Abstract:
With limited nutrients within the avascular disc, the water-retaining proteoglycans begin to diminish, resulting in dehydration, flattening and/or bulging of the disc. The flattened disc causes segmental instability, eroding the facet joints and causing pain. 
     In this invention, a disc inserting device contains a horizontally oriented protrusion with superior and inferior plateaus for inserting into the degenerated disc to maintain or restore disc height. The horizontally oriented protrusion is adjoined to a vertically oriented concave bracket with screw holes for fastening the concave bracket to the vertebral bodies sandwiching the degenerated disc. Thereby, the disc height is restored and fortified to reduce segmental instability and erosion of facet joints for pain relief. Furthermore, by altering the slopes of the plateaus, thickness and depth of the protrusion, spinal stenosis, scoliosis, kyphosis, lordosis or spondylolisthesis can be corrected with the disc inserting device.

Description:
CROSS REFERENCES 
       [0001]    This application is a continuation of U.S. Ser. No. 10/470,181, filed on Jul. 21, 2003 as the US national application of PCT/US2002/04301, filed on Feb. 13, 2002. 
         [0002]    This continuation application also claims priority of U.S. Provisional 60/268,666 filed on Feb. 13, 2001; U.S. Provisional 60/297,556 filed on Jun. 11, 2001; U.S. Provisional 60/310,131 filed on Aug. 3, 2001; U.S. Provisional 60/325,111 filed on Sep. 26, 2001; U.S. Provisional 60/330,260 filed on Oct. 17, 2001. 
     
    
     FIELD OF INVENTION 
       [0003]    This invention relates to devices and methods for occupying and maintaining the intervertebral disc space by fastening the disc space inserting devices to one or more vertebral body to treat spine pain. 
       BACKGROUND, EXISTING SURGICAL PRACTICES AND PRIOR INVENTIONS 
       [0004]    Low-back pain is one of the most prevalent, costly and debilitating ailments afflicting mankind. Seventy to eighty-five percent of all people have back pain at some time in their life. Symptoms are most common among middle-aged adults and are equally common among both men and women. Back pain related to disc disorders, however, is more prevalent among men. The recurrence rate of low back pain ranges from 20% to 44% annually, with lifetime recurrences of 85% (National Institute of Health Guide, Vol. 26, 16, May 16, 1997). 
         [0005]    Low back pain is very costly to patients, our health care system and society. For many, no position can ease their pain or numbness, not even bed rest. It is often the reason for decreased productivity due to loss of work hours, addiction to pain-killing drugs, emotional distress, prolonged hospital stays, loss of independent living, unplanned early retirements and even financial ruin. Each year in the US, about 2% of the work force have back injuries covered by worker&#39;s compensation, with about $12 billion spent directly on medical costs in 1994. 
       Bulging or Herniated Intervertebral Discs 
       [0006]    Most back pain is initiated with a defective or damaged intervertebral disc. The disc is comprised of nucleus pulposus and annulus. The nucleus pulposus is highly gelatinous with a composition of 70-90% water, 25-60% proteoglycan (dry weight) and 10-20% collagen (dry weight). The function of the nucleus pulposus is to sustain prolonged compression during the day and to resiliently re-inflate and reestablish disc height during the night. The pulposus is retained and surrounded by layers of cartilaginous annulus. Together the pulposus and the annulus behave as a resilient cushion. In the erect position, the weight of the body constantly compresses upon a stack of these cushions alternating between a series of vertebrae. During constant compression, the pulposus in each disc also behaves as a water reservoir, which is slowly and constantly being squeezed and drained of its water content through the end plates connected to the vertebrae. As a result, the disc height decreases throughout the day. During bed rest, the weight of the body no longer compresses the disc. Due to the water absorbing nature of the nucleus pulposus, the flow of water then reverses from the vascular vertebrae back into the proteoglycan and collagen. As a result, the disc height is reestablished and ready to provide support for another day. 
         [0007]    With aging and degeneration, the viscoelastic property of the nucleus pulposus undergoes a transition from fluid-like to solid-like behavior (J. C. Iatridis et. al., Journal of Orthopaedic Research, 15:318-322, 1997). Under dynamic conditions, the gelatinous nucleus pulposus exhibits predominantly solid-like behavior with values for dynamic modulus ranging from 7 to 20 kPa (J. C. Iatridis et. al., J. Biomechanics, Vol. 30, No. 10, 1005-1013, 1997). As a result, both the resiliency and disc height diminish. 
         [0008]    Bulges are most commonly reported at the posterior-lateral regions of the discs. The bulging regions are commonly divided into zones. The posterior region where the spinal cord is located is called the central zone. Adjacent to both sides of the central zone are the entrance zones, followed by pedicle zones, the exit zones, and the far lateral zones. Bulges at the far lateral zones, the most accessible area, have the highest surgical success rate. 
         [0009]    Some causes that contribute to low back pain are classified. Type I: Acute back sprain involves damage to ligaments, muscles or even the vertebral end plates from physical overload. Type II: Organic idiopathic spine pain occurs from increased fluid uptake by the disc. Type III: Disruption of posteriolateral annular fibers irritates nerves associated with the sacroiliac region, buttock and the back of the thigh. This situation may resolve itself through reabsorption or neutralization by phagocytosis of the disrupted annular fibers. Type IV: Nerve root irritation by the bulging disc leads to sciatica. This type of disc protrusion is traditionally repaired surgically by tissue removal, chemonucleolysis or percutaneous discectomy. Type V: Nerve irritation by wandering sequestered disc material has unpredictable exacerbation and remission. Type VI: Sequestrum of the annulus and/or nucleus into the spinal canal or intervertebral foramen results in nerve irritation from inflammation, mechanical pressure, chemical irritation, autoimmune response or combinations of irritants. Type VII—A degenerated disc, with substantial decrease in mechanical properties, is often associated with pain and disability. 
         [0010]    The most common reason for recurrent pain is the bulging or herniation of an intervertebral disc. The traditional surgical treatment for a bulging or herniated disc is a series of tissue removing, filling and supporting procedures: (1) laminectomy, excision of the posterior arch of a vertebra which covers part of the herniated disc, (2) discectomy, removal of the disc, (3) bone harvesting usually from the patient&#39;s iliac crest, (4) donor bone packing into the vacant disc space, (5) supporting adjacent vertebral bodies with rods, connectors, wire and screws, (6) bone cement filling the donor site, and finally (7) closing multiple surgical sites. 
         [0011]    Numerous postoperative complications can occur after a back surgery. The major ones are lumbar scarring and vertebral instability. The scar tissue extends and encroaches upon the laminectomy site and intervertebral foramen, then once again, pain returns, which leads to more surgery. In fact, repeat operations are very common, 10-20%. Unfortunately, the success rates of repeat operations are often less, in some cases, far less than the first. More operations lead to more scarring and more pain. Current recommendations to the patients are to avoid surgical procedures unless the pain and inconveniences are absolutely unbearable. Even for the fortunate patients with long term success following discectomies performed twenty years ago, their isokinetic test results clearly indicate weaknesses compared to populations without discectomies. 
         [0012]    There was and still is increasing interest in more effective and less invasive surgical techniques on the spine to reduce both trauma and cost. The major objectives of surgery on bulging or herniated lumbar discs are (1) decompression of the involved nerve root or roots, and (2) preservation of bony spine, joints and ligaments. 
         [0013]    Chymopapain is an enzyme used to digest the nucleus pulposus, the viscous and gel-like substance in the central portion of the disc, which then creates space for the bulging part of the disc to pull back from the encroached nerve root. The needle for injecting the chymopapain is accurately guided to the mid-portion of the disc by a stereotaxic device. The overall success rate is documented as high as 76%. However, some patients are allergic to the treatment and die from anaphylaxis. Some suffer from serious neuralgic complications, including paraplegia, paresis, cerebral hemorrhage and transverse myelitis. 
         [0014]    Percutaneous nuclectomy is an alternative method for removing nucleus pulposus without the allergic reaction of chymopapain, and it rarely causes epidural scarring. Similar to the chymopapain injection, a needle followed by a tube-like instrument is guided and confirmed by anteroposterior and lateral fluoroscopy. The nucleus pulposus is then removed mechanically or by vacuum. As a result, a void is created within the disc and the bulging decreases, like the air being released from a worn out tire, with the hope that the bulging portion of the disc will recede and no longer encroach upon the adjacent nerve root. This type of procedure is often referred to as one of the decompression procedures. However, the amount of nucleus pulposus removed has been documented to be insignificantly small, with unpredictable results and a low rate of success. 
         [0015]    Recently, several devices (U.S. Pat. No. 5,800,550 to Sertich, 1998; U.S. Pat. No. 5,683,394 to Rinner, 1997; U.S. Pat. No. 5,423,817 to Lin, 1995; U.S. Pat. No. 5,026,373 to Ray et. al., 1991) were designed to fortify the disc space between vertebrae. These types of devices are frequently referred to as spinal cages. Before inserting the device into the disc, the affected disc with portions of vertebral bone above and below the disc are cored out. Usually two holes are cored on each side of the disc for insertion of two spinal cages. Donor bone or bone growth promoting substances are packed into the porous cages. As the vertebrae heal from the coring, new bone grows into and permanently secures the porous cages. The purpose of using spinal cages is to replace the disc and keep the vertebrae apart. However, these vertebrae are permanently fused to each other, without resilient cushion, rotation or mobility. 
