US20100286730A1

Movatterモバイル変換

Info

Publication number: US20100286730A1
Application number: US12/779,258
Authority: US
Inventors: Jeffrey D. Gordon
Original assignee: Individual
Current assignee: Individual
Priority date: 2004-08-30
Filing date: 2010-05-13
Publication date: 2010-11-11
Also published as: US7763053B2; US20060047282A1

Abstract

A device for correction of a spinal deformity includes an implant having a first end portion and an opposite second end portion, the first end portion being attachable to an extraspinal bone, the second end portion being attachable to a vertebra, the implant being configured for being adjusted without penetrating skin and thereby for adjusting a tension of the implant so as to impose a corrective displacement on the vertebra.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This is a continuation of U.S. patent application Ser. No. 11/215,725, entitled “IMPLANT FOR CORRECTION OF SPINAL DEFORMITY”, filed Aug. 30, 2005, which is incorporated herein by reference. U.S. patent application Ser. No. 11/215,725 is a non-provisional application based upon U.S. provisional patent application Ser. No. 60/605,548, entitled “IMPLANT FOR CORRECTION OF SPINAL DEFORMITY”, filed Aug. 30, 2004, which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to a device for treatment of spine disorders, and in particular to the utilization of an implant to impose a corrective displacement on a vertebra of a patient so as to incrementally correct abnormal spinal curvature(s) of the patient.

2. Description of the Related Art

Scoliosis is a spinal deformity that has an abnormal lateral curvature of the spine when viewed from a posterior perspective. The abnormal curvature of the spine is commonly associated with abnormal spinal rotation causing ribs to protrude posteriorly into what is commonly referred to as “rib hump”. The scoliosis is classified with infantile scoliosis and adolescent idiopathic scoliosis. The adolescent idiopathic scoliosis is the most prevalent type of scoliosis which develops during adolescence in an otherwise healthy patient and typically ceases at the onset of skeletal maturity. The cause of the disease is presently unknown.

Currently, surgical treatments of a spinal curvature deformity involve manipulation of the spinal column by attaching a correction device and then fusion of the spine. One such system, used primarily for scoliosis, is the Cotel-Dubousset system, as disclosed in U.S. Pat. No. 5,147,360 to Dubousset, which is understood to the use of rigidly attaching metal rods to the spine with plates and screws. The metal rods are then manipulated during the surgical procedure in an attempt to straighten the abnormal curvatures and reduce the rotation of the spinal column. The spine is then fused with a bone graft, typically requiring extensive discectomies, removal of spinous processes as the bone graft harvest, and injury to the spine itself to induce bleeding for improving the bone fusion. It is believed that the surgery is arduous, invasive, and has an array of potential complications including excessive blood loss. The discs above and below the fusion zone are in jeopardy of degeneration due to the increased biomechanical demands placed on them. Also, flat back syndrome could be problematic if normal lordosis and kyphosis are not restored. Recovery could be a lengthy and painful process. Even a successful procedure rarely results in a normal spinal curvature and the patient is left with an immobile spinal section.

A flaw in the conventional implants for correction of the spinal curvature deformity is that the implants are usually of a part of the load path of the spinal column. For example, it is understood that the Cotel-Dubousset system rigidly attaches stiff stainless steel rods to the spine. For a structure having two members placed in parallel, it relies primarily on the stiffest member for transmission of a load. Therefore, loads exerted on an instrumented spine are transferred through the implant instead of through the spine. Spinal loads could be large, and the geometry of the implants used is such that they may not support such large loads indefinitely. Fatigue failure of the implant occurs if fusion is delayed.

A further disadvantage of the conventional implants for correction of the spinal curvature deformity is the potential for neurologic damage. It has been shown that loads required for correction of the spinal curvature deformity during the surgery warrant concern for spinal cord trauma. For this reason, nerve functions are usually monitored during the surgery. Even after the surgery, the spinal loads could be large enough to cause nerve damages.

Additionally, viscoelastic properties of the spinal structures including the intervertebral discs, ligaments, nerves, muscles and other connective tissues have a time-dependent relationship between force and displacement: the stiffness of viscoelastic structures decreases with time under action of a sustained force. Stress-relaxation and creep are manifestations of viscoelasticity. The creep is gradual displacements under the action of the sustained force, while the stress-relaxation is gradual reductions of an internal force (resistance) under the action of an imposed displacement. It has been shown that dramatic stress-relaxation occurs within minutes of spinal curvature correction procedures. However, stiff instrumentation provides negligible additional correction even though resistive forces in the spine are decreasing.

