Abstract:
A method and apparatus for treating self treating internal muscle and trigger point related to pelvic pain in women and men. The apparatus includes a rod having a handle attached to a straight portion at a first end of the rod and a pressure applicator attached to a second end of the rod, where a first curved portion is disposed between the straight portion of the rod and the second end of the rod. In the method of the present invention, a trigger point is located in the patient&#39;s pelvic floor, the patient inserts the apparatus either vaginally or rectally to allow contact of the pressure applicator of the apparatus with the pelvic floor, and pressure is applied to the trigger point using the apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Patent Application No. 60/928,033, filed May 7, 2007. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to a method and apparatus for treating pelvic pain in women and men. 
       BACKGROUND OF THE INVENTION 
       [0003]    Pelvic pain has long been a problem among women and men. Conventional medicine has treated pelvic pain in various ways including, 1) an organ specific focus in which pelvic pain is believed to be a symptom of inflammation in the bladder, inflammation or infection in the prostate gland, or pathology of the uterus; 2) focus on the idea of the pudendal nerve being entrapped and needing release; 3) focus on an autoimmune process; 4) or focus supposed on psychiatric problems deriving from a fear of sexual activity, a propensity toward malingering, or neurotic somatization. While all of these treatments have failed to resolve the problem of pelvic pain, an example of one of these approaches is shown in U.S. Pat. No. 2,478,786, which shows a prostate gland massaging implement. In the field of urology, prostate massage derives from the goal of expelling the prostate fluid suspected of containing inflammatory or infectious pathogens, for treating urinary frequency, urgency, dysuria and other related symptoms of bacterial or inflammatory prostatitis. 
         [0004]    The approaches described above are based on a misunderstanding of the nature of most cases of pelvic pain commonly diagnosed as prostatitis. In recent years, evidence has emerged that a large majority of pelvic pain in men and women is related to muscle dysfunction and muscle related pain. Understanding most cases of prostatitis and pelvic pain as muscle related pain is an entirely new paradigm in urology. This new understanding sees chronic tension in the pelvic muscles producing trigger points, or taut bands within muscles either at the surface of the muscle, inside the muscle, in the belly or the attachment of the muscle. These trigger points are rather like mini-spasms in muscle that refer pain to remote sites, and when pressed routinely recreate a patient&#39;s symptoms. When pressed in a specific way these trigger points can release, often attended by a significant reduction or abatement in pain and dysfunction. Trigger points have been found to be strongly exacerbated with anxiety and other perpetuating factors. Trigger point release, particularly for trigger points located on the outside of the body has become a subspecialty within medicine. The inventor of the present invention, David Wise, Ph.D, along with his colleague and coauthor Rodney Anderson, M.D., professor of urology at Stanford University, previously described techniques for identifying and manipulating trigger points in their book  A Headache in the Pelvis: A New Understanding and Treatment for Prostatitis and Chronic Pelvic Pain Syndromes , which was originally published by the National Center for Pelvic Pain Research in 2003, and is incorporated herein in its entirety by reference. 
         [0005]    The research of Wise, Anderson and Sawyer has discovered that daily trigger point release along with other methods provides the most effective relief for pelvic pain. Many pelvic pain patients do not have access to professionals competent in internal trigger point release, are not able to afford the ongoing level of treatment, or are not able to find the time necessary to receive trigger point release. Thus, many patients have an urgent need for ongoing trigger point release related to pelvic pain that remains unmet due to the financial and time related problems existing in conventional professional treatment of internal trigger points and to the scarcity of internal trigger point practitioners. Previously known self-treatment apparatuses have proven ineffective for internal trigger point release because they were designed for other purposes and not for internal trigger point release. Previous apparatuses have not had the structural design to enable the patient to locate the often hard to find internal trigger points, nor have they provided any assistance in applying the appropriate pressure to release the trigger point and, importantly, at the same time to cause no bleeding tissue damage or perforation. 
         [0006]    Accordingly, need remains for a method and apparatus by which patients could treat their own internal trigger points, accessed either vaginally or rectally using trigger point release techniques, without need for a visit to a physician or therapist. 
