Methods and systems for constraint of multiple spine segments

p00001Structures to restrict spinous processes with a single connector

BACKGROUND OF THE INVENTION

p00003[0001] 1. Field of the invention. The present invention generally relates to a spinous process restriction structure for restricting spinal flexion in patients who have backaches or other spinal ailments.

p00004[0002] An important cause of chronic low back pain is discogenic pain, also known as internal disc disruption. Patients suffering from discogenic pain are usually young or, if not, healthy people suffering from localized back pain. Discogenic pain usually occurs in the discs located at the L4-L5 or L5-S1 junctions of the spine (Fig. 1). The pain usually increases when patients flex their lumbar spine (that is, when they sit or lean forward) and remits when they extend their lumbar spine (that is, when they arch backwards). Discogenic pain can be quite disabling and, in some patients, it can drastically affect your ability to work and lead a normal life.

p00005[0003] This pain experienced by patients with discogenic low back pain can be considered as instability in flexion and is related to instability in flexion manifested in other ailments. The most revealing is spondylolisthesis, a spinal disease in which an abnormal segmental translation is accentuated due to segmental flexion. The device described in this document is also useful for these other spinal disorders associated with segmental flexion, for which prevention or control of spinal segmental flexion is desired.

p00006[0004] Current treatment alternatives for patients diagnosed with chronic discogenic pain are very limited. Many patients follow a traditional line of treatment, such as physical therapy, massage, anti-inflammatory and analgesic, muscle relaxants and epidural steroid injections, but usually continue to suffer a significant degree of pain. Other patients choose to undergo spinal fusion surgery, which usually requires a dissectomy (removal of the disc) along with the fusion of adjacent vertebrae. Fusion is not normally recommended for discogenic pain since it is irreversible, expensive, is associated with high morbidity and its efficacy is questionable. However, despite its drawbacks, spinal fusion for discogenic pain remains a common practice due to the lack of viable alternatives.

p00007[0005] Recently a less invasive and potentially more effective treatment for discogenic pain has been proposed. A spinal implant that inhibits spinal flexion has been designed while allowing a barely restricted spinal extension. The implant is placed on one or more adjacent pairs of spinous processes and provides an elastic restriction to the extension of the spinous processes that occurs during flexion. Such devices and procedures for their use are described in US Patent Application 2005/0216 017A1, published on September 29, 2005 and having common inventors with those of the present application.

p00008[0006] As illustrated in Fig. 2, an implant 10 such as that described in application '017 normally comprises an upper belt component 12 and a lower belt component 14 joined by a pair of adaptable elements 16. The upper belt 12 is shown disposed on the upper part of the spinous process SP4 of L4, while the lower belt 14 is shown extending over the lower part of the spinous process SP5 of L5. The adaptable element 16 normally includes an internal element, such as a rubber block spring, which is coupled to the belts 12 and 14 such that the belts can be stretched "elastic" or "adaptable" as the processes Spiny SP4 and SP5 separate during flexion. In this way, the implant provides an elastic tension in the spinous processes, which provides a force that resists flexion. The force increases as the processes continue to separate. Normally, the straps are not essentially adaptable, so that the degree of elasticity or adaptability can be controlled and provided only by the adaptable elements 16.

p00009[0007] Ideally, the adaptable elements 16 will remain horizontally aligned and generally separated between the spinous processes SP4 and SP5. However, in some cases, the desired symmetry may be lost if the structure 10 of the implant moves circumferentially around the spinous processes SP4 and SP5. Such displacement may affect the ability of the implant to provide a symmetrical and uniform elastic force to inhibit the flexion of the spinous processes of a spinal segment according to the desired treatment. In addition, the symmetrical designs illustrated in Fig. 2 can be difficult to achieve from the side that would be a preferred approach in percutaneous delivery techniques.

p00010[0008] For these reasons, it is desirable to provide spinal implants and improved procedures to inhibit flexion in patients suffering from discogenic pain. It is particularly desirable that the improved devices provide the desired elastic forces to the spinous processes with a minimal risk of displacement or loss of symmetry of the device over time. It is more desirable that the designs facilitate a lateral percutaneous delivery and from other approaches. In addition, it is advantageous for implants and implantation procedures to be carried out with minimal tissue breakage through percutaneous procedures and open surgery. The invention satisfies at least some of these objectives, as described below.

