Abstract:
Systems and methods prevent magnetic implant migration and extrusion in the upper airway. The systems and methods relate both to surgical techniques as well as structural features to address the problem of magnetic implant migration.

Description:
RELATED APPLICATIONS 
     This application claims the benefits of U.S. Provisional Patent Application Ser. No. 60/739,519, filed Nov. 23, 2005. This application is also a continuation-in-part of U.S. patent application Ser. No. 11/397,744 now U.S. Pat. No. 7,721,740, filed Apr. 4, 2006 entitled “Devices, Systems, and Methods Using Magnetic Force Systems In or On Tissue,” which is a continuation-in-part of U.S. patent application Ser. No. 10/806,372, filed Mar. 22, 2004 now U.S. Pat. No. 7,441,559 entitled “Devices, Systems, and Methods to Fixate Tissue Within the Regions of the Body, Such as the Pharyngeal Conduit,” which is a continuation-in-part of U.S. patent application Ser. No. 10/718,254, filed Nov. 20, 2003 now U.S. Pat. No. 7,360,542 entitled “Devices, Systems, and Methods to Fixate Tissue Within the Regions of the Body, Such as the Pharyngeal Conduit,” which is a continuation-in-part of U.S. patent application Ser. No. 10/656,861, filed Sep. 6, 2003 now U.S. Pat. No. 7,188,627 entitled “Magnetic Force Devices, Systems, and Methods for Resisting Tissue Collapse within the Pharyngeal Conduit,” which further claims the benefit of U.S. Provisional Patent  Application Ser. No. 60/441,639, filed Jan. 22, 2003 and U.S. Provisional Patent Application Ser. No. 60/456,164, filed Mar. 20, 2003, and which is a continuation-in-part of U.S. patent application Ser. No. 10,236,455, filed Sep. 6, 2002 now U.S. Pat No. 7,216,648 and entitled “System and Method for Moving and/or Restraining Tissue in the Upper Respiratory System.” This application also claims the benefit of U.S. Provisional Patent Application Ser. No. 60/754,839, filed Dec. 29, 2005. All of the foregoing are incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The invention is directed to devices, systems, and methods for improved stabilization of magnetic force devices used in and/or on a body. The improved stabilization may be realized both during placement and at an implanted position. 
     BACKGROUND OF THE INVENTION 
     I. Characteristics of Sleep Apnea 
     First described in 1965, sleep apnea is a breathing disorder characterized by brief interruptions (10 seconds or more) of breathing during sleep. Sleep apnea is a common but serious, potentially life-threatening condition, affecting as many as 18 million Americans. 
     There are two types of sleep apnea: central and obstructive. Central sleep apnea, which is relatively rare, occurs when the brain fails to send the appropriate signal to the breathing muscles to initiate respirations, e.g., as a result of brain stem injury or damage. Mechanical ventilation is the only treatment available to ensure continued breathing. 
     Obstructive sleep apnea (OSA) is far more common. Normally, the muscles of the upper part of the throat keep the airway open to permit air flow into the lungs. When the muscles of the soft palate at the base of the  tongue and the uvula (the small fleshy tissue hanging from the center of the back of the throat) relax and sag, the relaxed tissues may vibrate as air flows past the tissues during breathing, resulting in snoring. Snoring affects about half of men and 25 percent of women—most of whom are age 50 or older. 
     In more serious cases, the airway becomes blocked, making breathing labored and noisy, or even stopping it altogether. In a given night, the number of involuntary breathing pauses or “apneic events” may be as high as 20 to 30 or more per hour. These breathing pauses are almost always accompanied by snoring between apnea episodes, although not everyone who snores has the condition. Sleep apnea can also be characterized by choking sensations. 
     Lack of air intake into the lungs results in lower levels of oxygen and increased levels of carbon dioxide in the blood. The altered levels of oxygen and carbon dioxide alert the brain to resume breathing and cause arousal. The frequent interruptions of deep, restorative sleep often lead to early morning headaches, excessive daytime sleepiness, depression, irritability, and learning and memory difficulties. 
     The medical community has become aware of the increased incidence of heart attacks, hypertension and strokes in people with moderate or severe obstructive sleep apnea. It is estimated that up to 50 percent of sleep apnea patients have high blood pressure. 
     Upon an apneic event, the sleeping person is unable to continue normal respiratory function and the level of oxygen saturation in the blood is reduced. The brain will sense the condition and cause the sleeper to struggle and gasp for air. Breathing will then resume, often followed by continued apneic events. There are potentially damaging effects to the heart and blood vessels due to abrupt compensatory swings in blood pressure. Upon each  event, the sleeping person will be partially aroused from sleep, resulting in a greatly reduced quality of sleep and associated daytime fatigue. 
     Although some apneic events are normal in all persons and mammals, the frequency of blockages will determine the seriousness of the disease and opportunity for health damage. When the incidence of blockage is frequent, corrective action should be taken. 
     II. Sleep and the Anatomy of the Upper Airway 
     The upper airway consists of a conduit that begins at the nasal valve, situated in the tip of the nose, and extends to the larynx. Although all tissue along this conduit is dynamic and responsive to the respiratory cycle, only the pharynx (the portion that starts behind the nasal cavity and ends in its connections to the supraglottic larynx is totally collapsible. 
     The cross sectional area of the upper airway varies with the phases of the respiratory cycle. At the initiation of inspiration (phase I), the airway begins to dilate and then to remain relatively constant through the remainder of inspiration (Phase II). At the onset of expiration (Phase III) the airway begins to enlarge, reaching maximum diameter and then diminishing is size so that at the end of expiration (Phase IV), it is at its narrowest, corresponding to the time when the upper airway dilator muscles are least active, and positive intraluminal pressure is lowest. The upper airway, therefore, has the greatest potential for collapse and closure at end-expiration. [ref: Schwab R J, Goldberg A N. Upper airway assessment: radiographic and other imaging techniques. Otolaryngol Clin North Am 1998; 31:931-968] 
     Sleep is characterized by a reduction in upper airway dilator muscle activity. For the individual with obstructive sleep apnea (OSA) and perhaps the other disorders which comprise much of the group of entities  called obstructive sleep-disordered breathing (SDB), it is believed that this change in muscle function causes pharyngeal narrowing and collapse. Two possible etiologies for this phenomenon in OSA patients have been theorized. One is that these individuals reduce the airway dilator muscle tone more than non-apneics during sleep (the neural theory). The other is that all individuals experience the same reduction in dilator activity in sleep, but that the apneic has a pharynx that is structurally less stable (the anatomic theory). Both theories may in fact be contributors to OSA, but current studies seem to support that OSA patients have an intrinsically structurally narrowed and more collapsible pharynx [ref: Isono S. Remmers J, Tanaka A Sho Y, Sato J, Nishino T. Anatomy of pharynx in patients with obstructive sleep apnea and in normal subjects. J Appl Physiol 1997:82:1319-1326.] Although this phenomenon is often accentuated at specific sites, such as the velopharyngeal level [Isono], studies of closing pressures [Isono] supports dynamic fast MRI imaging that shows narrowing and collapse usually occurs along the entire length of the pharynx. [ref: Shellock F G, Schatz C J, Julien P, Silverman J M, Steinberg F, Foo T K F, Hopp M L, Westbrook P R. Occlusion and narrowing of the pharyngeal airway in obstructive sleep apnea: evaluation by ultrafast spoiled GRASS M R imaging. Am J of Roentgenology 1992:158:1019-1024.]. 