Therefore, a heretofore unaddressed need exists in the art to address the aforementioned deficiencies and inadequacies.

SUMMARY OF THE INVENTION

In one aspect, the present invention relates to a device for correction of a spinal deformity. In one embodiment, the device includes a cable having a first end portion, and an opposite, second end portion, and a tension member having a cylindrical magnet, a leadscrew and a body. In one embodiment, the leadscrew has a helically threaded exterior surface, an interior surface defining a bore for housing the cylindrical magnet rigidly, an axis therethrough the bore, a first end and an opposite, second end, and a length, L₂, defined therebetween. The body has a first end portion and an opposite, second end portion defining a cylindrical chamber therebetween, a longitudinal axis therethrough the cylindrical chamber, a U-shape cut formed in the first end portion, and a length, L₁, defined therebetween the first end portion and the second end portion, where L₁>L₂. In one embodiment, the cylindrical chamber has a first chamber portion and a second chamber portion neighboring to the first chamber portion. The first chamber portion and the second chamber portion are sized with a diameter, d₁, and d₂, respectively, where d₂>d₁such that a step is formed at the junction of the first chamber portion and the second chamber portion. The first chamber portion is helically threaded for engaging with the leadscrew such that when the leadscrew is received in the cylindrical chamber, the axis of the leadscrew is substantially coincident with the longitudinal axis of the body and the leadscrew is capable of moving back and forth along the longitudinal axis as being rotated around the longitudinal axis. In one embodiment, the tension member further has a first cap and a second cap attached to the first end and the second end of the leadscrew, respectively. The second cap is sized to fit the second chamber portion of the cylindrical chamber such that as assembled, the second cap prevents the leadscrew from moving out of the cylindrical chamber of the body of the tension member.

Furthermore, the device includes a shackle. In one embodiment, the shackle is formed in a clevis-shape and has a first end portion, a second end portion and a body portion defined therebetween, where in use the first end portion and the second end portion are secured to a pelvic bone, and the body portion is received in the U-shape cut of the body of the tension member such that the tension member is capable of rotating around a first axis and a second axis perpendicular to the first axis, respectively. In one embodiment, the first axis and the second axis are perpendicular to the axis of the body of the tension member.

Moreover, the device includes a first engaging member mechanically engaging the first end portion of the cable with the tension member. In one embodiment, the first engaging member includes a ball-and-socket joint mechanism. The first engaging member has a swaged ball attached to the first end portion of the cable, and a pivot cap having a shoulder and a hole formed on the shoulder. As assembled, the first end portion of the cable is received through the hole of the pivot cap and the pivot cap is attached to the first end cap of the tension member such that the swaged ball articulates with the shoulder of the pivot cap, and thus rotating the leadscrew around its axis does not cause the cable to rotate and twist.

Additionally, the device includes a second engaging member arranged, in use, mechanically engaging the second end portion of the cable with a vertebra such that the tension of the cable is adjustable for imposing a corrective displacement on the vertebra. In one embodiment the second engaging member has a bone screw having a screw head, at least one spherical recess formed on the screw head, a hole formed through the at least one spherical recess, and a body portion having helical threads for threading into the vertebra, a ball having a hole formed therethrough, and a crimp. As assembled, the second end portion of the cable is received through the hole in the bone screw and the hole formed in the ball, respectively, and secured by the crimp such that a change in angulation between the tension member and the vertebra is accommodated by articulation of the ball with the spherical recess. In another embodiment, the second end portion of the cable is formed with a loop portion, and the second engaging member has a pair of bone screws attached to the vertebra, a rod connected the pair of bone screws, and a crimp. As assembled, the loop portion of the second end portion of the cable engages with the rod and is secured with the crimp.

The device also includes means for rotating the leadscrew of the tension member around the axis of the body of the tension member. In one embodiment, the rotating means comprises an actuator. The actuator has a first axle and a second axle each having a first end and a second end, a first pulley and a second pulley mounted onto the second end of the first axle and the second end of the second axle, respectively, a cylindrical magnet magnetized diametrically and symmetrically formed on the second axle, a crank attached to the first end of the first axle such that when a torque is applied to the crank to cause the first axle to rotate, a torque is simultaneously applied to the first pulley, and a belt engaging with the first pulley and the second pulley for transferring torques from the first pulley to the second pulley so as to rotate the cylindrical magnet.

