SE510257C2 - Brace device for correcting curvature of spinal column - Google Patents

Abstract

The device comprises at least two brace holders (1-5), each adapted to be arranged against an associated vertebral body (7-11) in the spinal column. A securing screw (6,6') is used for fixing the respective brace holders to the vertebral body and at least one elongated brace (12) which is made to extend through and between brace holders and locked thereto. The brace is rectangular in cross-section and that the brace holder is designed to support the brace in such a manner that the first flat side of the brace faces the abutment surface of the brace holder on the vertebral body, whereby the brace during mounting in the brace holders and during correction is deformable in only one geometric plane.

Description

510257 552 10 15 20 25 30 35 In the case of posterior fusion, the spinal column is exposed from the dorsal side, after which a brace is usually applied to the concave side of the spinal column. The strut is fixed to the spine by means of screws or so-called “hooks”, and the scoliosis is corrected by clamping the entire structure together with the help of a special instrument. The stability of the corrected vertebral column can then be improved by attaching a so-called compression strut to the convex side. The struts are then connected to each other via cross struts.

In anterior fusion, the spinal column is exposed from the trunk side, after which the anterior portions of the spinal column are explored from its convex side. Usually four to six disks are exposed, which are then resected. Holders are fixed to the vertebral bodies by means of screws that are attached to the spongy body of the vertebral body. Then a brace is fixed to the holders in such a way that the spine is corrected, compressed and stabilized. Anterior fusion is mainly used for certain types of spinal deformities in the lower thoracic and lumbar spine, which cannot be remedied by posterior fusion. These can be scoliosis with large defects in the posterior arch, such as spina bifida, rigid and severe scoliosis, congenital scoliosis, or severe forms of kyphosis.

Posterior and anterior fusion are often combined in cases where the frequency of pseudoarthrosis is high. Such a combined merger will also be more stable.

The operation time for a combined fusion can often amount to 10 -11 hours, which is an annoyingly long time from both the surgeons' and the patient's point of view.

Background Art EP-A-0 558 883 describes a type of device for correcting and stabilizing a spinal column by anterior fusion. The device comprises partly threaded struts with and partly vertebral screws, the heads of which have annular recesses for circular cross-section, and partly adjusting nuts, receiving said struts. The vertebral screws are fastened in suitable vertebral bodies in the vertebral column, after which the threaded struts are arranged to extend through said screw heads. During 10 15 20 25 30 35 U1 ... XC) DJ (31 x, J this working step, the adjusting nuts are placed on the threaded strut between the screw heads and screwed into abutment against them. By turning an adjusting nut on the threaded strut in relation to screw head, the surgeon can thus distract or compress the spine pillar.The adjusting nut can be secured in the desired position by means of an additional nut, which must have been applied to the strut together with the adjusting nut.

This known construction has a number of disadvantages. Due to the large number of loose parts that according to the above are included in the construction, this becomes relatively difficult and time-consuming to assemble. The surgeon may also find it difficult to perform the work of turning the nuts. Another serious disadvantage is that the stay is completely rigid. During the work, the extent of the stay must be adapted to the extent of the corrected vertebral column. This adjustment is done by bending the stay with the help of a special instrument and of course takes time and requires space. The construction is also associated with a certain risk that the strut will turn postoperatively, which will result in the defect recurring. In addition, the structure in its assembled condition will protrude a considerable distance from the spine, which means that adjacent blood vessels can be damaged by these protruding parts when the patient begins to move after the operation.

In the brochure published by COLORADO “Systeme Colo- (1995) device comprising holders and rigid struts with cirrado pour la colonne” a similar corrective cross-section is described. Both the holders and the struts lack threads.

The holders are fastened by means of screws in suitable vertebrae along the vertebral column, after which the strut is arranged to extend through all the holders. The stay is then attached to a first holder, which is anchored in the lower vertebral body of the portion to be corrected. Thereafter, the strut is attached to the next holder while the spine is straightened and compressed to the desired extent. The process is repeated 510 257 4 10 15 20 25 30 35 until the applied portion of the spine is straightened, compressed and stabilized.

Apart from the fact that it consists of fewer parts, this construction has in principle the same disadvantages as the above-mentioned device, ie rigidity of the struts, time-consuming assembly, risk of the struts twisting postoperatively, and protruding parts which can damage adjacent tissues.

