Annular assistance device

Abstract

The present invention relates to a discal annular assistance device and the surgical instruments necessary for the insertion and removal thereof. This new device assists the annulus fibrosus following the exeresis of the nucleus pulposus of a lumbar intervertebral disc, to stop accelerated progression towards the discoligamentous instability of a vertebral unit operated on for a nucleus pulposus hernia.

Claims

1. An annular assistance device (AAD) for its positioning in a disc space between vertebrae of a spinal unit, comprising: a semi-rigid ring of non-uniform height, having a variable geometry that stabilizes at its final working position in a form of a cardioid; said cardioid having two lateral poles, distal and proximal in relation to an operator, and two perimeter portions, one anterior and one posterior; wherein said poles serve as anchor points for a closing element; and wherein supporting ribs are projected in a centripetal manner from said perimeter portions; fastening spikes at ends of the supporting ribs; an elongated closure element placed on a major or transverse axis of the semi-rigid ring that ensures, by means of its traction, a final geometric configuration, once housed inside the disc space; and a positioning element that rests temporarily on the distal pole of the semi-rigid ring to control its positioning; wherein a posterior section of the distal pole of the semi-rigid ring has two slots located between a base of a most distal posterior supporting rib and the anchor point for the closing element; and wherein the positioning element is made from a resistant polymer that links to the distal pole of the semi-rigid ring by entering, loosely, by one of the slots and exiting through an other one of the slots.

2. The annular assistance device, according to claim 1, wherein in its final architectural configuration, the semi-rigid ring has a sagittal section with a convex outer surface in its ventral and lateral aspect and is concave in its posterior aspect.

3. The annular assistance device according to claim 2, wherein the semi-rigid ring is concave in its interior aspect.

4. The annular assistance device, according to claim 2, wherein in a sagittal section, upper and lower edges of the semi-rigid ring are convex and congruent with a surface of a disc platform, through which it relates to an adjacent vertebra.

5. The annular assistance device according to claim 1, wherein the semi-rigid ring can change its geometry from a configuration of minimum interior space when folded around its transverse axis, to that of a cardioid with its major axis perpendicular to a mid-sagittal plane of a vertebral unit.

6. The annular assistance device according to claim 1, wherein the maximum height of the semi-rigid ring has a maximum height equal to an average distance between vertebrae adjacent to the disc space.

7. The annular assistance device according to claim 6, wherein the maximum height of the semi-rigid ring is minimally exceeded by the fastening spikes at the ends of the supporting ribs projected from the posterior perimeter portion.

8. The annular assistance device according to claim 1, wherein the elongated closure element is made from a biocompatible material and has a cylindrical section with its anterior and posterior ends truncated, the elongate closure element further comprising an inner duct that runs through the elongated closure element from its proximal end to a section of the elongated closure element that is inside the semi-rigid ring, wherein the elongated closure element crosses the major axis of the semi-rigid ring and is solidly anchored to the distal pole of the semi-rigid ring.

9. The annular assistance device according to claim 8, wherein the distal pole of the semi-rigid ring has an increase in thickness that defines a resistant anchor point in which there is an entry hole with a countersunk conical section with a gap; said gap serving as a unidirectional hook to accommodate and secure in its position a first portion of the elongated closure element.

10. The annular assistance device according to claim 8, wherein the elongated closure element presents a solid portion of a conical section with an increase in diameter that defines a unidirectional lock and that is anchored in the distal pole of the semi-rigid ring, without distorting its outer surface.

11. The annular assistance device according to claim 8, wherein the inner duct of the elongated closure element communicates with an inner space of the semi-rigid ring through a plurality of micro perforations.

12. The annular assistance device according to claim 1, wherein the proximal pole of the semi-rigid ring comprises a unidirectional book and a tubular exit hole for the elongated closure element, said tubular exit hole allows the elongated closure element to completely cross the semi-rigid ring and extend towards a place from where it is handled.

13. The annular assistance device according to claim 12, wherein elongated closure element comprises a section having locking elements in its ventral face, said locking elements functioning as a unidirectional lock for fixing said elongated closure element to the semi-rigid ring.

14. The annular assistance device according to claim 13, wherein between the locking elements is a space greater than a distance that separates the unidirectional hook at the proximal pole of the semi-rigid ring from the tubular exit hole thereof.

15. The annular assistance device, according to claim 13, wherein the elongated closure element presents marks indicating that a last locking element is captured in the unidirectional hook of the proximal pole of the semi-rigid ring; said marks being arranged in an extension of the elongated closure element near the operator.

16. The annular assistance device according to claim 13, wherein the elongated closure element has a diameter reduction between each of its locking elements; said diameter reduction defining a structural weakness point.

17. The annular assistance device according to claim 13, wherein the section with locking elements of the elongated closure element comprises a first distal end, and a gap whose geometry and tolerance define the unidirectional hook for locking elements.

18. The annular assistance device according to claim 17, wherein the tubular exit hole of the semi-rigid ring has a tolerance immediately proximal to the unidirectional hook of the locking elements that, after a rotation of the elongated closure element, cuts it just outside the semi-rigid ring.

19. The annular assistance device according to claim 12, wherein a surface of the proximal pole of the semi-rigid ring presents two holes, one upper and one lower with respect to the tubular exit hole of the elongated closure element, for receiving a tool for pushing the annular assistance device into the disc space.

20. The annular assistance device according to claim 12, wherein a surface of the proximal pole of the semi-rigid ring comprises a posterior perforation with respect to the tubular exit hole of the elongated closure element, whose longitudinal axis leads to the unidirectional hook.

21. The annular assistance device according to claim 1, wherein the supporting ribs projecting from the posterior perimeter portion of the semi-rigid ring comprise securing slots whose dimension is coincident with an outer diameter of a body of the elongated closure element.

