Abstract:
A logarithmically increasing decompression force is applied to a spinal column in a progressively changing direction lying in the mid-sagittal plane. This focuses the decompression force as compared with a straight-line pull. A table to achieve this decompression force has a fixed table section, a moveable table section, a reciprocating arm which acts as a movable pre-tension section, a vertically adjustable upstanding support supported by the pre-tension section, an attachment point attached to a tensionometer-head associated with the upstanding support for attachment to a harness, a moveable table section drive for extending the moveable table section from the fixed table section and for retracting the moveable table section toward the fixed table section, a reciprocating arm drive for extending and retracting the reciprocating arm from the movable table section, and an upstanding support drive for driving the upstanding support to different vertical positions.

Description:
BACKGROUND 
     Back pain is among the most common conditions for which patients seek medical care. More than 70 percent of adults suffer back pain or neck pain at some time in their lives. In the United States, medical treatment of back pain is estimated to cost $25 billion dollars annually. Workers compensation costs and time lost from work add another $25 billion. 
     Medical management is the first treatment choice. If there is no improvement in the patient&#39;s condition, surgery is often the next treatment of choice. Despite the uncertainty about how effective surgery is for patients, the number of fusion surgeries rose 127% from 1997 to 2004, to more than 303,000. Recent research demonstrates that even after two years patients treated conservatively are as well off as those treated surgically. Surgical costs are continuing to rise, as patients receive ever more aggressive treatments. 
     Recently, vertebral axial decompression therapy for the spine and discs has emerged as a frontline treatment for back pain. This is a non-surgical treatment for herniated discs, degenerative disc disease, posterior facet syndrome and failed back surgery. With traditional traction therapy, forces are applied in a linear fashion and the resultant muscle guarding prevents the discs from being decompressed. Paraspinal muscles are conditioned to oppose abrupt and linear changes in tension, but will relax if the force is applied in a smooth gradual manner whereby the rate is slowed progressively according to a logarithmic time scale. 
     It has been shown that tension forces to the spine applied in a ‘logarithmic’ time/force curve will decompress the discs and spine. Vertebral axial decompression is the only treatment that has been shown in clinical study to decrease the intervertebral disc pressure to negative levels and to decompress the lateral nerve roots that supply the legs. 
     While this known vertebral axial decompression therapy is advantageous, an improved vertebral decompression therapy would be desirable. 
     SUMMARY 
     A logarithmically increasing decompression force is applied to a spinal column in a progressively changing direction lying in the mid-sagittal plane. This allows the decompression force to be focused on selective vertebrae. 
     A table to achieve this decompression force has a fixed table section, a moveable table section, a vertically adjustable upstanding support supported by the moveable table section, an attachment point associated with the upstanding support for attachment to a harness; a first drive for extending the moveable table section from the fixed table section and for retracting the moveable table section toward the fixed table section, and a second drive for driving the upstanding support to different vertical positions. 
     Other features and advantages will be apparent from the following description in conjunction with the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the figures which illustrate example embodiments of the invention, 
         FIG. 1  is a schematic side view of a vertebral decompression table made in accordance with this invention, 
         FIGS. 2 and 3  are perspective views of the table of  FIG. 1  shown in use, 
         FIG. 4  is a perspective partial view of the table of  FIG. 1  shown in use, 
         FIG. 5  is an exploded view of the cervical-head harness, 
         FIG. 6  is a side view of the cervical-head harness shown in  FIG. 5 , 
         FIG. 7  is an angled view of an integrated cervical-head harness and anchor strap assembly which may be used with the table of  FIG. 1 , 
         FIG. 8  is a screen shot from a computer display associated with the table of  FIG. 1 , 
         FIGS. 9 and 10  are schematic side partial view of the table of  FIG. 1  illustrating its operation, 
         FIGS. 11 ,  12 ,  13  and  14  are force vector diagrams illustrating operation of the table of  FIG. 1 , 
         FIG. 15  is a schematic side view of a vertebral decompression table made in accordance with another embodiment of this invention, and 
         FIG. 16  is a schematic side view of a vertebral decompression table made in accordance with a further embodiment of this invention. 
