Patent ID: 12251134

DETAILED DESCRIPTION OF THE INVENTION

General Characteristics of the Present Invention

Described herein are improved surgical methodologies for correcting scoliosis that overcome the disadvantages of the prior art, including but not limited to those described herein. Referred to as non-fusion anterior scoliosis correction (NFASC), the present invention as illustrated inFIG.1implements soft tissue disc releases100for optimal correction of the curvatures of the spine, multi-planar (three-dimensional) de-rotation of the spine102, and the use of double screws/double cords104in certain cases. These improved NFASC methodologies are less invasive, result in minimal muscle damage, and may be applied to a variety of scoliosis types, including those with a thoracic, thoracolumbar or lumbar curve(s) of any magnitude. As set forth herein, depending in the type and degree of severity of the scoliosis being addressed, the surgeon may opt to implement any or all of these inventive techniques in various combinations.

Generally speaking, the NFASC techniques described herein use growth modulation and remodeling, which partially restrains one side of the spine to allow growth and remodeling on the other side in order to reverse the abnormal scoliosis growth pattern or residual deformity in the vertebral body and disc. As described further below, titanium pedicle anchor screws are placed on the convexity (outside) of the vertebra that are within the scoliosis curve, and a white polyethylene-terephthalate flexible tensioning cord is disposed within each of the anchor screws in the vertebral bodies of the spine. After the vertebra is adjusted and the tensioning cord is tensioned and secured (tightened) within the anchor screws, the resulting adjustment corrects and straightens the spine. The affected curve(s) show an improvement immediately after surgery, and continued improvement over time as the spine grows. In patients whose spine is not growing, their spine remodels to the new position of the spine held by the anchor screws and tensioning cords.

The improved NFASC techniques of the present invention implement several improvements over the prior art. For example, the use of portals in the prior art, such as described in the '736 patent referenced above, is partially or wholly eliminated by using a mini-opening approach, which advantageously allows direct access to the center of the spine deformity. Portals as used in the prior art scoliosis surgical techniques are inhibitive in several ways, including unduly limiting the view of the interior of the patient by the surgeon and limiting the maneuvers the surgeon can make. By using a small opening (referred to as a mini-opening) in the patient, rather than fixed-diameter portals, the surgeon can get a better view of the areas being operated on, as well as gain increased maneuverability within the patient to accomplish the maneuvers required by this technique. When the scoliosis curves are too large and/or stiff, complete three-dimensional correction through prior art cord tethering cannot be accomplished through the portals, and the mini-open approach solves that problem. Also, mini-open access without portals allows access to lumbar curves, whereas the prior art portal-based VBT methodology does not.

Notwithstanding, portals may be useful at the end of the scoliosis curves for additional anchor screw fixation points depending on the length of the spine and the number of vertebrae involved. This mini-open approach implements the process of making small vertical incisions hidden under the arms of the patient, rather than oblique incisions or posterior incisions as in posterior spinal metal rod fusion. VBT also uses openings in the side of the patient, but portals are used to give access to the surgeon of the vertebra being operated on. Portals within the center of the scoliotic curve are restricted by the ribs and thus cannot be moved as desired during surgery. Thus, stiff (non-flexible) and larger curves (less than 60°) usually cannot be addressed by VBT using the prior art portal technique.

Rather than tethering as in the prior art VBT technique, the present invention applies what is referred to as a de-tethering approach through the use of soft tissue disc releases. In the prior art VBT technique, the manipulations made in the tethering process are only very small due to the use of limiting portals. Mini-open procedures, without using prior art portals, enable more complex and greater amounts of manipulations during the surgery. The NFASC approach of the present invention uses a disc release technique to enable de-rotation of the spine more aggressively than with prior art VBT portal-based techniques. The correction obtained is held in place by using the anchor screw/cord instrumentation.

Thus, NFASC is used to release the ligaments as may be required and thus loosen the spine, which enables optimal correction of the patient's scoliosis through de-rotation and/or double screws/double cords. With many occurrences of scoliosis, on the inside of every curve are ligaments and the disc annulus (hereinafter referred to as soft tissue) that contracts and cannot stretch out enough to allow for straightening of the spine. De-rotational correction is advantageously attained with release of these soft tissues as described further herein.

A unique aspect of this inventive technique is using the now released disc space to assist with correction while the surgeon is tensioning and securing the cord. The surgeon can place an instrument called a disc space trial and help move the vertebra proxillaly, reducing the risk of the anchor screw plowing in the vertebra.

Thus, by using the mini-opening approach rather than just prior art portals, implementation is realized of the inventive disc release, three-dimensional de-rotational maneuver, and double screw/double cord procedures. Notably, the NFASC techniques of the present invention enable de-rotation of the spine to the normal position, while traditional rod based and VBT techniques do not provide or allow for such intricate de-rotation. De-rotation of the spine is especially advantageous in the cases wherein there are multiple aspects of the scoliosis on more than one plane, rather than a simple single-plane correction that is addressed by the prior art.

Furthermore, the use of the mini-open procedures allows for strategic and precise placement of the anchor screws. The use of portals in the prior art allows the surgeon only limited access to the vertebra for placement of the anchor screws. By eliminating the portals through the mini-open procedure, the surgeon can more easily place the anchor screws in specific and strategic locations above and below the segmental vessels as desired and preserve them from being damaged during the operation. The prior art portal-based techniques do not allow for such precise placement of the anchor screws and segmental vessel preservation.

In a third major aspect of the invention, double screws and/or double cords are advantageously implemented. Here, two separate rows of anchor screws are attached to the vertebra in strategic locations, and (at least) two independently tensioned cords are disposed, tensioned and secured within these two sets of anchor screws accordingly. By having two or more tensioning cords being manipulated independently, the surgeon can accomplish a greater degree of correction, especially de-rotation of the spine, than otherwise possible with a single row of anchor screws and a single tensioning cord. Two independent tensioning cords provide for more tightening range than one tensioning cord and prevents loss of the rotation correction that occurs with single screw/cord constructs. Double screws/double cords are also advantageous in addressing a double curve of the spine, where the vertebrae forms a double scoliosis curve.

This specification is provided with reference to components bearing identifying indicia as follows:300patient302area of procedure304C-arm head306Steinmann pin308line marking310darkened line312scalpel314retractor316muscle318mini-opening322anchor screw322afirst anchor screw322bsecond anchor screw322cposterior anchor screw322danterior anchor screw322esingle anchor screw322fupper posterior anchor screws322gupper anterior anchor screws322hlower posterior anchor screws322ilower anterior anchor screws322jupper neutral anchor screw322klower neutral anchor screw324staple326vessel328hemostat330portal332disc334annulus338tensioning cord338aposterior tensioning cord338banterior tensioning cord338cupper posterior tensioning cord338dupper anterior tensioning cord338eupper bridge tensioning cord338flower posterior tensioning cord338glower anterior tensioning cord338hlower bridge tensioning cord338iposterior crossover tensioning cord338janterior crossover tensioning cord340stationary tower342de-rotation tower346counterforce vector348de-rotation force vector350translational force vector352screwdriver354paddle356unreleased disc358distractor360posterior row of anchor screws362anterior row of anchor screws364upper curve366upper set of vertebrae368lower curve370lower set of vertebrae372neutral vertebra374upper posterior row376upper anterior row378lower posterior row380lower anterior row382approximate vertical center line384approximate horizontal center line
Overall Process Flow

FIG.1Ais a flowchart showing the three major aspects/methodologies of the invention as described herein; i.e. disc release100, de-rotation of the spine102, and the use of double screws/double cords104. Depending on the type and severity of the scoliosis, the surgeon may implement any or all of the aspects of the invention.

