of said mechanisms is elevating a single vertebra. It is important to mention that in case of tandem arrangement adequate synchronized distraction among vertebrae may be used.

Fig. 6A schematically illustrates a device of the invention comprising several pairs of rotary output shafts 130a, 130b and 130c, and designed to concurrently manipulate a number of vertebrae. In this example said pairs of rotary output shafts activators 130a, 130b and 130c, have a rotating pivot which axis is perpendicular to the axis of the body of the activators, wherein a respective eccenter 79a, 79b and 79c is mounted on the rotating pivot of each manipulator. This vertebrae manipulating device comprises two elongated members 131 which may comprise, or alternatively function as, the hollow elongated body of rotary output shafts 130a, 130b and 130c. When such device is implemented with several activators, in order to manipulate each vertebra independently, the eccentiricity of the eccentric cam should be gradually increased from lower to upper manipulated vertebra respectively.

The elongated members of this vertebrae manipulating device are affixed (e.g., by screws) to the lowermost and upper most platforms, 531 and 53u. The eccenters 79a, 79b and 79c are coupled to intermediate platforms 53a, 53b and 53c, via respective cam followers 80a, 80b and 80c, rotatably attached to lower side of said intermediate platforms. This device allows manipulating the respective vertebrae to which said intermediate platforms (53a, 53b and 53c) are attached relative to the vertebrae to which said uppermost and lowermost platforms (53u and 531) are attached.

Fig. 6B schematically illustrates a device of the invention comprising a tandem of axial (linear) activators 18 and designed to concurrently manipulate a number of vertebrae. Axial activators 18 are affixed (e.g., via screws or clamping) to the lower platform 53a, wherein the moving arms of said activators are attached to the lower side of the consecutive platform 53b via support members 136b. The consecutive platforms 53c and 53d are attached to platforms 53b and 53c, respectively, via rods, 135c and 135d, and support members, 136c and 136d, assemblies, wherein rods 135c and 135d are affixed to platforms 53b and 53σ, respectively. In this way W 2

-40- the vertebrae located above the vertebra to which platform 53a is attached may be manipulated by the device.

Fig. 6C schematically illustrates a device of the invention comprising a tandem of axial (linear) activators 18 and designed to concurrently operate on a number of vertebrae with linear guidance means. In this example axial activators 18 are affixed to lower platform 531. Said activators 18 comprise elongated moving arms 131 which slidably pass through the upper platform 53u and thus provide linear guidance. The vertebrae located between said upper and lower platforms (53u and 531) , 50a-50c, have respective pairs of rods 132a-132c attached at their lateral sides. Respective pairs of support members 133a-133c are distributed along elongated moving arms of activators 18, and are engaged with said rods 132a-132c, such that the axial movements applied by activators 18 are transferred to vertebrae 50a-50c.

Fig. 6D schematically illustrates a device of the invention comprising a number of rotary activators 30b, 30c, 3Od, mounted in-between each pair of vertebrae and designed to concurrently manipulate a number of vertebrae with linear guidance means. In these examples supporting shaft 138 connects the lower and the upper vertebrae platforms 53a and 53e, wherein bushings 137b, 137c and 137d, are linearly guided onto mutual linear shaft 138 on both sides. In this case each moving vertebra is being guided on the same mutual shafts 138 which are attached to the lowermost and uppermost vertebrae 53a and 53e, and thereby provide linear guidance. Each vertebra platform is being attached to the linear guiding bushing via clamping, welding or screwing.

In the example shown in Fig. 6D, the rotary activator 30b is affixed to the lowermost platform 53a and eccenter 79 mounted on its rotating pivot is coupled to cam follower 80 rotatably attached to the lower side of platform 53b. Alternatively, each pair of vertebrae may be driven by separate activator.

Fig. 6E schematically illustrates a device of the invention comprising a number of axial activators 18b, 18c, 18d, and designed to concurrently manipulate a number of vertebrae with linear guidance means. These examples are substantially similar to the device described with reference to Fig. 6D, respectively. As demonstrated in these figures The moving arm of activator 18 may be attached to the respective platforms via clevis means 140b, 140c, and 14Od, respectively.

All of the abovementioned parameters are given by way of example only, and may be changed in accordance with the differing requirements of the various embodiments of the present invention. Thus, the abovementioned parameters should not be construed as limiting the scope of the present invention in any way. In addition, it is to be appreciated that the different shafts, rods, pivots, and other members, described hereinabove may be constructed ^■ in different shapes (e.g. -having oval, square etc. form in plan view) and sizes differing from those exemplified in the preceding description.