In operation, the actuator is positioned such that when the cylindrical magnet of the actuator rotates, a magnetic filed generated by the cylindrical magnet of the actuator causes the cylindrical magnet of the tension member to rotate, which in turn causes the leadscrew of the tension member to rotate so as to cause the tension member to move from a first state to a second state that is different from the first state. In one embodiment, the first state of the tension member is characterized by an angle, α, of the axis of the body of the tension member relative to a horizontal axis, and the second state of the tension member is characterized by an angle, β, of the axis of the body of the tension member relative to the horizontal axis, wherein 0≦α<π/2, 0≦β<π/2, and β≠α.

In one embodiment, the cable is made of a biocompatible material. The biocompatible material includes a polymer, a composite, a metal, an alloy, or any combination thereof. In one embodiment, the cable is coated with a material to reduce abrasion and adhesion of biologic tissues.

In another aspect, the present invention relates to a device for correction of a spinal deformity. In one embodiment, the device includes a cable having a first end portion, and an opposite, second end portion, a tension member, a first engaging member mechanically engaging the first end portion of the cable with the tension member, a second engaging member mechanically engaging the second end portion of the cable with a vertebra, and a third engaging member mechanically engaging the tension member with a pelvic bone.

In one embodiment, the tension member has a leadscrew which has a head, a shank extending from the head, and a threaded portion extending from the shank. The tension member further has a one-way clutch coupled with the shank such that when rotating in one of the clockwise and counterclockwise directions, the one-way clutch engages with the shank, and when rotating in the other of the clockwise and counterclockwise directions, the one-way clutch freewheels on the shank. The tension member also has a body having an interior surface complementarily threaded for receiving the leadscrew, an axis, a first end portion, an opposite, second end portion, and a U-shape cut and a hole formed in the second end portion, where the hole of the body has an axis perpendicular to the axis. Additionally, the tension member has a toggle. The toggle, in one embodiment, has a first end portion and an opposite, second end portion defining a chamber therebetween for housing the one-way clutch rigidly, a pair of wings radially protruding from the second end portion, and a hole formed on the first end portion.

In one embodiment, the first engaging member includes a ball-and-socket joint mechanism. The first engaging member has a swaged ball attached to the first end portion of the cable, and a pivot cap having a shoulder and a hole formed on the shoulder. As assembled, the first end portion of the cable is received through the hole of the pivot cap and the pivot cap is attached to the head of the leadscrew of the tension member such that the swaged ball articulates with the shoulder of the pivot cap, and thus rotating the leadscrew around its axis does not cause the cable to rotate and twist. In another embodiment, the first end portion of the cable is formed with a loop portion, and the first engaging member has a pin, and a crimp. As assembled, the loop portion of the first end portion of the cable engages with the pin and is secured with the crimp.

The second engaging member in one embodiment, has a bone screw having a screw head, at least one spherical recess formed on the screw head, a hole formed through the at least one spherical recess, and a body portion having helical threads for threading into the vertebra, a ball having a hole formed therethrough, and a crimp. As assembled, the second end portion of the cable is received through the hole in the bone screw and the hole formed in the ball, respectively, and secured by the crimp such that a change in angulation between the tension member and the vertebra is accommodated by articulation of the ball with the spherical recess. In another embodiment, the second end portion of the cable is formed with a loop portion, and the second engaging member comprises a pair of bone screws attached to the vertebra, a rod connected with the pair of bone screws, and a crimp. As assembled, the loop portion of the second end portion of the cable engages with the rod and is secured with the crimp.

In one embodiment, the third engaging member includes a clevis-shape shackle. The clevis-shape shackle in one embodiment has a first end portion, a second end portion and a body portion defined therebetween, where in use the first end portion and the second end portion are secured to the pelvic bone, and the body portion is received in the U-shape cut of the body of the tension member and secured by placing a pin into the hole of the body of the tension member such that the tension member is capable of rotating around a first axis and a second axis, respectively. In one embodiment, the first axis is substantially coincident with the axis of the hole of the body of the tension member, and wherein the second axis is perpendicular to the first axis and the axis of the body of the tension member, respectively.

In operation, by pressing alternately on each of the pair of wings of the toggle of the tension member, the one-way clutch rotates alternately in the clockwise and counterclockwise directions thereby causing the leadscrew to rotatably advance into the body so as to cause the tension member to move from a first state to a second state that is different from the first state, whereby the tension of the cable is adjustable for imposing a corrective displacement on the vertebra. In one embodiment, the first state of the tension member is characterized by an angle, α, of the axis of the body of the tension member relative to a horizontal axis, and the second state of the tension member is characterized by an angle, β, of the axis of the body of the tension member relative to the horizontal axis, wherein 0≦α<π/2, 0≦β<π/2, and β≠α.