Referring the general flowchart ofFIG.1A, for all of the procedures described herein, a vertical mini-opening is created at step106by the surgeon in the side of the patient to enable the surgeon to access the vertebrae. In accordance with a first major aspect of the invention, a disc release procedure118may be performed on discs located between pairs of adjacent vertebrae to enable the pairs of adjacent vertebrae to be adjusted, by incising the disc near its center to allow additional movement of the adjacent vertebrae during the operation. By releasing the discs in step118, an optional distraction procedure120may also be performed on at least one pair of adjacent vertebrae of the spine of the patient by inserting a paddle in a previously released disc between two vertebrae adjacent the vertebrae to be compressed and rotating the paddle in order to urge the adjacent vertebrae together. Further optionally, a segmental vessel preservation procedure116may be performed as will be described in further detail below. It is noted that the disc release procedure118may be performed before or after the segmental vessel preservation procedure116.

Next, staples and corresponding anchor screws are inserted into the vertebrae to be adjusted at step108. As known in the art, each anchor screw has a channel suitable for accepting a tensioning cord, which will be used to enable an adjustment procedure on each of the vertebrae by urging and maintaining the anchor screws and corresponding vertebrae in a straight or substantially straight line with each other. At step110, the tensioning cord is disposed within the channels of one or more of the anchor screws to enable an adjustment procedure on the vertebrae.

At step112, a vertebrae adjustment procedure is performed in which each of the vertebrae is adjusted with respect to at least one other adjacent vertebra. This may be implemented utilizing a de-rotation procedure122in accordance with a second major aspect of the invention. The tensioning cord is tensioned after the vertebrae are de-rotated, then secured within the channel to maintain the de-rotational adjustment. This is repeated until all of the vertebrae have been adjusted as desired.

In certain cases, such as for double scoliosis curves, it may be advantageous to utilize two rows of anchor screws and two (or more) tensioning cords, which is shown at step124. Many of the procedures set forth for single screw/cord applications above will also be utilized for double screw/double cord applications, modified accordingly and as explained in further detail herein. Once the surgeon has implemented the desired procedures, the process is complete at step114. The details of these procedures are now described in further detail.

Patient Preparation

FIG.1Bis a flowchart showing the detailed procedure for creating the mini-opening in the patient, and accompanyingFIG.2illustrates a patient300lying on her side in preparation for the anterior scoliosis correction procedures of the present invention. With reference toFIG.2, as part of the pre-operation preparation, at step126the patient300is placed in a lateral position, laying on their side, with their arm pulled away from and immobilized from the area302where the surgeon will perform the procedure.FIG.3illustrates the patient ofFIG.2showing the use at step128of a Steinman pin306in conjunction with intra-operative x-ray imaging of the lateral spine for determining positioning of the midline of the vertebral bodies being operated on. Using the C-arm head304of an x-ray machine (not shown) as a guide, the pin306is centered over the skin of the patient, over the vertebral bodies along the spine where the anchor screws will be inserted (as shown in phantom lines inFIG.3), and markings are then made on the skin of the patient300to delineate the area where the surgeon will incise the mini-opening along the side of the patient, which will be approximately 4-6 inches long, e.g. near the L1 vertebra.FIG.4illustrates the resulting marking308made by the physician of the patient300along the lateral vertebral body midline, wherein the darkened line310denotes the location of the exact incision to be made using the scalpel312.

FIG.5illustrates a mini-thoracotomy being performed at step130on the patient300with a vertical incision through the latissimus dorsi muscle316to create a mini-opening318, in which the skin and muscle are retracted at step132using a retractor314in anticipation of the surgical procedure. After the surgeon has made the desired incision using the scalpel312to create the mini-opening318along the patient's side, the latissimus dorsi muscle316is visible. The lung will be deflated at this point, thus providing an essentially empty cavity. The rib cage, vertebrae and discs will then be visible to the surgeon. Optionally, at step134a thorascopic portal330may be inserted at approximately the T6 location (see e.g.FIG.8) and/or the L1 location. In order to gain access to the vertebrae that are not exposed directly through the mini-opening incision, the surgeon will undermine the uncut skin by cutting a plane in the tissue under the skin in order to stretch the incision from below. That is, by cutting the plane under the skin adjacent to the mini-opening, the surgeon can lift up the skin since the muscle has been dissected, and then for example make a puncture and insert the portal330at the T6 (and/or L1) interspace as shown without making a separate incision (or without extending the mini-opening incision longer than necessary). It is noted that in the prior art, the physician usually incises the patient horizontally (straight across), which kills the distal end of the muscle, whereas in the present invention the incision is made vertically as shown in order to, inter alia, spare the muscle.

Segmental Vessel Preservation

Reference is now made toFIG.1C, which is a flowchart showing the sub-steps of the optional segmental vessel preservation procedure116ofFIG.1Ain further detail. In addition,FIG.7illustrates the surgeon performing the segmental vessel preservation procedure using a right-angle hemostat328(or another surgical instrument that may be appropriate). In the prior art, segmental vessels (i.e. those vessels that go from the aorta across the vertebral body into the paranum) are sacrificed when the anchor screws are inserted into the vertebra. See, for example, the '736 patent. In the present invention, however, the segmental vessels may be preserved by the surgeon, as follows. At step136, the segmental vessel326may be preserved by retracting it from the target area on the vertebra by manipulating the hemostat328, exposing the side of the vertebra at step138, enabling insertion of the staple324and anchor screw322into the desired target area of the vertebra at step140. The surgeon then inserts a staple324into the side of the bone (vertebra), and the anchor screw322may then be inserted into the bone via the staple324as known in the art (see alsoFIG.6). The staple324provides a stable anchoring point to ease the insertion of the anchor screw322. It is noted that the segmental vessels may only be preserved by this procedure in the vertebral bodies that are exposed to the surgeon through the mini-opening.

FIG.6illustrates the typical placement of the anchor screws322and staples/washers324laterally along the side of each vertebral body T6, T7, T8, T9, T10, T11, T12 and L1 through the mini opening318in the procedure, performed optionally in conjunction with the segmental vessel preservation procedure described above. InFIG.6, the ribs of the patient, which have been spread to give better access by the surgeon to the vertebra, are not shown for sake of clarity.

Using the prior art VBT techniques, usually only one staple324is placed onto the vertebra. The surgeon can place the two prongs of the staple324close to the end plate, a single prong close to the segmental vessel326, and then the staple324may be malleted into the vertebra. In general, the surgeon has much more flexibility for the angle of placement of the staples324in a vertebral body using the mini-open vertical incision of the present invention, as opposed to the prior art portal access method alone.