22. The annular assistance device, according to claim 21, wherein the fastening spikes are arranged at the ends of the posterior supporting ribs in such a way that, when the elongated closure element is housed in the securing slots located in its meridian plane, the fastening spikes protrude beyond an upper and lower limit of the semi-rigid ring.

23. The annular assistance device according to claim 1, made from a biocompatible, osteoinductive and radiolucent material, with or without shape memory, and having a stable structure and behavior at body temperature, in addition to inserts of osteoinductive metal on the spikes of the posterior supporting ribs.

24. A procedure for placing an annular assistance device (A DD) into the a disc space between vertebrae of a spinal unit, said procedure comprising the steps of” providing said annular assistance device comprising: a semi-rigid ring of non-uniform height, having a variable geometry that stabilizes at its final working position in a form of a cardioid; said cardioid having two lateral poles, distal and proximal in relation to an operator, and two perimeter portions, one anterior and one posterior; wherein said poles serve as anchor points for a closing element; and wherein supporting ribs are projected in a centripetal manner from said perimeter portions; fastening spikes at ends of the supporting ribs; an elongated closure element placed on a major or transverse axis of the semi-rigid ring that ensures, by means of its traction, a final geometric configuration, once housed inside the disc space; and a positioning element that rests temporarily on the distal pole of the semi-rigid ring to control its positioning; wherein a posterior section of the distal pole of the semi-rigid ring has two slots located between a base of a most distal posterior supporting rib and the anchor point for the closing element; and wherein the positioning element is made from a resistant polymer that links to the distal pole of the semi-rigid ring by entering, loosely, by one of the slots and exiting through an other of the slots; arranging the elongated closure element of the annular assistance device on a transverse axis of the semi-rigid ring of the annular assistance device by introducing the elongated closure element, first through an entry hole in the distal pole of the semi-rigid ring, and then pulling the elongated closure element from an inside of the semi-rigid ring through an exit slot of the proximal pole, thus allowing to secure a unidirectional lock of a distal end of the elongated closure element and to hook said unidirectional lock to secure the elongated closure element in the proximal pole of the semi-rigid ring; inserting the positioning element of the annular assistance device into slots of the distal pole of the semi-rigid ring; shortening to a minimum a minor axis of the semi-rigid ring, with its elongated closure element and its positioning element, to place them inside a solid capsule at a distal end of an insertion cannula whose shape allows it to act as a separation piece of the disc space, with its elements properly positioned in its core; inserting the annular assistance device housed in the solid capsule in the disc space, using the a standard microsurgical approach route generated for resection of a lesion of the a nucleus pulposus, with endo- or exoscopic microsurgical discretion; pulling the elongated closure element to obtain a final cardioid geometric configuration of the annular assistance device; administering, through an inner canal of the elongated closure element, bioactive materials of clinical utility in an inner confined space of the annular assistance device, and cutting off the end of the elongated closure element protruding from the semi-rigid ring with the annular assistance device in its correct working position.

25. A procedure for removing an annular assistance device (ADD) from a disc space between vertebrae of a spinal unit, said annular assistance device comprising: a semi-rigid ring of non-uniform height, having a variable geometry that stabilizes at its final working position in a form of a cardioid; said cardioid having two lateral poles, distal and proximal in relation to an operator, and two perimeter portions, one anterior and one posterior; wherein said poles serve as anchor points for a closing element; and wherein supporting ribs are projected in a centripetal manner from said perimeter portions; fastening spikes at ends of the supporting ribs; an elongated closure element placed on a major or transverse axis of the semi-rigid ring that ensures, by means of its traction, a final geometric configuration, once housed inside the disc space; and a positioning element that rests temporarily on the distal pole of the semi-rigid ring to control its positioning; wherein a posterior section of the distal pole of the semi-rigid ring has two slots located between a base of a most distal posterior supporting rib and the anchor point for the closing element; and wherein the positioning element is made from a resistant polymer that links to the distal pole of the semirigid ring by entering, loosely, by one of the slots and exiting through an other of the slots; said procedure comprising the steps of: a. destroying a locking element of the elongated closure element of the annular assistance device, by inserting an extraction rod, having a conical and striated tip placed at the end of it, that is sufficiently long for its handling from outside of a surgical field, through a posterior perforation with respect to a tubular exit hole of the elongated closure element, located at the proximal pole of the semi-rigid ring of the annular assistance device; b. hooking the annular assistance device which, when disassembled, acquires a geometry in which its interior space can collapse until a bi-laminar section is acquired; and c. removing the annular assistance device through a split tubular cannula that exposes its distal portion in the disc space by conveniently separating it to facilitate removal of the device.

Description

DESCRIPTION OF THE FIGURES

(1) FIG. 1a: Isometric view of the semi-rigid ring;

(2) FIG. 1b: Axial view of the semi-rigid ring with detail in support ribs (b′, upper rib; b″, lower rib);

(3) FIG. 1c: Sagittal view of the semi-rigid ring;

(4) FIG. 1c′: Detail view of the upper pole of the semi-rigid ring, focused on the portion of anterior and posterior ribs;

(5) FIG. 1d: Axial view of the semi-rigid ring with its closure element (d′, detail view of locking element, d″, detail view of locking elements in proximal pole);

(6) FIG. 1x: Fibrous ring present in the intervertebral disc;

(7) FIG. 1A: Axial section view in of the semi-rigid ring inserted in the disc space, in its spinal unit;

(8) FIG. 1B: Isometric view of the semi-rigid ring contained inside a spinal unit, composed of an intervertebral disc and its adjacent vertebrae;

(9) FIG. 2a: Axial view of the semi-rigid ring;

(10) FIG. 2a′: Ventral section view, oriented from the anterior face towards the posterior face;