p00011[0009] 2. Description of the prior art. The document US 2005 / 0216017A1 has been previously described. Other patents and published applications of interest include: U.S. Patents 4,966,600, 5,011,494, 5,092,866, 5,116,340, 5,282,863, 5,395,374, 5,415,658, 5,415,661, 5,449,361, 5,456,722, 5,462,542, 5,496,318, 5,540,698, 5,609,634, 5,645,599, 5,725,582, 5,902,305, Re. 36,221, 5,928,232, 5,935,133, 5,964,769, 5,989,256, 6,053,921, 6,312,431, 6,364,883, 6,378,289, 6,391,030, 6,468,309, 6,436,099, 6,451,019, 6,582,433, 6,605,091, 6,626,944, 6,629,975, 6,652,527, 6,652,585, 6,656,185, 6,669,729, 6,682,533, 6,689,140, ​​6,712,819, 6,689,168, 6,695. 852, 6,716,245, 6,761,720, 6,835,205; US patent applications published under US number 2002/0151978, US 2004/0024458, US 2004/0106995, US 2004/0116927, US 2004/0117017, US 2004/0127989, US 2004/0172132, US 2005/0033435, US 2005 / 0049708, US 2006/0069447; PCT applications published with number WO 01/28442 A1, WO 02/03882 A2, WO 02/051326 A1, WO 02/071960 A1, WO 03/045262 Al, WO 2004/052246 A1 WO 2004/073532 A1; and foreign applications published under number EP 0322334 A1 and FR 2 681 525 A1.

p00012[0010] US 6451019 discloses a complementary column fixation device that includes a guiding element and a spacer for moving away adjacent spinous processes. The device has hook elements that are hooked to the first and the second spinous process. With the spinous processes separated and the hook elements in the spinous processes, the hook elements can be rigidly fixed to a bushing in order to rigidly fix the spinous processes around the spacer. With this arrangement an additional force is applied to the vertebral bodies to promote fusion.

p00013[0011] US 2005/0123581 describes a compressed high density fibrous polymer suitable as an implant.

p00014[0012] US 2002/0095154 describes a dynamic thrust device for applying elastic force to adjacent vertebrae.

p00015[0013] US 5609634 describes a prosthesis that includes a flexible ligament with a narrow first part and a second wider part that can be passed around a spinous process of two adjacent vertebrae in a pattern of figure in eight.

p00016[0014] Document FR 2828398 describes a vertebra stabilization assembly comprising a rear cushion implant configured to be placed laterally in the laminar-spinal junction of two vertebrae and at least one intercorporal cushion implant configured to be inserted between the end plates verticals of the two vertebrae treated.

p00017[0015] EP 0743045 describes an osteosynthesis device of the type prepared with a material that has shape memory.

p00018[0016] US 2004/0117017 describes a self-locking fixable intervertebral implant.

p00019[0017] WO 2005/110258 describes an intervertebral implant that is fixedly placed between spinous processes to maintain the predetermined space between the spinous processes.

p00020[0018] FR 2884136 describes a surgical intervertebral implant that forms a rotating joint.

p00021[0019] FR 2717675 describes a buffer buffer block that is placed between adjacent vertebrae.

p00022[0020] FR 2722980 describes an interspinal vertebral implant comprising a substantially U-shaped body that has elastic flexibility in the area of ​​its central part and two pairs of support elements that project from the outer face of the two. Branches of the body, defining these support elements stirrups to accommodate the spinous processes of the vertebrae and comprising means to allow them to be fixed to the processes.

p00023[0021] US 2005/0203624 describes an interspinous implant having a generic horseshoe shape, a damping element within the horseshoe and a porous coating on its outer surface.

p00024[0022] Document FR 2693364 describes an intervertebral prosthesis that includes a flexible ligament with a thinner narrow first part and a wider second part that forms an extension of, and that has a width and thickness greater than, the first part, part that can be passed around the spinous processes of two adjacent vertebrae in a pattern of figure in eight, while the second part surrounds the processes. A semi-flexible block located between the processes with two pairs of passageways that have different cross sections receives the respective parts of the ligament, whose ends are joined.

p00025[0023] WO 2005/037150 describes a non-rigid system for stabilizing displaced bone elements that includes a flexible unit of mooring material coupled to displaced bone elements to restore a desired shape, curvature or relationship between bone elements without limiting in excess mobility of bone elements.