Disc Release

As referenced above, a first major inventive aspect of the present invention is to release the ligaments as may be required and thus loosen the spine, which provides for optimal correction of the patient's scoliosis. With many occurrences of scoliosis, on the inside of every curve are ligaments and the disc annulus (i.e., soft tissue) that contracts and cannot stretch out enough to allow for straightening of the spine. Rotational correction is advantageously attained with release of these soft tissues. A unique aspect of this disc release correction technique is using the now released disc space to assist with correction while the surgeon is tightening the tensioning cord. The surgeon can place an instrument called a disc space trial and help move the vertebra proxillaly, reducing the risk of the anchor screw plowing in the vertebra.

FIG.8shows a diagrammatical perspective view of the complete installation of staples/washers324and corresponding anchor screws322with the surgeon approaching the mini-open318with a scalpel312in anticipation of releasing the discs, andFIG.9illustrates the surgeon performing the disc release procedure. InFIG.8, all of the screws and washers have now been inserted into the vertebral bodies T6, T7, T8, T9, T10, T11, T12 and L1.

With reference toFIG.9, another advantage provided by the techniques of the present invention as described herein is the ability for the surgeon to release the disc332by incising the disc, releasing the eccentric nucleus, and incising the annulus334including the anterior longitudinal ligament circumferentially. The surgeon can access the entire disc area and use leverage because of the mini-open access that is otherwise unobtainable via prior art portals.

Notably, the disc release can decompress an eccentric fixed nucleus proposus that prevents recreation of kyphosis during the rotation maneuver. This indirectly allows shortening of the column of the spine and removes the force vectors of the spine trying to rotate back to scoliosis (referred to as de-torqueing the spine deformity)

It is noted that in some cases the discs must be released first if the curve of the spine is so severe, in order to straighten out the spine and make insertion of the screws and staples easier. In these cases, the disc release procedure is performed prior to insertion of the anchor screws, rather than afterwards as shown in the above example. In some cases, the surgeon may not be sure if the patient will require release of the discs, so the anchor screws would be inserted first and if the spine is too stiff then the disc release may be performed later on.

Cord Placement

Once the anchor screws322have all been attached to the patient's vertebra T6, T7, T8, T9, T10, T11, T12 and L1 through the mini opening318as described above, the next step is to place a tether or tensioning cord338(e.g. a white polyethylene-terephthalate flexible cord as known in the art, seeFIG.10A) within a corresponding channel of the anchor screws322at step110ofFIG.1Ain order to provide tension at desired locations along the spine and maintain the correction. First, the cord338is inserted in the anchor screw322at T6 and secured (tightened to the anchor screw) to form an initial reference point. Then the cord338is placed through the channel of the anchor screw322on the next adjacent vertebra (T7) so that T7 may be corrected (de-rotated) with respect to T6 as will be described below. This process continues down the spine, one vertebra at a time, until all the vertebrae have been corrected. Note that inFIG.10A, the cord is shown disposed through the anchor screw at T6, T7, T8, and T9 since these vertebrae have already been corrected, and T10, T11, T12 and L1 are awaiting correction. (In an alternative embodiment, the tensioning cord338may be disposed initially through the channels of all of the anchor screws as shown inFIG.10B, prior to correcting any of the vertebrae). If a portal is (optionally) located at L1, then the cord will exit the body of the patient through that portal (not shown). By using the access provided by the mini-open procedures, the surgeon is able to use correction maneuvers such as translation, compression, and enhanced de-rotation, as explained in further detail below, and then the spine correction is held by tensioning and securing of the cord338between the anchor screws322.

De-Rotation

The preferred embodiment of the vertebrae adjustment procedure112is the de-rotation procedure122, which forms a second major aspect of the present invention, and which is now explained in detail with respect toFIG.1D. A detailed example of de-rotation of the T9 vertebra with respect to the spine, in particular with respect to T6, will be described. In practice, the surgeon will have performed the same de-rotation procedure first on vertebra T7 with respect to T6, and then on T8 with respect to T6. The de-rotation of vertebra T9 with respect to T6 has been chosen for the detailed discussion since the juxtaposition of these two vertebrae lends itself to greater clarity of explanation. After T9 has been de-rotated, then the procedure continues as may be required for T10, T11, etc.

It is further noted that portals may be used at T6 and L1 because they remain essentially stationary against which the rotation is performed through the mini-opening, and thus the mini-opening is not required all the way from T6 to L1. This is generally preferred since it is beneficial to not incise the patient along the mini-opening any more than necessary in order to accomplish the techniques of this invention.

Tower Placement

FIGS.11A and11Bboth illustrate the initial offset locations of a first tower, referred to as a stationary tower340, and a second tower, referred to as a de-rotation tower342, along the spine. As shown, the stationary tower340is mated with a proximal or first anchor screw322alocated on a first vertebra (T6, via the portal330) at step154ofFIG.1D. The de-rotation tower342is mated with a distal or second anchor screw322bon a second vertebra T9 at step156ofFIG.1D. In particular,FIG.11Aillustrates the initial offset setup locations of the stationary tower340and the de-rotation tower342from the anterior perspective along the axis of the spine, prior to performing the de-rotation procedure, andFIG.11Billustrates the initial offset setup locations of the stationary tower340and the de-rotation tower342ofFIG.11Abut from the cranial perspective, prior to performing the de-rotation procedure. As shown, the stationary tower340is disposed substantially vertically, generally perpendicular to the patient300. The de-rotation tower342is disposed at an approximately 45-degree angle with respect to the vertically aligned stationary tower340. As previously described, an optional portal330is inserted as shown over the T6 vertebra, through which the stationary tower340may be inserted and adjoined with the first anchor screw322aon the T6 vertebra. By using a portal330to hold the stationary tower at T6, the length of the mini-open incision may be kept as small as possible while still providing the advantages of the present invention. The portal330is a viable option since it is not necessary for the surgeon to be able to see directly the T6 vertebra while performing the de-rotation procedure, and since the stationary tower340will remain substantially stationary during de-rotation as will be described.

If the surgeon does not have direct access to place the tower342on the anchor screw head from the thoracotomy opening, then a small puncture is made through the intercostal space for example going through the intercostal space of T7-T8 to get to the T7 anchor screw and/or the T8 anchor screw. A separate incision is not made; rather, the skin is lifted and then punctured through the intercostal muscle.

As shown inFIG.11A, the tensioning cord338has already been disposed, tensioned and secured in the channels of the anchor screws322at T6, T7, and T8 which have already been de-rotated in this example. The tensioning cord338is then disposed in the channel of the second anchor screw322b, ready for de-rotation of T9, tensioning and securing as now described.

De-Rotation Maneuvers

FIG.12Aillustrates the performance of the de-rotation maneuvers from the anterior perspective along the axis of the spine, andFIG.12Billustrates the performance of the de-rotation maneuvers ofFIG.12Abut from the cranial perspective. De-rotation of the spine is the critical correction force to correct the scoliosis deformity maximally or as much as desired. To achieve this correction result, the following steps are performed with additional reference toFIG.1D.

The surgeon will be standing on the posterior side of the patient, the head is closest to the viewer. The de-rotation tower342will be translated towards the table as explained below, pushing the spine towards a corrected position. Essentially, the stationary tower340is the stabilizing force and the de-rotation tower342is used to de-rotate the spine.