       SUMMARY OF THE INVENTION 
       [0007]    In accordance with the invention, an apparatus and method for treating pelvic pain is provided. The apparatus includes a rod or wand having a handle attached to a straight portion at a first end of the wand and a pressure applicator attached to a second end of the wand, where a first curved portion is disposed between the straight portion of the wand and the second end of the wand. The first curved portion may be substantially semicircular, and may define an arc of approximately 180 degrees. 
         [0008]    In some embodiments, the apparatus includes a wand having a second curved portion disposed between the first curved portion and the second end of the wand. The second curved portion of the wand may form an angle between 45 to 90 degrees with respect to the first curved portion of the wand, and the first curved portion of the wand and the second curved portion of the wand may cooperate to define a reverse curve. 
         [0009]    In other embodiments, the apparatus includes a stop or platform that is adjustably disposed on the wand for adjustably restraining insertion of the pressure applicator into the body cavity. The stop includes a flange that is engageable with an external surface of the patient&#39;s body and a collar that is disposed on the wand. A positioning element may be provided on the collar of the stop, the positioning element moveable between an engaged position, where the positioning element engages the wand to restrain movement of the stop with respect to the wand, and a disengaged position, where the positioning element does not engage the wand and does not restrain movement of the stop with respect to the wand. Furthermore, the positioning element may have a threaded aperture formed through the collar and a set screw receivable within the threaded aperture for engagement with the wand. 
         [0010]    In some other embodiments, the apparatus may include a pressure sensor and a display electrically connected to the pressure sensor to display a pressure value. The pressure sensor may be disposed in the pressure applicator, or the pressure sensor may be disposed in the straight portion of the wand. 
         [0011]    In yet another embodiment, the pressure applicator is fabricated from an electrically conductive material, the wand fabricated from a non-electrically conductive material, and the apparatus includes an electrical stimulation unit electrically connected to the pressure applicator for supplying electrical current to the pressure applicator. 
         [0012]    In the method of the present invention, a trigger point is located in the patient&#39;s pelvic floor, with a lubricated glove or condom covering the distal end the patient inserts the apparatus either vaginally or rectally to allow contact of the pressure applicator of the apparatus with one or more trigger points located on the pelvic floor, and pressure is applied to the trigger point using the apparatus in order to release the trigger point. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    The description herein makes reference to the accompanying drawings, wherein like reference numerals refer to like parts throughout the several views, and wherein: 
           [0014]      FIG. 1  is an illustration showing a first embodiment of the apparatus for treating pelvic pain according to the invention; 
           [0015]      FIG. 2  is an illustration showing use of the first embodiment of the apparatus for treating pelvic pain according to the invention by a user; 
           [0016]      FIG. 3  is a partial cross section of the pelvis of the user showing engagement of the first embodiment of the apparatus for treating pelvic pain according to the invention with a myofascial trigger point; 
           [0017]      FIG. 4  is a side view of a second embodiment of the apparatus for treating pelvic pain according to the invention; 
           [0018]      FIG. 5  is a side view of a third embodiment of the apparatus for treating pelvic pain according to the invention; 
           [0019]      FIG. 6  is a side view of a fourth embodiment of the apparatus for treating pelvic pain according to the invention; 
           [0020]      FIG. 7  is a side view of a fifth embodiment of the apparatus for treating pelvic pain according to the invention; 
           [0021]      FIG. 8  is a side view of a sixth embodiment of the apparatus for treating pelvic pain according to the invention; and 
           [0022]      FIG. 9  is a side view of a seventh embodiment of the apparatus for treating pelvic pain according to the invention 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0023]    Referring to  FIGS. 1-3 , there is shown an apparatus  10  in accordance with a first embodiment of the invention. The apparatus  10  includes a substantially j-shaped rod or wand  12 , a handle member  14  connected to a first end of the wand  12 , and a pressure applicator  16  connected to a second end of the wand  12 . The handle member  14  and the pressure applicator  16  are connected to the wand  12  in any suitable conventional manner. The wand  12 , the handle member  14 , and the pressure applicator  16  may be fabricated from any suitable material, such as acrylic. 