         [0016]    An improved version of a metallic spinal fusion implant (U.S. Pat. No. 5,782,832 to Larsen and Shikhman, 1998) tries to provide both rotational and cushioning capabilities. This invention resembles a disc prosthesis following a complete discectomy. Therefore, at the least, all the complications and postsurgical problems associated with a discectomy also apply when this device is used. 
         [0017]    Patent application, WO 00/40159 by Yeung et al., introduces some devices and methods for fastening herniated and/or bulging discs. The application covers a resiliently bent fastener, screw, suture, staple and tack, with methods to fasten and hold in the bulging annulus. Another patent application, WO 01/95818, by Yeung, introduces more devices and methods for fastening the intervertebral disc to treat nerve impingement, vertebral instability and spinal stenosis. 
       Spinal Stenosis 
       [0018]    Disc degeneration has been shown to be the first stage in the aging processes of the spine. As the process develops, the circumferential and radial tears of the annulus become evident, proteoglycan and collagen dehydrates (water content of nucleus pulposus fall from 85% to 70%), resulting in decreased disc height. As the annulus continues to degenerate, the disc bulges and/or flattens, narrowing the central canal. The condition is called spinal stenosis. Spinal stenosis is a progressive and dynamic process. Depending on the amount and location of the stenosis, the symptoms may be restricted to a single isolated root, as in lateral recess stenosis, or may involve multiple levels. A normal lumbar canal has a 12-mm or greater anterior-posterior diameter. However, the nerve root within the small neuroforamen is particularly susceptible to impingement from a lateral bulging disc and is often further aggravated by facet joint erosion or alteration. 
         [0019]    Mechanical compression of spinal nerve roots from spinal stenosis has a variety of clinical symptoms, including weakness, reflex alterations, pain and paresthesias. Intermittent neurogenic claudication (limping) has been found in patients with stenosis. Clinical features include low back pain and dysesthesia (sense impairment) spreading diffusely down the posteriolateral parts of the lower extremities, often asymmetrically. Pain is typical and often exacerbated by walking and standing. Symptoms disappear with sitting, recumbency or other changes in posture that reverse the lumbar lordosis (curvature). To distinguish clinically between spinal stenosis and herniated disc, restriction of straight-leg raising is frequently not painful in patients with spinal stenosis, but painful in patients with disc herniation. Spinal stenosis complicated by a herniated disc and spondylosis was noted to occur in 39% of 227 patients with low back pain. Spinal stenosis was the only cause of symptoms in only 8% of patients (M. Camins. et. al., The Lumbar Spine, Raven Pres, NY, 1987, pp. 149). 
         [0020]    As the disc space narrows, the settling of the facet joints greatly increases mechanical stress, leading to joint erosion. As the joint erodes, the narrowed space of the neuroforamen diminishes. The nerve root is entrapped and surrounded by the pedicle (the bony extension forming the facet joint) superiorly, the bulging disc inferiorly, the vertebral body osteophytes anteriorly and the hypertrophied degenerative facets posteriorly. Most nerve entrapment occurs in the vicinity of the pedicle. This has been referred to as the hidden zone. The nerve root and ganglion are highly protected and covered by bone. Decompression of the nerve root using current surgical technique requires a significant amount of bone and disc removal, making the procedure very invasive. Nerve root impingement at the extraforaminal zone is usually from ligament, lateral disc herniation or tumor. 
         [0021]    Although the majority of lumbar spinal conditions should initially be treated conservatively, certain conditions do require urgent surgical intervention. Significant or progressive weakness of the lower extremity in the form of either footdrop or the inability to toe stand may result in irreversible damage. It is imperative to initiate early diagnostic evaluation followed by prompt surgical treatment. 
         [0022]    Decompression laminectomy (excision of the posterior arch of a vertebra) is the standard procedure advocated. The ligamentum flavum is usually left intact to protect the dura, and the facet joints are protected. But in certain instances less aggressive laminotomies (removal of a portion of lamina) may be appropriate with hospitalization 5 to 7 days postoperatively. Ambulation may begin within 24 hours after surgery and often on the same day. Despite the invasiveness of the procedure, mortality rate is low (0.1-0.6%). Other complications include neurologic deficit, temporary in 5%, permanent deficit in 1.3%, cerebrospinal fluid fistulas (leakage) 4.6%, infection 0.5%-8.5%, reoperation 9.8% and increased risk of facet fractures. 
         [0023]    A 20-year follow-up study, noted complete relief of preoperative signs and symptoms in 68% of patients. The remaining patients (32%) continue having lumbago (pain in low back and buttocks), intermittent claudication (lameness), motor deficit, sciatica (pain radiating from the back into lower extremity), paraplegia (paralysis of the legs) and/or micturition (the passage of urine). 
       Segmental Instability 
       [0024]    Instability across the motion segment (vertebral body-disc-vertebral body) can occur as the disc degenerates. Segmental instability resembles an out-of-control car riding on one or more flat tires with deflated and unsupported sidewalls. A flattened intervertebral disc causes excessive movement between vertebral bodies, leading to pain in surrounding ligaments and facet joints. Depletion of nucleus pulposus from the percutaneous nuclectomy procedure can accelerate disc flattening or thinning, leading to segmental instability and/or spinal stenosis. Although it might not be grossly detected radiographically, this instability is most apparent during compressional or rotational movements. Under normal conditions, the spinal motion segment and particularly the neuroforamen can smoothly and symmetrically accommodate rotational motions, as well as flexion and extension, without significant alteration of available space. However, as the disc degenerates, the ligaments buckle, the facet joints mal-align and unstable movement appears during routine vertebral motions. With narrowing of the central canal and neuroforamen, unstable vertebral movements produce irritation, inflammation and pain. 
         [0025]    Treatment recommended for segmental instability is mostly rest and drug therapy, including analgesics, anti-inflammatory agents, oral steroids, muscle relaxants and antidepressants. 
       Spondylolisthesis 
       [0026]    The axial compression force upon the L5-S1 level is between 1500 and 2500 N, bending moment between 15 NM and 25 NM. Due to the curvature of the spine, approximately 20% of the axial compression force is a forward-directed shear force. (Bergmark A., Acta Orthop Scand Suppl: 230-238, 1989). As the shear force works on an aging and degenerating disc, the forward sliding process begins. The shear force intensifies as the L5 moves forward and provides more and more leverage. Finally, the ventral (forward) sliding of L5 in relation to S1, called spondylolisthesis, brings a great deal of pain from many possible nerve impingements, including impingement by the transverse process and ligament. 
         [0027]    When slippage is less than 50%, vertebral traction alone can usually reposition the L5-S1 disc without removing the L5-S1 disc. Lumbosacral fusion is followed. However, if the slippage is greater than 50%, additional instrumentation may be required to reposition the L5. During the repositioning process, the L5-S1 disc may not be spared. Lumbosacral fusion is necessary and usually done with pedicle screws and instrumentation in an open surgery. 
       Deformities of Spine 
       [0028]    Most spine deformities are innate. Surgical correction of these deformities is highly invasive and many require repeat surgeries due to instrumentation fatigue/failure or complications. Scoliosis is a condition involving lateral curves or angular deviations of one or more vertebral segments. Commonly known as humpback, kyphosis is an exaggeration of the posterior convexity of the thoracic vertebral column. Three common causes of kyphosis are (1) absence of T-12 vertebral body, (2) malformation and incomplete segmentation of vertebral body, and (3) indentation of anterior portion of vertebral body from compression. Lordosis is an exaggeration of the posterior concavity of the spine characteristic of the lumbar region. Commonly known as swayback, it indicates extreme anterior curvature of the lumbar spine. 
       SUMMARY OF INVENTION 
       [0029]    Majority of back pain can be traced to degenerated discs, which are likely caused by occlusion of calcified endplates hindering diffusion of nutrients from the vertebral bodies into the avascular intervertebral disc. With limited nutrients within the avascular disc, the water-retaining proteoglycans begin to diminish, resulting in dehydration, flattening and/or bulging of the disc. The flattened disc causes segmental instability, eroding the facet joints and causing pain. 
         [0030]    In this invention, a disc inserting device contains a horizontally oriented protrusion with superior and inferior plateaus for inserting into the degenerated disc to maintain or restore disc height. The horizontally oriented protrusion is adjoined to a vertically oriented concave bracket with screw holes for fastening the concave bracket to the vertebral bodies sandwiching the degenerated disc. Thereby, the disc height is restored and fortified to reduce segmental instability and erosion of facet joints for pain relief. Furthermore, by altering the slopes of the plateaus, thickness and depth of the protrusion, spinal stenosis, scoliosis, kyphosis, lordosis or spondylolisthesis can be corrected with the disc inserting device. 
         [0000]    
       