Thus, at step158, the surgeon imparts a downwards translational force vector350by pressing down on the de-rotation tower342. The surgeon then executes the de-rotation maneuver with the de-rotation tower342by pushing the de-rotation tower342laterally along the de-rotation force vector348, while simultaneously applying a lateral counterforce vector346to the stationary tower in opposition to the lateral de-rotation force vector being 348 applied to the de-rotation tower.

That is, the rotation uses the stationary tower340at T6 for a counterforce with the de-rotation tower342on T9 being pushed anteriorly away from the surgeon affecting a de-rotation maneuver of the vertebrae. Simultaneously, the surgeon is translating by pushing the vertebrae towards the table.

This de-rotation maneuver is sometimes held in place for several minutes, and then additional (same) correction forces vectors,346,348and/or350may be applied again as determined by the surgeon to be needed. This is also referred to as stress relaxation of the soft tissue.

FIG.13Aillustrates a surgeon performing a cord tensioning/securing step, andFIG.13Billustrates the cord tensioning/securing ofFIG.13Ain side elevation cross-section at the anchor screw322. Once the desired correction of the vertebra under de-rotation is obtained, then compression (also referred to as tensioning) is applied by a surgical assistant between the two anchor screws at T8 (which was previously secured) and T9 so the tensioning cord338is tensioned at step160, and the cord is secured to the second anchor screw322bon T9 with the locking set screw of the second anchor screw322btightened at step162by a screwdriver (or other screwdriver-type device)352inserted into the upper portion of the de-rotation tower342. It is noted that the screwdriver352may be engaged with the tower342before the de-rotation maneuvers are executed, if desired.

The cord tensioning step160is important since it maintains the de-rotational translation and juxtaposition between the vertebra being maneuvered by the surgeon. It is noted that this is a step known in the art of this type of procedure, such as shown in the '736 patent referred to above and thus need not be repeated in detail.

After the cord has been tensioned and secured in the second anchor screw322bat T9, thus completing the de-rotation of T9, at step164the tensioning cord338is threaded through and disposed within the channel of the next anchor screw at T10 (unless the cord has been disposed through all the anchor screws initially as inFIG.10B), and the de-rotation tower342is relocated to the anchor screw at T10 as well. This is referred to as segmental correction of each vertebral body in the curvature since they are de-rotated one at a time. The same step158of translation and then de-rotation is then performed as above. Once the desired correction of T10 is obtained, then compression is applied on the cord between the next two anchor screws and the locking set screw is once again tightened to engage the cord338in the anchor screw in a tensioned manner. As shown by step166, these steps are repeated as desired, until all of the vertebrae have been de-rotated and the cord secured in each anchor screw.

The stationary tower at T6 will stay located at T6 while the surgeon de-rotates several adjacent vertebrae, e.g. T7, T8, T9. After that, the surgeon will likely move the stationary tower down several vertebrae, e.g. to T9, so that the ensuing de-rotation takes place over only a few vertebrae at a time. So, a typical sequence may be:a. Locate stationary tower340on T6, locate de-rotation tower342on T7b. De-rotate T7, tension and secure the cord at T7c. Dispose cord within channel of T8, relocate tower342to T8d. De-rotate T8, tension and secure the cord at T8e. Dispose cord within channel of T9, relocate tower342to T9f. De-rotate T9, tension and secure the cord at T9g. Remove tower342from T9, relocate stationary tower340to T9h. Dispose cord within channel of T10, relocate tower342to T10i. De-rotate T10, tension and secure the cord at T10j. Continue process accordingly
Distraction

Referring now toFIG.14, there may be occasion with very severe and stiff curves where the disc space between adjacent vertebral bodies remains excessively wedged open, even after the de-rotation procedure. In this case, it is not advisable to simply further tension and tighten the cord, since that may lead to plowing of the anchor screws. In order to address this problem, the prior disc release between these vertebrae is utilized to enable the surgeon to insert a paddle354flat in the vacant disc space in the next adjacent disc area and rotate the paddle, which urges the adjacent vertebra together. Thus, inFIG.14, the disc between T8 and T9 is wedged open, so by placing the paddle354in the disc space between T9 and T10 and rotating as inFIG.15, the T8/T9 disc space is compressed to an acceptable level, and the cord is tightened to maintain the vertebrae together. This distraction technique (step120ofFIG.1A) may be done as part of the cord tensioning and securing process when necessary but may only be done when there was a prior disc release to enable insertion of the paddle354as shown.

FIG.16illustrates a condition where there is an unreleased disc between adjacent vertebrae that is compressed and needs to be decompressed. That is, occasionally at the distal aspect of the deformity, for example T11-T12 or T12-L1, the curve is very flexible, and it is easy to inadvertently overcorrect that segment with reverse wedging of the disc. In this scenario it is recommend using a distractor (spreader)358through the incision to parallel the discs before tightening the set screws. The surgeon utilizes the distractor358as shown inFIG.17between the screws of the adjacent vertebrae to urge them away from each other un-decompress the disc356as desired.

FIG.18illustrates an example of a mature patient with a stiff thoracic curve having undergone disc releases, application of the anterior instrumentation and utilization of the manipulations described above.FIG.19is a post-operative illustration showing the corrected spine and the anchor screws322and tensioning cord338in place.

FIG.20illustrates a patient with severe hypokyphosis of the thoracic spine, andFIG.21illustrates the restoration of kyphosis having utilized disc releases and de-rotation as described above.

Double Screw/Double Cord Technique

In a third major aspect of the invention, two sets of anchor screws may be used in conjunction with two (or more) tensioning cords in order to provide more precise adjustment of the spine than hereto done in the prior art. This may be of particular importance when treating an excessive angle of scoliosis, such as multiple planes that require de-rotation of the spine for correction. This not only helps with correction of the deformity, but more importantly holds the de-rotation correction more securely then does a single screw/single cord as described above. The single screw/single cord embodiment described above may not be rotationally stable enough for a given application, and it may in certain cases allow the spine to rotate back a few degrees at each segment when the patient is erect, resulting in loss of the ultimate scoliosis correction.

In these cases, a first example of the double cord/double screw methodology is undertaken by inserting two separate and independently operating sets of anchor screws, each set having a different cord that may be tensioned differently by the surgeon. This adds greatly to the rotational stability of the corrective procedure and counters the tendency for the spine to try to rotate back to the uncorrected position. Thus, if possible, it is preferred to implement the inventive double screw/double cord methodology.

In some other cases, a patient may have a severe condition in which a double curve of the spine exists. For example, the upper portion of the spine may curve in one direction, while the lower portion of the spine curves in the opposite direction. To address this problem, a second example of the double cord/double screw methodology is undertaken in which two independent and oppositely disposed sets of double cords/double screws may be implemented to provide more precise correction as will be described further below.

With respect to the simpler case of a single curve, reference is now made to the thoracic region ofFIG.22, which illustrates two sets of anchor screws (and corresponding staples/washers) inserted in the vertebrae T7, T8, T9, T10, T11, T12, and L1. It is noted that double sets of anchor screws are generally not used for T6, since T6 is relatively smaller and it is difficult for it to maintain adequately two sets of screws due to its smaller mass. The same issue may also exist for T7 if the patient is small.

