News Column

Patent Issued for System and Devices for the Repair of a Vertebral Disc Defect

July 8, 2014

By a News Reporter-Staff News Editor at Life Science Weekly -- According to news reporting originating from Alexandria, Virginia, by NewsRx journalists, a patent by the inventors Evans, Douglas G. (Downingtown, PA); Kelly, Jeffrey C. (Downingtown, PA); Bradica, Gino (Ewing, NJ); Carouge, Michael K. (West Chester, PA); Oeffinger, Brian (Philadelphia, PA), filed on February 14, 2012, was published online on June 24, 2014 (see also Kensey Nash Corporation).

The assignee for this patent, patent number 8758351, is Kensey Nash Corporation (Exton, PA).

Reporters obtained the following quote from the background information supplied by the inventors: "The invention relates generally to methods and devices for human surgery, and in particular these methods and devices may be useful for spinal surgery. More particularly, certain embodiments of the invention relate to devices and methods for treating injuries, defects or surgical procedures associated with the intervertebral disc.

"Injuries to the human spine and subsequent pain are one of the most prevalent debilitating conditions affecting the human population. For many of those affected, no position can ease the pain or discomfort associated with spinal injuries or deformities. Such spine related pain can lead to decreased productivity due to loss of work hours, addiction to pain-killing drugs, emotional distress, and prolonged hospital stays. The economic impact of such problems is significant. One common cause for many instances of chronic pain is the bulging, or herniation of the intervertebral disc.

"The intervertebral disc is made of two parts, a tough collagen outer layer, known as the annulus fibrosus (hereinafter also referred to as 'AF' or 'annulus'), and a soft central core known as the nucleus pulposus. The annulus fibrosus is composed of numerous concentric rings or layers of fibrocartilaginous tissue. Fibers in each ring cross diagonally, and the rings attach to each other with additional radial fibers. The rings are thicker anteriorly (ventrally) than posteriorly (dorsally). The nucleus pulposus (hereinafter also referred to as 'NP' or 'nucleus') is a gelatinous material, which forms the center of the disc. The discs tend to vary in size and shape with their position in the spine. The nucleus pulposus is composed of a loose, nonoriented, collagen fibril framework supporting a network of cells resembling fibrocytes and chondrocytes. This entire structure is embedded in a gelatinous matrix of various glucosaminoglycans, water, and salts. This material is usually under considerable pressure and is restrained by the annulus.

"A tear or weakening in the layers of the annulus fibrosus portion of the disc can allow the soft center portion of the disc (the nucleus) to leak out of the annulus, alternatively, the weakened annulus may simply bulge. A ruptured disc may allow the leaking nucleus propulsus material to press up against a spinal nerve root or spinal cord, causing pain, numbness, tingling and/or weakness in a person's extremities. Herniated discs may occur at any level of the spine, but are more common in the lumbar area, followed in frequency of occurrence by the thoracic region and cervical region. Weakening or tearing of the annulus fibrosus may also result in bulging of the annulus fibrosus due to pressure of the nucleus pulposus against the annulus. The bulging tissue may also impinge upon the nerve root or spinal column, causing pain.

"The traditional surgical method for treating a damaged, bulging, or herniated disc involves tissue removing procedures to relieve the impingement of the annulus fibrosus or the nucleus pulposus from the surrounding nerves. The procedure is commonly known as a discectomy, and consists of the removal of at least a portion of the disc; it may be performed in an open procedure, a minimally invasive procedure, or an endoscopically assisted procedure. These procedures generally result in a large defect of the annulus fibrosus and in a certain percentage of cases, may lead to progressive degradation of the disc, both nucleus pulposus and annulus fibrosus, lysthesis of adjacent vertebral bodies, stenosis of the nerve canals and increases in related pain symptoms. A means of mechanically and/or biologically repairing the annulus fibrosus may delay or prevent this degeneration cascade of the disc.

"Newer technologies and procedures, such as nucleus replacement with injectable or solid prosthetic nucleus devices may also result in a breach in the otherwise coherent annulus fibrosis. In these cases, it is desirable to mechanically close, or otherwise repair the defect in the annulus created to insert the prosthetic material and prevent such material from leakage and extravasation.