         
               
             
               
               
             
           
               
                   
               
               
                 REFERENCE NUMBER 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 100 
                 Intervertebral disc 
               
               
                 101 
                 Tightening elements 
               
               
                 102 
                 Nerve 
               
               
                 103 
                 Trocar 
               
               
                 104 
                 Sleeve with windows 
               
               
                 105 
                 End-plate 
               
               
                 106 
                 Slit opening 
               
               
                 107 
                 Strut 
               
               
                 108 
                 Head of sleeve with window 
               
               
                 109 
                 Thread 
               
               
                 110 
                 Hole for screw or bolt 
               
               
                 111 
                 Disc compressor 
               
               
                 112 
                 Indented portion 
               
               
                 115 
                 Epiphysis 
               
               
                 116 
                 Bolt head 
               
               
                 117 
                 Stabilizer lumen 
               
               
                 118 
                 End of lift spring 
               
               
                 119 
                 Annulus contact surface 
               
               
                 120 
                 Hole for bolt 
               
               
                 121 
                 Lift spring 
               
               
                 122 
                 Supporting plate 
               
               
                 123 
                 Spinal cord 
               
               
                 124 
                 Delivery device 
               
               
                 125 
                 Coil spring 
               
               
                 126 
                 Pivoting means 
               
               
                 127 
                 Elastic fastening means 
               
               
                 128 
                 Nucleus pulposus 
               
               
                 129 
                 Facet joint 
               
               
                 130 
                 Tip of the compressor 
               
               
                 131 
                 Delivery capsule 
               
               
                 132 
                 Latch 
               
               
                 133 
                 Socket drive 
               
               
                 134 
                 Stabilizer 
               
               
                 135 
                 Lip of stabilizer 
               
               
                 139 
                 Bracket 
               
               
                 140 
                 Sacrum 
               
               
                 142 
                 Superior articular process 
               
               
                 143 
                 Inferior articular process 
               
               
                 159 
                 Vertebral body 
               
               
                 160 
                 Tissue ingrowth opening 
               
               
                 161 
                 Bolt 
               
               
                 162 
                 Nut 
               
               
                 163 
                 Washer 
               
               
                 164 
                 Indentation 
               
               
                 165 
                 Slit hole for bolt or screw 
               
               
                 167 
                 Anterior longitudinal ligament 
               
               
                 170 
                 Sloped surface 
               
               
                 171 
                 Plateau surface 
               
               
                 172 
                 Pivotal peg or screw 
               
               
                 173 
                 Stop 
               
               
                 176 
                 Widening tool 
               
               
                 177 
                 Clamp grabber 
               
               
                 178 
                 Lock screw of widening tool 
               
               
                 179 
                 Lock wheel of widening tool 
               
               
                 180 
                 Hinge of lock screw 
               
               
                 181 
                 Handle of widening tool 
               
               
                 182 
                 Pivotal joint of widening tool 
               
               
                 183 
                 Lock slot 
               
               
                 184 
                 Impingement of nerve 
               
               
                 185 
                 Trocar guide 
               
               
                 187 
                 Screw 
               
               
                 188 
                 Casing of compressor 
               
               
                 194 
                 Ventral/dorsal ramus nerve root 
               
               
                 195 
                 Posterior longitudinal ligament 
               
               
                 196 
                 Nerve shield 
               
               
                 198 
                 Clamp 
               
               
                 199 
                 Widening mount 
               
               
                 201 
                 Support mount 
               
               
                 202 
                 Trough on shield 
               
               
                 212 
                 Strap 
               
               
                 213 
                 Distal tip of the nerve shield 
               
               
                 214 
                 Open channel of nerve shield 
               
               
                 215 
                 Staple 
               
               
                 216 
                 Sinuvertebral nerve 
               
               
                 217 
                 Screw entry 
               
               
                 218 
                 Biodegradable sleeve 
               
               
                 220 
                 Trocar sleeve 
               
               
                 221 
                 Label showing direction of curved 
               
               
                   
                 trocar 
               
               
                 223 
                 Trough or indentation of compressor 
               
               
                 224 
                 Bleeding sites 
               
               
                 225 
                 Lumen of sleeve with window 
               
               
                 226 
                 Screw head 
               
               
                 228 
                 Opening for socket or screw driver 
               
               
                 229 
                 Locking mechanism 
               
               
                 230 
                 Dilator 
               
               
                 231 
                 Indentation of disc clamp 
               
               
                 233 
                 Outer surface 
               
               
                 234 
                 Spinal fusion 
               
               
                   
               
             
          
         
       
     