It should be noted that the activator used in the device of the invention may be driven using other wirelessly energizable means, such as linear or rotary piezoelectric motors (e.g., Nanomotion linear piezo electric) , motors that may actuated by an external applied alternating magnetic or electromagnetic filed (e.g., rotary synchronized magnetic or electromagnetic field which could drive invasive permanent core) .

2. Operative procedures: 2.1 Scoliosis distraction procedure:

Prior to the surgical procedure requiring the use of the device of the present invention, the patient will have already undergone a spinal fixation procedure. During this earlier procedure, pedicular screws will have been inserted into certain, relevant vertebrae, and a helically-twisted rod inserted and wound (in accordance with the Cotrel-Dubouset maneuver) in order to achieve unwinding of the abnormally curved vertebral column. Bone chips (usually obtained by autografting from other anatomical sites) are placed between the transverse processes on both sides of adjacent vertebrae in the treated region. With time, growth of the bone chips will result in the formation of a single, unified bone bar on each side of the vertebral column, thereby resulting in spinal fixation .

Turning now to the surgical procedure of the present invention, for causing vertebral distraction (i.e. regaining lost height following spinal fixation) , said procedure comprises the following steps:

1. Removal of one the rods that was necessary for reduction of the spinal deformity.

2. Replacement of that rod by a device of the present invention, by connecting it to the pedicular screws that are already placed or adding new pedicular screws, or replacing the old pedicular screws by new ones, as clinically necessary. The connection will be performed by connectors that will enable straight alignment of the rod.

3. Removal of the second rod and its replacement by a second device of the present invention, in a similar fashion.

4. The replacement by the fixation rods by devices of the present invention can be performed either at the end of the first operation, or later on, when elongation is decided upon.

5. The two devices may be interconnected by one or more interconnecting elements (as described hereinabove) , in order to co-ordinate the distraction of one side of the vertebral column with the other, contralateral side.

6. If performed primarily, and elongation is required acutely, the distraction will start between 3 to 28 days post operatively, preferably after 7 days.

7. If elongation will be performed after bony union of the immobilized column has been achieved, the any bone bridges between to vertebrae, should be severed and soft tissues should be released to allow elongation to take place. The distraction will start between 3 to 28 days post operatively, after the bone bar and soft tissue release, preferably after 7 days.

Following completion of the foregoing surgical procedure, progressive distraction of the vertebral column in the region where the device of the present invention is implanted is accomplished by means of application of an external magnetic field -induced by an external coil or open magnet. Whilst any suitable electromagnet coil or coils may be used, the following two alternative embodiments are particularly preferred:

1) A single electromagnetic coil placed over the trunk region of the patient being treated, such that it overlays the length of the vertebral column that is being treated with the device of the present invention. In this way, a homogenous magnetic field is created, such that an attractive magnetic force is applied to the magnetic or ferromagnetic elements situated within the telescopic or sliding member pair(s). 2) A pair of electromagnetic coils is placed in contact with the body surface overlaying the region of the vertebral column that is being treated with the device of the present invention, such that the current flowing through one coil runs in the opposite direction to the current flowing through the other coil. The design of the two coils and the precise position of placement thereof are such that the area of the magnetic field generated by one coil is connected to the magnetic field area generated by the second coil by way of the magnetic/ferromagnetic material located in the telescopic or sliding member pair(s) of the present invention. In this way, an attractive force is exerted on one or more of the members of each pair.

The two alternative configurations described above are given by way of non-limiting example only: many other suitable magnetic field generators may also be used in connection with the device and methods of the present invention, without deviating from the scope thereof.

By way of further example, a suitable magnetic coil would be one generating a magnetic field at total current in about 500 amps, the power consumption at that field being about 25 KW. Such a coil, when used together with the exemplary 8-pair ferromagnet configuration described hereinabove, has been found to exert a 2 Kg force on the telescopic or sliding member pair.

It is to be reiterated that the magnetic coil parameters and ferromagnet details provided hereinabove relate only to one particular coil that is- suitable for use in conjunction with the device of the present invention. Said list is therefore not intended to be limiting in any way.

The application of the magnetic field is performed at least once per day for a period of between 1 and 150 days, preferably for a period of one month. This regime will normally result in elongation of the treated vertebral column by 0.05 mm to 2 mm per day, preferably lmm per day.