     III. Treatment Options 
     To date, the only modality that addresses collapse along the entire upper airway is mechanical positive pressure breathing devices, such as continuous positive airway pressure (CPAP) machines. All other modalities, such as various surgical procedures and oral appliances, by their nature, address specific sectors of the airway (such as palate, tongue base and hyoid levels), but leave  portions of pharyngeal wall untreated. This may account for the considerably higher success rate of CPAP over surgery and appliances in controlling OSA. Although CPAP, which in essence acts as an airway splint for the respiratory cycle, is highly successful, it has some very significant shortcomings. It can be cumbersome to wear and travel with, difficult to accept on a social level, and not tolerated by many (for reasons such as claustrophobia, facial and nasal mask pressure sores, airway irritation). These factors have lead to a relatively poor long-term compliance rate. One study has shown that 65% of patients abandon their CPAP treatment in 6 months. 
     An alternative method would “splint” the airway during sleep that would give the benefits afforded by CPAP without some of its shortcomings would therefore be advantageous. In this method magnetic energy is used either attractively (opposite poles of two or more magnets facing one another, resulting in attractive forces) or repulsively (like poles of two or more magnets facing one another, resulting in forces which repel one another). Magnets implanted in the tongue interact either by attractive or repulsive forces with other magnets implanted in various organs of the upper airway system or external to the body within a neck collar. 
     Since the “splint” method using magnetic forces did not eliminate all magnetic interaction, implants within the tongue and pharyngeal wall often were often difficult to stabilize in their specified locations. The magnetic implants could interact with one another causing the implants to fold or lose their shape, as well as with magnetic instruments. The implants could also rotate or migrate from their original implant position. 
     The need remains for simple, cost-effective devices, systems, and methods for improved stabilization of  magnetic force devices used in and/or on a body, including improved stabilization during placement and at an implanted position. 
     SUMMARY OF THE INVENTION 
     The invention provides devices, and methods to improve implant tolerance generally, prevent implant migration, and stabilize a magnetic implant in tissue, e.g., the tongue, oropharynx, and pharyngeal wall. The invention is particularly useful to prevent sleep disordered diseases such as Obstructive Sleep Apnea (OSA) and hypopnea (a partial obstruction of the airway during sleep). 
     One aspect of the invention provides an implant device comprising at least two ferromagnetic components carried by a support structure in a spaced apart relationship. The implant device includes at least one opening formed in the support structure between the ferromagnetic components. The openings can provide stabilization after implantation, e.g., by providing flexibility, and/or tissue in-growth, or placement of external fixation elements, such as a suture, or a staple, or glue. 
     In one embodiment, the support structure comprises a net-like array of openings. 
     In one embodiment, the opening occupies a geometric center of the support structure. 
     In one embodiment, the support structure is either generally U-shaped or O-shaped. 
     Another aspect of the invention provides an implant device comprising a ferromagnetic component carried on a a support structure. According to this aspect of the invention, at least one protrusion extends from the support structure. The protrusion is sized and configured for engaging tissue to stabilize the support structure. The protrusion can comprise, e.g., a barb, or a hook. In  one embodiment, the implant device includes means for selectively withdrawing and extending the protrusion relative to the support structure. 
     Another aspect of the invention provides an implant device comprising a ferromagnetic component carried by a support structure. According to this aspect of the invention, the support structure includes a first side having a textured surface sized and configured for contact with tissue and a second side having a generally smooth surface. Contact between the textured first side and tissue within an airway stabilizes the implant, while the generally smooth surface, which faces the airway, minimizes interference with normal functions such as swallowing or speech. 
     Another aspect of the invention provides an implant device comprising a ferromagnetic component carried on a support structure. According to this aspect of the invention, the implant is shaped to prevent motion, migration and extrusion while implanted in tissue. The support structure can be sized and configured, e.g., with rounded corners, and/or irregular outer edges forming alternating wide and narrow areas, and/or regions of different thickness. 
     According to another aspect of the invention, an implant device includes multiple magnetic arrays, and means for preventing attraction between the arrays to facilitate placement of the device in or on a tissue region. 
     According to another aspect of the invention, a system is provided that comprises a magnetic implant device, and a pocket surgically created in tissue. The pocket is sized and configured with an irregularly shape such that, when the magnetic implant is placed in the pocket, intact tissue around the implant prevents motion of the magnetic implant.  
     Another aspect of the invention provides a system comprising first, second, and third magnetic structures, each having a north magnetic pole. The first and second magnetic structures are sized and configured for placement in or on a first tissue region in a spaced apart relationship. The magnetic north poles or the first and second magnetic structures are mutually oriented toward a second tissue region. According to this aspect of the invention, the third magnetic structure is sized and configured for placement in or on the second tissue region. The magnetic north pole of the third magnetic structure is oriented toward the first tissue region between the first and second magnetic structures. The offset between the third magnetic structure and the first and second magnetic structures lends stability to the repelling interaction among the magnets in the system. 
     Another aspect of the invention provides a system for implanting a magnetic implant comprising side-by-side arrays of magnets that can flip or fold upon itself to form a folded-up structure. The system comprises first means for separating the folded-up structure and positioning the magnetic implant in tissue, and second means for holding the magnetic implant in place while the first means separates the folded-up structure. 
     Another aspect of the invention provides a method for stabilizing a magnetic implant comprising side-by-side first and second magnetic sections. The method threads a placement suture through two adjacent inner holes in the first magnetic section and ties the placement suture to form a loop. The method folds the implant so that the first section overlaps the second section and places the implant while folded through the incision into a pocket formed in wall tissue. The method positions a first instrument to hold the second section against fascia while placing a second instrument through  the suture loop. The method pulls the ends of the placement suture to apply force to separate the first and second sections, while using the second instrument to guide the first section into a side-by-side relationship with the second section. The method places anchoring sutures at the four corners of the separated magnetic implant and then cuts the loop to remove the placement suture. 
     Another aspect of the invention provides methods for inserting a various shaped implants in soft tissue. 
     One method implants a U-shaped implant. The method cuts two incisions in the soft tissue, and cuts a U-shaped pocket in the soft tissue. The method uses a tool to push suture through one incision into the U-shaped pocket, until one end of the suture comes out through the other incision. The method ties one end of the suture to the U-shaped implant. The method uses a tool to push from one end of the implant, while pulling the suture at the other end of the implant, to fit the U-shaped implant into the specified pocket. The method closes the two incisions. 
     Another method implants an L-shaped implant. The method cuts an incision in the soft tissue and cuts an L-shaped pocket in the soft tissue. The method uses a tool to push the L-shaped implant into the L-shaped pocket and closes the incision. 
     Another method implants an O-shaped implant. The method cuts an incision into the soft tissue and cuts an O-shaped pocket into the tissue. The method inserts an O-shaped implant with an open link into the pocket. The method closes the open link of the O-shaped implant in the pocket and closes the incision. 
     The implant devices, systems, and methodologies that embody technical features of the invention are well suited for placement in structures of the airway, such as  the tongue, soft palate/uvula, and pharyngeal wall. 