(11) FIG. 2a″: Sagittal section view of the semi-rigid ring, oriented from the proximal pole to the distal pole;

(12) FIG. 2b: Sectional view of the sagittal plane of the semi-rigid ring, oriented in perspective view from the proximal pole to the distal pole;

(13) FIG. 2b′: Detail view, showing the slight concavity of the interior aspect of the anterior face;

(14) FIG. 2b″: Detail view, showing the slight concavity of the inner aspect of the posterior face;

(15) FIG. 2c: Sagittal section of the semi-rigid ring inside its spinal unit, in the disc space;

(16) FIG. 3: Axial view of the semi-rigid ring, in a configuration of minimum interior space, inside the intervertebral disc;

(17) FIG. 4a: Sagittal section view of the semi-rigid ring, contained in its spinal unit, focused on its posterior face;

(18) FIG. 4a′: Detail view of the posterior support rib of the semi-rigid ring in contact with the upper vertebra;

(19) FIG. 4a″: Detail view of the posterior support rib of the semi-rigid ring in contact with the lower vertebra;

(20) FIG. 4A: Axial view of a spinal unit;

(21) FIG. 5a: Detail view of the inside of the semi-rigid ring with its closure element housed in the securing slots of the posterior support ribs;

(22) FIG. 5b: Detail view of the semi-rigid ring, focused on the access of the distal pole and the posterior support rib with its slot;

(23) FIG. 5b′: Detail view of the semi-rigid ring, housing the closure element in its distal pole;

(24) FIG. 5A: Semi-rigid ring with its closure element, oriented in a perspective view towards the anterior face and the distal pole;

(25) FIG. 6a: Axial view of the semi-rigid ring armed with the closure element and the positioning element;

(26) FIG. 6a′: Detail view of the posterior face and distal pole of the semi-rigid ring, indicating the location of the positioning element;

(27) FIG. 6b: Detail perspective view of the semi-rigid ring, focused on its posterior face and distal pole of the positioning element;

(28) FIG. 7a: Detail view of the closure element showing the hole towards the inside of the semi-rigid ring;

(29) FIG. 7b: Detail view of the closure element indicating the distal pole along with its unidirectional lock;

(30) FIG. 7A: Axial section view of the closure element from its distal to proximal pole;

(31) FIG. 8a: Isometric view of the semi-rigid ring, oriented towards the posterior face and proximal pole;

(32) FIG. 8a′: Detail view of the proximal pole indicating the tubular exit hole for the closure element;

(33) FIG. 8b: Axial section view of the semi-rigid ring indicating the location of the closure element from the inside towards the surgical area;

(34) FIG. 9a: Axial view of the closure element from the distal pole to the section with the locking elements in its proximal pole;

(35) FIG. 9a′: Detail perspective view of the section with the locking elements of the closure element;

(36) FIG. 9b: Perspective view of the semi-rigid ring in axial section, together with its closure element positioned in the proximal pole;

(37) FIG. 10a: Axial view of the proximal pole of the closure element focused on its locking elements;

(38) FIG. 10a′: Detail view of the proximal pole of the closure element, highlighting the reductions in diameter by section;

(39) FIG. 10b: Axial section view of the semi-rigid ring and of the closure element mounted in its working position, from its distal pole to its locking elements;

(40) FIG. 10b′: Detail view of the proximal pole of the closure element;

(41) FIG. 11a: Ventral view of the semi-rigid ring towards the anterior face;

(42) FIG. 11a′: Sagittal section view towards the distal pole of the semi-rigid ring;

(43) FIG. 11b: Detail view of the semi-rigid ring on its posterior face, indicating the securing slots of the support ribs, without the closure element;

(44) FIG. 11c: Detail view of the semi-rigid ring on its posterior face, indicating contact of the securing slots with the closure element;

(45) FIG. 11c′: Detail view of the support rib, with its slot in contact with the closure element;

(46) FIG. 12a: Axial section view of the semi-rigid ring;

(47) FIG. 12a′: Detail view of the tubular exit hole, in the proximal pole of the semi-rigid ring which is divided into a distal and a proximal portion;

(48) FIG. 12a″: Detail perspective view of the distal portion of the tubular exit hole containing the closure system;

(49) FIG. 12b: Detail perspective view of the proximal portion of the tubular exit hole, indicating the fastening area of the closure element;

(50) FIG. 12b′: Detail view, in perspective, of the semi-rigid ring in axial section and the closure element, with the closure system between the closure element and the semi-rigid ring;

(51) FIG. 13a: Axial section view of the semi-rigid ring in its minimum interior space configuration, while the closure element is being inserted, the projections of the elements are all inside the semi-rigid ring;

(52) FIG. 13a′: Axial section view of the semi-rigid ring in its fully assembled state, the number of locks of the closure element is “y”;

(53) FIG. 13b: Detail view of the closure element exiting the removal instruments, when the semi-rigid ring is in its minimum space configuration, the number of projections “x” at the instruments exit is zero;

(54) FIG. 13b′: Detail view of the closure element exiting the removal instruments, in the fully assembled state of the semi-rigid ring, the number of projections “y” at the exit of the instrument is greater than “x”;

(55) FIG. 14a: Axial section view of the proximal pole of the semi-rigid ring next to the closure element in its armed position;

(56) FIG. 14a′: Axial section view of the proximal pole of the semi-rigid ring, closure element separated by fracture in the distal portion of the tubular exit hole;

(57) FIG. 14b: Axial view of the distal pole of the semi-rigid ring, indication of detachment of the positioning element of the semi-rigid ring, after its location in the disc space;

(58) FIG. 15a: Isometric view of the semi-rigid ring focused on the proximal pole and posterior face;