2.2 Spinal fusion procedure:

As discussed hereinabove, spinal fixation procedures, when performed according to the prior art are not uniformly successful. Rather, on many occasions (especially when local blood supply is compromised) , complete fusion of the bone bars does not always occur.

In the procedure according to the present invention, any preexisting rods are removed and replaced by the presently- disclosed devices, essentially as described in steps 1 to 5 of section 2.1, hereinabove. However, in the case of the spinal fusion procedure, either ^ompj^e^si^on, that is reduction of the total -end-to-end length of the elongate member pair(s), or axial oscillation of said elongate member pairs (rather than distraction) is performed by application of an external magnetic field, as described above. It should be noted that, in addition to the use of the instantly-described procedure in the cases of unsuccessful fusion, said procedure may also be used as a primary treatment, i.e. as a method of first choice for obtaining spinal fusion

In the oscillation mode, the reverse-direction movement is driven by means of spring or other return mechanism as described hereinabove. The amplitude of the oscillatory motion is controlled by standard means such as slot and fin mechanisms that are well known in the art. The frequency of the oscillatory motion is generally between 0.01 and 50 Hz, preferably 0.5 Hz. This oscillatory motion may be induced between 1 and 50 times per day, preferably once a day for a period of 20 minutes.

When used to cause compression, a total end-to-end distance reduction in the range of 0.1 to 3 mm is desirable. The compressive force is applied for a period of between 1 milisecond and 120 minutes, between once per day and fifty times per day, preferably once per day for 20 minutes. A constant compressive force can also be changed to other level by applying an appropriate magnetic field produced by the coil system that decrease the length of the device thus inducing compression force

Without wishing to be bound to any particular theory, in both of the above-described modes (axial oscillation and compression) , the mechanical movements of the elongate members cause stimulation of the bone growth and healing processes, thereby assisting in causing the closure of the bone chips, thus creating the continuous bone bars.

It should be noted that both the oscillation and compression procedures may be used also to expedite fusion of bone chips at the end of a primary scoliosis surgery.

The above examples and description have of course been provided only for the purpose of illustration, and are not intended to limit the invention in any way. As will be appreciated by the skilled person, the invention can be carried out in a great variety of ways, .employing more than one technique from those described above, all without exceeding the scope of the invention.

Claims

1. A device for manipulating the spinal vertebrae of a subject, comprising at least one activator having a moveable element which is capable of being displaced in response to externally induced energizing signals, wherein said activator is affixed to at least one vertebra, and coupled to at least one other vertebra, such that said activator is capable of moving the vertebra (e) to which it is coupled in an axial direction, wherein said movement can be unidirectional, resulting in either distraction or compression of the vertebrae, or bidirectional, resulting in an oscillatory movement of the vertebrae.

2. The device according to claim 1, further comprising one or more elongated platforms, each of which is horizontally affixed to one of the vertebrae of said subject, wherein said elongated platforms are used for affixing said at least one activator, and/or for attaching coupling means, to the respective vertebra.

3. The device according to claim 1, further comprising linear guidance means slidably attached to the sides of the two or more vertebrae.

4. The device according to claim 1 or 2, further comprising stabilizing and synchronizing arms rotatably attached to the sides of some of the at least two vertebrae and/or to elongated platforms horizontally affixed thereto.

5. The device according to claim 1, wherein coupling means are used to transfer the displacements of the movable element of the activator to at least one vertebra.

6. The device according to claim 5, wherein the coupling means are implemented by lever arms.

7. The device according to claim 5, wherein the coupling means are implemented by ramp surfaces.

8. The device according to claim 5, wherein the energizing signals are implemented by an externally induced magnetic field.

9. The device according to claim 1, wherein the activator comprises at least one pair of ferromagnetic/magnetic elements, wherein each of said pairs comprises a stationary ferromagnetic/magnetic element affixed to the internal wall of said activator and a movable ferromagnetic/magnetic element affixed in proximity to said stationary ferromagnetic/magnetic element to a shaft coaxially and slidably supported therein.

10. The device according to claim 9, wherein magnetic attraction forces are evolved between the magnetic elements in the presence of a magnetic field, and wherein said magnetic attraction forces may affect axial movements of said shaft.

11. The device according to claim 9, wherein the activator further comprises a gear unit coupled to the shaft by means of a clutch and motion conversion units.

12. A device for manipulating the spinal vertebrae of a subject, comprising at least one parallel pair of activators affixed to the lateral sides of at least one vertebra and coupled to another vertebra.