     Other inventions and technical features shall be apparent based upon the accompanying description, drawings, and claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an anatomic view of a magnetic force system that includes a first magnetic component implanted in the back of the tongue and a second magnetic component implanted in a posterior region of the pharyngeal wall, the first and second magnetic components having the same polarity to magnetically interact by the generation of a repelling force between them, which prevents the tongue from moving in a posterior direction and closing or restricting the pharyngeal conduit or airway. 
         FIG. 2  is an anatomic view of a magnetic force system that includes a magnetic (or ferrous) array implanted near the posterior surface of the tongue and an external magnet that is mounted in a form fitting collar below the mandible and located forward, near the anterior surface of the chin, the magnetic or ferrous array and the external magnet being of opposite polarities to magnetically attract the implanted magnets forward, pulling the tongue in an anterior direction and opening the airway. 
         FIGS. 3 to 6  are alternative views of a magnetic force system of the type shown in  FIG. 2 . 
         FIG. 7A  diagrammatically shows an array of three repelling magnets oriented in a relatively stable repelling position, due to the creation of a magnetic force field saddle shown in  FIG. 7B . 
         FIGS. 8A ,  8 B, and  8 C show various implantable magnetic arrays desirably shaped to provide both stability after implantation, as well as the healing rate post-operatively. 
         FIGS. 9A ,  9 B, and  9 C show representative embodiments  of magnetic implants having at least one side with variegations to provide a tissue gripping surface, thereby providing stability after implantation. 
         FIGS. 10A ,  10 B,  10 C, and  10 D show various types of magnetic implants with hooks, barbs, or a combination of the two, or equivalent components, to prevent migration and folding of the magnetic implant upon itself. 
       FIGS.  11 A( 1 ) to  11 A( 4 );  11 B( 1 ) to  11 B( 5 ); and  11 C( 1 ) to  11 C( 4 ) show various representative alternative embodiments of stabilized magnetic implant structures especially adapted for implantation in a posterior pharyngeal wall. 
         FIGS. 12 and 13  show various types of magnetic implants that include apertures through which external fixation means, e.g., suture or staples, can be passed to attach the implant to surrounding tissue. 
         FIGS. 14A and 14B  show an implant of the type shown in  FIG. 8A , which includes a network of holes that can be filled with a growth-stimulating medium to encourage the in-growth of tissue to stabilize the implant. 
         FIG. 15  shows an implant of the type shown in.  FIG. 8A , which includes a network of holes filled a tissue adhesive or glue to give immediate post-op tissue stability. 
         FIGS. 16 to 18  show various types of magnetic net array implants, including magnets or ferrous discs linked together by a net-like webbing with flanges which provide large areas in which the opposing surfaces of the surgically produced pocket may be closed (sutured or otherwise) for fast rejoining and healing of the tissue. 
         FIGS. 19 to 22  show surgically formed pockets into which magnetic net array implants of the type show in  FIGS. 16 to 18  can be implanted for use. 
         FIG. 23  shows a surgically formed pocket that, with respect to the lateral and longitudinal dimensions of a  given implant is laterally-tight but longitudinally-loose to accommodate anterior-posterior movement of the implant, but restrict lateral movement of the implant. 
         FIG. 24  shows a U-shaped implant placed in a tissue pocket of the same shape (e.g., in a tongue), the implant shape being keyed to prevent migration and limit relative tissue-to-implant motion. 
         FIGS. 25A  to D illustrate a way of inserting a U-shaped implant as shown in  FIG. 24  in the tongue. 
         FIG. 26A  shows an O-shaped implant placed in a tissue pocket of the same shape (e.g., in a tongue), the implant shape being keyed to prevent migration and limit relative tissue-to-implant motion. 
         FIGS. 26B and 26C  show an O-shaped implant of the type shown in  FIG. 26A  where magnets are positioned on only one side, the side without magnets acts as a rudder to distribute the force of the tongue and to stabilize the implant. 
         FIGS. 27A to 27D  illustrate a way of inserting an O-shaped implant, as shown in  FIGS. 26A  or  26 B, in a tongue. 
         FIGS. 28 and 29  show magnetic implants having a structure that prevents folding during implantation. 
         FIGS. 30A to 30C  show a magnetic implant which includes flexible hinges between arrays of magnetic discs, which allow the arrays to pivot into a serpentine shape (see  FIG. 30C ), but prevent the arrays from folding upon themselves. 
         FIG. 31  shows a magnetic implant (shown prior to implantation) having magnetic arrays that are prone to folding or flipping upon itself in response to magnetic interaction. 
         FIGS. 32A to 32D  show tools and related methodology for controlling the separation of the magnetic arrays of the magnetic implant shown in  FIG. 31 , to prevent folding  or flipping during implantation. 
         FIG. 33  shows a magnetic implant having preferential flexibility allowing the implant to remain in position because it closely mimics the movements of the surrounding anatomy. 
         FIGS. 34A and 34B  a magnetic implant having a support brace to help stabilize the implant. 
         FIG. 35  shows an alternative, circular design for the magnetic posterior pharyngeal wall implant. 
         FIG. 36  shows a magnetic implant having preferential flexibility that takes into account the shape and movement of the tongue. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     This Specification discloses various magnetic-based devices, systems, and methods for improved stabilization of magnetic forces both during implantation and at an implanted position. For example, the various aspects of the invention have application in procedures requiring the restriction of tissue collapse in and/or around the body, such as a passageway within the body. The devices, systems, and methods that embody features of the invention are also adaptable for use with devices, systems, and methods that are not restricted to tissue based applications. 
     The devices, systems, and methods are particularly well suited for treating sleep disordered breathing, including sleep apnea. For this reason, the devices, systems, and methods will be described in this context. Still, it should be appreciated that the disclosed devices, systems, and methods are applicable for use in treating other dysfunctions elsewhere in the body, which are not necessarily sleep disorder related. 
     I. Magnetic Force Systems 
       FIG. 1  shows, in an anatomic view, an illustrative magnetic force system  10 . The magnetic force system  10   resists the collapse of tissue in a targeted passageway, such as a pharyngeal structure and the individual anatomic components within the pharyngeal conduit during sleep. As generally shown in  FIG. 1 , the magnetic force system includes a first magnetic component  12  implanted in the back of the tongue and a second magnetic component  14  implanted in a posterior region of the pharyngeal wall. The first and second magnetic components  12  and  14  have the same polarity. They magnetically interact by the generation of a repelling force between them. The magnetic repelling force prevents the tongue from moving in a posterior direction and closing or restricting the pharyngeal conduit or airway. 
     It should be appreciated that the magnetic force system  10  can be differently configured and arranged, both anatomically and with respect to the position and polarity of the magnets. 
     For example,  FIG. 2  shows a cross section of a human head showing the nasal and oral cavities, tongue, oropharynx, chin and neck. A magnetic (or ferrous or ferromagnetic) array  16  is implanted near the posterior surface of the tongue. An external magnet  18  is mounted in a form fitting collar  20  such that the magnet is positioned below the mandible and located forward, near the anterior surface of the chin. A soft pad  22  provides comfort for the wearer, preventing the magnet  18  from pressing directly against the flesh of the chin. An outer covering  24  encases the magnet and wraps around for the collar  20  to stabilize and anchor the magnet  18  in the desired location. The collar  20  can include a closure means such as a buckle or Velcro® strap for ease of use. The strap may further be elastic to provide a degree of stretch in the collar  20  for head movement, etc. The collar  20  may be comprised of a foam interior with a stretchable fabric covering for softness and  breathability. 