(59) FIG. 15a′: Detail view of the semi-rigid ring, highlighting the two previous perforations for tool pushing and mill drilling;

(60) FIG. 15b: Axial section view of the proximal pole and posterior face of the semi-rigid ring, indicating the perforation for the entry of the extraction rod, line of action on the closure system;

(61) FIG. 15b′: Axial section view of the proximal pole and posterior face of the semi-rigid ring, indicating the behavior of the extraction rod when entering through the perforation and unloading the material in front of it;

(62) FIG. 16a: Axial view of the semi-rigid ring, with closure element at the access of the posterior distal pole;

(63) FIG. 16a′: Axial view of the semi-rigid ring, with closure element partially inserted in its interior;

(64) FIG. 16a″: Axial view of the semi-rigid ring, with closure element located completely inside;

(65) FIG. 17a: Ventral posterior view of the spinal unit, indicating the workspace in the vicinity of the neural elements of the spinal canal;

(66) FIG. 17b: Sagittal section view of the untreated spinal unit, indicating the height of the disc space “y”;

(67) FIG. 17b′: Sagittal section view of the spinal unit with the action of the distal end of the insertion cannula, separating the disc space to a dimension “x”, greater than the previous “y” space;

(68) FIG. 17A: Axial view of the surgical instruments, traveling along the route used to resect the lesion of the nucleus pulposus, towards the treated disc, the instruments contain the semi-rigid ring with its closure element and the positioning element;

(69) FIG. 18: View of the posterior face of the semi-rigid ring, oriented in perspective towards the distal pole, indicating the behavior of the biocompatible fluid when passing through the middle area of the closure element mounted in the meridian canal, the biocompatible fluid enters through the holes, as indicated by the arrows;

(70) FIG. 19: Axial view of the semi-rigid ring in its two-dimensional position after the closure element is broken;

(71) FIG. 20a: Axial section view of the extraction cannula, positioned inside the disc space and the extraction rod inside the semi-rigid ring after cutting the closure system;

(72) FIG. 20a′: Detail view of the disc space proximal to the work hole, the extraction rod breaks the locking element of the tubular exit hole of the semi-rigid ring;

(73) FIG. 20a″: Axial view of the disc space where the semi-rigid ring is in its minimum space configuration after breaking the closure system, extraction rod is collected by dragging the semi-rigid ring to the extraction cannula;

(74) FIG. 21a: Isometric view of the insertion instruments, assembled in working position, consisting of insertion cannula (A), pushing cannula (B) and assembly instrument (C);

(75) FIG. 21b: Isometric view of insertion instruments, disassembled;

(76) FIG. 22a: Isometric view of the pushing cannula of the insertion instruments;

(77) FIG. 22a′: Detail view of the distal pole of the pushing cannula, focused on a cross section where the work holes a″ and a′″ go through;

(78) FIG. 22a″: Detail view of the distal pole of the pushing cannula with a portion of the closure element located in its work hole;

(79) FIG. 22a′″: Detail view of the distal pole of the pushing cannula with a portion of the positioning element located in its work hole;

(80) FIG. 23a: Sagittal view of the pushing cannula and the insertion cannula of the insertion instruments, comparison of lengths from the most distal pole of the handle of the pushing cannula;

(81) FIG. 23b: Detail view of the distal poles of the pushing cannula and the insertion cannula, the comparison of length under the same reference, the distance to the distal pole of the pushing cannula “y”, is less than the distance to distal pole of the insertion cannula “x”;

(82) FIG. 24a: Detail view of the distal pole of the pushing cannula of the insertion instrument, in perspective towards the distal pole, focused on the connecting protuberances;

(83) FIG. 24b: Sagittal section view of the pushing cannula of the insertion instruments and cross section of the semi-rigid ring in the posterior proximal pole, where the anchoring holes are located, line of action where both pieces match;

(84) FIG. 25a: Detail view of the proximal pole of the pushing cannula of the insertion instruments, focused on the cannula handle;

(85) FIG. 25a′: Detail view of the pushing cannula in its proximal pole having a variation in diameter to serve as a stop in the assembly;

(86) FIG. 25b: Axial section view, in perspective, of the distal pole of the pushing cannula of the insertion instruments, the closure element and the positioning element pass through the handle through the threaded hole;

(87) FIG. 25b′: Detail view of the axial section of the distal pole of the pushing cannula, indicating the configuration of the housing wire to the assembly instruments;

(88) FIG. 26a: Isometric view of the assembly instruments, composed of a locking screw (C1) and a twisting lock (C2), a hollow canal can be seen in the locking screw from the distal pole to the proximal tubular portion, where the twisting lock is positioned;

(89) FIG. 26a′: Detail perspective view of the pushing cannula in sagittal section complemented with the thread of the distal portion of the locking screw where they are screwed;

(90) FIG. 26a″: Detail perspective view of the locking screw in axial section at its proximal pole, the tubular portion where the twisting lock is housed is indicated;

(91) FIG. 27a: Isometric view of the twisting lock of assembly instruments;

(92) FIG. 27b: Axial sectional view of the twisting lock, indicating the canals for the closure element and the positioning element, in the most proximal pole the canal of the closure element reduces its diameter to generate tension in the same;

(93) FIG. 28a: Isometric view of the insertion cannula of the insertion instruments;

(94) FIG. 28a′: Detail view of the distal portion of the insertion cannula, with sagittal section prior to the hem i-ovoid form;

(95) FIG. 28b: Detail view of the distal portion of the insertion cannula housing the distal portion of the pushing cannula, the lines indicate the ability of the pushing cannula to rotate and move linearly within its interior;

(96) FIG. 28b′: Detail view of the insertion and pushing cannula set in sagittal section, position of the pushing cannula in its initial position;