     
    
    
     DETAILED DESCRIPTION 
     Turning to  FIG. 1 , a vertebral decompression table  10  has a fixed table section  12  and a moveable table section  14 . The fixed table section  12  has a linear actuator  16  which may be activated to push the moveable table section  14  away from the fixed table section  12  or draw the moveable table section  14  toward the fixed table section  12 . The fixed table section also has a pair of handgrips  28 . A motor  29  controls the longitudinal position of these handgrips. The moveable table section has a reciprocating arm  18  which may be extended outwardly from the end  20  of the moveable table section  14  or retracted inwardly toward the end  20  of the moveable table section by a linear actuator  22  housed within the moveable table section. The base  26  of a vertically adjustable support  30  is joined to arm  18 . Base  26  houses a linear actuator  32  which may extend support  30  upwardly or retract support  30  downwardly. 
     A tensionometer-head  36  is pivotably attached to the vertically adjustable support  30  at horizontal pivot  38  so that the tensionometer-head may pivot up and down. The tensionometer-head  36  houses a tensionometer  40  with a protruding attachment  42  for attachment to a harness. The attachment may be a protruding metal tang with a central opening to connect to a seat-belt like buckle. 
     Each of linear actuators  16 ,  22 , and  32  are operatively connected to a controller  46 . The controller  46  is input by the output of the tensionometer  40  and the output of positional encoders  17 ,  23 , and  33  attached to each linear actuator  16 ,  22 , and  32 , respectively. The controller is operatively connected to a personal computer  48  which is pivotably mounted to the fixed table section  12  on arm  50 . 
     Controller  46 , which may be a microprocessor, and computer  48  may be loaded with software from a computer readable media such as CD  84 . 
     Turning to  FIG. 2 , a patient  60  may lie prone on table  10 , with feet facing tensionometer  40 . The patient wears a pelvic harness  62  with straps  64  attached to attachment  42  of the tensionometer. A suitable pelvic harness is described in U.S. Pat. No. 5,115,802 issued May 26, 1992, the contents of which are incorporated herein by reference. The patient&#39;s upper body may be restrained by wearing a thoracic restraint  66  attached to handgrips such that the handgrips act as mounts. Alternatively, or additionally, the patient may grip the handgrips  28 . Similarly, as shown in  FIG. 3 , a patient  60  may lie in a supine position on table  12  with feet facing the tensionometer. As in the prone position, the patient may wear a pelvic harness attached to attachment  42  and a thoracic restraint  66  attached to handgrips  28 . 
     With reference to  FIG. 4 , as a further alternative, the patient  60  may lie in a supine position on table  10  with their head facing tensionometer  40 . In this instance, the patient may wear a cervical-head harness  70  composed of a support collar  71  and anchor strap assembly attached to attachment  42  of the tensionometer  40 . In this orientation, there is no need to tether the body of the patient to the table because the decompression forces applied by the table to the head and neck are too low to overcome body weight. 
     The cervical-head harness  70  is detailed in  FIGS. 5 ,  6 , and  7 . Turning to these figures, collar  71  has a curved dorsal member  74  and a curved ventral member  76 . A strap  78  extends from each side of the dorsal member and is provisioned with hook fasteners. A loop fastener strap  79  is attached to each side of the ventral member. Thus, the dorsal and ventral members may be placed around the neck of a patient and the straps  78 ,  79  connected with a hook-and-loop (VELCRO™) attachment. Many alternate arrangements for the cervical collar are possible. For example, a single piece flexible collar could be flexed to allow placement around the neck of a patient and then the free ends joined by straps to complete its attachment to a patient. 