     In use, the magnet  18  has a polarity that is opposite the polarity of the magnetic or ferrous or ferromagnetic array  16 . As a result, the magnet  18  will attract the implanted magnets or ferrous or ferromagnetic array  16 , pulling the tongue in an anterior direction and opening the airway. This will prevent closure and occlusion of the airway during sleep. 
       FIG. 3  shows an alternative embodiment of a neck collar  20  with the magnet  18  placed just under the chin. 
       FIG. 4  shows another alternative embodiment. The magnetic or ferrous or ferromagnetic array  16  is implanted near the posterior surface of the tongue. The external magnet  18  of opposite polarity is mounted in a form fitting collar  20  such that the magnet is positioned against the anterior surface of the chin. This arrangement will cause the direction of the attractive force on the implanted array  16  to be directly forward, as opposed to a more-downward direction as in  FIG. 2 . 
       FIG. 5  shows an alternative embodiment, in which the external magnet  18  is held in place by a form fitting appliance  26  and collar  20 . Closure and adjustability can be provided by a buckle and strap arrangement or by a Velcro® strap  32 . 
       FIG. 6  shows yet another embodiment, in which a headgear  30  is provided consisting of flexible webbing straps. Side straps  32  extend downwardly to cup the magnet and chin cup  34  with the magnet  18  fixed within the chin cup  34 . This arrangement has the further advantage of preventing the mouth from falling open during sleep. Open mouth breathing is blamed by some in loud snoring, drying of the mouth and exacerbation of the tendency of the tongue to fall backward into the airway. 
     Magnetic forces field systems (repelling and/or attracting) can create a magnetic field to resist the  collapse of tissue in targeted pharyngeal structures and individual anatomic components within the pharyngeal conduit during sleep. The targeted pharyngeal structures and individual anatomic components within this region can include the pharyngeal walls; the base of the tongue; the vallecula; the hyoid bone and its attachments; the soft palate with uvula; the palatine tonsils with associated pillar tissue; and the epiglottis. 
     The implanted ferromagnetic material and/or the source of magnetic force can each comprise a single or discrete source of magnetism having a given desired orientation. For example, a single permanent magnet, comprising a body of a ferromagnetic material, can comprise a single source of magnetism having a given orientation. 
     As another example, a flexible or compliant array of magnets can also comprise individual sources of magnetism carried as a unit on a support carrier, or otherwise directly linked together, as will be described. 
     II. Magnetic Stabilization. 
     As previously described, when two or more magnets are placed near each other, a repelling or attracting force will be present and will act upon the two or more magnets. 
     An attracting force can also be generated between a ferrous alloy/ferromagnetic material and a magnet. The force, when properly directed, provides the benefit of the system  10  in its various embodiments, as described. 
     The magnetic force can also create difficulty in implanting or positioning the magnets at the targeted tissue region, and can also contribute to the unwanted movement (i.e., migration or extrusion) of the magnets in the tissue region after implantation or positioning. It is desirable to provide magnetic field systems that are stabilized, both during implantation or positioning and  after implantation during use. 
     A. Prevention of Migration and Extrusion After Implantation 
     1. Offset Repelling Pole Orientation 
     A repelling magnetic force system is inherently less stable than a counterpart attracting magnetic system. The inherent instability can be mitigated, e.g., by the relative orientation of repelling magnets to provide a preferred repelling position. 
     For example,  FIG. 7A  shows an array  300  of three repelling magnets  302   a ,  302   b , and  302   c  in a relatively stable repelling position. The array  300  orients two magnets  302   a  and  302   b  in a laterally spaced-apart relationship, with the magnetic north poles (N) in parallel side-by-side axial alignment. A lateral space  304  separates the magnets  302   a  and  302   b.    
     The array  300  places the third magnet  302   c  in an indirect facing relationship with the two magnets  302   a  and  302   b . As shown in  FIG. 7A , the magnetic north pole (N) of the magnet  302   c  is oriented parallel to the magnetic north poles (N) of the magnets  302   a  and  302   b , but does not directly face the north poles (N) of the magnets  302   a  and  302   b . Instead, the north pole (N) of the magnet  302   c  is offset and faces the lateral space  304  separating the magnets  302   a  and  302   b . The offset array  300  creates a repelling force saddle  306  (see  FIG. 7B ) in the magnetic force field, which serves to stabilize or give a preferred repelling position. 
     2. Shapes that Promote Stabilization 
     The shape of a magnetic implant&#39;s outer edge influences both the stability of an implant in its chosen location, as well as the healing rate post-operatively.  FIG. 8A  shows an implant  36  comprising flexible or compliant array of magnets  38  arranged in a polymer matrix having an outer profile or shape that is  representative of a shape that provides stability in tissue after implantation. As  FIG. 8A  shows, the magnetic implant  36  has an irregular outer edge  40 , with alternating wide and narrow areas. The wide areas prevent motion of the implant as healing occurs around the margins. The capsule that forms around the implant  36  after implantation will contract, grabbing the narrow areas. Holes  43  may be provided to allow tissue in-growth. The rounded corners of the implant  36  allow for faster healing of the surrounding tissues. 
       FIG. 8B  shows an alternate embodiment of a magnetic implant  56  having a profile that is also designed to discourage migration. The implant&#39;s flowing curves permit a large area of the surrounding tissues to grow around and grip the implant thus providing a natural anchor. This implant  56  is particularly well suited for implantation in the tongue, which has a naturally curved morphology that matches the profile of the implant  56 . The rounded corners  60  and beveled edges  62  further allow for faster healing of the surrounding tissues. 
     3. Integrated Protrusions for Soft Tissue Fixation 
       FIG. 8C  shows a magnetic implant  36  of a type shown in  FIG. 8A  having a textured underside  42 , or “bottom treads,” to grip tissue. Stabilization of the implant  36  (or any implant in general) can also be achieved through attachment of implant parts to the underlying tissue using, e.g., sutures or staples or glue, as will be described in greater detail later. The treads  42  will limit motion relative to the tissue to encourage rapid healing. 
       FIG. 9A  shows a magnetic implant  48  having a posterior, tissue-facing, side that includes variegations  44  to provide a tissue gripping surface. In  FIG. 9A , the opposite anterior side  46  of the implant  48  (which  typically faces an airway) can also be variegated, but in  FIG. 9A  the anterior side  46  is shown to be smooth, to aid the epithelial tissue in gliding over the implant during dynamic movement of the surrounding tissue, e.g., during swallowing or speech. In the two-sided arrangement shown in  FIG. 9A , the implant  48  provides both stabilizing for the magnetic implant  48  (due to the presence of the variegations  44  on the posterior tissue-facing side), as well as increasing tolerance in patients by avoiding interference with the process of swallowing (due to the relatively un-variegated anterior airway-facing side  46 ). 
       FIGS. 9B and 9C  show further embodiments, which are particularly useful for soft tissue fixation in the posterior pharyngeal wall. The posterior pharyngeal wall implants  36  each includes a caudal (inferior)-facing protrusion  47  and  49 , shown in  FIGS. 9B and 9C , respectively. The caudal-facing protrusions  47  and  49  allow the magnetic implants  36  to become stabilized in a therapeutically-effective caudal-to-cranial orientation (i.e., inferior-to-superior) within the posterior pharyngeal wall, while also avoiding misalignment with respect to the associated magnetic implant or implants in the tongue and/or soft palate/uvula placed to magnetically interact with the pharyngeal wall implants  36 . 