WO 93/20771 discloses a correction device, which, among other things, is intended to make the stay more flexible in order to facilitate the surgeon's work. This device comprises screws, holders and wires. The holders are fastened with the help of the screws in suitable vertebrae. Two parallel wires, spaced apart from each other, are set up between the holders. The wires are attached to a first holder, passed through the next holder, subjected to the appropriate tension and attached to this holder while the spine is straightened and compressed to the desired extent, after which the wires are passed on to the next holder. The process is repeated until the applied portion of the spine is straightened and compressed.

This device is certainly compliant during assembly, but unfortunately compliance is also found in the assembled construction. The device lacks, for example, a complete ability to absorb longitudinal forces. Furthermore, this device exhibits poor torsional rigidity, which is a disadvantage in the correction of scoliosis, since a scoliosis-affected vertebral column, as described above, is often rotated about its own longitudinal axis.

Accordingly, a device for stabilizing a straightened, scoliosis-affected vertebral column should be able to absorb torsional forces. The wire construction is also difficult to assemble because the wires lack inherent stability. There is therefore a risk that the surgeon tightens the wires too hard, which can lead to an overcorrection of the spine.

Since the wires will necessarily have smaller cross-sectional dimensions than the above-mentioned rigid struts and in addition will be subjected to significant clamping forces in the holders, this device has a increased risk of crime. A wire break would cause the surrounding blood vessels to be destroyed, and the patient risks bleeding.

U.S. Pat. No. 4,448,191 discloses a rear fusion fusing device which comprises a resiliently biased strut, which is intended to be arranged against the spine in such a way that it is straightened via the biasing force of the strut. The spine is thus forced to adapt to the stay. The correction thus takes place in one step by applying the strut to the spine, and the surgeon therefore has no possibility of gradually working his way along the spine. Although the device achieves a lateral straightening of the spine, it also complicates the surgeon's work of twisting and compressing the spine and should therefore be unsuitable for correcting structural scoliosis. The device also has protruding, sharp parts which, when mounted, can cause injuries to the patient.

US-3-648,691 discloses a device for stabilizing a spine by posterior fusion. This device also does not allow compression of the spine because the device lacks adequate fastening means for this purpose.

Furthermore, the ability of the device to absorb torsional forces should be insufficient to correct scoliosis.

SUMMARY OF THE INVENTION It is an object of the present invention to completely or at least substantially overcome the above-described problems of the prior art, and in particular to provide a device for correcting deviating curvature of a spine, which device is easy to apply to the spine and thus allowing shorter operating times.

The device shall, in its assembled condition, fully or partially stabilize the corrected spine.

It is another object of the invention to provide a device which can be firmly anchored to the spine and which has a low probability of crime. 510 257 i 6 10 15 20 25 30 35 It is also an object to enable and facilitate compression of the spine in connection with mounting of the device.

It is a further object to provide a device which easily allows readjustment of the corrected spine.

It is also an object to provide a device which during the operation is resilient and which, when mounted, is able to absorb torsional forces.

It is also an object of the present invention to provide a device which, when assembled, has little tendency to damage adjacent blood vessels.

These and other objects, which will become apparent from the following description, have now been achieved with a device and a stay holder of the type defined in the following claims 1 and 10, respectively. Subordinate claims indicate preferred embodiments.

By using a correction device according to the invention, the operating times can be significantly shortened.

The surgeon first mounts a number of brace holders on suitable vertebral bodies along the vertebral column, after which the disc-shaped brace is mounted in the brace holders with a flat side facing the abutment surfaces of the brace holders on the vertebral bodies. Due to its formability, the disc-shaped strut can be easily and quickly bent or bent to follow the extent of the uncorrected spine. The surgeon then locks the strut in a first strut holder and then works step by step while vertebrae are displaced and compressed into a corridor along the vertebral column, vertebra by vertebra, the pillar is rotated, geared position and while the strut is simultaneously tensioned and locked in the strut holders .

Thanks to its disc shape, the strut is sufficiently flexible to facilitate assembly, but at the same time has an inherent rigidity that gives a small risk of overcorrection of the spine in this context. In the assembled state, the strut also has a considerable torsional rigidity and is able to absorb the rotating force of the corrected spine. lO 15 20 25 30 35 ou _ .. \ ct »r ~> m -J The disc shape of the strut also enables such a form-locked locking in the strut holders that postoperative rotation is made impossible.