     As part of the anchor strap assembly, a pair of straps  72 D extend from the dorsal member to a crossbar  80  and a second pair of straps  72 V extend from the ventral member to the crossbar. When the cervical collar is properly positioned, these straps extend on either side of the head of the patient with the dorsal member straps  72 D directly behind the ventral member straps  72 V. Also, with the collar properly positioned on the patient, the attachment connectors  75 V of the ventral straps  72 V lie below the patient&#39;s mandible and between the chin and the ear of the patient. The attachment connectors  75 D of the dorsal straps  72 D lie below the patient&#39;s occiput on each side. The straps  72 D,  72 V extend upwardly and slightly outward from their attachment points to the crossbar  80 . A main strap  77 M extends from the middle of the crossbar and terminates in a buckle  82 . The straps  72 D and  72 V are adjustable in length, and can be tightened or loosened independently by adjustable connectors  73 V and  73 D. The dorsal straps may be tightened more than the ventral straps in order to apply more force to the occiput of the head. Alternatively, the ventral straps may be tightened more than the dorsal straps in order to direct and apply more force to the patient&#39;s mandible. Straps may also be tightened or loosened from left side or right side, to direct the force more to one side. 
     Returning to  FIG. 1 , with the patient tethered to the table  10 , the operator may enter via computer  48  a pre-tension, a maximum tension, a starting and ending height, a cycle time, the time to reach maximum tension (i.e., the time for the decompression phase), and the time to return to the pre-tension (i.e., the time for the retraction phase). Then, once the operator presses a start button, the controller will first control linear actuator  32  to adjust the height of the tensionometer-head  36  to match the entered starting height. Next, the controller  46  will operate linear actuator  22  to extend arm  18  in order to linearly increase the distracting tension on the patient&#39;s spine, up to the pre-tension. A tension feedback signal from the tensionometer  40  allows the controller to apply an appropriate drive signal to the linear actuator  22  to achieve this result. With lumbar treatments, when the pre-tension has been achieved, the controller may then activate both linear actuator  16  in order to increase the separation of the table halves and linear actuator  32  in order to move the tensionometer-head  36  vertically. These movements are controlled so that the tensionometer-head moves in an arc toward the specified ending height and so that the tension on the patient&#39;s spine logarithmically increases to the specified maximum tension. After reaching the maximum tension, the controller controls linear actuators  16  and  32  to move the tensionometer-head in the same arc back to its initial position in a retraction phase in order to reduce the tension logarithmically to the pre-tension. Indeed, as the head  36  returns to its initial position; the tension may begin to fall below the desired pre-tension and so, the controller controls linear actuator  22  in order to maintain the desired pre-tension at the end of the retraction phase. The controller may then repeat the cycle to maximum force and back to pre-tension. Once a specified number of cycles have been completed, the controller, after a rest phase at the pre-tension, releases the pre-tension. 
     As the table operates, the computer  48  may display a tension versus time curve as shown in  FIG. 8 . Turning to  FIG. 8 , curve segment  90  shows the linear increase in the tension to the pre-tension amount. Following a short rest segment  92  at the pre-tension level, segment  94  shows the tension increasing logarithmically to the maximum tension at point  96 . Segment  98  shows the tension thereafter logarithmically decreasing back to the pre-tension amount. After a rest period, a new cycle commences. The computer may also display the current height of the tensionometer-head  36  above the plane of the table with bar  102 . 
     The tensionometer provides a mechanism for registering the reaction of the spinal column structures as the distraction tension is applied progressively along the spinal column. Reactions such as release of facets, myofascial strictures, and/or compressive lesions register immediately as irregularities or deviations in an otherwise smooth display captured in the displayed time versus tension curve. The controller quickly adjusts so that the reactions register as brief irregularities. 