     Treatment of sleep apnea may necessitate insertion of a wide, flat implant in order to generate an effective magnetic field and, at the same time, limit bulking the tissue and making the obstruction worse. In such a case, protrusions such as hooks and barbs are desirably provided to grab the top tissue and limit motion. 
       FIGS. 10A and 10B  show a representative embodiment of a generally flat implant  50  with hooks  52  that dig into tissue, e.g., in the tongue or oropharynx.  FIGS. 10C   and  10 B show a representative embodiment of a generally flat implant  50  with barbs  52  that provide the same function. The hooks, barbs, or a combination of the two, or equivalent components, prevent migration and folding of the magnetic implant upon itself. 
     FIGS.  11 A( 1 ) to  11 A( 4 ) show a representative embodiment of an implant  54  having at least one tissue piercing barb or hook  61 , which is especially adapted for implantation in a posterior pharyngeal wall. FIG.  11 A( 1 ) shows the implant  54  that includes at least one anchoring assembly  55 . Either or both cranial (superior) and/or caudal (inferior) ends of the implant  54  may be straight, gently rounded or curved. The anchoring assembly  55  comprises, at one end, a loop  57  sized and configured for accommodating passage of a tissue suture or staple. In use, the loop  57  is intended to project beyond the cranial edge of the implant  54  for this purpose. The anchoring assembly  55  includes, at the opposite end, a sharp, tissue-piercing or anchoring barb or hook  61 . In use, the barb  61  is intended to project beyond the caudal edge of the implant  54 . The barb or hook  61  can be manufactured. e.g., from resilient shape memory NiTi wire, resilient formed stainless steel  316 L, or any other medical grade metal. The barb or hook  61  can be resiliently straightened by the application of external pressure (as FIG.  11 A( 2 ) shows), and will resiliently return toward its curved hook shape in the absence of applied pressure (as FIG.  11 A( 1 ) shows). 
     In the illustrated embodiment (see FIGS.  11 A( 1 ) and  11 A( 2 )), the anchoring assembly  55  is sized and configured to be passed, hook end  61  first, through a constricted cranial-caudal channel  63  formed in the implant  54 . The channel  63  can be formed, e.g., from NiTi tubing. In use, the channel  63  extends in a cranial-caudal direction, parallel to the longitudinal anatomic  axis of the pharyngeal conduit. The channel  63  may extend through holes formed through the individual magnets  65  carried by the implant  54 . Alternatively, as shown in FIG.  11 A( 1 ), the channel  63  passes through the flexible polymer matrix material of the implant  54  itself. 
     When introduced into the cranial end of the channel  63  (see FIG.  11 A( 3 )), the hooked end  61  will resiliently straighten within the confines of the channel  63 . The hooked end  61  will resiliently return to its hook shape (see FIG.  11 A( 4 )) when freed of the caudal end of the channel  63 . It should be appreciated that a given implant  54  can include more than one channel  63  to accommodate a plurality of anchoring assemblies  55 , each with a suture loop  57  and a barbed end  61  for fixation of the implant  54  in tissue. 
     During implantation (see FIG.  11 A( 3 )), the implant device  54  can be placed within a pocket P, e.g., surgically created in tissue in the pharyngeal conduit wall. An X-ray or any other suitable image is desirably taken to ensure that the position of the implant  54  within the tissue pocket P is correct. Once the correct position of the implant  54  in the tissue pocket P is confirmed, the desired number of anchoring assemblies  55  is passed, hook end  61  first, through a channel  63 , from cranial end toward the caudal end (see FIG.  11 A( 3 )). Free of the channel  63 , the end(s)  61  resiliently return(s) to the hook shape (see FIG.  11 A( 4 )), piercing pharyngeal wall tissue within the pocket P, to anchor the caudal portion of the implant  54  within the pocket P. The cranial end of the implant  54  can then be anchored by suture material S passed through the loop  57  (as FIG.  11 A( 4 ) also shows). 
     Should the implant  54  need to be re-positioned or removed, the suture material S can be removed from the loop  57 . By then pulling on the freed loop  57 , the hook   61  can be withdrawn from tissue and back into the caudal end of the channel  63  (as FIG.  11 A( 2 ) shows). Once the hook  61  is withdrawn and straightened within the channel  63 , the implant  54  can be completely removed from the pocket P, or it can be re-positioned and then re-affixed, according to the patient&#39;s needs. 
     FIG.  11 B( 1 ) shows another representative embodiment of an implant  54  having at least one tissue piercing barb or hook  67 , which is especially adapted for implantation in a posterior pharyngeal wall. In FIG.  11 B( 1 ), two hooks  67  are shown. Each barb or hook  67  can be manufactured. e.g., from NiTi wire, stainless steel  316 L, or any other medical grade metal. In the embodiment shown in FIG.  11 B( 1 ), each barb or hook  67  is permanently affixed to the implant  54 , e.g., by coupling to one or two of the magnetic components. The barb or hook  67  extends from the caudal end of the implant  54 . A removable protective cover  69  (e.g., made from u-shaped nitinol or any other biocompatible material) is desirably fitted over the barb or hook  67  prior to use (as FIG.  11 B( 1 ) shows) and/or during implantation (as shown in FIG.  11 B( 2 )). 
     During implantation (see FIG.  11 B( 2 )), an implant pocket P is surgically created in the pharyngeal conduit tissue. In this arrangement, the pocket P that is formed is desirably longer than the implant  54  itself, by a distance designated D in FIG.  11 (B)( 2 ), e.g., by at least 3 mm. The implant  54  is placed into the pocket P, caudal end first, as FIG.  11 B( 2 ) shows. An X-ray or any other suitable image is taken to ensure that the position of the implant  54  is correct. Once the correct position of the implant  54  in the tissue pocket is confirmed, the implant  54  is lowered by a distance less than D (e.g., by approximately 2 mm) into the pocket P, and the protective cover  69  is removed (see FIG.  11 B( 3 )). Each barb or hook  67  pierces pharyngeal wall tissue within the pocket P, to  anchor the caudal portion of the implant  54  within the pocket P. The cranial end of the implant  54  can then anchored by suture material S passed through the apertures in the cranial end of the implant  54  (as FIG.  11 B( 3 ) shows). 
     Should the implant  54  need to be removed or re-positioned, the implant pocket P is re-opened, again re-creating a pocket P at least 3 mm longer than the implant  54 . The sutures S at the cranial end of the implant  54  are cut and the implant  54  is lowered within the pocket P to release each barb or hook  67  from the surrounding tissue, so that the protective cover  69  can be fitted back over the barbs or hooks  67 . 
     As FIG.  11 B( 4 ) shows, a special spatula tool  300  can be used to facilitate of the release of the barbs or hooks  67 . The spatula tool  300  has a distal end  302  that is generally the same width as the implant  54 . The distal end  302  includes a soft polymer material, sized and configured to engage the sharp ends of the barbs or hooks  67 . In use, as FIG.  11 B( 4 ) shows, the spatula tool  300  is inserted behind the implant  54  to the implant device  54  to help free the barbs or hooks  67  from the tissue. Once the barbs or hooks  67  of the implant  54  are free of tissue, they will grab the soft polymer material of the distal end  302 . The spatula tool  300  and the attached implant  54  can now be readily removed from the pocket P as FIG.  11 B( 5 ) shows. Once removed from the pocket P, the barbs or hooks  67  can be disengaged from the distal end  302 , and the protective cover  69  can be fitted back over the barbs or hooks  67 . The implant  54  is again ready to be re-positioned into the pocket, if desired, in the manner previously described. 