In yet another aspect, the present invention relates to a device for correction of a spinal deformity. In one embodiment, the device includes a cable having a first end portion, and an opposite, second end portion attachable to a vertebra, means for adjusting the tension of the cable so as to impose a corrective displacement on the vertebra, and means for attaching the body to a pelvic bone. In one embodiment, the adjusting means comprise a screw having a threaded portion and engaged with the first end portion of the cable, and a body having an interior surface complementarily threaded for receiving the screw such that when the screw rotatably advances into the body, the tension of the cable is adjusted.

In yet a further aspect, the present invention relates to a device for correction of a spinal deformity. In one embodiment, the device includes a tension adjusting member having a first end, a second end, and a body defined therebetween the first end and the second end. The device further includes a tension member having a first end portion, a second end portion and a body portion defined therebetween the first end portion and the second end portion, and movably engaged with the body of the tension adjusting member such that the first end portion of the tension member is movable relative to the first end of the tension adjusting member for adjusting the tension of the tension member. In use, the second end portion of the tension member is to be secured to a vertebra and the first end of the tension adjusting member is to be secured to a pelvic bone so that when the first end portion of the tension member moves away from or toward to the first end of the tension adjusting member, the tension of the tension member is adjusted so as to impose a corrective displacement on the vertebra.

These and other aspects of the present invention will become apparent from the following description of the preferred embodiment taken in conjunction with the following drawings, although variations and modifications therein may be affected without departing from the spirit and scope of the novel concepts of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein:

FIG. 1ashows schematically a posterior view of a scoliotic human spine with an implanted device according to one embodiment of the present invention;

FIG. 1bshows schematically a posterior view of a corrected human spine with the implanted device shown inFIG. 1b;

FIG. 2 shows a perspective exploded view of a device according to one embodiment of the present invention;

FIG. 3 shows a perspective view of the device shown inFIG. 2;

FIG. 4 shows a sectioned view of the device shown inFIG. 2 in an extended configuration;

FIG. 5 shows a sectioned view of the device shown inFIG. 2 in a collapsed configuration;

FIG. 6 shows a perspective exploded view of a second engaging member according to one embodiment of the present invention;

FIG. 7 shows a perspective view of the second engaging member shown inFIG. 6;

FIG. 8 shows a perspective view of an actuator and a device according to one embodiment of the present invention;

FIG. 9 shows a side view of the actuator and the device shown inFIG. 8;

FIG. 10 is a cross-sectional view of the actuator and the device shown inFIG. 8, showing magnetic flux lines;

FIG. 11 shows schematically a posterior view of a scoliotic human spine with an implanted device according to another embodiment of the present invention;

FIG. 12 is a perspective view of an alternative embodiment of the second engaging member;

FIG. 13 is a perspective view of a device according to another embodiment of the present invention;

FIG. 14 is a perspective exploded view of the device shown inFIG. 13;

FIG. 15 shows a sectioned view of the device shown inFIG. 13 in an extended configuration; and

FIG. 16 shows a sectioned view of the device shown inFIG. 13 in a collapsed configuration;

Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate embodiments of the invention, and such exemplifications are not to be construed as limiting the scope of the invention in any manner.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is more particularly described in the following examples that are intended as illustrative only since numerous modifications and variations therein will be apparent to those skilled in the art. Various embodiments of the invention are now described in detail. Referring to the drawings, like numbers indicate like parts throughout the views. As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein and throughout the claims that follow, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.

The description will be made as to the embodiments of the present invention in conjunction with the accompanying drawings1-16. In accordance with the purposes of this invention, as embodied and broadly described herein, this invention, in one aspect, relates to an implant for a surgical correction of abnormal spinal curvatures by imposing corrective displacements on abnormal spinal vertebras. For ease of understanding, the present invention is described with specific reference to scoliosis. However, the present invention disclosed herein is generally applicable to all classifications of spinal curvature disorders, including lordosis and kyphosis in the spine.