     If the starting height is lower than the ending height, the arc followed by the tensionometer-head  36  will be an ascending arc, as shown in  FIG. 9  at  110 . If the starting height is higher than the ending height, the arc followed by the tensionometer-head  36  will be a descending arc, as shown in  FIG. 10  at  112 . Notably, as seen in  FIG. 9 , the tensionometer-head  36  pivots so that the attachment point  42  always aligns with the patient. This ensures that the tensionometer will accurately measure the applied tension. The display of  FIG. 8  may also indicate whether the arc is ascending or descending. In particular,  FIG. 8  illustrates at  104  a descending arc. 
     As shown in  FIG. 11 , the patient&#39;s spine has cervical vertebrae C, thoracic vertebrae T, and a lumbar vertebrae L. With a patient lying prone on table  10  and tethered to the tensionometer-head  36  of the table, with a pelvic harness  62  as shown in  FIG. 2 ,  FIG. 11  shows the ascending force vectors  120   a ,  120   b ,  120   c ,  120   d ,  120   e  progressively applied to the patient&#39;s spine  122  during logarithmic tension increase where the tensionometer-head  36  follows an ascending arc  123 .  FIG. 12  shows the descending force vectors  130   a ,  130   b ,  130   c ,  130   d ,  130   e  progressively applied to the patient&#39;s spine during logarithmic tension increase where the tensionometer-head  36  follows a descending arc  131 . It will be apparent that these force vectors lie in the mid-sagittal plane of the patient and, with the table top horizontal, this mid-sagittal plane will be a vertical plane. 
     The progressively ascending and increasing force illustrated in  FIG. 11  (applied to the spine of a person in the prone position) tends to increase the lordotic curvature of the lumbar spine L on an anterior/posterior plane and so the lumbar spine is progressively extended as the direction of the force progressively inclines. Anatomical, physical dynamics tend to apply the force, as its direction progressively ascends, progressively higher along the lumbar spine, i.e., toward the L1 vertebra. This may be seen by recognising that the direction of the force is initially misaligned with the predominant line of the lumbar spine. In consequence, the force is applied more heavily toward the base of the lumbar spine, i.e., toward L5. As the direction of the force ascends, the direction lies progressively closer to the predominant line of the lumbar spine. With the force more aligned with the lumbar spine, the force is applied more evenly to each lumbar vertebra and hence more of the force reaches the upper lumbar vertebrae. This ascending change in vectors targets vertebral segments higher in the lumbar vertebral chain. The extending force will apply more force at the anterior border of the annulus and so may open disc spaces higher in the lumbar chain anteriorly. 
       FIG. 12  illustrates (the spine of a person in the prone position and) the situation where the direction of the force progressively descends while the magnitude of the force increases. This tends to decrease the lordotic curvature of the lumbar spine; thus the lumbar spine is progressively flexed as the direction of the force descends. Anatomical, physical dynamics (as the force becomes progressively more mis-aligned with the predominant line of the lumbar spine) tend to apply this changing force progressively lower along the lumbar spine, i.e., toward the L5 vertebra. The flexing force will apply more force at the posterior border of the annulus and so may open disc spaces lower in the lumbar chain posteriorly. 
     If the patient were lying in a supine position on table  10  and tethered to the tensionometer-head  36  of the table  10  with a pelvic harness  62  as shown in  FIG. 3 , applying a progressively greater, progressively more upwardly directed forces progressively flexes the lumbar spine. Anatomical, physical dynamics tend to apply this changing force progressively lower along the lumbar spine. On the other hand, with the patient tethered to the table in this manner, applying a progressively greater, progressively more downwardly directed force progressively extends the lumbar spine and anatomical, physical dynamics tend to apply this changing force progressively higher along the lumbar spine. 
     With a patient lying in a supine position on table  10  and tethered to the tensionometer-head  36  of the table  10  with a cervical-head harness  70  as shown in  FIG. 4 ,  FIG. 13  shows the ascending force vectors  140   a ,  140   b ,  140   c ,  140   d  progressively applied to the patient&#39;s spine during logarithmic tension increase where the tensionometer-head  36  follows an ascending arc  142 . During cervical spine treatments, the use of a full ascending curve (arc) progressively flexes the cervical spine from C2-C3 to C7-T1 as the tension increases gradually. 