     The anchoring systems described, with one or more barbs or hooks, allow posterior pharyngeal wall implants to stabilize in desired positions so as to maximize the  therapeutic effects of the implant systems. 
     FIGS.  11 C( 1 ) and  11 C( 2 ) show another representative embodiment of an implant  54  having at least one tissue piercing barb or hook  71 , which is especially adapted for implantation in a posterior pharyngeal wall. 
     As shown in FIG.  11 C( 1 ), the implant  54  includes an anchoring assembly  73  comprising a U-shaped carrier  75 , which carries at least one tissue piercing barb or hook  71 . In the illustrated embodiment, the carrier.  75  carries a plurality of barbs or hooks  71 , As before described, each barb or hook  71  can be manufactured, e.g., from resilient shape memory NiTi wire, resilient formed stainless steel 316L, or any other medical grade metal. The U-shaped carrier  75  slides within tracks  79  formed within the implant  54  between a first position (shown in FIG.  11 C( 1 )) and second position (shown in FIG.  11 C( 2 )). In the first position (FIG.  11 C( 1 )), the barbs or hooks  71  are retracted within the implant  54 . In the second position (FIG.  11 C( 2 )), the barbs or hooks  71  extend through holes in the track  79  outward from the implant  54 . 
     During implantation, the implant  54  is placed within a surgically formed tissue pocket P (see FIG.  11 C( 3 )) (e.g., formed in a posterior pharyngeal wall), with the carrier  75  in the first position, retracting the barbs or hooks  71 . Once the desired position for the implant  54  is achieved, the carrier  75  is moved to the second position (see FIG.  11 C( 4 )), advancing the barbs or hooks  71  into piercing contact with tissue within the pocket P. One or more sutures S can be applied to the carrier  75  at the cranial end of the implant  54 . Should repositioning or removal of the magnetic posterior pharyngeal wall implant  54  be necessary, the carrier  75  can be pulled up to the first position, retracting the barbs or hooks  71 , so that the implant  54  re-positioned within or removed from the  pocket P. 
     In an alternative arrangement, the U-shaped carrier  75  need not include side barbs or hooks  71 , but comprise an elongated staple that slides within the tracks  79  and exits the caudal end of the implant  54  to engage tissue. In this arrangement, should repositioning or removal of the implant  54  be necessary, the carrier  75  can be pulled up to retract the staple at the caudal end, so that the implant  54  re-positioned within or removed from the pocket P. As before described, one or more sutures can be applied to the carrier  75  at the cranial end of the implant  54 . 
     4. External Fixation Means 
     Implants need to have features to reduce the stress on the implant, but still allow them to maintain the device shape. Another way to limit stress on a given implant  62  is to include apertures  64  through which external fixation means, e.g., suture or staples, can be passed to attach the implant to surrounding tissue, as illustrated in  FIG. 12 . This attachment may be to tissue either on the cranial end or the caudal end of the implant. Additionally, if the thickness of the underlying tissue permits, barbs such as silicone extensions (as previously described) may be also incorporated in the implant  62 . This design will limit the amount of force applied at the implant edges and prevent motions that can lead to extrusion. Rounded corners  60  are also provided (as previously described) to allow for faster healing of the surrounding tissues. 
       FIG. 13  shows an implant  66  whose inner edge  68  contains holes  70  to allow the use of surgical thread or suture  72  to anchor the implant to tissue, e.g., into the pharyngeal wall. 
     5. Tissue In-Growth 
     The implant  36  shown in  FIG. 8A  includes a network  of holes or cutouts  43  that allow tissue in-growth. The in-growth of surrounding tissue that the holes or cutouts  43  allow further stabilizes the implant. The implant  36  shown in  FIG. 8A  can be used, e.g., as a tongue implant, with the predetermined cut-outs  43  strategically positioned to promote tissue in-growth. Promoting tissue in-growth is beneficial in providing a lock-in position that further discourages implant migration. 
     The curved implant  56  shown in  FIG. 8B  also incorporates an opening  58  in the center of the implant  56  allow for tissue in-growth, further stabilizing the implant. As before stated, this embodiment is particularly well suited for implantation in the tongue. The implant&#39;s flowing curves permit a large area of the surrounding tissues to grow around and grip the implant thus providing a natural anchor. 
     6. Stimulating Tissue In-Growth 
       FIGS. 14A and 14B  show an implant  36  of the type shown in  FIG. 8A , in which the network of holes  43  is filled with a growth-stimulating medium  74 , which bridges the gap between the upper and lower tissue layers, encouraging rapid healing.  FIG. 14B  shows a close-up of the growth media  74  used in the implant. The growth-stimulating substance  74  could be bio-absorbable, or act as a scaffold for cell growth. The tissue in-growth will help stabilize the implant. 
     7. Bio-Compatible Glue 
       FIG. 15  shows an implant  36  of the type shown in  FIG. 8A , in which the network of holes  43  are filled a tissue adhesive  76  or glue (e.g. fibrin glue, cyanoacrylate). Such glue may be used by itself or in conjunction with growth stimulating media  74  (shown in  FIGS. 14A and 14B ) to give immediate post-op tissue stability. 
     8. Net Array Implants   
       FIG. 16  is a plan view of a net array implant  98 . Magnets or ferrous discs  100  are linked together by a net-like webbing with flanges  102  surrounding each of the magnets or ferrous shapes. Each disk  100  is linked to the adjacent disc by a cross web  104 , providing protection and isolation from body fluids and tissue. 
     Openings  106  provide large areas in which the opposing surfaces of the surgically produced pocket may be closed (sutured or otherwise) for fast rejoining and healing of the tissue. Further, the narrow flanges surrounding the discs provide clearance for further approximation of the tissue faces. The periphery of the discs (see  FIG. 17 ) is sloped  108  to allow the tissue to form closely around the discs and provide maximum surface tissue contact between the opposing faces of the tissue pocket in which the implant  98  will reside. 
     The material of which the net array web is produced will preferably be a polymer or compound providing a predictable flexural modulus to allow normal speech and swallowing without discomfort or otherwise affecting these functions. Certain medical grades of silicone rubber, PTFE (polytetrafluoroethylene) Teflon® and certain laminates using Gore Tex® are suitable candidates for this application. An additional and desirable characteristic of the material of which the array web is made will be providing a surface that supports attachment by the surrounding tissue (in-growth). Expanded PTFE and Gore Tex® are known to exhibit this characteristic. 
       FIG. 18  shows an alternative embodiment of a net array implant  98 . In this embodiment, the flanges  110  are linked together around the outside of the array. Also, cross ties  112  diagonally join the discs  100 , to provide further stabilization. 
     Many different configurations of the webbing may be employed to provide varying flexibility or stiffness. For  instance, all cross webbing and peripheral links may follow a serpentine path instead of a straight line. This will allow the disks to move toward or away from one another when the muscular tongue tissue lengthens or shortens during speech, swallowing, etc. 
     Furthermore, the magnetic or ferrous shapes may be other than circular, such as (but not limited to) square, rectangular, oval, elliptical, etc. 