With further respect to the flowchart ofFIG.1E, at step170multiple pairs of anchor screws322c,322dare first inserted into each vertebra T7, T8, T9, T10, T11, T12, and L1 as shown, and a single anchor screw322eis inserted into T6. As a result of this placement of the pairs of anchor screws322c,322d, a substantially aligned posterior row360of posterior anchor screws322cis formed along the vertebrae next to a substantially aligned anterior row362of anterior anchor screws322dformed along the vertebrae.

Next, at step172, a posterior tensioning cord338ais disposed within the channels of the posterior anchor screws322cto enable a posterior adjustment procedure on each of the vertebrae. A posterior vertebrae adjustment procedure is performed at step176in which the plurality of vertebrae is adjusted with respect to at least one other vertebra and the posterior tensioning cord338ais secured within the channels of the corresponding posterior anchor screws322cin order to maintain the posterior adjustment of the vertebrae.

Likewise, at step176an anterior tensioning cord338bis disposed within the channels of the anterior anchor screws322dto enable an anterior adjustment procedure on each of the vertebrae. An anterior vertebrae adjustment procedure is performed at step178in which each of the plurality of vertebrae is adjusted with respect to at least one other vertebra and the anterior tensioning cord338bis secured within the channels of the corresponding anterior anchor screws322din order to maintain the anterior adjustment of the vertebrae.

Although not required, in the preferred embodiment the posterior vertebrae adjustment procedure and the anterior vertebrae adjustment procedure incorporate the methodologies of the de-rotation procedure described above with respect to the typical single cord situation and as shown inFIGS.11A,11B,12A,12B,13A and13B. In particular, for the posterior vertebrae adjustment de-rotation procedure, a stationary tower is located initially on a first posterior anchor screw322cof a first vertebra, and a de-rotation tower is located initially on a second posterior anchor screw322cof a second vertebra. For example, the stationary tower may be located initially on T6 and the de-rotation tower located initially on T7. The posterior de-rotation maneuver is performed by applying a downwards translational force vector to the de-rotation tower, applying a lateral force vector to the de-rotation tower, and simultaneously applying a lateral counterforce vector to the stationary tower in opposition to the lateral force vector being applied to the de-rotation tower. Next, the posterior tensioning cord338ais tensioned in the channel of the second posterior anchor screw322c(on T7) and secured in the channel of the second posterior anchor screw322cin order to maintain the de-rotation of the T7 vertebra. The de-rotation tower is then re-located to the posterior anchor screw322cof the next vertebra (e.g. T8), and the de-rotation maneuver is repeated until all of the vertebrae have been de-rotated using the posterior tensioning cord338aas desired.

After this posterior vertebrae adjustment de-rotation procedure is performed on all the vertebrae as desired, the anterior vertebrae adjustment de-rotation procedure is performed in a similar manner. That is, for the anterior vertebrae adjustment de-rotation procedure, a stationary tower is located initially on a first anterior anchor screw322dof a first vertebra (e.g. T7), and a de-rotation tower is located initially on a second anterior anchor screw322dof a second vertebra (e.g. T8). The anterior de-rotation maneuver is performed by applying a downwards translational force vector to the de-rotation tower, applying a lateral force vector to the de-rotation tower, and simultaneously applying a lateral counterforce vector to the stationary tower in opposition to the lateral force vector being applied to the de-rotation tower. Next, the anterior tensioning cord338bis tensioned in the channel of the second anterior anchor screw322d(on T8) and secured in the channel of at the second anterior anchor screw322din order to maintain the de-rotation of the T8 vertebra. The de-rotation tower is then re-located to the anterior anchor screw322dof the next vertebra (e.g. T9), and the de-rotation maneuver is repeated until all of the vertebrae have been de-rotated using the anterior tensioning cord338bas desired. Note that since the initial posterior vertebrae adjustment procedure has likely substantially aligned the vertebrae, the amount of adjustment provided by the anterior vertebrae adjustment procedure may be only incremental, but is still useful in maintaining alignment of the vertebrae. In an alternative embodiment, the anterior vertebrae adjustment procedure may be executed before the posterior vertebrae adjustment procedure, if desired.

As a result,FIG.22illustrates the corrected spine, with all vertebrae shown corrected using the posterior tensioning cord338aand the anterior tensioning cord338bas explained above.

InFIG.23, a lumbar curve is shown at T10, T11, T12, L1, L2, L3, and L4. Here, the use of two sets of screws and two tensioning cords may be taken advantage of since these vertebrae have enough mass to hold both sets adequately. The process for correction of the vertebrae is carried out in a similar manner as described above with respect toFIG.22.

FIG.24is a is an anterior elevation of a spine having a double curve consisting of an upper curve364and a lower curve368. Here, it is desired to use double screws/double cords to correct both of the curves and to maintain rotation and decrease fatigue on the cord(s). It is noted that in this example, T12 is considered to be neutral since it is essentially the transitional bridge between the upper curve364and the lower curve368. As such, we are unable to place double screws on each side of T12, as the mass of T12 would not enable it to hold four screws in total. So, in this example, a single screw is used on each side of T12 in order to bridge the transition between the curves as follows.

InFIG.24, the upper curve364is defined by an upper set of vertebrae366(T6, T7, T8, T9, T10, and T11) and the lower curve368is defined by a lower set of vertebrae370(L1, L2, L3, and L4). In this example, the upper curve364is disposed in a first direction, and the lower curve is disposed in substantially the opposite direction, thus presenting the problem that is addressed by this invention. T12 is considered to be a neutral vertebra372since it is located between the upper set of vertebrae366and the lower set of vertebrae370and is essentially a transition between the two curves.

As can be seen fromFIGS.25,26and27, the layout of the anchor screws for the two separate curves results in four distinct regions; upper posterior and upper anterior (seeFIG.26), and lower posterior and lower anterior (seeFIG.27). In general, the surgeon will insert all of the anchor screws into the vertebrae in these four regions and then perform the separate adjustment procedures (e.g. de-rotation) on the four different regions using the appropriate tensioning cords in order to accomplish the desired straightening of the spine, using an upper posterior adjustment procedure, an upper anterior adjustment procedure, a lower posterior adjustment procedure, and a lower anterior adjustment procedure. It is noted that in order to access the vertebrae in the upper curve (right thoracic curve), the mini-opening is made at the right chest as described above, and in order to access the vertebrae in the lower curve (left lumbar curve), a second mini-opening is made at the left lower chest.

Thus, for the upper set of vertebrae366, shown in detail inFIG.26, the surgeon inserts pairs of anchor screws into each of the upper vertebrae366along the convexity of the upper curve364, such that a substantially aligned upper posterior row374of upper posterior anchor screws322fare formed along the upper vertebrae366next to a substantially aligned upper anterior row376of upper anterior anchor screws322gformed along the upper vertebrae366.

For the lower set of vertebrae370, shown in detail inFIG.27, the surgeon inserts pairs of anchor screws into each of the lower vertebrae370along the convexity of the lower curve368(which is substantially opposite the convexity of the upper curve364as shown), such that a substantially aligned lower posterior row378of lower posterior anchor screws322hare formed along the lower vertebrae370next to a substantially aligned lower anterior row380of lower anterior anchor screws322iformed along the lower vertebrae370.

For the neutral vertebra372, the surgeon inserts an upper neutral anchor screw322jinto the neutral vertebra372on the same side as the upper curve364, and the surgeon also inserts a lower neutral anchor screw322kinto the neutral vertebra372on the same side as the lower curve368.