         [0024]    The wand  12  is a continuous member that has a straight portion  18  that extends from the handle member  14  for approximately ten inches before reaching a semicircular portion  20 . The semicircular portion  20  defines an arc of approximately 180 degrees. However, it should be understood that the semicircular portion  20  need not be exactly semicircular, as long as it forms a generally u-shaped curve. The wand  12  may be either hollow or solid, as desired. The wand  12  is substantially slender member, having a diameter of for example, three eighths to one half of an inch, such that the diameter of the wand  12  is large enough to provide sufficient strength to the apparatus  10  to allow the user to apply pressure using the pressure applicator  16  without undue deformation of the apparatus  10 . Furthermore, this dimension is considered critical in that the diameter of the wand  12  must be small enough so that rectal insertion of the apparatus  10  does not induce defecation when the wand  12  is inserted rectally by a patient, and so that the uncomfortable sensation caused by insertion of the wand  12  does not overpower the patient&#39;s ability to sense engagement of the pressure applicator  16  of the apparatus  10  with a trigger point  3 . 
         [0025]    The pressure applicator  16  is a substantially spherical or semi-spherical member adapted for engagement with trigger points  3  in the pelvic floor  4 , as will be explained herein. The pressure applicator  16  is sized similarly to the tip of a human index finger (not shown), and is between nine-sixteenth of an inch in diameter and one and one-quarter inches in diameter. Preferably, the pressure applicator  16  is approximately eleven-sixteenths of an inch in diameter, which allows effective, safe pressure to be applied to the trigger point  3  to cause palpation of the trigger point. This range of dimensions is considered critical, in that pressure applicators  16  in larger sizes, such as one inch and seven-eights of an inch in diameter were tested, and found to be unsuitable, as these pressure applicators  16  did not allow sufficient pressure to be applied to trigger points, and made locating trigger points  3  difficult. Conversely, pressure applicators  16  in smaller sizes make palpating the trigger points  3  difficult, and can cause excessive pressure to be applied. Although shown and described herein as substantially spherical, it should be understood that the pressure applicator  16  could be provided in other, non-spherical shapes. 
         [0026]    The apparatus  10  is a device used for patient&#39;s self-treatment of pelvic pain to deactivate trigger points inside their own pelvic floor  4  by inserting the device vaginally or rectally. More particularly, the apparatus  10  of the first embodiment allows the user to access anterior trigger points (trigger points toward the front of the pelvic floor  4 , closer to the belly than the back) and perform ischemic compression (pressure that squeezes the blood out of what is being pressed) on anterior trigger points. It is meant to enable the user to do pressure release, strumming, stroking and other methods of trigger point release on these internal pelvic trigger points and areas of restriction, usually associated with pelvic floor  4  pain, urinary and defecatory dysfunction, on the muscles of the levator ani, coccygeus, pubococcygeus, obturator internus, piriformis and other internally accessed trigger points. The apparatus  10  may also be used to stretch restricted, shortened, chronically contracted internal pelvic muscle tissue so that it elongates and reduces in its pain, soreness and ability to refer these sensations. Trigger point release using the apparatus  10  involves finding the internal trigger point  3 , which is described in detail in the 4th edition of  A Headache in the Pelvis  and in Travell and Simon&#39;s book,  A Trigger Point Therapy Manual , holding it and pressing on it for a period of 30-90 seconds to release it and reduce it&#39;s ability to refer pain and symptoms to sites either remote from it or directly at the site of palpation. 
         [0027]    The trigger point release aims to free the muscles in and around the pelvis of active trigger points  3  and to restore the muscles of the pelvic floor  4  to a flexible and lengthened state. The phenomenon of trigger points was introduced into medicine by Travell and Simon who published the first edition of  Myofascial Pain and Dysfunction: The Trigger Point Manual  in 1983, which was followed by a second edition in 1992. These books were the culmination of research that went back to 1942 when Dr. Travell published her first article on myofascial pain. 
         [0028]    The concept of trigger points  3  is relatively new to medicine. Trigger points  3  are specifically defined herein as taut bands within a muscle, either at the surface of the muscle or inside the muscle, in the belly or at the attachment of the muscle. The trigger point  3  characteristically elicits a twitch response, detectable on ultrasound or via electromyograph (a machine that measures the electrical activity in a muscle in millionths of a volt), that can be felt by a trained practitioner while palpating the trigger point. When the trigger point is pressed there is often a ‘jump’ response in the patient, due to the reflexive reaction of the patient to the often exquisite tenderness of the trigger point upon palpation. Furthermore, the trigger point  3  characteristically refers pain/sensation to the site being pressed or to a site remote from it. 