     The magnetic net array  98  provides a highly stable implanted magnetic or ferrous device, overcoming difficulties related to migration magnet flipping and inadequate forces needed to prevent occlusion of the airway during a sleep related obstructive breathing event. Furthermore, the magnetic net array will allow the healing of the surgical implantation site prior to the application of any attractive or repelling forces and promote speedy healing through close approximation of the wound surfaces. 
     The net array  98  can be implanted in a stable manner in various ways. 
       FIG. 19  shows a surgically produced pocket  114  with an opening  116  from the left posterior surface of the tongue. A magnet or ferrous load net array  98  is positioned for placement into the open pocket.  FIG. 20  shows the net array  98  inserted and the opening  116  closed using sutures, staples, tissue adhesive or other accepted wound closure means  118 . Further suturing  120  or other tissue securing means can be applied in the open areas of the net array  98  to provide tight approximation of the opposing internal surfaces of the pocket. A template may be provided to the surgeon to aid in accurate placement of the sutures in the openings in the array  98 . 
       FIG. 21  shows a surgically produced pocket  114  that is oriented vertically instead of the horizontal  orientation described above. This approach may be preferred by the surgeon, may be less difficult to perform or may result in improved surgical result. Either approach or other orientation such as angular will be within the intent of the present invention. The opening  116  of the pocket  114  is upward and the net array  98  is positioned into the pocket  114 .  FIG. 22  shows a net array  98  implanted and the opening closed with suitable closure means  118  as described above. Further, additional sutures or other anchoring means  120  are placed in areas of openings in the net array  98 . A template may be provided to the surgeon to aid in accurate placement of the sutures in the openings in the array  98 . 
     9. Specially Dimensioned Surgical Pockets 
     As  FIG. 23  shows, a surgically formed pocket  96  may be formed that, with respect to the lateral and longitudinal dimensions of a given implant (for example, implant  36  shown in  FIG. 8A ), is laterally-tight but longitudinally-loose.  FIG. 23  shows, for the purposes of illustration, the implant  36  to be of the type shown in  FIG. 8A , but the pocket  96  can be sized to accommodate other types of implants. The pocket dimensions accommodate anterior-posterior movement of the implant  36 , but restrict lateral movement of the implant  36 . The dimensions of the pocket prevent implant migration, while allowing the implant  36  to move with the tissue, e.g. the tongue, during normal activities. 
     In addition to the laterally-tight but longitudinally-loose surgical pocket, many different embodiments of surgical pockets are contemplated for “keyed” shapes implants. Such embodiments include, but are not limited to, U-, O-, and L-shaped surgical pockets. 
     10. Open Implants 
     Preceding embodiments stabilize various styles of  implants by allowing and/or encouraging surrounding tissue to grow through a net-like structure of the magnetic implant&#39;s polymer matrix. Another way to stabilize implants is by leaving the tissue in the center of the implant substantially intact. 
       FIG. 24  shows a U-shaped implant  78  placed in a tissue pocket  82  of the same shape (e.g., in a tongue). The tissue  81  in the center of the implant  78  is left substantially intact. Implant shape is keyed to prevent migration and limit relative tissue-to-implant motion. 
       FIGS. 25A to 25D  illustrate a way of inserting a U-shaped implant  78  in the tongue. In  FIG. 25A  two incisions  80  are made in the tongue. The two incisions  80  are used to cut out a U-shaped implant pocket  82  in the tissue. In  FIG. 25B , using curved forceps, suture  84  is pushed through the U-shaped pocket  82 . One end of the suture is then tied to the implant  78 . In  FIG. 25C , using curved forceps at one end for pushing the implant and gently pulling the implant from the other end, the U-shaped implant  78  is fitted into the pocket  82 . During this process, one leg of the U-shaped pocket becomes enlarged as the implant turns in the pocket. In  FIG. 25D , the two incisions  80  are closed up with stitches  84 . This method allows the implant to effectively stabilize in its specified location. 
       FIG. 26A  shows an O-shaped implant  86  placed in a tissue pocket  88  of the same shape (e.g., in a tongue). As with the U-shaped implant  78 , the O-shaped implant  86  leaves tissue  90  in the center of the implant  86  substantially intact. This implant shape is also keyed to prevent migration and limit relative tissue-to-implant motion. 
       FIG. 26B  shows an O-shaped implant  86  where magnets  87  are positioned on only one side. The side  89  without magnets acts as a rudder to distribute the force of the  tongue and to stabilize the implant. The opening in center incorporates intact tongue raphe tissue to resist de-centering.  FIG. 26C  shows a side view of the interaction between the one-sided O-shaped implant  86  of the type shown in FIG,  26 B and a corresponding repelling pharyngeal wall implant  101 . 
       FIGS. 27A to 27D  illustrate a way of inserting an O-shaped implant  86 , as described. The O-shaped implant  86  may have magnets  87  on both sides, as for example the embodiment shown in  FIG. 26A , or only on one side, as for example the embodiment shown in  FIG. 26B . Both types of O-shaped implants would use the same insertion method. In  FIG. 27A , an incision  92  is cut in the tongue and the O-shaped pocket  88  is created in the tissue. In  FIG. 27B , the O-shaped implant  86  with open links L 1  and L 2 , i.e., in an open configuration, is inserted into the O-shaped pocket  88 . In  FIG. 27C , the open link L 2  of the O-shaped implant  86  is inserted around a posterior corner of the O-shaped pocket  88 , drawing the other open link L 1  to the opposite posterior corner. The links L 1  and L 2  adjoin (as  FIG. 27C  shows), thus changing the implant  86  to a closed configuration. In  FIG. 27D , the incision  92  is closed up with stitches  94 . With this method as well, the implant is firmly stabilized in its specified location. 
     B. Prevention of Implant Folding or “Flipping” During and After Implantation 
     Arrays of side-by-side magnets can attract each other during implantation and (if not suitably stabilized) after implantation, causing the implant to fold or flip inward upon itself. 
     Such implant assemblies can be stabilized by providing more rigid cross-support structures between the arrays to prevent the motion of attracting the two arrays together.  FIG. 13 , previously described, shows an implant  66  with stiff sections  122  between the two magnetic  arrays  124  and  126 . The stiff section  122  prevents migration of the two sections  124  and  126  of the implant toward one another via attraction during implantation. 
       FIG. 28  shows an alternative embodiment of a magnetic implant  128  having a structure that prevents folding during implantation. The magnetic implant  128  consists of two main magnetic sections  130  and  132 , flexibly joined together by two smaller rigid structures  134  and  136 . The flexible juxtaposition of the two smaller rigid structures  134  and  136  provides four potential twisting points through which the implant  128  may flexibly twist, but the implant  128  will avoid folding. 
       FIG. 29  shows an alternative embodiment of a magnetic implant  138  which includes middle webbing  140  integrated between two magnetic sections  142  and  144  into the magnetic implant device to keep the implant  138  from folding upon itself during implantation. The middle webbing  140  contains a rigid structure for increased rigidity during the insertion process. Once the implant  138  is in a desired (and stabilized) position (e.g., by suturing through the holes  146  provided), the middle webbing  140  may be cut and removed. The implant  138  is thereby rendered flexible after implantation, while resisting folding during implantation. 