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0031]      FIG. 1  depicts a common disc  100  protrusion at or near the neuroforamen, impinging upon the ventral/dorsal ramus nerve root  194 . 
           [0032]      FIG. 2  shows a nerve shield  196  with a thin but blunt distal tip  213  to reach into or near the neuroforamen and a trough  202  to protect the nerve exiting from the neuroforamen. 
           [0033]      FIG. 3  indicates the nerve shield  196  reaching into or near the neuroforamen by sliding over the bulging annulus of the disc  100 . 
           [0034]      FIG. 4  depicts two nerve shields  196  protecting the nerves  194  from instrumentation. 
           [0035]      FIG. 5  shows an elastic clamp  198  comprising two disc compressors  111  with annular contact surfaces  119 , sloped surfaces  170 , plateau surfaces  171 , stops  173 , widening  199  and support  201  mounts. 
           [0036]      FIG. 6  shows a clamp-widening tool  176  equipped with clamp grabbers  177  and a locking mechanism capable of slow release. 
           [0037]      FIG. 7  depicts widening and placement of the disc clamp  198  by the widening tool  176  around the protruded disc  100 . 
           [0038]      FIG. 8  shows alleviation of nerve  194  impingement by clamping of the bulging annulus with compressors  111 . The size of the clamp/compressors  198 / 111  is enlarged disproportionately to the disc  100 , for clarification. 
           [0039]      FIG. 9  indicates the locations of compression by the compressors  111 . The important compressions are at area C and I, common locations of disc  100  protrusion. 
           [0040]      FIG. 10  indicates an elastic strap  212  threaded through the support mount  201  to support the disc clamp  198 . The elastic strap  212  is secured by a staple  215  anchored in the vertebral body  159 . 
           [0041]      FIG. 11  depicts a coronal view of the clamped disc  100  during initial clamping. The sloped surfaces  170  of the compressors  111  rest on the surface of the annulus. 
           [0042]      FIG. 12  shows penetration of the sloped surfaces  170  with time. Further penetration is halted by the stops  173  resting on the sides of the vertebral body  159 . 
           [0043]      FIG. 13  depicts a coronal view of two unsymmetrical compressors  111  installed on a scoliotic vertebral segment. 
           [0044]      FIG. 14  shows correction or straightening of the scoliotic vertebral segment with time, by selectively elevating, wedging or shimming the concave side of the vertebral segment. 
           [0045]      FIG. 15  depicts a disc clamp  198  with thick compressors  111  installed on a disc  100  displaying spinal stenosis. The size of the clamp/compressors  198 / 111  is enlarged disproportionately to the disc  100 , for clarification. 
           [0046]      FIG. 16  shows penetration of the sloped surfaces  170  and plateau surface  171  with time into the disc  100  to thicken the intervertebral disc  100 . 
           [0047]      FIG. 17  depicts a coronal view of compressors  111  initially installed around a disc  100  displaying spinal stenosis. Bone spurs have grown around the vertebral body  159 . 
           [0048]      FIG. 18  shows penetration and shimming of the compressors  111  with time into the disc  100  to elevate disc height. The penetration is halted when the stops  173  rest on the vertebral body  159 . 
           [0049]      FIG. 19  shows that the compressors  111  can be modular components individually fitted on a disc clamp  198 . 
           [0050]      FIG. 20  depicts the modular compressor  111  comprising an annulus contact surface  119 , sloped surface  170 , plateau surface  171 , stop  173  and pivotal peg  172  for inserting into the clamp. 
           [0051]      FIG. 21  indicates a modular compressor  111  including a casing  188  with anchoring screws  187  and the disc contact portion of the compressor  111 . 
           [0052]      FIG. 22  depicts a vertical cross-sectional view of a compressor  111  with two stops  173 , an outer surface  233 , upper and lower plateau surfaces  171 , sloped surfaces  170  and annular contact surface  119 . 
           [0053]      FIG. 23  shows a compressor  111  with no stop and a very round annular contact surface  119 . 
           [0054]      FIG. 24  depicts a compressor  111  with multiple slopes in the sloped surfaces  170 . 
           [0055]      FIG. 25  shows a compressor  111  with unsymmetrical sloped surfaces  170 . 
           [0056]      FIG. 26  depicts a compressor  111  with tissue ingrowth openings  160  on the plateau surfaces  171  to promote annular ingrowth and stability of the compressor  111 . 
           [0057]      FIG. 27  shows a compressor  111  with non-parallel plateau surfaces  171 . 
           [0058]      FIG. 28  indicates the clamp  198  width measurement and the reach-in distance to stabilize the fastened clamp  198 . 
           [0059]      FIG. 29  depicts a typical strain vs. stress profile of nickel-titanium (nitinol) alloy suitable for fabricating into a disc clamp  198 . 
           [0060]      FIG. 30  indicates a compressor  111  pivotally fastened with a screw  187  to a bracket  139 . 
           [0061]      FIG. 31  shows a one-piece compressor  111  with a bracket  139 . 
           [0062]      FIG. 32  depicts the one-piece compressor  111  and bracket  139  fastened by two bolts  161  or screws onto the side of the vertebral body  159 , compressing the disc  100 . 
           [0063]      FIG. 33  shows a coronal view of disc  100  compression by the compressors  111  on brackets  139  fastened with bolts  161  and nuts  162  through the vertebral body  159 . 
           [0064]      FIG. 34  depicts a bolt  161  with two longitudinal slits  106  cut in series. The bolt  161  is made with elastic material, such as nickel-titanium (nitinol). 
           [0065]      FIG. 35  depicts the slits  106  being shimmed open and shaped, forming four elastic and compressible struts  107 . The length of the bolt  161  is elastically and resiliently shortened. 
           [0066]      FIG. 36  shows a sleeve  104  with a lumen  225  and four windows  114 , sized and configured to allow protrusion of the elastic struts  107  of the bolt  161 , as shown in  FIG. 35 . 
           [0067]      FIG. 37  indicates the insertion of the bolt  161  with the elastic struts  107  being resiliently compressed and fitted within the sleeve  104  in an out-of-phase position. 
           [0068]      FIG. 38  depicts protrusion of the opened struts  107  from the windows  114  by turning the bolt  161  relative to the sleeve  104  from the out-of-phase to an in-phase position. 
           [0069]      FIG. 39  indicates a coronal view of a spinal stenosis segment fastened with two compressors/brackets  111 / 139  by two elastic bolts  161  containing slits  106  in out-of-phase position. 
           [0070]      FIG. 40  indicates disc  100  compression and penetration with time by the compressors  111 , activated or initiated by turning the elastic bolts  161  to in-phase position with the sleeve  104 . 
           [0071]      FIG. 41  depicts a compressor/bracket  111 / 139  installed on the concave curvature of a scoliotic vertebral segment. 
           [0072]      FIG. 42  shows disc  100  compression and penetration with time by the compressor  111  to correct or straighten the scoliotic vertebral segment. 
           [0073]      FIG. 43  indicates a biodegradable sleeve  218  restricting the elastic struts  107  of the bolt  161  from opening and elastically shortening. 
           [0074]      FIG. 44  shows a coil spring  125 . 
           [0075]      FIG. 45  depicts a coronal view of disc  100  compression by the compressor  111  and coil spring  125  assembly. 
           [0076]      FIG. 46  indicates shimming of the compressor  111  into the disc  100  with time, compressed by the coil spring  125 . 
           [0077]      FIG. 47  shows a spring  124  including of two connecting lift springs  121 , which can provide disc compression similar to the coil spring  125 . 
           [0078]      FIG. 48  indicates a compressor  111  with an elastic fastening means  127  installed at the anterior portion of a kyphosis vertebral segment. 
           [0079]      FIG. 49  shows correction of the kyphosis vertebral segment by disc  100  elevation and penetration of the compressor  111 . 
           [0080]      FIG. 50  depicts a disc compressor  111  on a lengthened bracket  139  designed to fuse the vertebral segment and elevate disc space. 
           [0081]      FIG. 51  shows spinal fusion and disc  100  compression with the lengthened compressor/bracket  111 / 139  fastened with bolts  161  or screws concealed in the indentation  164 . 
           [0082]      FIG. 52  indicates a coronal view of spinal fusion and disc  100  compression with the lengthened compressor/brackets  111 / 139  fastened on the vertebral bodies  139 . 
           [0083]      FIG. 53  indicates a coronal view of normal bulging of annular layers during axial compression. 
           [0084]      FIG. 54  shows annular delamination due to inward and outward bulging caused by aging or a dehydrated nucleus pulposus  128 . 
           [0085]      FIG. 55  depicts seepage of nucleus pulposus  128  through damaged annular layers, possibly from the weakened, delaminated annular layers. 
           [0086]      FIG. 56  indicates disc  100  compression by the compressors  111 , promoting inward annular bulging to minimize further delamination. 
           [0087]      FIG. 57  shows the sinuvertebral nerve  216  ingrowth into the disc  100 , causing discogenic pain. 
           [0088]      FIG. 58  depicts compression of the sinuvertebral nerves  216  by the compressors  111  to atrophy the nerves  216 . 
           [0089]      FIG. 59  depicts the insertion of a trocar  103  laterally through the bulging disc  100 , with the aid of a guide  185  (optional). 
           [0090]      FIG. 60  indicates the insertion of a dilator  230  over the trocar  103 . 
           [0091]      FIG. 61  shows the withdrawal of the trocar with the dilator  230  remaining in the disc  100 . 
           [0092]      FIG. 62  depicts the insertion of a bolt  161 , compressor  111  and washer  163  assembly into the dilator  230 . 
           [0093]      FIG. 63  indicates the withdrawal of the dilator to expose the thread  109  of the bolt  161 . 
           [0094]      FIG. 64  shows the installation of another compressor  111  onto the bolt  161  with washer  163  and nut  162 . 
           [0095]      FIG. 65  depicts disc  100  compression by tightening the nut  162  on the bolt  161 . 
           [0096]      FIG. 66  depicts fastening of a compressor/bracket  111 / 139  with a screw  187  through part of the disc  100  into vertebral body  159 , another screw  187  through the bracket  139  into the side of vertebral body  159 . 
           [0097]      FIG. 67  shows surgically inflicted bleeding sites  224  by a trocar  103  at the end plate  105  for annular adhesion and/or regeneration and a deep puncture for screw entry  217 . 
           [0098]      FIG. 68  depicts surgically inflicted bleed sites  224  at the end plate  105  by a curved trocar  103 . 
           [0099]      FIG. 69  shows a screw  187  through a compressor  111  with a trough  223  or indentation to conceal a screw head  226 . 
           [0100]      FIG. 70  shows the installation of the compressor  111  into the end plate  105  through a protruded disc  100  impinging  184  on a nerve  102 . 
           [0101]      FIG. 71  shows disc  100  fastening by the compressor  111  to alleviate the impingement of an adjacent nerve  102 . 
           [0102]      FIG. 72  depicts a coronal view of the compressor  111  fastened through the outer portion of the disc  100  into the end plate  105  with bleeding sites  224  created to promote annular adhesion and regeneration. 
           [0103]      FIG. 73  depicts nerve impingement  184  from spondylolisthesis. 
           [0104]      FIG. 74  shows surgically inflicted bleeding sites  224  at the end-plate  105  by a trocar  103  to promote adhesion and reattachment between the disc  100  and vertebral body  159 . 
           [0105]      FIG. 75  depicts a rigid sleeve  220  sliding on an elastically curved trocar  103  with a label  221  on the handle indicating the direction of the curvature. 
           [0106]      FIG. 76  shows that the curvature of the elastic trocar  103  is resiliently straightened within the lumen of the sleeve  220 . 
           [0107]      FIG. 77  demonstrates that the end plate  105  can be reached even when the sleeve  220  is introduced perpendicularly to the disc  100 . 
           [0108]      FIG. 78  depicts a bulging disc  100  sandwiched between two vertebral bodies  159 . The bulges may result in spinal stenosis and/or segmental instability. 