The upper set of screws322f,322g,322jon the patient's right side will address the upper curve to her right side as shown, and the lower set of screws322h,322i,322kwill address the lower curve on the patient's left side as shown.

Referring again toFIG.26, during the upper posterior adjustment procedure on the upper set of vertebrae366, an upper posterior tensioning cord338cis disposed within the channels of the upper posterior anchor screws322fand the upper neutral anchor screw322j, and an upper bridge tensioning cord338eis disposed within the channels of the upper neutral anchor screw322jand the upper posterior anchor screw322fadjacent the upper neutral anchor screw322j. The upper bridge tensioning cord338eoverlaps the relevant portion of the upper posterior tensioning cord338csince they share the same set of anchor screws322f,322j.

Likewise, during the upper anterior adjustment procedure on the upper set of vertebrae366, an upper anterior tensioning cord338dis disposed within the channels of the upper anterior anchor screws322g.

Referring again toFIG.27, during the lower posterior adjustment procedure on the lower set of vertebrae370, a lower posterior tensioning cord338fis disposed within the channels of the lower posterior anchor screws322hand the lower neutral anchor screw322k, and a lower bridge tensioning cord338his disposed within the channels of the lower neutral anchor screw322kand the lower posterior anchor screw322hadjacent the lower neutral anchor screw322k. The lower bridge tensioning cord338hoverlaps the relevant portion of the lower posterior tensioning cord338fsince they share the same set of anchor screws322h,322k.

Likewise, during the lower anterior adjustment procedure on the lower set of vertebrae370, a lower anterior tensioning cord338gis disposed within the channels of each of the lower anterior anchor screws322i.

The surgeon performs the adjustment procedures on the four different regions (upper posterior, upper anterior, lower posterior, lower anterior) as follows (preferably but not necessarily in that order).

The surgeon performs the upper posterior vertebrae adjustment procedure in which each of the set of upper vertebrae366is adjusted with respect to at least one other upper vertebra and the upper posterior tensioning cord338cand upper bridge tensioning cord338eare each secured within the channels of the corresponding upper posterior anchor screws322f(and the upper neutral anchor screw322j) in order to maintain the upper posterior adjustment of the vertebrae. The surgeon then performs the upper anterior vertebrae adjustment procedure in which each of the set of upper vertebrae366is adjusted with respect to at least one other upper vertebra and the upper anterior tensioning cord338dis secured within the channels of the corresponding upper anterior anchor screws322gin order to maintain the upper anterior adjustment of the vertebrae.

The surgeon performs the lower posterior vertebrae adjustment procedure in which each of the set of lower vertebrae370is adjusted with respect to at least one other lower vertebra and the lower posterior tensioning cord338fand lower bridge tensioning cord338hare each secured within the channels of the corresponding lower posterior anchor screws322h(and the lower neutral anchor screw322k) in order to maintain the lower posterior adjustment of the vertebrae. The surgeon then performs the lower anterior vertebrae adjustment procedure in which each of the set of lower vertebrae370is adjusted with respect to at least one other lower vertebra and the lower anterior tensioning cord338gis secured within the channels of the corresponding lower anterior anchor screws322iin order to maintain the lower anterior adjustment of the vertebrae.

In a preferred embodiment, each of the above vertebrae adjustment procedures (i.e. the upper posterior vertebrae adjustment procedure, upper anterior vertebrae adjustment procedure, lower posterior vertebrae adjustment procedure, and lower anterior vertebrae adjustment procedure) is executed using the de-rotation procedure described above.

Thus, the upper posterior vertebrae de-rotation procedure is performed by the surgeon locating a stationary tower on a first upper posterior anchor screw of a first upper vertebra and a de-rotation tower on a second upper posterior anchor screw of a second upper vertebra. A de-rotation maneuver is performed by applying a downwards translational force vector to the de-rotation tower, applying a lateral force vector to the de-rotation tower, and simultaneously applying a lateral counterforce vector to the stationary tower in opposition to the lateral force vector being applied to the de-rotation tower. The surgeon tensions the upper posterior tensioning cord in the channel of the second upper posterior anchor screw, and then secures the upper posterior tensioning cord in the channel of at the second upper posterior anchor screw in order to maintain the de-rotation of the upper vertebrae. The de-rotation tower is re-located to the upper posterior anchor screw of a subsequent upper vertebra, and the de-rotation maneuvers are repeated until all of the upper vertebrae have been de-rotated as desired. When adjusting the neutral vertebra, both the upper posterior tensioning cord and the upper bridge tensioning cord are tensioned and secured simultaneously.

The upper anterior vertebrae de-rotation procedure is performed by the surgeon locating a stationary tower on a first upper anterior anchor screw of a first upper vertebra and a de-rotation tower on a second upper anterior anchor screw of a second upper vertebra. A de-rotation maneuver is performed by applying a downwards translational force vector to the de-rotation tower, applying a lateral force vector to the de-rotation tower, and simultaneously applying a lateral counterforce vector to the stationary tower in opposition to the lateral force vector being applied to the de-rotation tower. The surgeon tensions the upper anterior tensioning cord in the channel of the second upper anterior anchor screw, and then secures the upper anterior tensioning cord in the channel of at the second upper anterior anchor screw in order to maintain the de-rotation of the upper vertebrae. The de-rotation tower is re-located to the upper anterior anchor screw of a subsequent upper vertebra, and the de-rotation maneuvers are repeated until all of the upper vertebrae have been de-rotated as desired.

The lower posterior vertebrae de-rotation procedure is performed by the surgeon locating a stationary tower on a first lower posterior anchor screw of a first lower vertebra and a de-rotation tower on a second lower posterior anchor screw of a second lower vertebra. A de-rotation maneuver is performed by applying a downwards translational force vector to the de-rotation tower, applying a lateral force vector to the de-rotation tower, and simultaneously applying a lateral counterforce vector to the stationary tower in opposition to the lateral force vector being applied to the de-rotation tower. The surgeon tensions the lower posterior tensioning cord in the channel of the second lower posterior anchor screw, and then secures the lower posterior tensioning cord in the channel of at the second lower posterior anchor screw in order to maintain the de-rotation of the lower vertebrae. The de-rotation tower is re-located to the lower posterior anchor screw of a subsequent lower vertebra, and the de-rotation maneuvers are repeated until all of the lower vertebrae have been de-rotated as desired. When adjusting the neutral vertebra, both the lower posterior tensioning cord and the lower bridge tensioning cord are tensioned and secured simultaneously.

The lower anterior vertebrae de-rotation procedure is performed by the surgeon locating a stationary tower on a first lower anterior anchor screw of a first lower vertebra and a de-rotation tower on a second lower anterior anchor screw of a second lower vertebra. A de-rotation maneuver is performed by applying a downwards translational force vector to the de-rotation tower, applying a lateral force vector to the de-rotation tower, and simultaneously applying a lateral counterforce vector to the stationary tower in opposition to the lateral force vector being applied to the de-rotation tower. The surgeon tensions the lower anterior tensioning cord in the channel of the second lower anterior anchor screw, and then secures the lower anterior tensioning cord in the channel of at the second lower anterior anchor screw in order to maintain the de-rotation of the lower vertebrae. The de-rotation tower is re-located to the lower anterior anchor screw of a subsequent lower vertebra, and the de-rotation maneuvers are repeated until all of the lower vertebrae have been de-rotated as desired.