13. The device according to claim 12, further comprising at least one elongated platform horizontally affixed to at least one vertebra, wherein the at least one pair of activators, and/or coupling means coupled thereto, are affixed to the lateral sides of at least one vertebra by means of said at least one elongated platform.

14. An activator for manipulating displaceable elements by means of externally induced energizing signals, comprising at least one pair of ferromagnetic/magnetic elements, wherein each of said pairs of ferromagnetic/magnetic elements comprises a stationary ferromagnetic/magnetic element affixed to the internal wall of said activator and a movable ferromagnetic/magnetic element affixed in proximity to said stationary ferromagnetic/magnetic element to a shaft coaxially and slidably supported therein, wherein said shaft is coupled to a moveable element which is capable of being displaced in response to movements of said shaft.

15. The activator of claim 14, wherein the coupling between the shaft and the movable element is achieved directly and/or by means of a gear and clutch devices .

16. The activator of claim 14, wherein the energizing signals are implemented by an externally induced magnetic field.

17. A method for regaining lost height in a subject having already undergone a spinal fixation procedure comprising the steps of: a) removing one of the fixation rods previously implanted for the purpose of reducing a spinal deformity; b) connecting a first device of the present invention as defined in any one of claims 1 to 13, to the same side of the spinal column from which the previously implanted fixation rod was removed in step (a) ; c) removing the second fixation rod; d) connecting a second device of the present invention as defined in any one of claims 1 to 13, to the same side of the spinal column from which the second fixation rod was removed in step (c) ; e) optionally interconnecting the two devices by means of one or more interconnecting elements (as described hereinabove) ; f) applying a magnetic field induced by an externally placed coil to the region of the spinal column in which the devices were implanted, such that the activators of said devices respond by applying distracting forces to the vertebrae to which they are coupled in order to increase the distance between the said vertebrae and the vertebrae to which the other ends of said activators are affixed; and g) Optionally applying, at the end of the distraction phase, a magnetic field induced by an externally placed coil to the region of the spinal column in which the devices were implanted, such that the activators of said devices respond by oscillating the vertebrae to which they are coupled in order to increase the healing process and reduce the healing time.

18. The method according to claim 17, wherein the subject is a patient being treated for scoliosis.

19. The method according to claim 17, wherein the magnetic field is applied at least once per day between 1 second to 30 minutes for a total period of between 1 and 30 days.

20. The method according to claim 17, wherein the magnetic field is applied in pulses, wherein, the width of said magnetic pulses is in the range of 0.001 second to 10 seconds and the frequency of said pulses is in the range of 0.01 Hz to 500 Hz.

21. A method for causing spinal fusion comprising the steps of: a) connecting a first device of the present invention as defined in any one of claims 1 to 13, to one side of the spinal column and a second said device to the other side of the spinal column; b) optionally interconnecting the two devices by means of one or more interconnecting elements (as described hereinabove) ; c) applying a magnetic field induced by an externally placed coil to the region of the spinal column in which the devices were implanted, such that the activators of said devices respond by applying compressive forces to the vertebrae to which they are coupled in order to reduce the distance between the said vertebrae and the vertebrae to which the other ends of said activators are affixed.

22. The method of claim 21, wherein the compressive force is applied between once and fifty times per day, each time for a period of between 1 second and 120 minutes.

23. The method according to claim 22, wherein the compressive force is applied once per day for a period of 20 minutes.

24. A method for causing spinal fusion comprising the steps of: a) connecting a first device of the present invention as defined in any one of claims 1 to 13, to one side of the spinal column and a second said device to the other side of the spinal column; b) optionally interconnecting the two devices by means of one or more interconnecting elements (as described hereinabove) ; c) applying a magnetic field induced by an externally placed coil to the region of the spinal column in which the devices were implanted, such that the activators of said devices respond by applying axially-directed oscillatory forces to the vertebrae to which they are coupled thereby causing axial oscillation of said vertebrae.

25. The method according to claim 24, wherein the frequency of the axial oscillation is between 0.01 and 50 Hz.

26. The method according to claim 25, wherein the frequency of the axial oscillation is preferably 0.5 Hz.

27. The method according to claim 25 or claim 26, wherein the oscillatory motion is induced between 1 and 8 times per day.

28. The method according to claim 27, wherein the oscillatory motion is induced once a day for a period of 20 minutes.

29. The method according to any one of claims 17 to 28, wherein the first and second devices are preferably connected to the vertebral column using pedicular screws.