           [0109]      FIG. 79  depicts disc  100  compression, stabilization and elevation with two compressors  111  anchored through the end plate  105  into the vertebral body  159 . 
           [0110]      FIG. 80  shows disc  100  thickening with the fastened compressor  111  to reduce spinal stenosis. 
           [0111]      FIG. 81  depicts disc  100  fastening with screws  187  anchoring into vertebral bodies  159 , above and below the intervertebral disc  100 . 
           [0112]      FIG. 82  shows a bolt  161  traversing through the end-plate  105  and the vertebral body  159  to fasten the compressor  111  with a nut  162  supported by a washer  163 . 
           [0113]      FIG. 83  depicts a compressor  111  with multiple tissue ingrowth openings  160 . 
           [0114]      FIG. 84  depicts a compressor  111  with outwardly curved tips  130  and tissue ingrowth openings  160  penetrating through the thickness of the compressor  111 . 
           [0115]      FIG. 85  shows a resilient compressor  111  in an open or predisposed position. 
           [0116]      FIG. 86  depicts the resilient compressor  111  being constricted or folded within a delivery capsule  131 . 
           [0117]      FIG. 87  indicates the insertion of the delivery capsule  131  onto a protruded disc  100 . 
           [0118]      FIG. 88  shows the advancing screw  187  anchoring in the vertebral body  159  and expelling the compressor  111  from the capsule  131  onto the protruded disc  100 . 
           [0119]      FIG. 89  indicates disc  100  fastening with the compressor  111  in an expanded or compressed position. 
           [0120]      FIG. 90  depicts a stabilizer  134  inserted within the delivering capsule  131  to minimize tilting of the screw head  226  during disc  100  fastening. 
           [0121]      FIG. 91  shows a clamp/compressors  198 / 111  with large tissue ingrowth openings  160 . 
           [0122]      FIG. 92  shows bone ingrowth from upper and lower vertebral bodies  159  into the tissue ingrowth openings  160  of the clamp/compressors  198 / 111  leading to spinal fusion  234 . 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0123]      FIG. 1  depicts a common nerve  194  impingement from a protruded disc  100  at or near the narrow channel of the neuroforamen. For protection during disc  100  repair, a nerve shield  196  contains a thin and blunt distal tip  213  for reaching into or near the neuroforamen, a trough  202  to partially surround and protect the nerve  194  and an open channel  214  for the nerve  194  to exit from the trough  202 . Through anterior or lateral incision, the nerve shield  196  is introduced by sliding over the bulging annulus of the disc  100 , as shown in  FIG. 3 , to minimize potential damage to the ventral/dorsal ramus nerve root  194 . The shield  196  is then gently pressed against the partially surrounded nerve  194 . Similarly, another nerve shield  196  is used contralaterally to protect both nerves  194  existing from the neuroforamen, as shown in  FIG. 4 . 
         [0124]      FIG. 5  shows an elastic intervertebral disc clamp  198  with an annular contact surface  119 , a sloped surface  170 , a plateau surface  171  and stops  173  on the compressors  111  portions. The saddle-shaped compressors  111  are used to bracket the dysfunctional disc  100  bilaterally. The clamp/compressor  198 / 111  has a support mount  201 , an indentation  231  and two widening mounts  199  for engagement with a widening tool, as shown in  FIG. 6 . The clamp  198  can be made with nickel-titanium, nitinol, or other elastic alloy or polymers.  FIG. 6  shows a clamp-widening tool  176  equipped with clamp grabbers  177  for engaging with the widening mount  199  on the compressors  111 , a pivotal joint  182 , handles  181  and a locking mechanism capable of slowly releasing the compressor  111 . The mechanism contains a hinge  180  anchoring a lock screw  178  fastened with a lock wheel  179 . The lock screw  178  is sized and configured to fit into a lock slot  183  to lock the handle  181  of the widening tool  176 . For quick release of the handle  181 , the lock screw  178  can be picked up from the slot  183 . For slow release, the lock wheel  179  can be rotated to slowly open the handle  181 , thus slowly closing the disc clamp  198 . 
         [0125]      FIG. 7  depicts widening and placement of the disc clamp  198  by the widening tool  176 . The clamp  198  fits around the intervertebral disc  100 , while nerves  194  are protected by nerve shields  196 . The distal tips of the compressors  111  are thin and tapered to prevent impingement of the nerve  194 . The clamp  198  is then slowly released by dialing the lock wheel  179 , as shown in  FIG. 6 .  FIG. 8  shows the disc  100  being clamped by the disc clamp  198  as the compressors  111  press the bulging annulus inwardly to alleviate nerve  194  impingement. The size of the clamp/compressor  198 / 111  is enlarged disproportionately to the disc  100 , for clarification.  FIG. 9  indicates the locations of compression from the disc clamp  198 . The preferred compressions are at areas C and I, common protruding locations of the disc  100 , with areas E and G as supporting locations. From a disc  100  fastening cadaveric study, nearly the entire disc  100  was distracted, elevated and slightly lengthened from compression by the compressors  111 . The portion of annulus remote to the compressors  111  was also distracted, pulling inward. The previously protruded areas B and J in  FIG. 9  would similarly be distracted as well. Annulus distraction is wide spread and far reaching, way beyond the area of direct compression. The benefit of the far-reaching capability of the compressors  111  is most significant in repairing annular impingements commonly occurring around the narrowed neuroforamen. The compressors  111  can be fastened a distance away from the impinging neuroforamen, yet the distraction of the annulus can draw in the distant bulge, alleviating the impingement. Alternatively, decompressing the nerve impingement within the neuroforamenal region (the hidden zone) surrounded by the disc  100 , vertebral body  159 , pedicle and facet joint  129  is very invasive using current surgical procedures, and it may result in increased scarring and a permanently weakened spine. 
         [0126]    As the disc  100  is compressed by the body weight, area F located at the indentation  231  and area A are allowed to naturally and resiliently bulge as indicated by arrows in  FIG. 9 , since they are least restricted by the clamp  198 . The thinning or tapering of the distal tips of the compressors  111  are essential to avoid nerve  194  impingement, as shown in  FIGS. 8 and 9 . To minimize possible damage to the disc  100 , the annular contact surfaces  119  of the compressors  111  are generally cylindrical or blunt, thickening into the sloped surface  170 , as shown in  FIG. 5 , with an optional plateau surface  171 . 
         [0127]    To prevent migration of the clamp  198 , especially during initial installation, an elastic strap  212  is threaded through the support mount  201  and secured by a staple  215  anchored in the vertebral body  159 , as shown in  FIG. 10 . More than one strap  212  and staple  215  can be used. The strap  212  can be a biodegradable suture or material to initially secure the clamp  198  until the sloped surfaces  170  of the compressors  111  penetrate the annulus and adequately secure the clamp/compressors  198 / 111 . 
         [0128]      FIG. 11  depicts a coronal view of initial clamping of the disc  100  with the sloped surface  170  resting on the disc  100 . With time, the sloped surface  170  of the compressor  111  slowly penetrates into the disc  100  until the stops  173  gently rest on the lateral side of the vertebral body  159  below the disc  100 , as shown in  FIG. 12 . The stop  173  is a protrusion, a small wall or a leg from the under side of the compressor  111 . The clamp/compressors  198 / 111  is designed to compress the protruded annulus, alleviating the nerve impingement. The clamp/compressors  198 / 111  also restricts, support and stabilize the bulging annulus to alleviate pain from segmental instability. 
         [0129]    Current surgical treatment for scoliosis is invasive, most frequently done on young female patients to correct the deformity. Instrumentation failure or breakage of pedicle screws is likely after decades of wear and tear, mandating a second surgery.  FIG. 13  depicts a coronal view of a scoliotic vertebral segment initially clamped and compressed by the unsymmetrical compressors  111  of a disc clamp  198  (not shown). The concave side of the curved vertebral segment is fitted with a thick compressor  111  comprising a wide plateau surface  171 , while the convex side of the vertebral segment is fitted with a thin compressor  111  containing a narrow or absent plateau surface  171 .  FIG. 14  shows correction or straightening of the scoliotic vertebral segment with time, by selectively wedging, shimming and elevating the concave side of the curved vertebral segment and by inserting the plateau surface  171  of the compressor  111  between the dense epiphyses  115 . To straighten the entire spine, multiple selective disc  100  elevations are required, much as multiple pedicle screws and instrumentation are used in current procedures. Scoliosis is corrected through selective shimming by the compressor  111  to alter the lateral curvature of the spine. Nickel-titanium compressors  111  are expected to be durable between the epiphyses  115 ; and the clamp  198  is under minimal strain after settlement in the disc  100 . Thus the clamp/compressors  198 / 111  are expected to be long lasting, perhaps even permanent without revisional surgery. 
         [0130]    Spinal stenosis is a progressive disorder.  FIG. 15  depicts a flattened disc  100  with a dehydrated nucleus pulposus  128 . The initial disc height, H, is indicated at the anterior portion of the disc  100 . A clamp  100  with two symmetrical compressors  111  with wide plateau surfaces  171  is clamped around the flattened disc  100 . The size of the clamp/compressors  198 / 111  is enlarged disproportionately to the disc  100 , for clarification. Gentle compression and wedging action of the clamp/compressors  198 / 111  allow time for the annulus to grow and thicken. The surrounding ligaments, including the posterior  195  and anterior  167  longitudinal ligaments and facet joint ligaments, also require time to lengthen. As the sloped surface  170  wedges into the disc  100 , the plateau surfaces  171  establish stable positions between epiphyses  115  to thicken the disc  100  and provide elevated disc height, H, as shown in  FIG. 16 . With elevated intervertebral disc space, nerve impingement caused by spinal stenosis is minimized or alleviated. Disc  100  penetration by the compressors  111  halts when the stops  173  reach the lateral surfaces of the vertebral body  159 , in this case below the disc  100 .  FIG. 17  depicts a coronal view of a clamp  198  (not shown) and compressors  111  initially clamped around a disc  100  sandwiched by bone spurs, common among patients with spinal stenosis. With time,  FIG. 18  shows wedging and penetration of the sloped surfaces  170  followed by the plateau surfaces  171  into the disc  100  between the epiphyses  115  of the vertebral bodies  159 . Thus, disc  100  height increases to alleviate nerve impingement common among spinal stenosis patients. Penetration of the compressors  111  halts when the stops  173  rest upon the vertebral body  159  below the disc  100 . The plateau surface  171  maintains disc height without the need of further compression. In contrast to current surgical techniques, which cut or bur away anatomical structure to make room for the progressively narrowing disc space, the clamp/compressors  198 / 111  restore or increase the disc  100  height to minimize or alleviate nerve impingement. 
         [0131]    The clamp  198  and the compressors  111  can be made separately as modular components assembled into a device as shown in  FIG. 19 . The vertical cross-section of the clamp  198  can be semi-circular, elliptical, circular or another shape with blunt surfaces to prevent abrasion to the disc  100 , abdominal contents or blood vessels. The saddle-shaped compressor  111  contains a pivotal peg  172  for inserting into the clamp  198 , a smooth and blunt annular contact surface  119 , a sloped surface  170 , a plateau surface  171  and a stop  173 , as shown in  FIG. 20 . The concave curvature of the annular contact surface  119  of the compressor  111  is designed to conform and fit partially around the disc  100 . Since most discs  100  are not circular, the concave or crescent curvature of the annular contact surface  119  is likely to be complex or to contain multiple radiuses in order to conform to the surface of a disc  100 . One of the tips  130  of the compressor  111  is particularly thin and tapered, designed to minimize nerve impingement especially near the neuroforamen. The compressor  111  can also be made with modular components, as shown in  FIG. 21 . The annular contacting part of the compressor  111  can be made with biocompatible polymer, such as polyurethane, polypropylene, polyethylene, PEEK, Delrin, polysulfone, polytetrafluoroethylene, polycarbonate, ultra high molecular weight polyethylene or other low friction polymer. The casing  188  with pivotal peg  172 , as shown in  FIG. 21 , can be made with stainless steel, titanium, nickel-titanium or metal, or even a polymer. The components can be assembled with screws  187  also shown in  FIG. 21 . 