The use of the disc-shaped strut in combination with the strut holders according to the invention leads to the device in the assembled state being streamlined and not projecting from the spine.

Brief Description of the Drawings The invention and its advantages will be described in more detail in the following with reference to the accompanying drawings, which for exemplary purposes show a presently preferred embodiment.

Fig. 1 is a side view of a device according to the invention in mounted condition, the device being mounted on a healthy and thus uncorrected vertebral column for reasons of convenience, and Fig. 2 is a cross-sectional view along the line II in Fig. 1, the vertebral body and vertebral screws not shown for the sake of clarity.

Description of a preferred embodiment Fig. 1 shows the device according to the invention in mounted condition on a spine. In the example shown, the device has five strut holders 1, 2, 3, 4, 5, two vertebral screws 6, 6 'for fastening the respective strut holder 1, 2, 3, 4, 5 to the vertebral body 7, 8, 9, 10, 11, and an elongate, disc-shaped strut 12. Normally, a corresponding device is also arranged on the opposite side of the spine.

The bracket holder 1 has, as can be seen from Fig. 2, a body comprising an elongate bottom plate 13, which in its respective end portion has a through-going fastening hole 14, 14 'for receiving a fuse screw 6, 6'. The underside of the base plate 13 has a shape which substantially corresponds to the outer surface of the vertebral body 7. On the upper side of the base plate 13, two flanges 15, 15 'projecting perpendicularly from the base plate 13 between the through mounting holes 14, 14' are formed, which extends over the width of the base plate 13 and delimits a space and a flat bearing surface 16 therebetween. Q1 ~ <1 w the bearing surface 16, a projecting locking element 17 is formed in the form of two tips, the size of which, however, has been exaggerated 15 'away from the bottom plate 13 facing edge portions are guide flanges 18, 18' in Fig. 2. 15, which extend away from each other in a geometric plane which is substantially parallel to the plane of the support surface 16.

The strut holder 1 further comprises a C-shaped cover plate 19. On the inside of said C, two opposite grooves 20, 20 'are formed in such a way that they can be form-fitted. The cover plate 19 has a through-threaded hole 21 for receiving a locking plate. take said guide flanges 18, 18 '. in the form of a screw 22. The screw 22 has a pointed end portion 23 for engagement with the strut 12. On the opposite end portion of the screw 22, a hexagonal recess is designed for engagement with a suitable hexagon wrench. It will be appreciated that the design of the recess is not critical to the invention. The strut holder 1 is preferably designed such that the screw 22 in its locking position in the strut 12 is countersunk in the cover plate 19.

The spigots 6, 6 'are of the conventional type and are therefore not shown in more detail. They are designed to extend through the attachment holes 14, 14 'and into the vertebral bodies 7, 8, 9, 10, 11.

The strut 12 is elongate, disc-shaped and in cross-section preferably rectangular. The strut 12 has a first and a second, opposite flat side and two opposite edge surfaces. Thanks to its disc shape, the strut 12 can be easily deformed, ie bent or bent, in a geometric plane which extends perpendicular to the flat sides of the strut 12. The strut 12 can only be deformed with great difficulty in other geometric planes, where there is a large bending resistance. Due to its thickness, the Staget is preferably made of stainless steel, but other metallic materials are also The width of the Staget is about 4-10 mm, conceivable, eg titanium. preferably about 5-8 mm, and its thickness is about 1-3 mm, preferably about 1.5-2 mm.

In the following, the surgical procedure for mounting the correction device will be described in more detail. 10 15 20 25 30 35 m _. \ LD ro m -J Initially, the surgeon exposes a portion of the spine from the patient's ball face. Normally, four to six vertebral bodies and discs are exposed from the convex side of the scoliosis, after which a resection of the discs is performed, which the main part of the discs is removed. Then a first base plate 13 is applied to an exposed vertebral body 7 and fastened by screwing two vertebral screws 6, 6 'into the spongy legs of the vertebral body 7. The surgeon then attaches additional base plates to suitable vertebral bodies 8, 9, 10, 11 along the extent of the as yet uncorrected vertebral column.