BRIEF SUMMARY OF THE INVENTION

p00027[0024] The present invention is set forth in the appended claims. This document describes spinal implants and procedures to restrict the flexion of spinal segments for the treatment of discogenic pain and other spinal ailments, such as spondylolisthesis, in which a physician may wish to control segmental flexion. The systems described include spinous process restriction structures comprising a first coupling element adapted to be placed on a first spinous process, a second coupling element adapted to be placed on a second spinous process, and a single connector that joins the first element of coupling and the second coupling element. By "single connector" is meant that the connector joins a single point or location of the first coupling element to a single point or location of the second coupling element. In contrast, the above connectors shown in Fig. 2, for example, provide a pair of connection points and two connectors for attaching the upper component 12 to the lower belt component 14. The use of the single connector to join the first and the second coupling element reduces the probability that the coupling elements move and that the desired symmetric coupling geometry becomes asymmetric. A single connector also reduces the need to balance the elastic forces that are applied to opposite sides of the spinous processes. The only connector will also simplify the alignment of the implant during implantation, thereby simplifying percutaneous implantation and potentially minimizing tissue rupture in percutaneous protocols and other implantation protocols.

p00028[0025] The first and the second coupling element may have similar or different geometries. Exemplary geometries include open hook structures that can be placed around the spinous processes and can have a single coupling point for connection with the single connector. The coupling elements can also be loop structures that completely circumscribe the spinous process, where the loop is provided with a single connection point for connection with the single connector. The coupling elements will normally be placed on the spinous process without additional coupling. However, in other cases, it may be desirable to provide a secondary coupling to the spinous process, such as staples, stems, sutures, adhesives, energy regulated couplings (such as laser welding), or the like. In some cases, one of the two coupling elements may adhere to the adjacent spinous process, while the other coupling element may simply be placed on the adjacent spinous process without adhesions.

p00029[0026] The restriction structures of the present invention may comprise different components that are attached or that can be connected to each other. For example, the first coupling element, the second coupling element and the single connector can be formed separately and interconnected by conventional techniques, such as screwing, welding, joining with male and female coupling elements, joining by belts, welding or any Another fixing technique. In other cases, two or more of the restriction components of the present invention can be formed in a solidary or monolithic manner from a common structural element. For example, a pair of hook-like elements may be formed jointly with an intermediate connector forming the components from a single rod, wire, cable, polymeric substrate or the like.

p00030[0027] The spinous process restrictions of the present invention may further comprise an adaptable element arranged in or as part of the single connector. The adaptable element may have any structure that provides the desired elasticity in the connector to allow the first and second coupling elements to extend as the spinal segment flexes. Suitable adaptable elements are described in published US application number 2005/0216017 A1, which has already been incorporated herein by reference.

p00031[0028] In other embodiments, the single connector may comprise an elastomeric body that is disposed between the first and the second coupling element. In some cases, the elastomeric body may be placed on the supraspinatus ligament, and in some of those cases such elastomeric bodies may be adapted to be sutured or otherwise coupled to the supraspinatus ligament.

p00032[0029] This document describes procedures for restricting the flexion of a spinal segment comprising placing a first coupling element in a first spinous process and placing a second coupling element in a second spinous process, where the coupling elements are joined Through a single connector. The coupling elements can be placed in an open surgery procedure through the supraspinatus ligament or can be implanted percutaneously, optionally from a posterior approach of only one side avoiding the need to penetrate the supraspinatus ligament. In a specific example, the elements are joined with an elastic element, where the elastic element is preferably placed on the supraspinatus ligament. In particular examples, the methods further comprise coupling the elastic element to the supraspinatus ligament, for example by sutures. Typically, the procedures further comprise penetrating the supraspinatus ligament to allow passage of the coupling element (s) and / or the elastic element therethrough. Also optionally, the coupling elements can be coupled to the spinous processes, usually by stapling or any of the other coupling modalities described above.