(97) FIG. 28b″: Detail view of the insertion and pushing cannula set in sagittal section, position of the pushing cannula in rotation on its axis;

(98) FIG. 29, Axial view of the surgical field;

(99) FIG. 30a: Axial perspective view of the distal portion of the insertion cannula of the insertion instruments, of hemi-ovoid distal shape;

(100) FIG. 30a′: View of axial section of the distal portion of the insertion cannula, containing the semi-rigid ring in its minimum space configuration;

(101) FIG. 31a: Isometric view of the insertion cannula of the insertion instruments;

(102) FIG. 31b: Detail view of the proximal portion of the insertion cannula, focused on the T-handle;

(103) FIG. 31b′: Sagittal view of the proximal portion of the insertion cannula, indicating the housing of the closure sheet;

(104) FIG. 32a: Isometric view of the closure sheet of the insertion instruments;

(105) FIG. 32a′: Sagittal section view of the closure sheet, whose profile fits the space between the insertion and pushing cannulas;

(106) FIG. 32b: Detail view of the distal portion of the assembly formed by insertion and pushing cannulas, and closure sheet in sagittal section;

(107) FIG. 32b: Perspective view of the distal portion of the aforementioned assembly, indicating where the closure sheet is positioned between the insertion and pushing cannulas;

(108) FIG. 32c: Axial section view of the insertion cannula and the closure sheet in the distal portion, where the sheet is closed to prevent its displacement;

(109) FIG. 33a: Isometric view of the insertion tool snap;

(110) FIG. 33b: Perspective view of the housing of the closure sheet locking, in the proximal portion of the insertion cannula;

(111) FIG. 33c: Sagittal section view of the insertion cannula set, pushing cannula, closure sheet and snap;

(112) FIG. 34a: Isometric view of the removal instruments, assembled in working position, consisting of, extraction cannula (D), extraction rod (E);

(113) FIG. 34b: Isometric view of removal instruments, not assembled;

(114) FIG. 35a: Axial section view of the extraction cannula of the removal instruments, axis of the L-handle coinciding with the bevel of the distal portion;

(115) FIG. 35a′: Detail view of the distal portion of the extraction cannula, it presents a conical section of angle Θ1 beveled at an angle Θ2;

(116) FIG. 35b: Detail view of the proximal portion of the extraction cannula, focused on the L-handle and its final slot;

(117) FIG. 35b′: Detail view of the distal portion of the extraction cannula, focused on the slot that crosses the entire piece;

(118) FIG. 36a: Isometric view of the distal portion of the removal rod of the removal instruments;

(119) FIG. 36a′: Detail view of the base of the removal mill, in perspective towards the distal portion, indicating the configuration of the hooks on the base to cling to the semi-rigid ring;

(120) FIG. 36b: Axial section view of the distal portion of the extraction rod in line of action with the hole of the posterior proximal portion of the semi-rigid ring;

(121) FIG. 36b′: Axial section view of the distal portion of the extraction rod acting on the scraped region of the semi-rigid ring closure system;

(122) FIG. 37a: Detail view of the proximal portion of the extraction rod, indicating the proximal portion where there is a diameter reduction for hammer handling;

(123) FIG. 37b: Detail view of the proximal portion of the extraction rod, indicating the handle;

(124) FIG. 37A: Isometric view of the removal rod of the removal instruments.

DETAILED DESCRIPTION OF THE INVENTION

(125) To understand the details of the proposed inventive solution, the structure of the device to be implanted is described below, which, based on its functional behavior, we have called the Annular Assistance Device (AAD). The necessary surgical instruments are also detailed, both for insertion and removal, as well as the technique to carry out these procedures.

(126) It is clarified that the morphological description of the device and its instruments is not limited to their dimensions, the spinal level in which it is represented, the type of mechanical behavior, the material used, or the number of elements illustrated.

(127) As deduced from the comments made in the previous paragraphs, the AAD seeks to preserve and/or restore the anatomy of the spinal unit by preserving the height of the space that separates the vertebrae adjacent to a diseased intervertebral disc. This, after the excision of the nucleus pulposus compromised by degenerative pathology or other similar nosopathological situations, in the lumbar segment of the human spine.

(128) Its function is, as a prerequisite, to develop the nucleus discectomy with the least possible impact on the fibrous ring of the diseased disc and on the disc lamellae near it.

(129) As the figures show (FIG. 1A, 2c), once inserted into the intervertebral space the device is self-contained by a change in its geometry and by an adequate congruence between the same annular assistance device and the limits of the space where it is located, that is, the fibrous ring itself, viable nuclear debris, and both disc platforms. The device is also equipped with a minimum of protrusions that anchor it in its final position (FIG. 1c′; 4a, a′, a″).

(130) Architecture of the Annular Assistance Device

(131) For the purposes of its description, the definition of distal and proximal has been considered from the perspective of the operator.

(132) In general, the AAD consists of three fundamental elements. 1. A structural element, defined by a semi-rigid ring with asymmetric thickness, which, in the final position, acquires a cardioid shape with convex upper and lower edges in the axial plane (FIG. 1b, c). 2. A closure and securing element, with unidirectional locks, which by means of its traction allows the stabilization of the semi-rigid ring in its final geometric configuration. The closure element also serves as a route for the administration of bioactive materials into the ring cavity (FIG. 1d; 7; 9). 3. A positioning element defined by a strip that is temporarily attached to the distal pole of the semi-rigid ring allowing its manipulation at the time of installation of the AAD This strip, when pulled from one of its ends, is released from the fastening of the semi-rigid ring once it is already armed and arranged in the disc space in its final position. (FIG. 6a, a′, b; 14b).

(133) In its working position, the AAD offers its convexity towards the front and its concavity towards the back (FIG. 1b, d, A).