         [0132]    The thickness, curvature, surfaces  119 ,  170 ,  171  and/or stops  173  of the compressor  111  can vary to accommodate proper disc  100  compression.  FIG. 22  depicts a vertical cross-sectional view of a compressor  111  containing two stops  173  to improve stability.  FIG. 23  shows a compressor  111  with no stop  173  and a round annular contact surface  119  for gentle compression.  FIG. 24  indicates a compressor  111  with multiple sloped surfaces  170  to gain rapid annular penetration and provide initial stabilization of the clamp  198 .  FIG. 25  shows an unsymmetrical slope  170  for shimming into a disc  100  to correct or straighten some kyphosis, scoliosis, lordosis or other spinal deformity.  FIGS. 26  shows tissue ingrowth openings  160 , indentations or troughs to promote annular ingrowth and stabilization of the compressor  111 . The plateau surfaces  171  with tissue ingrowth openings  160  can also be non-parallel to each other, as shown in  FIG. 27 , to correct and stabilize some spinal deformities. 
         [0133]    For compressive strength, biocompatibility and durability, nickel-titanium perhaps is the most suitable material for fabricating the clamp  198 . The clamp width and reach-in portions are defined in  FIG. 28 . The reach-in portions of the clamp  198  are essential for securing the initial fastening and clamping of the disc  100 . The distal tips  130  are tapered to prevent nerve impingement by the reach-in portions of the clamp  198 .  FIG. 29  is a typical strain vs. stress profile of nickel-titanium alloy, a super elastic alloy suitable for fabricating into a disc clamp  198 . Various compressive stages of a nickel-titanium clamp  198  are also indicated in  FIG. 29 . The compressive force is greatest initially when it presses in the annular protrusion. As the protrusion is compressed, it relieves the strain of the clamp  198 ; the compressive force of the clamp  198  rapidly weakens. When the stops  173  reach the vertebral body  159 , the compressive force is insignificant, minimizing erosion on bone and annulus. Since the stress on the clamp  198  is minimal after protrusion compression, continual erosion of the disc  100  may not occur even in the absence of the stops  173  on the compressors  111 . 
         [0134]    The clamp/compressors  198 / 111  can also be installed through a lateral incision. A widening tool is modified to hold the clamp/compressors  198 / 111  laterally. The modified tool is also used as an extension to install the device  198 / 111  in the patient. Lateral insertion and device  198 / 111  maneuvering can minimize possible damages from excessive tissue retraction, especially for intervertebral discs  100  surrounded by blood vessels, muscles and nerves. For example, the L3-4 disc  100  is sandwiched bilaterally by the Psoas major muscles containing lumbosacral nerve roots, sensitive to excessive retraction. Aorta and inferior vena cava are anterior to the disc  100 . To compress the L3-4 disc  100 , the open side of the widened C-like clamp/compressors  198 / 111  is oriented vertically either superiorly or inferiorly to the patient, to make the insertion as thin as possible. Through a lateral incision, the widened and vertically oriented C-like clamp/compressors  198 / 111  is inserted between the L3-4 disc  100  and the blood vessels (aorta and inferior vena cava) anterior to the disc  100 . The clamp/compressors  198 / 111  is then slowly rotated to orient the open side posteriorly, placing both compressors  111  laterally around the L3-4  100 . The clamp/compressors  198 / 111  is then slowly released to compress the disc  100 , followed by retrieval of the widening tool. 
         [0135]    The compressor  111  can also be fastened to a bracket  139  by a screw  187 , as shown in  FIG. 30 . The bracket  139  is equipped with slits  165  for bolts or screws to fasten into the vertebral body  159 , thus compressing the protruded disc  100  with the compressor  111 . The compressor  111  can also be made with the bracket  139  in one-piece as shown in  FIG. 31 .  FIG. 32  depicts compression of the protruded disc  100  by the compressor/bracket  111 / 139  fastened by bolts  161  or screws into the vertebral body  159  with the heads of the bolts concealed in the indentation  164  of the bracket  139 .  FIG. 33  shows a coronal view of bilateral disc  100  compression fastened with compressor/bracket  111 / 139  and bolts  161  through the vertebral body  159 . In essence, the brackets  139  serve similar function as the stops  173  with attachment holes  165 ,  110 . 
         [0136]      FIG. 34  depicts a bolt  161  with two longitudinal slits  106  cut along the length of the bolt  161 . The bolt  161  is made with elastic metal, such as nickel-titanium. The slits  106  can be cut with laser, water jet, wire or sinker EDM (electron discharging machine).  FIG. 35  depicts the slits  106  after being shimmed open and shaped to form four elastic and compressible struts  107 . For nickel-titanium bolts  161 , the struts  107  are shaped by inserting shims or fixtures, heating the shimmed bolts  161  to about 500° C. for 5-10 minutes, then quickly quenching the heat-treated bolt  161  in cold water before removing the fixtures. It is also possible to mold or cast a bolt  161  with elastic and compressible struts  107  already in open positions, as shown in  FIG. 35 . Elastic polymers can also be used to mold into an elastic bolt  161  with compressible struts  107 . With the struts  107  open, the length of the bolt  161  is elastically or resiliently shortened.  FIG. 36  shows a sleeve  104  with lumen  225  and four windows  114  sized and configured for the protrusion of the elastic struts  107  of the bolt  161 .  FIG. 37  indicates the insertion of the bolt  161  with the elastic struts  107  being resiliently compressed and fitted within the sleeve  104 . The struts  107  and the windows  114  are in an out-of-phase position, where the windows  114  and direction of struts  107  deployments do not overlap. The length of the bolt  161  in out-of-phase position within the sleeve  104  is longer than the length of the bolt  161  with open struts  107 , as shown in  FIG. 35 .  FIG. 38  depicts turning of the bolt  161  relative to the sleeve  104  or turning of the sleeve  104  relative to the bolt  161 , from the out-of-phase position to an in-phase position, where the windows  114  align with the directions of struts  107  for deployment. As a result, the elastic struts  107  protrude out of the windows  114  and the overall length of the bolt  161  is elastically or resiliently shortened. 
         [0137]      FIG. 39  shows a coronal view of a vertebral motion segment with decreased disc height or symptoms of spinal stenosis. Two disc-compressor/brackets  111 / 139  are laterally anchored with two elastic bolts  161  containing slits  106  within two sleeves  104  in out-of-phase positions. The round sleeve head  108  and round nut  162  are designed to allow pivotal movement of the compressor/brackets  111 / 139  during disc  100  compression. The deployment of the struts  107  is activated or initiated by rotating the sleeves  104  from out-of-phase to in-phase positions, allowing the struts  107  to protrude out of the windows  114  of the sleeves  104  and to provide elastic or resilient inward pulling tension on both compressors/brackets  111 / 139 . Similar to the clamp/compressor  198 / 111 , the elastic disc  100  compression allows time for the surrounding ligaments to slowly extend and the annulus of the disc  100  to gradually thicken. As a result, tissue damage is minimized and disc  100  height is elevated to alleviate spinal stenosis, as indicated in  FIG. 40 . For ease of illustration,  FIG. 40  shows that the plane of the deployed struts  107  is perpendicular to the end plate  105 , but ideally the plane of the deployed struts  107  should be parallel to the end plate  105  to maximize the spread of the struts  107  without interfering with the end-plate  105 . Therefore, a marking on the bolt head  116  visible to the surgeon can be helpful to identify the plane of struts  107  deployment. 
         [0138]      FIG. 41  depicts a mono-lateral disc  100  compression into the concave side of the curved scoliotic vertebral segment.  FIG. 42  shows activation of elastic fastening by setting the bolt  161  and sleeve  104  to the in-phase position, slowly wedging the compressor  111  into the concave side of the curved spine to correct or straighten the scoliotic vertebral segment. To correct the entire scoliotic spine, multiple shillings can be done in multiple scoliotic segments. The degree of individual shimming can be individually selected or fitted with different thicknesses and shapes of the compressor  111 . The plateau surfaces  171  of the compressor  111  can be non-parallel, as shown in  FIG. 27 , to optimize the fit and correction. The plateau surfaces  171  can also be indented with a tissue ingrowth opening  160 , also indicated in  FIG. 27 , to promote annular ingrowth and minimize outward slippage of compressor  111 . 
         [0139]      FIG. 43  indicates a degradable sleeve  218  holding or restricting the elastic struts  107  of the bolt  161  from opening. The rate of strut  107  opening is determined by the rate of degradation of the degradable sleeve  218 . The major benefit to the degradable sleeve  218  is the elimination of the step of turning from the out-of-phase to the in-phase position. Furthermore, gradual opening of the struts  107  may be preferred with a slowly eroding degradable polymer to gently and gradually compress and shim into the disc  100 . The degradable sleeve  218  can be made with polylactide, polyglycolide, poly(lactide-co-glycolide), polycaprolactone, polydioxanone, polyanhydride, trimethylene carbonate, poly-beta-hydroxybutyrate, polyhydroxyvalerate, poly-gama-ethyl-glutamate, poly(DTH iminocarbonate), poly(bisphenol A iminocarbonate), poly-ortho-ester, polycyanoacrylate and polyphosphazene. There are natural biodegradable materials, including collagen, gelatin, cellulose, chitin and dextran. Many of these biodegradable materials are not biocompatible in bone or in disc  100 . However, the elastic bolt  161  and the degradable sleeve  218  combination can be used in other industries to provide elastic tensile fastening. The degradation can be initiated by water. For implant use, polylactide, polyglycolide or poly(lactide-co-glycolide) is most promising for making the degradable sleeve  218 . 
         [0140]    It is possible to have both elastic bolt  161  and sleeve  218  biodegradable for bone joining or tissue fastening. Degradation time for DL-polylactide is 12-16 months; 50/50 lactide and glycolide co-polymer is 1-2 months. The bolt  161  with open struts  107  can be made by injection molding with DL-polylactide (modulus 1.9 Gpa) and the sleeve  218  with 50/50 lactide and glycolide. Initiated by the degradation of the sleeve  218  within two months, the resilient strength of the bolt  161  begins. After 16 months, hopefully the wound has healed and the bolt  161  and nut  162  will also degrade. 
         [0141]    Similar to the elastic bolt  161 , a coil spring  125  as shown in  FIG. 44  can also provide compression onto the compressor/bracket  111 / 139 .  FIG. 45  depicts a coronal view of disc  100  compression by a bolt  161 , compressor/bracket  111 / 139 , washer  163 , compressed coil spring  125 , another washer  163  and nut  162 .  FIG. 46  shows disc  100  compression and compressor  111  shimming activated by the coil spring  125 . Other type of springs can also be used.  FIG. 47  shows two connecting lift springs  121  curving or arching outwardly. The springs  121  are connected at both ends  118 , and a screw hole  120  lies near the center of both springs  121 . The lift springs  121  can be used as the coil spring  125  in  FIGS. 45 and 46  to elastically compress the intervertebral disc  100 . 
         [0142]      FIG. 48  indicates a compressor/bracket  111 / 139  installed anterior to a kyphotic vertebral segment. The bracket  139  is anchored by a pivoting means  126  and an elastic fastening means  127  onto the vertebral body  159 . With time, the compressor  111  shims into the disc  100  to correct and straighten the kyphotic bend as shown in  FIG. 49 . The bracket  139  can also be made with elastic or resilient material installed under strain to compress into the disc  100 . 