BRIEF DESCRIPTION OF THE DRAWINGS

p00034[0030] Fig. 1 is a schematic diagram illustrating the lumbar region of the spine that includes spinous processes (SP), facet joints (FJ), a lamina (L), transverse processes (TP) and the sacrum (S ).

p00035[0031] Fig. 2 illustrates a spinal implant of the type described in US 2005 / 0216017A1.

p00036[0032] Fig. 3 illustrates an exemplary embodiment of a spinous process restriction structure, constructed according to the principles of the present invention.

p00037[0033] Figs. 4 to 11 are schematic illustrations of additional exemplary embodiments of the spinous process restriction structures of the present invention, where adjacent spinous processes are shown in section.

p00038[0034] Fig. 12 illustrates a further alternative embodiment of a spinal restraint structure of the present invention shown with a first coupling element placed on the spinous process of L5 and a lower coupling element coupled to the sacrum.

p00039[0035] Figs. 13 and 14 illustrate another embodiment of a spinous process restriction structure provided by the background of the present invention, where the coupling elements are placed on adjacent spinous processes and the single connector passes through and on the supraspinatus ligament.

DETAILED DESCRIPTION OF THE INVENTION

p00041[0036] Referring now to Fig. 3, a spinous process restriction structure 20 constructed according to the principles of the present invention comprises a first coupling element or upper coupling element 22 and a second coupling element or lower coupling 24. The first and second coupling elements are connected by a single connector 26, shown in the form of an elastic rod or cable. Normally, the coupling elements 22 and 24 are not distensible and are firmly placed on the spinous processes, shown as the spinous process SP4 of L4 and the spinous process SP5 of L5. The connector 26 is elastically distensible so that it comprises an elastic restraining force as a spinal segment flexes, which causes the spinous processes SP4 and SP5 to extend vertically. Although it is elastic in tension, the only connector 26 has great lumbar resistance, so that it exerts very little force on the spinous processes SP4 and SP5 when the spinal segment is extended and the processes approach vertically with each other. As used herein, the expression "spinal segment" is synonymous with the expression "functional spinal unit (FSU)" and refers to the smallest physiological movement unit of the spine that exhibits biomechanical characteristics similar to of the entire spine. A spinal segment or FSU consists of two adjacent vertebrae, the intervertebral disc and all adjacent ligaments between them and excludes other connective tissues, such as muscles. The resulting three joint complex is sometimes referred to as the "joint triad." Another term for the FSU is spinal movement segment. These definitions have been taken from the document “Clinical Biomechanics of the Spine”, (1990), by WhiteAA, Panjabi MM., Philadelphia, JB Lippincott.

p00042[0037] The first and second coupling elements 22 and 24 can wrap the associated spinous processes SP4 and SP5 without any additional adhesion or fixation. However, in some cases, it may be desirable to staple, suture, glue or otherwise couple the coupling elements to the underlying spinous process. It should also be noted that in many cases, the coupling elements may have a seam or closure that allows them to wrap the spinous process and close in situ thereon during an implantation procedure. Furthermore, it should be appreciated that the single connector 26 can be pre-coupled to either or both of the coupling elements 22 and 24. However, in other cases, it may be desirable to couple the connector 26 to either or both of the coupling elements 22 and 24 during the implantation procedure to allow the connector length to be adjusted. In particular, it is desirable that the length of the connector 26 be selected so that the connector is extended, generally, completely but not under significant tension when the spinal segment is in its neutral state (neither flexed nor extended). In such cases, the connector 26 will begin to apply tension to the spinous processes 22 and 24 as soon as they begin to flex while they collapse and no force is applied to the spinous processes as they extend. Fig. 4 is a schematic cross-sectional view of the spinous process restriction structure 20 of Fig. 3.

p00043[0038] Fig. 5 illustrates an alternative spinous process restriction structure 30 having a first and second coupling element 32 and 34, similar to those described in relation to Figs. 3 and 4, and joined by a single connector 36 having an adaptable element 38. In this embodiment, the only connector 36 is formed from a non-distensible material in which the desired elasticity is provided by the adaptable element 38.

p00044[0039] Referring now to Fig. 6, a spinous process restriction structure 40 is illustrated which has a first hook-like coupling element or upper hook-like coupling element 42 and a second coupling element. as a hook or coupling element as a lower hook 44. The first and second coupling elements 42 and 44 are connected by a single contiguous or integral connector 46, which is oriented transversely in the space between the upper spinous process SP4 and the lower spinous process SP5. The restriction structure 40 may be formed from a spring metal, such as spring steel or a nickel titanium alloy, or, alternatively, may be formed from an elastomeric polymer. In some cases, the hook-like coupling elements can be reinforced or otherwise modified to be substantially non-adaptable, while the connector 46 can be modified to improve its elasticity, for example by presenting a coil or coil spring structure.