       FIG. 14  shows the force vectors  150   a ,  150   b ,  150   c ,  150   d  progressively applied to the patient&#39;s spine during logarithmic tension increase where the tensionometer-head  36  follows a descending arc  152 . These force vectors lie in the mid-sagittal plane of the patient and, with the table top horizontal, this mid-sagittal plane will be a vertical plane. 
     The progressively directionally ascending and strengthening force illustrated in  FIG. 13  progressively pulls and rotates the cervical spine in flexion and so tends to decrease the lordotic curvature of the cervical spine C on an anterior/posterior plane. During application of this force, the thoracic spinal chain is essentially immobile due to the connections of the thoracic spine to the rib cage. Anatomical, physical dynamics tend to apply the force, as its direction progressively ascends (and the cervical vertebrae chain is progressively “straightened out”), progressively lower along the cervical spine, i.e., toward the C7 vertebra. 
     A downward dynamic curve as shown in  FIG. 14  pulls and rotates the cervical spine and patient&#39;s head in extension. This will tend to increase the curvature of the cervical spine. Anatomical, physical dynamics tend to apply the force, as its direction progressively descends, progressively higher along the cervical spine. 
     The logarithmic distraction force decompresses the spinal column and hence is a decompression force. Because changing the direction of the force changes which vertebrae are most exposed to the force, judicious selection of the starting height and ending height of the tensionometer-head  36  (and therefore the final direction of the force) allows a decompressive force to be selectively focused on different vertebral segments of the cervical or lumbar spine. This is in contrast to known tables which linearly apply a distraction force to the spine; with these known tables, the distracting force will be applied more or less evenly along the vertebral chain. In another mode of operation, table  10  may apply a logarithmic or linearly increasing uni-directional force by selecting a fixed vertical height of adjustable support  30 . 
     A suitable function for time versus tension for the logarithmic decompression phase is described in U.S. Pat. No. 6,039,737 issued Mar. 21, 2000, the contents of which are incorporated herein by reference. The same function may be used for the logarithmic tension retraction phase [0039] Turning to  FIG. 15 , where like parts have been given like reference numerals, vertebral decompression table  200  differs from the table  10  of  FIG. 1  in that linear actuator  22  and its arm  18  are omitted and the base  26  of vertically adjustable support  30  is joined directly to the moveable table section  14 . With this arrangement, linear actuator  16  is used to separate the table halves to establish and maintain a pre-tension and as well, linear actuator  16 , along with linear actuator  32 , operate, under control of controller  46 , to produce the logarithmic directionally changing forces hereinbefore described. 
     Turning to  FIG. 16 , where like parts have been given like reference numerals, a vertebral decompression table  300  differs from the table  10  of  FIG. 1  in two respects: firstly, linear actuator  22  and its arm  18  are omitted and, secondly, linear actuator  16  is provisioned with a reciprocating arm  318  which extends through the moveable table section  14  to join to the base  26  of vertically adjustable support  30 . With this arrangement, the controller  46  controls the linear actuator  16  to apply a pre-tension and then controls both linear actuator  16  and  32  to apply the aforedescribed logarithmic directionally changing forces. In doing so, moveable table section  14  may passively slide with the patient. With this embodiment, it would be possible to provide a table which has no moveable section, but this would have the drawback that the table would then frictionally engage the patient and distort the applied forces. 
     While the table has been described with linear actuators as drives, obviously any other controllable drive may be substituted as, for example, hydraulic cylinders and/or belt drives and/or pulleys. 
     While the retraction phase has been described as a logarithmic phase, alternatively, tension could be released linearly rather than logarithmically. 
     Other modifications will be apparent to those skilled in the art and, therefore, the invention is defined in the claims.