Alternative Embodiments

Several alternative embodiments may be implemented, alone or in conjunction with each other, as now described below.

Non-Centered Anchor Screws

In the main embodiments described above, the anchor screws322are inserted in substantially the center of the side(s) of the vertebrae in order to provide enough surrounding bone mass for the anchor screw to maintain its placement and not plow through or out of the bone. However, in some instances, it may be possible to offset the anchor screws either horizontally and/or vertically off-center of the side(s) of the vertebrae in order to provide certain biomechanical advantages that will aid in the vertebrae adjustment procedures, as now further described.

FIG.28illustrates the same side elevation of a kyphotic spine ofFIG.20, but with a subset of the anchor screws322offset horizontally from the approximate vertical center line382of the side of the vertebrae. In particular, the anchor screws322on T9 and T10 are offset posteriorly from the approximate vertical center line382. As a result of this horizontally offset placement of the anchor screws322on T9 and T10, the tensioning cord338will be offset horizontally and located more towards the posterior in the middle of the spine at T9, T10 during de-rotation.

FIGS.29a-29dillustrate the vertebrae at various stages of the corrective de-rotation of the spine in this embodiment. The vertebrae T7 and T8 are in initially de-rotated as previously described, and then the tensioning cord338is inserted into the horizontally offset anchor screw322on T9 as shown inFIG.29a. Vertebra T9 is then de-rotated, and the tensioning cord338is then inserted through the horizontally offset anchor screw at T10, prior to de-rotation of T10, as shown inFIG.29b.

Vertebra T10 is then de-rotated, andFIG.29cillustrates the tensioning cord inserted through the anchor screws at T9 and T10 after de-rotation of T9 and T10.FIG.29dillustrates the tensioning cord inserted through all of the anchor screws and after de-rotation of all the vertebrae T6 through L1. It is noted that the anchor screws at T9 and T10 may still be slightly off-center, even after their de-rotation.

This alternative posterior offset placement of the anchor screws322provides the surgeon with biomechanical advantages and increased leverage as he or she performs the de-rotation maneuvers discussed above. In a further alternative embodiment (not shown), the anchor screws322may be inserted into each vertebrae gradually more posteriorly from the approximate vertical center line382along the horizontal axis from T6 through T9, then gradually more anteriorly along the horizontal axis from T10 through L1.

In another alternative embodiment shown inFIGS.30and31, a subset of the anchor screws322are offset vertically from the approximate horizontal center line384of the side of the vertebrae. That is, the anchor screws322are inserted gradually more towards the upper end of each vertebrae (and offset from the approximate horizontal center line384) going from T10 upwards towards T6, and likewise gradually more towards the lower end of each vertebrae (and offset from the approximate horizontal center line384) going from T11 downwards towards L1.FIG.31illustrates the tensioning cord338when located through the anchor screws322ofFIG.30, and after corrective de-rotation of all vertebrae. This alternative vertical offset placement of the anchor screws also provides the surgeon with biomechanical advantages and increased leverage as he or she performs the de-rotation maneuvers discussed above. This alternate placement of the anchor screws also provides better bone fixation and resistance to plowing of the screw in the vertebral body during tensioning. Note that this vertical offset methodology may be combined with the horizontal offset shown inFIG.28if desired.

Crossover Tensioning Cords

Shown inFIG.32is an alternative embodiment in which one of the tensioning cords in the double screw/double cord application crosses over from one row of anchor screws into the other row of anchor screws. As shown in this thoracic portion of the spine, a single posterior anchor screw322cis inserted into T6 and T7 as shown, and both the posterior tensioning cord338aand the anterior tensioning cord338bare disposed within the channels of those posterior anchor screws during de-rotation of T7 with respect to T6. Then, the posterior tensioning cord338ais disposed within the posterior anchor screw322con T8, while the anterior tensioning cord338bcrosses over and is disposed within the anterior anchor screw322don T8. This is shown in closeup detail inFIG.32a. Vertebra T8 is then de-rotated with respect to T6 and T7 using the posterior anchor screws322c, and the posterior tensioning cord338acontinues along the posterior anchor screws322c. De-rotation proceeds along the remaining vertebrae using the posterior anchor screws322cand the posterior tensioning cord338a. Similarly, the anterior tensioning cord338bis located through the anterior anchor screw322don T8, which is de-rotated with respect to T7. De-rotation proceeds along the rest of the vertebrae, now using the anterior anchor screws322dand the anterior tensioning cord338b. The corrected spine is shown inFIG.32. This procedure is particularly useful in situations in which two tensioning cords are desired for the de-rotation maneuvers, but certain vertebrae have only enough mass to hold a single screw.

In the more complex case of a double scoliosis curve, a similar cross-over technique may also be implemented.FIG.33shows the same thoracic side elevation as inFIG.26, but where the use of the upper bridge tensioning cord338eis eliminated, and the upper anterior tensioning cord338dextends through the upper anterior screw322gand over to and through the upper neutral anchor screw322j.FIG.33ashows this modification in closeup detail. Likewise (although not shown), at the lumbar portion, the lower bridge tensioning cord may be eliminated and the lower anterior tensioning cord338gmay extend through the lower anterior screw322iand over to and through the lower neutral anchor screw322k.

Crisscrossed Tensioning Cords

Several alternative embodiments are provided that utilize one or more crisscrossed tensioning cords in a double screw/double cord application. In general, in these embodiments, a tensioning cord crosses over from one row of anchor screws to the other row of anchor screws and back, one or more times, in a crisscross or weaved type of pattern. Either or both of the tensioning cords may crisscross in this manner, thus providing further advantages in de-rotation of the spine by providing greater strength and control of the corrected vertebrae, for example. These crisscrossed tensioning cords may be implemented alone or in conjunction with single or double straight tensioning cords, as now described with more particularity.

FIG.34aillustrates an alternative embodiment in which the thoracic portion of the spine has a double screw/double cord embodiment with a pair of linear tensioning cords and a (single) posterior crossover tensioning cord. Shown inFIG.34ais the spine in the final, corrected position, with all tensioning cords secured in place. In particular, a posterior crossover tensioning cord338iis added to the thoracic portion of the spine having a double screw/double cord embodiment with a pair of straight tensioning cords338a,338b, similar to what is shown inFIG.22. That is, in addition to the posterior tensioning cord338aand anterior tensioning cord338b, the posterior crossover tensioning cord338iis added at the posterior anchor screw322con T8, which then crosses over to the anterior anchor screw322don T9, then over to the posterior anchor screw322con T10, then over to the anterior anchor screw322don T11, where the posterior crossover tensioning cord338iterminates, thus forming a crisscross pattern. Thus,FIG.34aillustrates the thoracic portion of the spine after all relevant vertebrae have been corrected through de-rotation in accordance with this invention.

This modification may provide increased de-rotational correction stability in certain cases, meaning the prevention of loss of rotational correction that may sometimes occur after the de-rotation. It is noted that this is an example of this tensioning crisscross embodiment; the specific crisscross pattern may vary in accordance with the particular effect the surgeon is attempting to accomplish. For example, the crossover pattern may start on a different vertebra than T8, and/or begin on the anterior row of anchor screws322drather than the posterior row of screws322c, or it may implement less crossovers, or more crossovers, if desired.