Referring toFIG. 1a,a posterior view of ascoliotic spine104 of a patient having an abnormal spinal curvature is shown schematically, where a device (implant)200 is attached to apelvic bone102 and avertebra100 of the patient, respectively, according to one embodiment of the present invention. The inventeddevice200, as described in details below, includes atension member201, acable204 having afirst end portion204aand an opposite,second end portion204b,a first engagingmember207 mechanically engaging thefirst end portion204aof thecable204 with thetension member201, a second engagingmember209 mechanically engaging thesecond end portion204bof thecable204 with thevertebra100, and ashackle202 mechanically engaging thetension member201 with thepelvic bone102. The tension of thecable204 is adjustable for imposing a corrective displacement on thevertebra100 to correct the abnormal spinal curvature of the patient. Theshackle202 is mounted to thepelvic bone102 with ashackle clevis screw210. In one embodiment, the second engagingmember209 has abone screw412 and aball404 adapted for securing thesecond end portion204bof thecable204 to thevertebra100. As implanted in relation to apelvic bone102 and avertebra100, thetension member201 forms an initial angle, α, relative to ahorizontal plane105, hence defining an initial distance (length), L, between afirst end201aof thetension member201 and thebone screw412, where 0≦α<π/2.

FIG. 1bshows a posterior view of thespine104 of the patient after correction of the abnormal spinal curvature with the implanteddevice200. As shown inFIG. 1b,after the correction, the angle between thetension member201 and thehorizontal plane105 is indicated by β, where 0≦β<π/2, and β≠α. In this exemplary embodiment, β<α. The distance between thefirst end201aof thetension member201 and thebone screw412 has been changed from L to L′. L′ may be greater or less than L. In the embodiment shown inFIG. 1b,L′<L.

Referring now toFIGS. 2-12 and first toFIGS. 2 and 3,device200 is shown to have thetension member201, thecable204, the first engagingmember207 and the second engagingmember209, and the third engagingmember202 according to one embodiment of the present invention. Thecable204 has afirst end portion204aand an opposite,second end portion204b. Thetension member201 has acylindrical magnet220 magnetized diametrically. In one embodiment, thecylindrical magnet220 has a first semi-cylindrical portion and an opposite, second semi-cylindrical portion. The first semi-cylindrical portion and the second semi-cylindrical portion of thecylindrical magnet220 are magnetized as a north pole, N, and a south pole, S, respectively, as shown inFIG. 8.

Thetension member201 further has aleadscrew218. In one embodiment, theleadscrew218 has a helically threadedexterior surface218aand an,interior surface218b,afirst end218dand an opposite,second end218e,acylindrical bore234 defined by theinterior surface218band between thefirst end218dand thesecond end218e,anaxis218ctherethrough thecylindrical bore234, and a length, L₂, defined by thefirst end218dand thesecond end218e. Thecylindrical bore234 is adapted for housing thecylindrical magnet220 rigidly. As assembled, thecylindrical magnet220 and theleadscrew218 are fixedly engaged such that thecylindrical magnet220 does not rotate relative to theleadscrew218 in operation. In one embodiment, the engagement of thecylindrical magnet220 with theleadscrew218 is implemented by an anti-rotation means, for example, an adhesive or a mechanical interlock (not shown). After thecylindrical magnet220 is received into thecylindrical bore234 of theleadscrew218, thefirst end218dand thesecond end218eof theleadscrew218 are hermetically sealed by afirst cap216 and asecond cap222, respectively. The sealing process, in one embodiment, is performed with a laser welding. Other sealing methods can also be used to practice the present invention.

Thetension member201 also includes abody203. Thebody203 has afirst end portion203aand an opposite,second end portion203bdefining a cylindrical chamber229 therebetween, alongitudinal axis203ctherethrough the cylindrical chamber229, aU-shape cut203dformed in thesecond end portion203b,and a length, L₁, defined between thefirst end portion229aand the second end portion. In one embodiment, L₁>L₂. The cylindrical chamber229 has afirst chamber portion229aand asecond chamber portion229bneighboring to thefirst chamber portion229a.Thefirst chamber portion229aand thesecond chamber portion229bare sized with a diameter, d₁, and d₂, respectively. In one embodiment, d₂>d₁, and thus astep229cis formed at the junction of thefirst chamber portion229aand thesecond chamber portion229b. In one embodiment, thefirst chamber portion229ais helically threaded for engaging with theleadscrew218. When theleadscrew218 is received in the cylindrical chamber229, theaxis218cof theleadscrew218 is substantially coincident with theaxis203cof thebody203, and theleadscrew218 is capable of moving back and forth along theaxis203cof thebody203 as being rotated around theaxis203cof thebody203 of thetension member201. In one embodiment, the second cap is sized to fit thesecond chamber portion229bof the cylindrical chamber229 such that as assembled, the second cap prevents the leadscrew218 from moving out of the cylindrical chamber229 of thebody203 of thetension member201. The second end cap maintains concentricity with and therefore alignment of theleadscrew218 relative to thebody203 of thetension member201.