"The annulus fibrosis (AF) of the intervertebral spinal disc is a lamellar configuration of collagen layers intended to maintain the soft viscous internal nucleus propulsus (NP), provide for motion and linkage of the adjacent vertebral bodies (VB). Certain degenerative or pathologic changes may occur either within the NP which can lead to over stress of the AF and subsequent damage to or tearing of the AF. If left untreated, herniation of the NP may occur, most importantly, the herniation may progress posteriorly toward the spinal cord and major nerve roots. The most common resulting symptoms are pain radiating along a compressed nerve and low back pain, both of which can be crippling for the patient. The AF may also be torn through traumatic injury, which can lead to progressive degenerative changes and herniation or ultimately listhesis of the adjacent VB.

"Herniation may be caused by, or be the result of weakening in the AF. Secondary to physiologic changes of the AF or NP, the AF may weaken and protrude from its normal anatomic space, similar to an air bubble bulge in a car tire, or in more severe cases, the AF may tear and allow extravasation of the NP contents to the surrounding anatomy. Symptoms may arise when the herniation or leakage of the NP impinges on the nerve root or spinal cord. There are therapies currently utilized for treatment of the herniation of a vertebral disc, and the resultant pain, starting with conservative therapies such as bed rest and pain medicines, to more invasive therapies, such as epidural injections, open or minimally invasive discectomies or aggressive therapies, such as complete discectomy and fusion of the disc space and adjacent vertebrae.

"The prior art describes various procedures and devices for repairing damage to the vertebral disc. The prior art describes repairing a herniated disk by various means, including prosthetic implants, and stressed members. For example, in U.S. Pat. No. 6,805,695, Keith et al. disclose devices and methods of reinforcing an annulus of the disc by introducing a circumferential reinforcement member around the annulus of the disc, or through the annulus and nucleus of the disc.

"In U.S. Pat. No. 6,371,990, Ferree discloses an apparatus and method for repairing annular tears and the prevention of further annular tears. Ferree seeks to control vertebral motion by augmenting the annulus with an implant, thereby minimizing the opportunity for annular tears. The augmenting implant is described as being a mesh that may be stapled into the interior of the annulus.

"Ferree also discloses in U.S. Patent Application 2004/0097980 an expandable material to fill a defect in a disk, and that the material may be anchored to the annulus with respect to the void filled. In an embodiment, the anchors are described as penetrating through the outer wall of the disc and serve to hold the flexible implant material in place.

"Yeung discloses in U.S. Pat. No. 6,530,933 a method and apparatus for herniated disc repair using resilient fastener elements that are implanted and spring back to an original shape to apply tension through gripping elements to hold tightly to the annulus. In an alternative embodiment, the annulus repair technique utilizes a suture affixed to a dumbbell shaped rod to serve as an anchor. The anchor is placed against the outside surface of the annulus, and the suture extends across the interior of the vertebral disc through the nucleus propulsus and out the other side of the disk, such that tension may placed against the disc to repair the hernia, and the tension may be maintained through the use of a washer and suture locking element, such as a knot. With this alternative embodiment, a sealing material may optionally be placed underneath the washer.

"In U.S. Pat. No. 6,592,625, Cauthen describes annular repair or reconstruction by insertion of a collapsible patch into the subannular space, whereupon the patch expands to fill the gap and seal off the opening from the escape of nucleus material. Cauthen describes his device as being useful to restore integrity after damage or discectomy to alleviate a herniated vertebral disc; Cauthen does not obviate the need for the discectomy procedure to repair a herniated disc.

"In U.S. Pat. No. 6,224,630, Bao describes the repair of an intervertebral disc using an expandable porous material that is inserted into an aperture, and subsequently becomes more permanently secured as the ingrowth of tissue into the pores is actively facilitated. Bao creates a device having a tamponade effect where the swelling of the material provides securement and does not describe a more secure mechanical anchorage using a rigid component in combination with a tissue regenerative material.