FIG.34billustrates the same thoracic spine as inFIG.34a, but with a fourth tensioning cord added to provide a shoelace type pattern. Shown inFIG.34bis the spine in the final, corrected position, with all tensioning cords secured in place. In particular, an anterior crossover tensioning cord338jis interwoven with the other tensioning cords338a,338band338i. As shown in this example, in addition to the posterior tensioning cord338a, anterior tensioning cord338b, and posterior crossover tensioning cord338i, the anterior crossover tensioning cord338jis added at the anterior anchor screw322don T8, which then crosses over to the posterior anchor screw322con T9, then over to the anterior anchor screw322don T10, then over to the posterior anchor screw322con T11, where the anterior crossover tensioning cord338jterminates, thus forming a crisscross pattern with the posterior crossover tensioning cord338i. Together, the posterior crossover tensioning cord338iand anterior crossover tensioning cord338jcrisscross (similar to a pair of shoelaces), and interoperate with the posterior tensioning cord338aand anterior tensioning cord338b, to provide increased de-rotational correction stability in certain cases, and also helps to prevent the loosening of the cords that may sometimes occur after the de-rotation correction. Again, this is an example of this tensioning crisscross embodiment; the specific crisscross pattern may vary in accordance with the particular effect the surgeon is attempting to accomplish. For example, the crossover pattern may start on a different vertebra, or it may implement less crossovers, or more crossovers, if desired.

FIG.35illustrates an alternative embodiment in which the thoracic portion of the spine has a double screw/double cord embodiment with a pair of crisscrossed tensioning cords338i,338jbut no straight tensioning cords as inFIG.34b. As shown in this example, a posterior crossover tensioning cord338iand anterior crossover tensioning cord338jare located through the various anchor screws similarly to what was described above with respect toFIG.34b. That is, the posterior crossover tensioning cord338iis located through the posterior anchor screws322cat T6 and T7, then crosses over to the anterior anchor screw322don T8, then over to the posterior anchor screw322con T9, then over to the anterior anchor screw322don T10, then over to the posterior anchor screw322con T11, then over to the anterior anchor screw322don T12, then over to the posterior anchor screw322con L1 where the posterior crossover tensioning cord338iterminates.

Similarly, the anterior crossover tensioning cord338jis located on the anterior anchor screw322don T7, which then crosses over to the posterior anchor screw322con T8, then over to the anterior anchor screw322don T9, then over to the posterior anchor screw322con T10, then over to the anterior anchor screw322don T11, then over to the posterior anchor screw322con T12, then over to the anterior anchor screw322don L1, where the anterior crossover tensioning cord338jterminates, thus forming a crisscross pattern with the posterior crossover tensioning cord338i. Together, the posterior crossover tensioning cord338iand anterior crossover tensioning cord338jcrisscross (similar to a pair of shoelaces) to provide increased de-rotational correction stability in certain cases, and also helps to prevent the loosening of the cords that may sometimes occur after the de-rotation correction. Again, this is an example of this tensioning crisscross embodiment; the specific crisscross pattern may vary in accordance with the particular effect the surgeon is attempting to accomplish. For example, the crossover pattern may start on a different vertebra, or it may implement less crossovers, or more crossovers, if desired.

FIG.36illustrates an alternative embodiment in which the lumbar portion of the spine has a double screw/double cord embodiment with a pair of linear tensioning cords and a posterior crossover tensioning cord, similar to what is shown for the thoracic spine inFIG.34a. As shown inFIG.36, in addition to the posterior tensioning cord338aand anterior tensioning cord338b, the posterior crossover tensioning cord338iis added at the posterior anchor screw322con T11, which then crosses over to the anterior anchor screw322don T12, then over to the posterior anchor screw322con L1, then over to the anterior anchor screw322don L2, then over to the posterior anchor screw322con L3, where the posterior crossover tensioning cord338iterminates, thus forming a crisscross pattern. Of course, the tensioning cords338a,338b, and338iare inserted through the anchor screws322c,322don each particular vertebra as that vertebra is corrected with respect to the prior vertebrae, as explained previously. Thus,FIG.36illustrates the lumbar portion of the spine after all relevant vertebrae have been corrected through de-rotation in accordance with this invention.

This modification may provide increased de-rotational correction stability in certain cases, and also helps to prevent the loosening of the cords that may sometimes occur after the de-rotation correction. It is noted that this is an example of this tensioning crisscross embodiment; the specific crisscross pattern may vary in accordance with the particular effect the surgeon is attempting to accomplish. For example, the crossover pattern may start on a different vertebra than T11, and/or begin on the anterior row of anchor screws322drather than the posterior row of screws322c, or it may implement less crossovers, or more crossovers, if desired.

FIG.37illustrates the same lumbar spine as inFIG.36, but with a fourth tensioning cord added to provide a shoelace type pattern. Thus, an anterior crossover tensioning cord338jis interwoven with the other tensioning cords338a,338band338i. As shown in this example, in addition to the posterior tensioning cord338a, anterior tensioning cord338b, and posterior crossover tensioning cord338i, the anterior crossover tensioning cord338jis added at the anterior anchor screw322don T11, which then crosses over to the posterior anchor screw322con T12, then over to the anterior anchor screw322don L1, then over to the posterior anchor screw322con L2, then over to the anterior anchor screw322don L3 where the anterior crossover tensioning cord338jterminates, thus forming a crisscross pattern with the posterior crossover tensioning cord338i. Together, the posterior crossover tensioning cord338iand anterior crossover tensioning cord338jcrisscross (similar to a pair of shoelaces), and interoperate with the posterior tensioning cord338aand anterior tensioning cord338b, to provide increased de-rotational correction stability in certain cases, and also helps to prevent the loosening of the cords that may sometimes occur after the de-rotation correction. Again, this is an example of this tensioning crisscross embodiment; the specific crisscross pattern may vary in accordance with the particular effect the surgeon is attempting to accomplish. For example, the crossover pattern may start on a different vertebra, or it may implement less crossovers, or more crossovers, if desired.

Interplay of Disc Release, De-Rotation, and Double Screw/Double Cord Methodologies

As taught herein, various major aspects of the invention are the releasing of discs, the use of de-rotation maneuvers, and the use of double screws/double cords. Each of these three major aspects of the invention may be used independently of the others, or if applicable a surgeon may use two of these techniques or all three of these techniques as desired. For example, the de-rotation methodologies described herein may be implemented with a single screw/single cord application, but if the patient's scoliosis is so severe that double screws/double cords are required, then the de-rotation may be implemented with double screws/double cords. In that case, the surgeon would preferably implement the de-rotation correction techniques with the first set of screws/cord (e.g. the posterior set), and then repeat the same maneuvers with the second set (the anterior set). Similarly, the disc release procedure may not be applicable or even advisable in certain situations, in which case would not be performed by the surgeon.

Since each of the three major methodologies described herein address different problems encountered by the surgeon as described, it is up to the surgeon using professional judgment and experience which of these methodologies, and in which combination, would be best suited for a given procedure.