The first engagingmember207 mechanically engages thefirst end portion204aof thecable204 with thetension member201. In one embodiment as shown inFIG. 2, the first engagingmember207 has a ball-and-socket joint mechanism in which a swagedball214 is fixedly attached to thefirst end portion204aof thecable204. The first engagingmember207 further has apivot cap208 that has ashoulder215, in which ahole213 is formed. As assembled, thefirst end portion204aof thecable204 attached to the swagedball214 is received through thehole213 of thepivot cap208 and thepivot cap208 is then fixedly attached to thefirst end cap216 of thetension member201 by welding or other attaching means. In this embodiment, the swagedball214 articulates with theshoulder215 of thepivot cap208, and thus rotating theleadscrew218 around itsaxis218cdoes not cause thecable204 to rotate and twist.

The second engagingmember209 for mechanically engaging thesecond end portion204bof thecable204 with thevertebra100, in one embodiment, as shown inFIGS. 6 and 7, includes abone screw402 having ascrew head412, twospherical recesses408 formed on two sides of thescrew head412, respectively, ahole410 formed through the twospherical recesses408, and abody portion414 having helical threads for threading into thevertebra100, aball404 having a hole formed therethrough, and acrimp406. As assembled, thesecond end portion204bof thecable204 is received through thehole410 in thebone screw402 and the hole formed in theball404, respectively, and secured by thecrimp406 such that a change in angulation between thetension member201 and thevertebra100 is accommodated by articulation of theball404 with thespherical recess408.

In another embodiment, as shown inFIGS. 11 and 12, the second engagingmember409 has a pair of bone screws602 attached to thevertebra100, arod610 engaged with the pair of bone screws602, and acrimp606. The bone screws602 has apolyaxial screw head603 and a helical threadedbody608 extending from thepolyaxial screw head603. As assembled, aloop portion600 formed in thesecond end portion204bof thecable204 engages with therod610 and is secured with thecrimp606. In one embodiment, therod610 is secured to the pair of bone screws602 by threading a pair ofscrew caps604 into the polyaxial screw heads603 of the pair of the bone screws602, respectively. The use of multiple bone screws enhances fixation of thedevice200 to thespine204.

The third engagingmember202 for mechanically engaging thetension member201 with thepelvic bone102 in one embodiment includes ashackle202. As shown inFIGS. 2-5, theshackle202 is formed in a clevis-shape and has afirst end portion202a,asecond end portion202band abody portion202cdefined therebetween.

Holes

205 and226 are formed in thefirst end portion202aand thesecond end portion202b,respectively. In one embodiment, one of the

holes

205 and226 is helically threaded for receiving aclevis screw210. Thebody portion202cis received in theU-shape cut203dof thebody203 of thetension member201 and secured by placing apin206 into ahole224 formed in thesecond end portion203bof thebody203 of thetension member201. Thetension member201 is not rigidly attached to theshackle202, but is capable of rotating around afirst axis230 and asecond axis232 perpendicular to thefirst axis230, respectively. In one embodiment, thefirst axis230 is substantially coincident with anaxis230 of thehole224 in thebody203 of thetension member201. Thefirst axis230, thesecond axis232 and theaxis203cof thebody203 of thetension member201 are perpendicular to each other. In this embodiment, theshackle202 allows thetension element201 to rotationally orient itself to a relatively straight path toward the spinal attachment site and causes changes in angulation of thetension element201 relative to thehorizontal plane105 as indicated by angles α and β inFIGS. 1aand1b, respectively. In one embodiment, thefirst end portion202aand thesecond end portion202bare secured to thepelvic bone102. As shown inFIGS. 1aand1b,a hole is drilled into thepelvic bone102, theclevis screw210 is then fed through ahole205 formed on thefirst end portion202aand the hole drilled in thepelvic bone102, and threaded into a threadedshackle hole226 formed in thesecond end portion202bto secure theshackle202 to thepelvis bone102.

Thedevice200 also includes means for rotating theleadscrew218 of thetension member201 around theaxis203cof thebody203 of thetension member201. In one embodiment, the rotating means includes an actuator. As shown inFIG. 8,actuator300 has afirst axle314 and asecond axle316 parallelly attached to aframe320 that has asupport flange310. Each of thefirst axle314 and thesecond axle316 has a first end and a second end. Theactuator300 further has a first pulley312aand asecond pulley312brigidly mounted onto the second end of thefirst axle314 and the second end of thesecond axle316, respectively. Theactuator300 also has acylindrical magnet302 magnetized diametrically and symmetrically formed on thesecond axle316. As shown inFIG. 8, thecylindrical magnet302 has a north pole, N, and a south pole, S. Additionally, theactuator300 has acrank306 that is fixedly attached to the first end of thefirst axle314 such that when a torque is applied to the crank306 to cause thefirst axle314 to rotate, a torque is simultaneously applied to the first pulley312a.Moreover, theactuator300 has abelt308 engaging with the first pulley312aand thesecond pulley312bfor transferring torques from the first pulley312ato thesecond pulley312bso as to rotate thecylindrical magnet302.