"The prior art also describes various methods for sealing a percutaneous closure, for example, Kensey et al. in U.S. Pat. No. 5,545,178 describe a system for sealing a puncture made through skin and having a tract extending through to underlying tissue. The puncture closure system consists of an anchor introduced into the underlying tissue and having a filament attached thereto, the filament extends out from the puncture, and facilitates the introduction of a plug material into the tract, whereupon tension is maintained through the use of a holding member. Kensey et al. does not describe the sealing of multiple sites through the employment of a single device, nor is the employment of multiple anchors or plugs on a single filament described.

"The prior art does not describe a device wherein the device may be capable of being implanted arthroscopically, among other methods known in the art, and is arranged to prevent the escape of nucleus propulsus from a defect in the annulus, while providing supporting and secured sealing means in a single device, and the device may be capable of preserving normal annulus geometry.

"Accordingly, there is a need for a device capable of meeting these and other objectives, wherein the device provides support and secure sealing means for a defect as well as the ability for cellular infiltration and subsequent repair occurring in or created in the annulus fibrosis. Furthermore, there is a need for a device capable of preserving or restoring normal annulus geometry (e.g., repairing a herniated disc), wherein there is support and secured sealing provided at each point of penetration or defect in the annulus.

"It is the intent of this invention to overcome these and other shortcomings of the prior art."

In addition to obtaining background information on this patent, NewsRx editors also obtained the inventors' summary information for this patent: "Various embodiments of the current invention strive to overcome these various shortcomings in the prior art. These embodiments allow for singular devices, or combinations of anchors or fastening devices which provide support for the annulus, while sealing the annulus, restoring or maintaining satisfactory disc geometry and providing the scaffold for regeneration of the damaged annulus.

"Certain of these embodiments have anchors which may be deployed on both sides of the annulus wall, thereby creating and exerting pressure on the wall. This pressure alone may serve to support and/or seal the annulus; however, the anchors themselves may feature or further be utilized in combination with a sealing means (e.g., elastic biomaterials, patches, collagen, etc.) that may be beneficial or necessary to aid sealing. The various embodiments of the invention contemplate the use of a variety of devices including, but not limited to, patches, plugs, staples, expandable materials, meshes, anchors, sutures, flowable materials, sealants, glues, gels and other wound and tissue repair devices known in the art.

"Several embodiments of the present disclosure utilize at least one sealing means. The sealing means, or sealing member, as the terms are used interchangeably herein, may be most beneficial if placed at the inside wall of the annulus or on the outside of the wall depending on the geometry of the device, the type of sealing means, and the geometry of the affected anatomy. Furthermore, the seal may be placed proximal or distal to the fastening device(s). It is recognized that the force internal to the annulus (i.e., the force from the fluid nucleus propulsus) may assist sealing by pressing the sealing means against the annulus, where such sealing means may be preferably located internal to the annulus.

"Overall disc or annulus geometry may be beneficially altered by placing a fastening device at or through a distal wall of the annulus, while placing a second fastening device at or through the proximal wall, where the devices are connected, e.g., by a tether, suture, flexible, or rigid member. This type of device would allow compression to be placed across each disc wall, while simultaneously compressing or restraining the disc across its diameter. Again, sealing means may be employed, as previously discussed.

"These various embodiments may be particularly useful in the situation where the annulus is torn. Since the annulus is fibrous, tears generally occur in the circumferential direction (i.e., not purely radial) along at least a portion of the fibers. Deploying a fastening device across the tear could cause compression to be placed across the torn annulus surfaces, thereby allowing the combination of securement and friction (thereby restricting movement of the torn surfaces against each other) to hold and support the annulus.

"Commonly, discectomies or laminectomies are performed to relieve pain. These embodiments may augment, if not replace these types of procedures. That is, multiple fasteners, or a single through-wall fastener, may be placed proximal and distal to the annulus entry tract (in the case of a discectomy), and a sealing patch may be placed adjacent either fastener, or the sealing patch may reside mid-wall to the annulus.

"It is also recognized that a sealing member may function as a fastener itself, thereby minimizing the number of device components, procedural steps, and/or procedural time. To that end, a sealing member may be rigid, compliant, or elastic; furthermore, the sealing member may be a composite of various materials, which are best suited for support and sealing functions. As a non-limiting example, such fasteners may be comprised of a rigid polymeric backing material (which may or may not be resorbable, e.g., PLA or polyurethane) which has a layer that contacts the tissue which comprises a malleable material, which may or may not be resorbable (e.g. polymer, collagen, etc.) to seal the tear or procedurally made opening. Such components may be comprised of materials inherently radiopaque or treated with substances which make them radiopaque when viewed under standard imaging techniques to allow the surgeon to visualize placement.