A disc-shaped strut 12 is then applied to the flat support surface 16 of the first base plate 13, whereupon the cover plate 19 is attached to the base plate 13 by sliding the grooves 20, 20 'over the guide flanges 18, 18', 22 into the hole 21 of the cover plate 19. is then pushed forward and applied to the support surface of a second follower and a locking element, the second bottom plate 24, after which a cover plate 19 and a locking element 22 are mounted thereon. This procedure is repeated until the distal base plate 27 is reached and the strut 12 consequently extends along the portion of the spine to be corrected. Thereafter, all locking elements 22 are clamped so that the tips 23 abut and engage the strut 12 from the vertebral bodies 7, 8, 9, 10, 11 facing flat side. It is understood that the pointed locking element 17 in the support surface 16 engages with the flat side of the strut 12 towards the vertebral bodies 7, 8, 9, 10, 11 and helps to lock the strut 12 in the respective strut holders 1, 2, 3, 4, 5. It deserves that It is pointed out that the strut 12, during its initial, unlocked mounting in the strut holders 1, 2, 3, 4, 5, is deformed to assume a shape which substantially follows the extent of the as yet uncorrected vertebral column.

The surgeon then loosens the locking element 22 of the second brace holder 2 and compresses the vertebral column section between the first and second holders 1, 2 by means of a special compression instrument (not shown). During this procedure, the scoliosis-related rotation and lateral displacement of the spine column are corrected. At the same time with comp- 10 15 20 25 30 35 ... \.

CI) 10 IQ U '"| recession, the locking element 22 of the second stay holder 2 is clamped against the stay 12, which is thus fixed in position. The procedure is then repeated for stay holders for stay holders along the spine until the correction is carried out.

The strut holder 1 is arranged on the vertebral body 7 to support the strut 12 in such a way that one flat side of the strut 12 faces the abutment surface of the strut holder 1 on the vertebral body 7. Thus, the strut 12 is deformable during assembly in only a geometric plane substantially parallel to the vertebral column of the vertebral column. , ie the plane in which the deviating curvature extends. The plane of error is when correcting scoliosis substantially perpendicular to the sagittal plane of the vertebral column, and when correcting kyphosis substantially parallel to said sagittal plane. Due to the shape of the disc, the surgeon * can relatively easily, without the aid of special instruments, deform the strut 12 to extend along the deviating curvature of the spine. The metallic strut 12 thus imparts to the vertebral column a certain resilient force which seeks to straighten it. The resilience of the strut 12 in the spine misalignment plane also facilitates the surgeon's work to the extent that during the stepwise correction he can easily adjust the extent of the strut 12 to the corrected spine.

The strut 12 naturally has different deformability depending on its thickness. Thin struts, with a thickness of about 1-1.5 mm, show great compliance. However, these struts should be supplemented with a standard, rear correction device to give the corrected vertebral column sufficient stability. However, such a rear correction device can be mounted relatively quickly since the spine column has already been corrected by means of the device according to the invention.

Stronger struts, with a thickness of about 1.5-3 mm, give the corrected spine a greater stability and can in some cases be used alone, ie without a rear correction device. These braces still have a sufficient deformability to facilitate the surgeon's correction work.

The use of a disc-shaped stay 12 together with the suitably designed stay holders 1, 2, 3, 4, 5 results in significantly reduced operating times. With conventional technology, the operation time in the case of anterior fusion is about 4-5 hours, of which about 2-2.5 hours are spent on the actual correction and stabilization of the spine. Clinical trials have shown that the use of a device according to the invention can reduce the operating time at anterior fusion to about 3-4.5 hours by shortening the work of stabilizing and correcting the spine by about 1-1.5 hours.

From the above description it appears that the device is intended for anterior fusion, more specifically for application to the vertebral bodies 7, 8, 9, 10, 11 of the vertebral column. The use of vertebral screws 6, 6 'provides a very reliable attachment of the strut holders 1, 2, 3, 4, 5 to the vertebral bodies 7, 8, 9, 10, ll.

Thanks to the disc shape of the strut, the device, despite its good resilience during assembly, has a good torsional rigidity in the mounted condition and can therefore absorb the twisted force of the corrected spine. The device is preferably used in pairs, ie another device is mounted on the opposite side of the spine.