Referring toFIG. 13-16, adevice700, which utilizes a toggle mechanism for correction of a spinal deformity, is shown according to an alternative embodiment of the present invention. Thedevice700 includes acables704, atension member701, a first engaging member for mechanically engaging thecable704 with thetension member701, and ashackle202 for mechanically engaging thetension member701 with a pelvic bone.

In one embodiment, thetension member701 has aleadscrew718 that has ahead708, ashank710 extending from thehead708, and a threadedportion712 extending from theshank710. Thetension member701 further has a one-way clutch714 coupled with theshank710. The one-way clutch714 is configured such that when rotating in one of the clockwise and counterclockwise directions, the one-way clutch714 engages with theshank710, and when rotating in the other of the clockwise and counterclockwise directions, the one-way clutch714 freewheels on theshank710. Thetension member701 also has abody703, which has an interior surface complementarily threaded for receiving theleadscrew718, afirst end portion703a,an opposite,second end portion703b,anaxis703c,aU-shape cut703dand a hole703eformed in thesecond end portion703b,where the hole703ehas anaxis730 perpendicular to theaxis703c.Additionally, thetension member701 has atoggle702. Thetoggle702, in one embodiment, has afirst end portion702aand an opposite,second end portion702bdefining achamber729 therebetween for housing the one-way clutch714 rigidly, a pair ofwings705 radially protruding from thesecond end portion702b,and a hole715 formed on thefirst end portion702a.

In one embodiment, as shown inFIG. 14, the first engaging member has apin716, and acrimp706. As assembled,loop portion738 formed in the first end portion704aof thecable704 engages with thepin716 and is secured with thecrimp706. The first engaging member in another embodiment includes a ball-and-socket joint mechanism.

Thedevice700 also includes a second engaging member for mechanically engaging thecable704 with a vertebra (not shown). Preferably, the second engaging member is capable of accommodating changes in the rotational orientation of the cable as curvature is corrected.

Theshackle202 mechanically engages thetension member701 with a pelvic bone, according to the procedures as described above. Other engaging means of thetension member701 with the pelvic bone can also be used to practice the present invention.

In operation, by pressing alternately on each of the pair ofwings705 of thetoggle702, the one-way clutch714 rotates alternately in the clockwise and counterclockwise directions thereby causing theleadscrew718 to rotatably advance into thebody703, which in turn pulls thecable704 into thebody703 of thetension member701, whereby the tension of thecable204 is adjustable for imposing a corrective displacement on thevertebra100. This operation causes thetension member201 to move from a first state to a second state that is different from the first state. In one embodiment, the first state and the second state are corresponding to an extended configuration and a collapsed configuration of thetension member701, as shown inFIGS. 15 and 16, respectively.

In one aspect, the present invention relates to a device for correction of a spinal deformity. In one embodiment, the device includes a cable having afirst end portion204a,and an opposite,second end portion204battachable to avertebra100, means for adjusting the tension of the cable so as to impose a corrective displacement on thevertebra100, and means for attaching the body to apelvic bone102. In one embodiment, the adjusting means comprise a screw having a threaded portion and engaged with the first end portion of the cable, and a body having an interior surface complementarily threaded for receiving the screw such that when the screw rotatably advances into the body, the tension of the cable is adjusted. The adjusting means includes a magnet driving mechanism, a toggle driving mechanism, a hydraulic driving mechanism, or the likes.

In one embodiment, the cable is made of a biocompatible material. The biocompatible material comprises a polymer, a composite, a metal, an alloy, or any combination thereof. In one embodiment, the cable is coated with a material to reduce abrasion and adhesion of biologic tissues.

In yet a further aspect, the present invention relates to a device for correction of a spinal deformity. In one embodiment, the device includes a tension adjusting member having a first end, a second end, and a body defined therebetween the first end and the second end. The device further includes a tension member having a first end portion, a second end portion and a body portion defined therebetween the first end portion and the second end portion, and movably engaged with the body of the tension adjusting member such that the first end portion of the tension member is movable away from the first end of the tension adjusting member for adjusting the tension of the tension member. In use, the second end portion of the tension member is to be secured to avertebra100 and the first end of the tension adjusting member is to be secured to apelvic bone102 so that when the first end portion of the tension member is movable away from or toward to the first end of the tension adjusting member, the tension of the tension member is adjusted so as to impose a corrective displacement on thevertebra100.

