The biomechanical function of each pair of facet joints is to guide and limit movement of the spinal motion segment. In the lumbar spine , for example, the facet joints function to protect the motion segment from anterior shear forces, excessive rotation and flexion. Facet joints appear to have little influence on the range of side bending lateral flexion. These functions can be disrupted by degeneration, dislocation, fracture, injury, instability from trauma, osteoarthritis , and surgery.
In the thoracic spine the facet joints function to restrain the amount of flexion and anterior translation of the corresponding vertebral segment and function to facilitate rotation. Cavitation of the synovial fluid within the facet joints is responsible for the popping sound crepitus associated with manual spinal manipulation, commonly referred to as "cracking the back.
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The facet joints, both superior and inferior, are aligned in a way to allow flexion and extension, and to limit rotation. This is especially true in the lumbar spine. In large part due to the mechanical nature of their function, all joints undergo degenerative changes with the wear and tear of age. This is particularly true for joints in the spine, and the facet joint in particular. This is commonly known as facet joint arthritis or facet arthropathy.
Facet joint arthritis often manifests as a dull ache across the back. However like many deep organs of the body it can be experienced by the patient in a variety of referral pain patterns. The location of facet joints, deep in the back and covered with large tracts of paraspinal muscles , further complicate the diagnostic approach. Typically facet joint arthritis is diagnosed with specialized physical examination by specialist physicians.
In the second round, Fire Storm hit Facet and pushing both robots off-balance in the next round. Bumping and ramming, Facet finally succeeded in flipping Fire Storm onto its back. Fire Storm self-righted, and then pushed and flipped Facet against a side wall.
This clever move left Facet unable to self-right. With the damage done and Facet immobilised, Sir Killalot came in and impaled its lance into the huge gap underneath Facet's flipper, drilling into it in the process. Sir Killalot then lifted Facet into the air and carried it towards the pit, but failed to drop the robot in before cease was called. In September that same year, Facet appeared at Sevenoaks and fought Ivanhoe 2 and at least two melees. Sign In Don't have an account? Start a Wiki. Contents [ show ]. Categories :. Cancel Save. This Robot Wars article is in need of rewriting to bring it up to a higher standard.
You can help Robot Wars Wiki by rewriting it. Moreover, artificial ligaments mat not attach directly on vertebra , but it may wrap around any bony protrusion in vertebra with or without any aid of another component such as a hook.
Various means of attachment are discussed later. The opposite ends artificial ligaments can also attach or wrap to various site on vertebra similar to vertebra Furthermore, artificial ligaments may attach to vertebra indirectly through the artificial facet joint Again, as non-limiting examples, same attachment mechanism such as bone screws can be used to attach both artificial facet joint and artificial ligaments , or artificial ligaments may attach to any part of artificial facet join , including the connector Any of the currently used artificial facet joints can be used as components of the device of the present invention.
In one embodiment, an artificial facet joint described in the U. Other embodiments include those described in U. The entire teachings of these patents and published applications are herein incorporated by reference. Other examples of suitable artificial facet joints are described in U. Three sequential vertebrae, , and , are shown in a patient following facetectomy between vertebra and and laminectomy on vertebra Artificial facet joint has been implanted.
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Artificial facet joint includes coupling member Connectors and connect coupling member to vertebrae and using pedicle screws and Artificial facet joint further includes spinous process support Spinous process support further contributes to restoration of natural function of the functional spinal units comprising vertebrae and and vertebrae and by supporting spinous process of vertebra Artificial ligaments are attached to spinous process support Therefore, vertebrae and are connected by the artificial ligaments An embodiment of artificial facet joint has been implanted.
Connectors and of facet joint connect support member to vertebrae and using pedicle screws and The device of the present invention further includes artificial ligaments that connect vertebrae and Artificial ligaments are attached to vertebra by pedicle screws The other ends of the artificial ligaments are attached by pedicle screws that are the same bone screws used to attach artificial facet joints Further, the embodiment of artificial facet joint of the device shown in FIG.
In this embodiment, artificial ligaments are attached to pedicle screws and Additional artificial ligaments additionally restores function lost by facetectomy and resection of the posterior spinal ligaments between vertebrae and , including capsulary ligaments interspinous ligaments and supraspinous ligaments. The attachment mechanism listed in FIGS. Variety of bone screws, hooks, rivets, wires, and cables can be employed to secure the artificial ligaments to the vertebra or wrap the artificial ligaments around the vertebra.