(134) Seen from a sagittal plane, both the upper and lower edges have convex surfaces in congruent opposition to those that, naturally, the disc platforms offer (FIG. 1c; 2c; 11a′).

(135) Support ribs with centripetal orientation are detached from the inner surface of the device, which, as they move away from the variable geometry ring, approach the geometric center of the device (FIG. 1a, b, b′, b″). Those that emerge from the posterior portion are characterized by having at their ends spikes of osteoinductive and radiopaque material, to favor the anchorage of the device and its intraoperative visualization under radioscopy, and for showing a slot in the midline of its sagittal section with the morphology necessary to house and secure the closure element of the annular assistance device (FIG. 4a, a′, a″; 1a; 5a).

(136) These support ribs protrude from the semi-rigid ring with a flexible behavior. In this way, its deprojection is made possible by allowing the deformation of the device to a minimum in the anterior-posterior axis and towards a complete reduction of the space inside the semi-rigid ring, at the moment when it is inserted into the disc space (FIG. 3; 13a; 17A).

(137) In the latero-lateral axis, the points furthest from the annular assistance device represent the place where the closure element of the ring is inserted in the semi-rigid ring. These points, in which said ring also has its greatest thickness, are called poles (FIG. 6a, b; 8a′).

(138) The global geometry of the AAD meets symmetry criteria in an axial section plane, which is why the same annular assistance device can be used for both right and left lesions, simply by inverting it (FIG. 2a′, a″).

(139) The height of the device is equivalent to the height that the diseased disc space offers, depending on: the level of the spinal lesion, age group, gender, and particular conditions of the patient.

(140) In a sagittal medium section, the height of the device will be symmetrical or asymmetrical between the maximum anterior and posterior dimensions, depending on the degree of lordotization required for its adjustment to the disc space post nucleus discectomy. Nevertheless, and only for the purposes of its description, the present exercise represents the device theoretically inserted into a disc of the middle lower lumbar region of a human being (FIG. 2c).

(141) The maximum average height of the AAD is exceeded only by the spikes at the ends of the posterior support ribs, which will become evident on this limit when closing and securing the device (FIG. 11c, c′).

(142) The AAD has a closure element, as shown in the figure (FIG. 1d; 5a, b′; 6a, a′; 7A), which consists of an elongated tubular structure made from a semi-rigid polymer, and that in its closed position brings the poles of the device closer on the transversal major axis of the cardioid.

(143) The closure element is introduced inside the semi-rigid ring of the AAD, prior to its insertion, through an opening and anchor hole, as seen in the figure (FIG. 16a′). The opening and anchor hole is located on the opposite side next to the patient's approach, being the most distal point of the annular assistance device with respect to the operator (FIG. 5b′; 6a, a′).

(144) On the surface of the proximal pole of the semi-rigid ring and in relation to the exit hole of the closure element, there are three other perforations, two ventral that serve as support points for the tool for introducing the device, and a posterior one that allows the insertion of the removal instruments of the annular assistance device (FIG. 15a, a′). In the particular case of the posterior perforation, the major axis thereof coincides with the geometric center of the locking ring of the semi-rigid ring (FIG. 15b; 24b). This arrangement allows a perforation guided by this axis to cause the rupture of the locking system of the AAD to promote its disassemble and removal (FIG. 15b, b′).

(145) In order to describe the AAD in terms of the structural relationships between its semi-rigid ring and its closure element, it is described as already armed in three designated sections: distal, middle and proximal (FIG. 6a).

(146) Distal Annular Section:

(147) In this section, the semi-rigid ring has an entry hole for the closure element (FIG. 6a, a′; 5b, b′). This hole has a diameter with a small increase in diameter (FIG. 5b), which gives support to the most distal portion of the closure element. The diameter of the perforation is sufficient for the insertion of the closure element and its unidirectional lock. This lock secures the closure element to the semi-rigid ring in the event that it is cut to facilitate the removal of the AAD (FIG. 5b; 19).

(148) The closure element has in its most distal portion a conical section congruent with the countersink of the entry hole of the semi-rigid ring, so that once its position is secured it does not distort its surface (FIG. 7b). As described before, it is equipped with a tab that acts as a unidirectional lock (FIG. 5b′). This, which is the strongest portion of the closure element, extends into the semi-rigid ring by means of a tubular section with a coronal section characterized by having its anterior and posterior faces truncated so that the larger diameter corresponds to the vertical plane and the smaller to the horizontal plane. In this section of the closure element a series of perforations that communicate the inner bore of the closure element with the interior space of the AAD can be observed (FIG. 5 a, b′; 6 a, 7 a). The larger diameter of this tubular section of the closure element is coincident with the securing slots of the support ribs arranged on the posterior face of the semi-rigid ring, whose purpose is to fix the closure element to said section of the AAD once it is geometrically stabilized in its working position (FIG. 5 a; 6 a; 11 b, c).

(149) On the posterior face of the distal section of the semi-rigid ring, there are a pair of slots arranged between the most distal support rib and the entry hole of the closure element (FIG. 6). These give way to the positioning strip element that allows to maintain the position of the distal pole, as posterior as possible at the time of the insertion of the device.

(150) Proximal Ring Section:

(151) This section corresponds to the area of the device in which the closure element secures the working configuration of the semi-rigid ring. In this segment, the semi-rigid ring is characterized by having a tubular exit hole, whose coronal section represents a cylinder with its front and posterior faces truncated (FIG. 8a, a′). On the anterior face, it has a small recess that serves as a hook to the locking elements of the anterior face of the closure element (FIG. 12a, a′, a″). This recess divides the tubular exit hole into a distal or internal portion (FIG. 12a″) and a proximal or external portion, with respect to the inside of the semi-rigid ring (FIG. 12b), in which the tolerance of its diameters allows that the rotation of the closure element, around its longitudinal axis, section it without burrs on the surface of the semi-rigid ring (FIG. 14a, a′).