         [0143]    The compressor/bracket  111 / 139  can also be lengthened to serve dual functions: disc  100  compression and spinal fusion, as shown in  FIG. 50 . Differing from the currently existing fusion plate, the extended compressor/bracket  111 / 139  compresses and thickens the disc  100  to increase disc space and possibly alleviate nerve impingement. The extended bracket  139  contains a compressor  111  near the mid-portion and screw/bolt holes  110  or slits  165  above and below the compressor  111 .  FIG. 51  depicts spinal fusion and disc compression with the extended compressor/bracket  111 / 139 . A coronal view of spinal fusion and disc compression with two compressors/brackets  111 / 139  fastened on the vertebral bodies  159  is shown in  FIG. 52 . For the best results, the bolts  161  or screws are fitted in the slits  165  and evenly fastened to compress the disc  100  and distract the vertebral bodies  159 . Then holes are then created in the vertebral bodies to fit bolts  161  or screws through the bracket holes  110  and to further secure the bracket  139 . Disc  100  compression with spinal fusion is expected to provide disc height elevation, which may be particularly suitable for severe segmental instability or spinal stenosis. Using current technique, disc heights commonly decrease after intervertebral body fusion (Watkins R., et. al., Comparison of Disc Space Heights after Anterior Lumbar Interbody Fusion, Spine 14(8):876-878, 1989). 
         [0144]      FIG. 53  depicts a mid-coronal view of a vertebral segment with normal outward bulging of the annular layers during axial compression. As the nucleus pulposus  128  ages, dries out or degenerates, the annular layers exhibit both inward and outward bulging during similar axial compressions (Seroussi R. E. et. al., Internal Deformations of Intact and Denucleated Human Lumbar Discs Subjected to Compression, Flexion, and Extension Loads, Journal of Orthopaedic Research, 7:122-131, 1989; Meakin J. R., Replacing the nucleus pulposus of the intervertebral disc, Clinical Biomechanics 16:560-565, 2001). It is speculated that the inward-outward bulging causes delamination in the inner core of the annular layers, as shown in  FIG. 54 . The delaminated annular layer is thin, unsupported and vulnerable to tearing. Usually, the delamination begins at the layers near the aging nucleus pulposus  128  and leads to seepage of nucleus pulposus  128  and disc  100  protrusion, as shown in  FIG. 55 , (Goel V. K. et. al., Interlaminar Shear Stresses and Laminae Separation in a Disc, Spine, 20(6): 689-98, 1995). The compressors  111  provide inward compression to the disc  100 , flatten the protrusion and promote inward bulging to minimize the progression of annular delamination and to halt the deterioration of the defective disc  100 , as indicated in  FIG. 56 . Disc  100  compression by the compressor  111  may also collapse and seal the seeping channels of nucleus pulposus  128  in a herniated disc  100  to minimize chemical irritation to nerves  102 . 
         [0145]    Chronic low back pain is generally thought to be caused by nerve  102  impingement. However, MRI often fails to show impingement of neural structures, even in the presence of sciatica. Furthermore, saline injection, discography and compression of the longitudinal spinal ligaments can reproduce back pain and sciatica. These observations have led to re-examination of the pathways and distribution of nociceptive (pain sensing) nerve endings in healthy and diseased spines. In the healthy disc  100 , only the outer third of the annulus is innervated. But among patients with chronic low back pain, nerves extend into the inner third of the annulus, some even into the nucleus pulposus  128  (Freemont A. J. et. al., Nerve ingrowth into diseased intervertebral disc in chronic back pain, The Lancet, Vol. 350, July 19:178-181, 1997). Nerve ingrowth in connective tissue is normally a sign of repair in progress. However, similar to the articular cartilage in joints, the healing progress of annulus is very slow and poor.  FIG. 57  depicts the ingrowth of sinuvertebral nerves  216  conducting the sensation of tensile or stretching pain from the delaminated pockets within the degenerating disc  100 . Sinuvertebral nerves  216  normally grow from the surface into the annulus only when the disc  100  begins to degenerate.  FIG. 58  depicts compression of the sinuvertebral nerves  216  leading into the degenerative disc  100  by the compressors  111 . With prolonged and intense compression from the compressors  111 , the sinuvertebral nerves  216  are expected to cease transmitting signals of pain from the degenerative disc  100  and atrophy within days, thus alleviating pain without discectomy. 
         [0146]    The compressors  111  can also be installed through a protruded disc  100 . With the aid of a trocar guide  185 ,  FIG. 59  depicts the insertion of a trocar  103  laterally through the protruded disc  100  impinging  184  upon a nerve  102 . Insertion of the trocar  103  and compressors  111  can be done endoscopically through a lateral incision as well as through the anterior approach shown in  FIG. 59 .  FIG. 60  indicates the insertion of a dilator  230  over the trocar  103 . Then the trocar  103  is withdrawn while the dilator  230  remains in the disc  100 , as shown in  FIG. 61 .  FIG. 62  depicts the insertion of a bolt  161 , an arcuate compressor  111  and washer  163  assembly into the dilator  230 .  FIG. 63  indicates the withdrawal of the dilator  230  to exposure the thread  109  of the bolt  161 .  FIG. 64  shows the installation of another compressor  111  onto the bolt  161  with washer  163  and nut  162 .  FIG. 65  depicts tightening of the bolt  161 , nut  162 , compressors  111  and washer  163  assembly to fasten the bulging disc  100  with the sloped surface  170  embedding into the disc  100 . For elastic compression, the resilient bolt  161  with elastic struts  107  can be used with the sleeve  104 , as shown in  FIG. 37 , or with the biodegradable sleeve  218  in  FIG. 43 . 
         [0147]    The compressor  111  can also be fastened through the outer layers of the disc  100 , and/or with a bracket  139  fastened on the vertebral body  159 , as shown in  FIG. 66 . The screw entry  217  can be made with a trocar  103 , as shown in  FIG. 67 . To enhance annular reattachment and/or regeneration of the otherwise slow healing, avascularized annulus, bleeding sites  224  at the end-plate  105  are created by the trocar  103  through the bulging disc  100 , as shown in  FIG. 67 . The entry of the trocar  103  depicted in  FIG. 67  is slanted or angled upward, able to fit between the superior and inferior surfaces of the laminae, to prevent or minimize laminectomy.  FIG. 68  shows a curved trocar  103  inflicting bleeding sites  224  in both superior and inferior end plates  105 , through a posterior/lateral approach. A saddle-shaped compressor  111  is shown in  FIG. 69  with a cylindrical annular contact surface  119 , sloped surface  170 , round contour tips  130 , a screw hole  110  and a trough  223  or indentation to conceal the screw head  226  of a screw  187 .  FIG. 70  depicts penetration of the screw  187  through the outer portion of a protruded disc  100  and the end plate  105  into the vertebral body  159 .  FIG. 71  shows compression of the protruded disc  100  by the compressor  111  fastened by the screw  187  anchored in the vertebral body  159  to alleviate nerve  102  impingement  184  shown in  FIG. 70 .  FIG. 72  shows a longitudinal view of a fastened disc  100  by the compressor/screw  111 / 187  with bleeding sites  224  inflicted on both end plates  105 . 
         [0148]    The strength of the fastened disc  100  may be greatly enhanced by healing initiated by the surgically inflicted bleeding sites  224 . Ligament reattachment to bone is a good example. A biodegradable suture rated merely for 20 pounds is used to attach a torn ligament onto a surgically inflicted bleeding bone. Within two weeks, the tensile strength of the reattached ligament can reach 50 pounds; strength increases with time. In essence, the suture is merely used to maintain the position of the torn ligament; reattachment and healing occur naturally with the surgically inflicted bleeding bone. As the bulging annulus is compressed by the compressor  111  as shown in  FIG. 72 , adhesions form from oozing of the bleeding sites  224  between the end plate  105  and the compressed annulus. Tissue adhesion and the fastened compressor  111  work in conjunction to hold the bulging annulus in place, alleviate nerve  102  impingement  184  and allow time for the annulus to regenerate. 
         [0149]    Similar to menisci in knees and articular cartilage in joints, the annulus has a limited capacity for healing and regeneration. For articular cartilage regeneration in the knee, an arthroscopic awl is used to create multiple holes on the articular cartilage surface, allowing blood and marrow elements to fill the defect, leading to formation of fibrocartilage. Patients have reported feeling significant improvement (Blevins F. T., et. al., Treatment of Articular Cartilage Defects in Athletes: An Analysis of Functional Outcome and Lesion Appearance, Orthopedics, July 21(7):761-7, 1998). No work has been done on end plate  105  puncturing to promote annular regeneration and adhesion. A qualitative in vitro investigation of adult human discs  100  showed that the end plates  105  are indeed partly permeable to solutes or nutrients. The permeation is associated with the presence of vascular contacts between the marrow spaces of the vertebral body  159  and the hyaline cartilage of the end plate  105 . One-third of the central portion and only one-tenth of the peripheral zone of the end plates  105  are available for diffusion, exchanging nutrients and waste between the disc  100  and vertebral bodies  159  (S. Holm, et. al., Nutrition of the Intervertebral Disk, Clinical Orthopaedics and Related Research, 129, November-December: 101-14, 1977). It has been suggested that nutritional deficiencies could lead to disc  100  degeneration (Nachemson A., et. al., In vitro diffusion of dye through the end plates and the annulus fibrosus of human lumbar intervertebral disks, Acta Orthop. Scand., 41:589, 1970). It has also been suggested that annular regeneration is slow due to calcified hyaline cartilage at the end plate  105  in adults, which greatly hinders transportation of nutrients. End plate  105  punctures with an awl or trocar  103  could provide passages for nutrients, leading to the acceleration of annular regeneration. Furthermore, as the disc  100  undergoes rapid repair through the open channels created in the end plate  105 , it is possible that fewer pain signals and/or shorter durations of them will be emitted from the degenerated annulus. Nerve  216  ingrowth into the disc  100  may decrease; the risks of future discogenic pain may decrease as well. 
         [0150]    Spondylolisthesis is a condition in which a vertebral body  159  detaches and slips from a disc  100 , usually the L5 and S1 disc  100 , as shown in  FIG. 73 . The slippage usually occurs with some erosion on the facet joint  129 , allowing the inferior articular process  143  of L5 to slip over the superior articular process  142  of S1, also shown in  FIG. 73 . Spondylolisthesis is normally surgically treated with lumbosacral fusion using instrumentation fastened by screws vulnerable to fatigue and breakage. Instead of using instrumentation to fuse the intervertebral segments, annular adhesion and regeneration may eliminate the need of instruments and hardware. After the spine with the affected vertebral body  159  is repositioned, bleeding sites  224  are created by the trocar  103  to initiate tissue adhesion between the end-plate  105  and the disc  100 , as shown in  FIG. 74 . A period (2-4 weeks) of low back immobilization followed by passive motion is required for proper adhesion and adequate reattachment to take place. 
         [0151]    A curved trocar  103  made with resilient material, such as nickel-titanium or spring tempered stainless steel, is housed in the lumen of a rigid sleeve  220 , as shown in  FIG. 75 . The handle of the trocar  103  contains a label  221  indicating the direction of the curvature. The curved trocar  103  can be resiliently straightened within the sliding sleeve  220 , as shown in  FIG. 76 . The curvature resumes when the sleeve  220  slides away from the curved section of the trocar  103 . The sleeve/trocar  220 / 103  assembly is placed perpendicular to the disc  100 . By pushing on the handle of the trocar  103 , the trocar  103  pierces through the disc  100 , resumes the unrestricted curvature and pierces into the end plate  105 , as indicated in  FIG. 77 . The resiliently curved trocar  103  provides the surgeon greater latitude in terms of patient safety and surgically accessible locations to create bleeding sites  224  at the end plate  105 . 