p00045[0040] Referring now to Fig. 7, an additional spinous process restriction system 50 comprises a hook-like upper coupling element 52 and a hook-like lower coupling element 54 connected by a single connector 56 The upper and lower coupling elements 52 and 54 as well as the connection section 56 may be formed of a metal or a polymer and are usually not distensible. The desired elasticity between the coupling elements is provided by an adaptable element 58.

p00046[0041] Referring next to Fig. 8, another additional spinous process restriction system 60 comprises a first and second hook-like coupling element 62 and 64. Instead of being connected in a pattern in the form of S, as shown in Fig. 6, hook elements 62 and 64 are connected in a C-shaped pattern, as shown in Fig. 8. Other aspects of the restriction system 60 may be similar to those described with respect to the restriction structure 40 of Fig. 6.

p00047[0042] Also, as shown in Fig. 9, a spinous process restriction system 70 comprises a first and second hook-like coupling element 72 and 74 arranged in a C-shaped pattern, generally as shown in Fig. 8, and further comprises an adaptable element 78 coupled to the single connector 76 (which is preferably not adaptable). Other aspects of the system can generally be as described in relation to the restriction structure 50 of Fig. 7.

p00048[0043] In a further embodiment, a spinous process restriction system 80, as shown in Fig. 10, comprises a first loop or envelope coupling element 82 and a second loop or envelope coupling element 84. coupling elements 82 and 84 are connected by a connector 86 which, instead of being coupled in the center of the coupling elements, is coupled laterally to one side. It should be appreciated that the connector 86 may also have been coupled laterally on the opposite side.

p00049[0044] Referring now to Fig. 11, a spinous process restriction system 90 comprises an upper and a lower coupling element 92 and 94 that are similar to those described in relation to the restriction structure 80 of Fig. 10. A single connector 96 is normally formed from a non-distensible material, and the desired elasticity is provided by an adaptable element 98 provided along the length of the single connector 96.

p00050[0045] As described so far, it has been intended to place the spinous process restriction systems in adjacent spinous processes. It should be appreciated that restriction systems can be placed in spinous processes that are not adjacent, for example separated by one or more additional spinous processes. It should also be appreciated that the spinous process restriction systems can be coupled at a first end or upper end to the spinous process SP5 of L5 and at a second end or lower end to the sacrum S, as shown in Fig. 12. Since the sacrum does not normally include any process or other structure that serves for coupling, with the coupling element described above, the spinous process restriction system 100 may include a first coupling element or upper coupling element 102 similar to any of those described above, and a second coupling element or lower coupling element 104 that is modified to engage the sacrum, for example, forming a loop through a hole H formed in the sacrum structure. Other coupling elements suitable for coupling to the sacrum are described in the application being processed together with the present application No. 111827.980 filed on July 13, 2007 (Publication No. US2008 0009866). A single connector 106 is provided between the upper and lower coupling elements 102 and 104, optionally including an adaptable element 108 to provide elasticity.

p00051desired.

p00052[0046] Referring now to Figs. 13 and 14, another spinous process restriction system, not claimed, and a method, not claimed, for its implementation are described as background information of the present invention. The spinous process restriction system 110 includes a first coupling element or upper coupling element 112 and a second coupling element or lower coupling element 114. The upper and lower coupling elements are joined by an elastic component, usually an elastomeric body 116 that is configured to be placed on the surface of the SSL supraspinatus ligament, as shown in Fig. 14. The advantage of the restriction structure 110 is that it minimally affects the structure of the supraspinatus ligament, which usually requires only small perforations to allow placement of the coupling elements 112 and

p00053114 Optionally, the elastomeric body 116 can be coupled to the SSL supraspinatus ligament, for example by sutures 118, adhesives, staples or by other conventional coupling means. Also, since the elastomeric body 116 will exert a backward force on the coupling elements 112 and

p00054fifteen 114, it is normally desirable to staple, nail, suture, glue or otherwise couple the coupling elements to the spinous processes SP4 and SP5. Although stems 120 are shown, it should be appreciated that other coupling means can also be used.

p00055[0047] Although the foregoing is a complete description of the preferred embodiments of the invention, several alternatives, modifications and equivalents can be used. Therefore, the above description should not be considered as limiting the scope of the invention, which is defined by the appended claims.