(152) In this region of the AAD the closure element maintains a cylindrical section with its truncated anterior and posterior surfaces so that it is congruently related to the shape and diameters of the tubular exit hole as described in relation to the securing slots in the posterior support ribs of the semi-rigid ring (FIG. 9; 11c, c′). The congruence of the faces of both parts of the AAD prevents axial rotation of the closure element within the limits of the semi-rigid ring. Once the distal margin of the tubular exit hole is crossed, the closure element can rotate freely, making its rupture possible (FIG. 14a′). This rupture is facilitated and guided by suitable diameter reductions arranged between the locking elements of the closure element (FIG. 10a, a′, b).

(153) Extra Annular Section of the AAD:

(154) Once the closure element passes through the exit hole of the semi-rigid ring, it maintains its axial section. In this section, it has no obstacles in a section equivalent to the distance between the exit hole from the semi-rigid ring and the traction element of the device insertion instruments (FIG. 16a″; 17A; 27b). In the most proximal portion of this segment, a new group of locking elements assure the armed instruments of the AAD (FIG. 1d, d″). Finally, the most proximal end of the closure element has a congruent section with a universal “luer lock” adapter, through which it is possible to access its internal conduit for the administration of bioactive materials inside the AAD These penetrate into the semi-rigid ring by means of the perforations described in the intra-annular segment of the closure element. (FIG. 29).

(155) The construction of the AAD considers biocompatible, osteoinductive, and radiologically lucid materials, both with shape memory and stable structure and behavior to human body temperature, although in its synthesis the possibility of mixing them is excluded, as it is the case of some osteoinductive metal inserts at the tips of the posterior ribs or shape memory materials in the structure of the semi-rigid ring itself. The metal inserts allow the positioning of the device under radioscopic guidance while offering an osteoinduction point and a minimum anchorage to further ensure the AAD in its working position.

(156) During its placement, the anterior-posterior axis and the interior area of the AAD are minimized, in order to allow its arrangement inside an insertion cannula, thus allowing its installation with criteria for protection of the spinal canal neural elements.

(157) As previously described, a strip-shaped positioning element made from a low friction coefficient polymer is temporarily attached to the distal pole of the semi-rigid ring, in the manner of reins, through the two slots located on the posterior face of this section of the semi-rigid ring.

(158) This structure leads the closure element into the insertion instruments, exceeding it by a sufficient length to ensure, by means of its traction, the position of the most distal pole of the AAD at the time of installation. Once the correct position of the device is confirmed, said closure element is removed by simply pulling one of its ends.

(159) Surgical Technique

(160) Insertion of the AAD

(161) The posterior approaches are, by far, the most used for accessing the dorsal aspect of the intervertebral disc in the lumbosacral region. These types of techniques conventionally require a deep dissection and a considerable area of removal of the erector spinae muscles and some intervertebral ligaments. At present, there is consensus regarding the parallelism between the damage inflicted on this musculature and other soft parts and the evolution of postoperative pain and compromise of the stability of the affected spinal unit.

(162) In the last decades, with the purpose of minimizing the damage on the musculoskeletal behavior by means of the separation of fibers and not the removal of the same, a considerable number of approach systems have been developed that make it possible to install in the surgical field a cannulated work path of small diameter without removing muscle fibers during its installation. This is the case, for example, of the METRx system developed by Sofamor-Danek.

(163) Tubular approach systems, such as the previously mentioned, allow for the stable protection of a small diameter work cylinder, exactly above the level of the spinal lesion to be treated. By this, a minimum mechanical and thermal impact on the soft tissues is ensured and, therefore, a scenario of less pain and shortening of the postoperative period is possible.

(164) The instruments described below that allow the implantation of the AAD have a conception similar to that previously mentioned and can be used both for standard microsurgical approach routes and for those necessary for the removal of a nucleus pulposus lesion with an endo- or exoscopic microsurgical criterion.

(165) The material has been divided, for its description, in relation to the procedures of insertion, assembly and eventual removal.

(166) Insertion Instrumental

(167) In this group the following instruments are considered: 1. Insertion Cannula: It is a tubular section structure having a tip with a hollow and hemi-ovoid shape in which the AAD is encapsulated in its entry position to the disc (FIG. 30), a cylindrical middle portion, and a proximal handle. This tool has a sufficient length for comfortable handling from outside the surgical field. Throughout the length of its medial face, with respect to the patient's middle sagittal plane, it has a slot. In this slot a closure sheet of the distal and middle portion of the cannula is inserted (FIG. 32b, b′, c). In its proximal portion, this cannula also has a T-handle arranged with its axis perpendicular to the longitudinal axis of the cannula, having a concave face towards the medial that optimizes the operator's vision towards the surgical field (FIG. 31b, b′). Two diameter increases of the cannula immediately adjacent to the handle, define an anchor point for a self-static fixation system to the surgical table and for the operation of a hammer with diapason, which allows the insertion and removal of the cannula in the intervertebral space (FIG. 31b). A snap located on the medial face of the proximal region of the middle tubular section of the instrument, allows for the securing of the closure sheet and the locking of movement of the pushing cannula arranged therein (FIG. 29; 33). 2. Pushing cannula: This instrument made from plastic or non-ferrous metal, with an equally cylindrical section, has a certain diameter and congruence that allows for its insertion, and longitudinal and rotational displacement in the core of the insertion cannula (FIG. 33c; 28b, b″, b″). Its length does not exceed the length of the insertion cannula (FIG. 23). In its distal pole, this instrument has two protuberances that coincide with the perforations that the semi-rigid ring of the AAD has in the proximal pole just in front of the exit hole that the semi-rigid ring has for the closure element. (FIG. 15a, a′; 24). These perforations define a competent anchor that ensures adequate pressure of the device at the time of its insertion. The working section of this cannula defines a cylinder with its medial face truncated, with two eccentric perforations (FIG. 22a′, a″, a′″). A lateral perforation that allows for the passage of the closure element of the AAD (FIG. 22a″) and a medial perforation that allows for the passage of the positioning element of the distal pole of the AAD (FIG. 22a′″). The perforations have axial sections with suitable, shapes, diameters and tolerances to facilitate the passage of the described elements. In its proximal pole, this instrument has a handle with medial concavity that in the medial axis presents a widening, with its walls conveniently threaded for the accommodation of the locking and securing screw of the AAD (FIG. 25a, b′). Immediately distal to this handle, the tubular portion of the instrument has, on its lateral face, an increase in diameter that allows it to be assembled with the insertion cannula. (FIG. 25a, a′).