         [0152]      FIG. 78  depicts a flattened or bulging disc  100  sandwiched between vertebral bodies  159 , a common cause of segmental instability and/or spinal stenosis. A pair of compressors/screws  111 / 187  is fastened through a portion of the disc  100 , through the end plate  105  and into the vertebral body  159 , as depicted in  FIG. 79 . The bulging or unstable sidewall of the disc  100  is compressed, supported, fortified, stiffened, restricted, tightened, pinched in and/or fastened by the compressors/screws  111 / 187  to minimize segmental instability. 
         [0153]    A pair of compressors/screws  111 / 187  was used to fasten a cadaveric lumbar motion segment in similar fashion as  FIG. 79 . Motion analysis was done on the fastened cadaveric segment, showing significant increase in stability in flexion/extension and lateral bending motions. The disc height was also increased after disc  100  fastening with the compressors/screws  111 / 187 . The result of the cadaveric study indicates potential for treating spinal stenosis by compressing, consolidating and tucking the bulging annulus back between the vertebral bodies  159  to build disc  100  thickness and intervertebral space and to alleviate nerve  102  impingement, as shown in  FIG. 80 . To prevent screws  187  from interfering with each other when multiple compressors  111  are used, screws  187  can be separately anchored into adjacent vertebral bodies  159 , as shown in  FIG. 81 . 
         [0154]    To minimize device migration, the compressor  100  can be fastened with a bolt  161  which penetrates obliquely through the vertebral body  159  and is fastened by a washer  163  and nut  162  assembly, as shown in  FIG. 82 . Promoting tissue ingrowth into the device can also minimize device migration.  FIG. 83  depicts a compressor  111  with tissue ingrowth openings  160 , channels or indentations to promote annular ingrowth and prevent migration of the compressor  111 . 
         [0155]    The compressor  111  shown in  FIG. 84  also indicates multiple tissue ingrowth openings  160  penetrating through the thickness of the compressor  111 . The large ingrowth openings  160  encourage annular ingrowth to prevent device migration with time. Different types of tissue ingrowth can be selected by varying the thickness of the compressor  111 . The thick compressor  111  with large ingrowth openings  160  fastened adjacent to or over the end plates  105  may encourage bone ingrowth and promote segmental fusion without removing the disc  100 . Existing spinal fusion procedure with discectomy often contributes to disc space narrowing, which may result in further nerve impingement. The segmental fusion induced by the bone ingrowth from upper and lower vertebral bodies  159  into the compressors  111  is accomplished after the distraction of the disc  100  with possible thickening of disc space. Osteoconductive material, such as bone growth factor collagen and/or hydroxyapatite, can be used to fill the tissue ingrowth openings  160 . The surfaces of the compressor  111  can also be textured or made porous, similar to hip prostheses, to promote bone ingrowth. 
         [0156]    For discs  100  at the thoracic or cervical region, rotational motion is also significant.  FIG. 84  depicts a compressor  111  with tips  130  slightly curved outwardly to minimizing annular puncture during excessive or unforeseen rotations. 
         [0157]    The compressor  111  can be made with a resilient or elastic material, such as nickel titanium, allowing up to 7% strain without losing shape memory.  FIG. 85  depicts a compressor  111  in an open or predisposed position. The resilient compressors  111  can be folded or restricted in a tubular delivery capsule  131 , as shown in  FIG. 86 , for endoscopic insertion. In the capsule  131 , the resilient compressor  111  is in a delivery position. The delivery capsule  131  assembly holding the resilient compressor  111  and a screw  187  is fitted into a delivery device  124 , secured by latches  132  and releasable by pinching, as shown in  FIG. 87 . The delivery device  124  is equipped with a drive  133  extending into the socket  228  opening of the screw  187 . With a small diameter or cross section of the delivery capsule  131 , it may be possible to reach the protruded disc  100  in the central zone by inserting the capsule  131  between laminae without laminotomy, as indicated in  FIG. 87 . The screw  187  is then advanced through the disc  100  into the end plate  105 . As the screw head  226  contacts the compressor  111 , the advancing screw  187  repels the restricted compressor  111  out of the capsule  131 , as shown in  FIG. 88 . To keep the resilient compressor  111  from rotating with the screw  187 , the cross section of the capsule  131  can be made non-circular. The repelled compressor  111  resumes the open position, spreading the legs of resilient compressors  111  on the protruded disc  100 , anterior to the nerve  102 . With further tightening of the screw  187  into the end-plate  105 , the screw head  226  presses against the compressor  111 , further spreading into a compressed position to fasten the previously bulging annulus, as shown in  FIG. 89 . 
         [0158]    The resilient compressor  111 , capsule  131  and screw  187  assembly is uniquely designed to accommodate the large moving range of the compressors  111  from the delivery position to the compressed position, a range even nickel-titanium alloy may not be able to provide. The uniqueness is in the open position, about half way between delivery and compressed positions. The magnitudes of the strain from the open to delivery position and from the open to compressed position are nearly equal but in opposite directions. In essence, the open or predisposed position is set at midway, making the large moving range of the compressor  111  possible, without shape memory loss. 
         [0159]    To minimize swaying of the screw  187  during tightening, a stabilizer  134  is inserted in the capsule  131  to restrict the screw head  226  within a lumen  117  of the stabilizer  134 , as shown in  FIG. 90 . The stabilizer  134  contains a lip  135  to prevent the stabilizer  134  from passing through the capsule  131 . As the screw head  226  in the lumen  117  advances through the disc  100 , lateral movement is greatly minimized during rotation of the socket drive  133 . 
         [0160]      FIG. 91  depicts a clamp/compressors  198 / 111  with large tissue ingrowth openings  160  to ensure annular ingrowth and prevent migration of the clamp/compressor  198 / 111 . The widening mounts  199  can also be a portion of the ingrowth openings  160 . The large ingrowth openings  160  may also allow bone ingrowth to promote spinal fusion  234  between upper and lower vertebral bodies  159 , as shown in  FIG. 92 . The spinal fusion  234  induced by the compressors  111  can be further promoted by thick and porous compressors  111  bridging between two adjacent vertebral bodies  159 , allowing the bone from adjacent vertebral bodies  159  to grow into the ingrowth openings  160  of the compressors  111 . It is also possible to make the compressors  111  osteoconductive as hip and joint implants are, allowing bone from adjacent vertebral bodies  159  to embed and fuse with the compressors  111  and create segmental fusion  234 . The uniqueness of this spinal fusion  234  is that it is accomplished with an intact and repaired disc  100  with the possibility of increased disc height induced by disc  100  compression. Similarly, compressors  111  with osteoconductive property, porous or large ingrowth openings  160  fastened with a bracket  139 , bolt  161  or a screw  187  would provide bone ingrowth and spinal fusion  234 . 
         [0161]    A wide range of materials can be used to fabricate the compressor  111 . Titanium, stainless steel, nickel-titanium alloy or other metallic material is preferred for strength and durability. To minimize tissue erosion, at least a portion of the compressor  111  can be made with biocompatible polymers, such as polyurethane, polypropylene, polyethylene, poly-ether-ether-ketone, acetal resin, polysulfone, polytetrafluoroethylene, polycarbonate, silicon, polyimide, ultra high molecular weight polyethylene or other. The compressor  111  can also be coated with lubricant, growth factor, nerve ingrowth inhibitor, nutrient, buffering agent, collagen, hydroxyapatite, analgesic, sealant for nucleus pulposus, blood clotting, antibiotic, radiopaque or echogenic agents. The casing  188  with pivotal peg  172 , as shown in  FIG. 21 , can be made with stainless steel, titanium, nickel-titanium or a rigid polymer. 
         [0162]    After the dysfunctional disc  100  has been repaired by the compressor  111 , perhaps accelerated by the surgically inflicted bleeding sites  224 , new annulus forms in a non-bulging position. Within months the strength of the repaired disc  100  may be mainly supported by the regenerated annulus cushioned between the vertebral bodies  159 , rather than from the fastening strength of the compressor  111 . Therefore, it may be possible to fabricate the compressor  111  and the supporting devices with biodegradable material, such as poly-lactate, poly-glycolic, polycaprolactone, trimethylene carbonate, combinations of these or other materials. A biodegradable device is particularly suitable for young patients to avoid device migration or other related complications in the distant future. All materials should be able to withstand sterilization by gamma, electron beam, steam, ETO, plasma or UV light to prevent infection. 
         [0163]    Twenty to forty percent of patients undergoing laminectomy and/or discectomy procedures do not find pain relief. Due to the high invasiveness of present procedures, epidural scarring and vertebral instability are the most common and often lingering post-surgical complications. These tissue-removing procedures are not reversible. For many patients, the pain often returns in five years or less. In contrast, the proposed compressors  111  and methods repair the dysfunctional discs  100  without tissue removal, minimizing epidural scarring and strengthening the vertebral segment. Disc compression thickens the disc  100  and distracts the adjacent vertebral bodies to alleviate pain without removing tissues and weakening the spine. The proposed devices are retrievable, and the methods do not involve with tissue removal. Discectomy, laminectomy, foraminotomy, traditional spinal fusion or other conventional procedures can be used as a fall back procedure in the event of an unsuccessful outcome. 
         [0164]    In summary, the compressors  111  on a clamp  198 , a bracket  139 , a bolt  161  (elastic or otherwise) or a screw  187  are used for (1) compressing a protrusion to alleviate impingement, (2) fortifying the annulus to stabilize a motion segment, (3) minimizing the inward/outward bulging to protect the disc  100  from progressive delaminations, (4) atrophying the nerve to treat discogenic pain, (5) correcting the curvature of spinal deformities, (6) elevating the disc space to treat spinal stenosis, (7) sealing the leakage of nucleus pulposus to treat herniated discs  100 , and/or (8) promoting bony ingrowth to fuse the motion segment. 
         [0165]    It is to be understood that the present invention is by no means limited to the particular constructions disclosed herein and/or shown in the drawings, but also includes any other modification, changes or equivalents within the scope of the claims. Many features have been listed with particular configurations, curvatures, options, and embodiments. The bracket  139  or the fusion plate in  FIG. 50  can also be viewed as the extended stop  173  of the compressor  111 . Any one or more of the features described may be added to or combined with any of the other embodiments or other standard devices to create alternate combinations and embodiments. 
         [0166]    It should be clear to one skilled in the art that the current embodiments, materials, constructions, methods, tissues or incision sites are not the only uses for which the invention may be used. It has been foreseen that the elastic bolt  161 , resiliently curved trocar  103  and/or resilient compressor  111  can be applied for other surgical and non-surgical purposes. Different materials, constructions, methods or designs for the compressors  111 , brackets  139  or the delivery devices  124  can be substituted and used. Nothing in the preceding description should be taken to limit the scope of the present invention. The full scope of the invention is to be determined by the appended claims.