A great advantage of the device lies in the fact that it can be mounted very close to the spine, which reduces the risk of protruding parts scarring adjacent blood vessels and tissues when the patient begins to move after the operation.

The design of the strut holder 1 with a releasable cover plate 19 facilitates the correction because the surgeon can bend the strut 12 to a direct abutment against the support surface 16 and then mount the cover plate 19 for retaining the strut 12 against its resilient force. Alternatively, it is conceivable to design the stay holder 1 in one piece with a continuous receiving channel (not shown) in this goat. 10 15 10 257 212 cases, however, the strut 12 must be bent and slid at the same time during assembly, which should complicate the work somewhat.

It is preferred that the distance between the projecting flanges 15, 15 'of the strut holder 1 exceeds the width of the strut 12 by preferably at least 1 mm. This simplifies the application of the strut 12 to the bearing surface 16 of the strut holder 1.

The stay holder 1 is designed so that the stay 12 postoperatively. In the locked condition, therefore, one flat side of the stay 12 abuts against the plane and cannot rotate in the holder 1. the bearing surface 16. In addition, the distance between the support surface 16 and the cover plate 19 is preferably less than the width of the stay 12.

It will be appreciated that the device can be easily readjusted by the surgeon loosening the strut 12 at the second strut holder 2 and again working his way along the spine according to the procedure above.

Claims (9)

10 15 20 25 30 35 13 01 ... Ä ca N: (_11 -4 PATENTKRAV Device for correcting and stabilizing deviating curvature of a vertebral column by anterior fusion, comprising at least two strut holders (1, 2, 3, 4, 5), each intended for application to a respective vertebral body (7, 8, 9, 10, 11) in the vertebral column, a fastening means (6, 6 ') for attaching the respective stay holder (1, 2, 3, 4, 5) to said vertebral body (7, 8, 9, 10, 11), and a and only an elongate strut (12), which in use for said correction and stabilization extends through and between said strut holders (1, 2, 3, 4, 5) and is locked thereto, characterized in that the strut ( 12) is substantially rectangular in cross section and has a width of about 5-8 mm and a thickness of about 1-3 mm and consists of stainless steel or titanium, so that the strut is manually deformable in a geometric plane that is perpendicular to one the large large side of the strut, and that the strut holder (1, 2, 3, 4, 5) supports the strut (12) in such a way that one large flat side of the strut (12) faces the strut holder even (1, 2, 3, 4, 5) abutment surface on said vertebral body (7, 8, 9, 10, 11), the strut (12) during mounting in the strut holders (1, 2, 3, 4, 5) without being locked at these and during the correction is deformable in only said geometric plane, to follow the deviating curvature of the spine. Device according to claim 1, in which the strut (12) has such a torsional rigidity that it resists the rotating torque of the corrected spine. Device according to one of the preceding claims, in which the strut (12) has a thickness of approximately 1.5-2 mm. Device according to one of the preceding claims, in which the fastening member (6, 6 ') is at least one screw which extends through a recess (14, 14') in the respective stay holder (1, 2, 3, 4, 5). Bracket holder in a device according to any one of the preceding claims, comprising a frame (13, 19) for receiving the brace (12), 14 and a first locking element (22), which is in threaded engagement with a recess ( 21) in the frame (13, 19) and that with its one end portion (23) abuts against the strut (12) for locking it in relation to the frame (5, 11), 19) comprises a bottom plate for abutment against the respective vertebral body (7, 8, 9, 10, (12), and one with the bottom plate cover plate (19), (19). A strut holder according to claim 5, wherein said end portion (23) is flat. A strut holder according to claim 5 or 6, wherein the bottom plate (13) has a strut (12) flat support (16). Bracket holder according to one of Claims 5 or 6, in which the base plate (13) (16) projects second locking element (17). Bracket holder according to any one of claims 5-8, wherein the first locking element (22) has such an extent that its second, opposite end portion at locked bracket (12) is (21) (19). characterized in that the frame (13, (13) ll) and for receiving the strut (13) (21) is designed in cover engagement, releasable and that the recessed plate is arranged to engage with the second receiving, surface of the strut (12) has a bearing surface designed with recesses in the recess in the cover plate