Coupling member s and connectors of an artificial facet joint of the device of the present invention can be rigid or flexible.
In one embodiment, the coupling members and the connectors are flexible. In another embodiment, the connectors are substantially rigid rods. Each flexible member can have a variety of configurations, shapes, and sizes.
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Coupling members can be formed from a wide range of biocompatible materials. Coupling members, in one embodiment, are formed from a polymer, and more preferably a biocompatible polymer, such as polyurethane, composite reinforced polyurethane, silicone, etc. Connecting members can be produced from such materials as metals, ceramics, polymers, etc. Artificial ligaments of a device of the present invention perform a function of any combination of natural interspinous ligament, supraspinous ligament, and facet joint capsulary ligament. Therefore, artificial ligaments should have tensile strength of at least 50 N, preferably N, more preferably N.
The artificial ligament should limit the flexion of a functional spinal unit to 15 degrees, preferably no more than 12 degrees of flexion.
However, the ligament should be flexible to easily bend. When implanted, the ligament may be slack in the neutral position to allow flexion of a functional spinal unit to at least 6 degrees, preferably at least 12 degrees. The artificial ligaments can be made of any biocompatible material including polyesters, polypropylene, polyethylene, carbon fiber, glass, glass fiber, polyurethane, plyaramide, metals, polymers, copolymers, polyactic acid PLA , polyglycolic acid PGA , silk, cellusoseic acid, polycaproactone fibers, or any combination of above. To increase the tensile strength multiple fibers can be weaved to form a band.
Furthermore, in some embodiments, the flexible members may have time-dependent behavior such as creep. Thereby, the property of the artificial ligament changes over time. For example, the flexible member may be very stiff e. Finally, the artificial ligaments can be made of at least in part by subintestinal submucosa SIS to assist in the formulation of natural ligamentous tissue. While this invention has been particularly shown and described with references to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention encompassed by the appended claims.
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An implantable device for stabilizing at least a portion of a spinal column, comprising: a one or more implantable artificial facet joints, each of the said artificial facet joints, when implanted, coupling two or more adjacent vertebrae;. The device of claim 1 , wherein at least one of the one or more implantable artificial facet joints couples two adjacent vertebrae.
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The device of claim 2 , wherein the additional vertebra not coupled by the artificial facet joint is superiorly adjacent to the superior of the two adjacent vertebrae coupled by the artificial facet joint. The device of claim 2 , wherein the additional vertebra not coupled by the artificial facet joint is inferiorly adjacent to the inferior of the two adjacent vertebrae coupled by the artificial facet joint. The device of claim 1 , wherein one or more of the artificial ligaments include means of attachment to at least one of the vertebrae, said means including at least one member selected from the group consisting of a screw, a rivet, a hook, a plate, a wire and a cable.
The device of claim 1 , wherein the artificial ligament wraps around a portion of the referred vertebra. The device of claim 1 , further including a connector that is attached to the artificial ligament, and which wraps around a portion of at least one of the vertebrae. The device of claim 1 , further including a bone anchor, wherein the artificial ligament wraps around the bone anchor which is attached to one of the vertebrae. The device of claim 8 , further including a connector and a bone anchor whereby the connector is attached to the artificial ligament and wraps around the bone anchor, said bone anchor being attached to one of the vertebrae.
The device of claim 1 , wherein the artificial ligament is attached to the artificial facet joint. The device of claim 1 , further including a connector that connects the artificial ligament to the artificial facet joint. The device of claim 1 , wherein the artificial ligament and the artificial facet joint share an attachment to the vertebra. The device of claim 1 , further including a connector that is attached to the artificial ligament, and wherein the connector and the artificial joint share an attachment to one of the vertebrae.
The device of claim 1 , wherein at least one of the artificial ligaments includes at least one terminal portion that is attachable to at least one pedicle of at least one vertebra by at least one pedicle screw. The device of claim 1 , wherein at least one of the artificial ligaments is connected to at least one of a bone rivet and a bone screw, the bone rivet or bone screw being attachable to a spinous process of at least one of the vertebra.
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