"These various embodiments may be at least partially made from permanent or biodegradable materials such as those listed in Table 1, and these devices may have a secondary or tertiary effect by the delivery of drugs or biologics such as those listed in Table 2. In an embodiment of a fastening or sealing device made from the materials described above, once implanted in a living being, the device may cause or induce the new growth or regrowth of cellular material. In this embodiment, the material encourages the ingrowth of cellular material that securely integrates the device into the surrounding tissues, thereby repairing the weakened area in a more effective manner.

"In the embodiment where the device is a resorbable material, the ingrowth of cellular material into the device allows for a permanent repair upon complete resorption of the resorbable device, as the material is replaced by the growth of cells to create a natural tissue material similar to and integrated with the surrounding structures.

"In the embodiment where the device is a non-resorbable material, the ingrowth of cellular material into the device allows the complete integration of the device with the surrounding tissue, thereby creating a suitable repair having nearly similar compliance and other physical characteristics as the original tissue material.

"Procedurally, these various embodiments may be delivered from posterior or anterior directions, based on the anatomical constraints as well as, among other things, herniation, disease, or type and geometry of the defect. While it is envisioned that similar, if not the same, delivery devices and methods may work for posterior as well as anterior procedures and placements, certain types of procedures may benefit greatly from devices or embodiments which sense their location or detect where they are located in the anatomy. For many annulus repair devices it may be beneficial to utilize minimally invasive methodologies to position the device. Minimally invasive procedures utilize laproscopic or endoscopic instruments to perform procedures through small openings in a patient's skin and can result in less trauma and faster healing times for the patient. However, such approaches are challenging in that the physician may not be able to directly visualize many aspects of the procedure. It has been discovered through experimentation in ex-vivo models that several embodiments of the devices of this invention can benefit by using delivery systems that can locate the transition between the annulus and the adjacent tissues to ensure proper device placement.

"Location detection devices are known in the art, for example U.S. Pat. No. 5,282,827, assigned to the assignee of the present disclosure, may be used to accurately place a hemostasis device in an artery (delivery of a hemostasis device using a location detector) also assigned to the assignee of the present disclosure. However, while these aforementioned devices may perform suitably for the currently contemplated procedures, certain modifications could improve their performance. That is, the annulus propulsus, as well as certain of the surrounding fluid, is normally more viscous and less able to flow to provide the 'perceptible signal' of the aforementioned patents.

"In order to improve upon these previous embodiments, the location detection means incorporated in the current embodiments may further comprise instrumentation or other features allowing for accurate placement of the device percutaneously. Such instruments may be calibrated at some portion so as to allow the surgeon to determine the exact thickness or dimension of the spinal disc component to be traversed with the fixation device. These placement instruments can also be comprised of an actual depth measurement instrument whereby the surgeon can engage the aspect of the disc to which the distal most portion of the device should engage and then determine the traversing distance. A location detection means may also beneficially stabilize the delivery system for the placement of a repair device in an intervertebral disk.

"In order to effectuate the proper placement of the various devices of the present invention, one may optionally employ various accessory instruments. For example, it may be beneficial to employ, for example, tools to determine the appropriate depth and size of the defect, tools that effectively dissect tissues at or adjacent to the defect in order to prepare an area for accepting the device, or tools that sever a suture or connecting element after a deployment of the device, such that excess suture length will not cause irritation to nearby tissues."

For more information, see this patent: Evans, Douglas G.; Kelly, Jeffrey C.; Bradica, Gino; Carouge, Michael K.; Oeffinger, Brian. System and Devices for the Repair of a Vertebral Disc Defect. U.S. Patent Number 8758351, filed February 14, 2012, and published online on June 24, 2014. Patent URL:

Keywords for this news article include: Legal Issues, Kensey Nash Corporation, Extracellular Matrix Proteins.

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Source: Life Science Weekly

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