(168) Instrumental Assembly of the AAD

(169) This group includes the following elements: 1. Locking Screw: This screw preserves the geometry of the handles of the insertion and pushing cannulas with a male pole that is screwed in the increase in diameter described on the handle of the pushing cannula (FIG. 26). Its design foresees that the thread passage of this screw be equivalent to a stable advance of the locking elements of the closure element at the time of unscrewing the locking screw (FIGS. 26a′ and 27b). In its core, the piece is perforated and in its proximal pole this perforation has an increase in diameter that allows for the assembly of a piece with a twisting function (FIG. 26a, a″). The diameters of the central perforation allow for free passage to both the closure element and the positioning element of the AAD 2. Twisting lock: This piece has a cylindrical portion that is secured with freedom of rotation in the increase in diameter of the proximal face of the locking screw (FIG. 26a, a″; 27a). In its longitudinal axis it has two perforations with the same configuration as in the pushing cannula of the AAD (FIG. 27a). At the most proximal point of the perforation, which gives way to the closure element, this piece has a diameter reduction that defines a unidirectional closure for the locking elements that the closure element presents at that height (FIG. 27b).

(170) For the assembly of the AAD, the closure element must pass through the locking screw, being fully screwed in the dilation that the pushing cannula conveniently has in its proximal portion, and its proximal portion inserted in the perforations of the proximal pole of the semi-rigid ring. In this position, the pushing cannula is housed inside the insertion cannula and the AAD is secured inside the distal capsule of this instrument.

(171) The assembly lock element secures the closure element against the locking screw.

(172) The insertion cannula is inserted into the disc space throughout its distal dilation. At this time, the diameter of said capsule subtly separates the adjacent vertebrae. The lateral closure sheet of the insertion cannula is retracted proximally, and the pushing cannula is moved forward under intraoperative radioscopic control. This maneuver is parallel to the traction of the traction element of the distal pole of the AAD Once arranged in its correct position, the locking screw is unscrewed against the twisting lock, thus pulling the entire length of the closure element. As this traction progresses, the locks that the closure element has in relation to the proximal hole of the semi-rigid ring preserve the geometry of the ring by approaching its poles. This advance is corroborated by the appearance of marks on the closure element proximal to the twisting lock.

(173) Once the final progression mark is verified, it is possible to remove the positioning strip element by pulling one of its ends. The technique progresses to the filling procedure inside the AAD, which can take place by connecting the closure element to a standard syringe by an ad-hoc means.

(174) Finally, the rotation of the pushing cannula inside the insertion cannula causes the section of the closure element, just as it exits from the inside the semi-rigid ring. The pushing cannula is removed with the assembly instruments and the insertion cannula is finally removed, taking its portion proximal to medial and consequently moving its distal third away from the AAD already armed.

(175) Removal Instrumental

(176) In the current state of art of spinal reconstruction techniques, there are no systems that allow the simple removal of intersomatic implants already arranged in their final working position. Currently, the removal of fusion systems or a prosthetic disc that progresses with problems requires a large retroperitoneal access surgery.

(177) The proposed system, unlike the above-mentioned, allows for the easy extraction of the AAD by means of the following instruments. 1. Extraction rod: Corresponds to a cylindrical piece of metallic material with a conical and striated tip, having in its base small spikes to ensure its hook in the hole that the semi-rigid ring of the AAD has on the posterior face of the proximal pole (FIG. 36a, a′). At its opposite end, this rod has a handle. Immediately distal to the handle, two increases in diameter allow the operation of a hammer with diapason to promote the removal of the tool (FIG. 37a, b). Once the device is identified in the surgical field, the conical and striated portion is inserted through the ad-hoc hole of the posterior face of the proximal pole of the semi-rigid ring (FIG. 36b, b′). When advancing through the structure of the closure system, the expansion of the conical and striated tip of the extraction rod breaks the closure system and, consequently, disassembles the AAD When crossing its wall, the conical tip of the instrument, acts as an arrowhead capturing the annular assistance device (FIG. 20 a′, a″). 2. Extraction cannula: Corresponds to a piece of cylindrical section with a diameter equivalent to the greatest height of the disc space and that along the entire length of its medial face, with respect to the patient's mid-sagittal plane, has a slot whose diameter allows for the free entry of the cylindrical portion of the extraction rod (FIG. 35b, b′). It has a tip with a conical reduction and a bevel with an axis perpendicular to the middle sagittal plane of the instrument (FIG. 35a, a′). This bevel facilitates the incorporation of the instrument into the disc space, which in turn facilitates the insertion of the AAD into its core once the closure system that secures its geometry has been broken. In its proximal pole, this cannula is provided with a handle whose medial axis is perpendicular to the middle axis of the instrument. Once inside, the extraction rod, together with the AAD already caught at its tip, can be extracted with absolute protection of the neural elements contained in the canal.