A surgical procedure for implantation of the invented device, in one embodiment, includes the following steps: at first, a device having a tension member, a cable engaging with the tension member, and a shackle engaging with the tension member is provided according to one embodiment of the present invention. Then openings at a pelvis bone and a spinal attachment site are incised, respectively. A small hole is drilled through the pelvis bone at a pre-selected position, possibly at or near the iliac crest. The shackle is then secured to the pelvis bone with a screw, clamp or pin. Next, the cable is attached to the spinal attachment site through the openings with an engaging member including bone screws. Once the device is implanted, the wounds are closed and correction of the spinal deformity is performed incrementally and non-invasively according to the procedures as described above.

The present invention, among other unique features, discloses a non-invasive or minimal invasive device (implant) for correcting abnormal spinal curvatures of a patient. One of advantages of the present invention is the potential to correct the abnormal spinal curvatures without spinal fusion. Permanent correction of the abnormal spinal curvatures is achieved by gradually realigning the spinal column so that force imbalances in the spine no longer exist. In certain cases, the onset of skeletal maturity marks the end of curve progression due to the fact that the supporting structures of the spinal column have reacted to the abnormal spinal curvature and imbalances are eliminated. However, in extreme cases of scoliosis the spinal deformity exceeds a critical point and equilibrium may not be reached and therefore the curve progression continues even after the skeletal maturity. It would appear that correcting the curvature and therefore eliminating the imbalances long enough to allow the viscoelastic properties of the supporting structures of the spinal column to react would result in a permanent curvature correction without the need for fusion. However, if the fusion is required, the implanted device would be removed and the fusion would be performed in a procedure known to the people skilled in the art.

The foregoing description of the exemplary embodiments of the invention has been presented only for the purposes of illustration and description and is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Many modifications and variations are possible in light of the above teaching.

The embodiments were chosen and described in order to explain the principles of the invention and their practical application so as to enable others skilled in the art to utilize the invention and various embodiments and with various modifications as are suited to the particular use contemplated. Alternative embodiments will become apparent to those skilled in the art to which the present invention pertains without departing from its spirit and scope. Accordingly, the scope of the present invention is defined by the appended claims rather than the foregoing description and the exemplary embodiments described therein.

Claims

1. A device for correction of a spinal deformity, comprising:

an implant having a first end portion and an opposite second end portion, said first end portion being attachable to an extraspinal bone, said second end portion being attachable to a vertebra, said implant being configured for being adjusted without penetrating skin and thereby for adjusting a tension of said implant so as to impose a corrective displacement on said vertebra.

2. The device ofclaim 1, wherein said implant includes a cable and an adjustment device coupled with said cable, said adjustment device including said first end portion of said implant, said cable including a third end portion and a fourth end portion, said fourth end portion being said second end portion of said implant, said adjustment device being configured for adjusting said tension of said implant so as to impose said corrective displacement on said vertebra, said adjustment device including a screw and a body, said screw having a threaded portion and being engaged with said third end portion of said cable, said body having an interior surface complementarily threaded for receiving said screw such that when said screw rotatably advances into said body said tension of said cable is adjusted.

3. The device ofclaim 2, wherein said implant includes a structure configured for attaching said body to a pelvic bone.

4. A device for correction of a spinal deformity, comprising:

a. a tension adjusting member having a first end, a second end, and a body defined therebetween; and

b. a tension member having a first end portion, a second end portion, and a body portion defined therebetween, said tension member being movably engaged with said body of said tension adjusting member such that said first end portion of said tension member is linearly movable relative to said first end of said tension adjusting member for adjusting a tension of said tension member.

5. The device ofclaim 4, wherein said second end portion of said tension member is configured for being secured to a vertebra and said first end of said tension adjusting member is configured for being secured to an extraspinal bone so that when said first end portion of said tension member moves one of away from and toward said first end of said tension adjusting member said tension of said tension member is adjusted so that said device is configured for imposing a corrective displacement on said vertebra.

6. A method for correcting a spinal deformity, said method comprising the steps of:

providing an implant including a first end portion and a second end portion opposite said first end portion;

attaching said first end portion to an extraspinal bone;

attaching said second end portion to a vertebra; and

adjusting said implant without penetrating skin and thereby adjusting a tension of said implant.