       FIGS. 30A to 30C  show an alternative embodiment of a magnetic implant  148  which includes flexible hinges  150  and  152  between two arrays  154  and  156  of magnetic discs  158 .  FIGS. 30B and 30C  show the north (N)-south (S) polarity of the magnetic discs  158 . The flexible hinges  150  and  152  allow the arrays  154  and  156  to pivot into a serpentine shape (see  FIG. 30C ), but prevent the arrays  154  and  156  from folding upon themselves. 
     Some of the implant assemblies described above are stiffened by the presence of rigid cross-support  structures between the magnetic arrays to prevent the attracting forces between the arrays from flipping or folding the arrays upon themselves. However, it may be desirable for certain implants to have a desired degree of flexibility, even if they are thereby made prone to flipping. For these implants, it is desirable, during implantation, to control the separation of the magnetic arrays until fixation and stabilization of the implant at the implant site can be accomplished, e.g., by suturing or other forms of fixation. 
       FIGS. 31 and 32A  to  32 D show tools and related methodology for controlling the separation of the magnetic arrays  200  and  202  of a magnetic implant  190  (shown prior to implantation in  FIG. 31 ) that is prone to folding or flipping upon itself in response to magnetic interaction. As  FIG. 32A  shows, suture  192  is threaded through one of the magnetic arrays  200  of the implant  190  and tied to form a loop  194 . As  FIG. 32A  also shows, after the suture loop  194  is formed, the implant  190  is folded so that the magnetic arrays  200  and  202  overlap. Folded over, the implant  190  is placed through an incision into a tissue pocket (e.g., like the pockets shown in  FIGS. 19 ,  21 , or  23 ). 
     As  FIG. 32B  shows, within the pocket, a first non-magnetic surgical instrument  196  holds the magnetic array  202  of the implant  190  against the tissue fascia. A second non-magnetic surgical instrument  198  is placed through the suture loop  194 . As  FIGS. 32B and 32C  show, the suture loop  194  is pulled as the first instrument  196  holds the magnetic array  202  against tissue, and as the second instrument  198  pulls the ends of the suture  192  up and slightly to the side to separate the magnetic array  200  from the magnetic array  202 . As the loop  194  is pulled, the second instrument  198  continues to guide the magnetic array  200  to separate the magnetic arrays  200   and  202  within the pocket. As  FIG. 32D  shows, with the magnetic arrays  200  and  202  separated, suitable anchoring sutures  206  are threaded through suture holes  204  provided in the arrays  200  and  202  to secure each magnetic array  200  and  202  to tissue within the pocket. The placement suture  192  is then cut and removed. The instruments  196  and  198  are withdrawn and the pocket closed. 
     The instruments  196  and  198  that can be used for separating magnetic arrays include: forceps, compass-like spreaders, forceps, tongue-blades and needle-holders. They are manufactured out of non-magnetic materials, e.g., titanium. 
     C. Other Technical Features 
     1. Implants for the Pharyngeal Wall 
     The pharyngeal wall is a dynamic structure that undergoes considerable movement on a daily basis. For a pharyngeal wall implant to be well tolerated, such an implant must be able to be stabilized effectively, while remaining flexible in a posterior-anterior direction. 
       FIG. 33  shows an implant  158  having spanning members  160  between the magnetic array sections  162 , extending along the vertical (elongated) axis on both sides of the centerline. The spanning members  160  each have a reduced thickness, compared to the thickness of the magnetic array sections  162 . The thinner cross section of the spanning members  160  facilitates flexibility in the anterior-posterior direction, while the thicker magnetic array sections  162  discourage flexibility in the medial-lateral direction. This preferential flexibility allows the implant to remain in position because it closely mimics the movements of the surrounding anatomy. 
     The implant  158  has other features described above to impart stability and comfort while implanted, e.g., holes for accommodating passage of sutures or fasteners  for fixation, and rounded corner edges and beveled side edges  166  to promote faster healing. 
     Posterior pharyngeal wall implants present special challenges due to the difficulty associated with the attachment/suturing of the caudal end of the implants to the tissue in the posterior wall. Rectangular posterior pharyngeal wall implants are often susceptible to misalignment with relation to the spine. A misalignment with respect to the spine will offset the magnetic interaction between the tongue/soft palate/uvula implant and the posterior pharyngeal wall implant. If the rectangular device is attached only on top part using sutures, then the magnetic force from the tongue base will swing laterally and misalign the back-wall plate. 
       FIGS. 34A and 34B  show a way to help stabilize the posterior pharyngeal wall implant  54  into a position that, while not hindering the natural movement of the posterior wall, provides enough stiffness to the posterior pharyngeal wall implant to prevent the pendulum-like motion. In other words, the implant  54  allows for posterior-anterior motion for the normal functioning of the posterior pharyngeal wall, while preventing lateral motion that would cause the tissue pocket to tear or re-open. 
     As shown in  FIGS. 34A and 34B , the implant  54  includes a support brace  180  secured to the posterior (tissue facing) side of the implant  54 . The support brace  180  is thin and combines the shape of a cross and the shape of a trident. The support brace  180  includes a vertical axis  181 , with a hole  183  on each of the caudal and cranial ends for suturing the cranial and caudal ends of the implant  54 . The support brace  180  includes a horizontal component  185  with two handles  187  raised at an angle between 90° and 180° from each end. Each of the  handles  187  contains a hole  189  for suturing the support brace  180  to the posterior pharyngeal wall tissue. 
     The posterior pharyngeal wall implant support is desirably made of a material that is elastic in its posterior-anterior movement while rigid with regard to lateral movement and twisting about the vertical axis of the support. Such materials include titanium, biocompatible plastics, as well as other biocompatible materials. 
       FIG. 35  shows an alternative design for the magnetic posterior pharyngeal wall implant. The posterior pharyngeal wall implant  184  is circular, with the attachment holes  186  placed in the center. The circular design is sutured into place over the spine at the center of the circle. 
     Assuming that the tongue implant is collinear with the spine, then the circular magnetic pharyngeal wall implant is attached at its center over the spine. The circular shape favors perfect alignment without any additional anchoring or correction. If the circular shape is attached at the center, then it has a self-centered geometry, as seen in  FIG. 35 . 
     2. Implants for the Tongue 
       FIG. 36  shows an implant  170  adapted for implantation in a tongue. The implant  170  provides preferential flexibility that takes into account the shape and movement of the tongue. The implant  170  includes flexible cross members  172  that extend along the long (longitudinal) axis that are thicker than (and thus less flexible than) the cross members  174  that extend along the short (transverse) axis. The design of this implant  170  promotes longitudinal stiffening and discourages the implant from folding in on itself. The thinner cross members  174  running across the narrower areas of the implant  170  allow for flexibility which  closely mimics the movements of the tongue during normal oral activities. This embodiment of the invention has the advantage of combining implant stability with increased tolerance in the patient. 
     The implant  170  has other features described above to impart stability and comfort while implanted. For example, the implant  170  also includes integrated fixation tabs  176  that extend outward from the magnetic discs  178  to engage adjacent tissue and provide enhanced fixation and stabilization. The implant also includes holes  180  for tissue in-growth or the placement of a tissue in-growth promoting material or bio-adhesive, as previously described. 
     Although the disclosure hereof is detailed and exact to enable those skilled in the art to practice the invention, the physical embodiments herein disclosed merely exemplify the invention which may be embodied in other specific structures. While the preferred embodiment has been described, the details may be changed without departing from the technical features of the invention.