         [0029]    A trigger point  3  can be active or latent. An active trigger point  3  is considered able to refer pain and recreate that pain upon palpation when the patient comes in with a complaint of pain. A latent trigger point  3  has the capacity to be the source of pain (i.e., has the capacity to become an active one) and under certain circumstances, becomes active but generally the patient does not complain of symptoms from latent trigger points. Trigger points  3  are latent in many people. Trigger points  3  refer pain directly on the trigger point  3  site or to a remote site, which means that where pain is felt is often not where it actually is coming from. For instance, testicular pain is often referred from trigger points in the quadratus lumborum. This is not obvious and is anti-intuitive. This trigger point  3  can be around 8-10 inches away from the site of the discomfort. The internal muscles that contain trigger points  3  are often close to each other. The relationship between symptoms and the location of associated trigger points  3  is mostly found in Travell and Simon&#39;s textbooks. 
         [0030]    Before using the apparatus  10 , the patient receives instruction on the use of the apparatus  10  by a qualified physician, osteopath, nurse, physical therapist or other designated professional. After receiving competent instruction, the user may use the apparatus  10  while sitting down on a toilet seat, in the lithotomy position lying down with the legs parted, a position commonly used in the gynecologist office when a doctor does a digital vaginal examination, or while the user lies on his or her side. The apparatus  10  is held in front of the patient&#39;s body, with the straight portion  18  of the wand  12  extending along the torso of the user&#39;s body, toward the user&#39;s head, and the pressure applicator is inserted, for example, through the rectal opening  5  and into the rectal cavity  6 . One of the user&#39;s hands  2   a  holds the handle  14  and pushes away from the user&#39;s body, while the other hand  2   b  holds the straight portion  18  of the wand  12  of the apparatus  10  near the semicircular portion  20  of the wand  12  and pulls it toward the body thereby exerting pressure on the pressure applicator  16  of the apparatus  10  at a level of pressure of 1-12 lbs as measured by the flexion of the straight rod at its tip as it engages the pelvic floor  4 , in order to access and palpate anterior trigger points  3 . A condom or rubber gloves are always placed over the tip of the apparatus  10  coming up 8-12 inches and sterile lubrication like KY Jelly® or Surgilube® is used to facilitate easy insertion and removal of the apparatus  10 . 
         [0031]    All of the internal trigger points  3  must be thoroughly evaluated and treated. When trigger points  3  are located, they are held with pressure release using the apparatus  10  which involves pressing on a trigger point  3  with constant pressure, usually for a period of 30-90 seconds. So that the patient may readily measure the elapsed time during trigger point release, the apparatus may include a timer (not shown) on the wand  12  or the handle member  14  of the apparatus  12 . 
         [0032]    Specific trigger points  3  in specific pelvic muscles tend to refer specific kinds of symptoms. For example, pain in the tip of the penis or the sense of urgency and frequency is typically created by active trigger points  3  in the anterior (front) portion of the levator ani muscle. When a patient uses the apparatus  10 , knowledge of the relationship between symptoms and pelvic trigger points  3  is essential to be able to use the wand properly and instructions in the use of the apparatus  10  are part of its proper use and appropriate prescription by a physician or designated health care professional. 
         [0033]    As shown in  FIG. 4 , an apparatus  110  according to a second embodiment of the invention includes all of the elements of the apparatus  10  of the first embodiment as well as an adjustable platform or stop  130  that is disposed on the wand  12 . The adjustable stop  130  serves to limit the depth to which the user of the apparatus  110  may insert the pressure applicator  16  into the vagina or rectum. 
         [0034]    This adjustable stop  130  allows the user to determine how far in to insert the wand  12  in order to accurately find and release internal pelvic floor  4  trigger points  3 . At first, the position of the adjustable stop  130  on the wand  12  is adjusted by a therapist who has mapped out the user&#39;s internal trigger points  3  and who is teaching the user how to locate, self-treat and release her or his own trigger points  3 . This is necessary since the locations of internal trigger points  3  are very difficult to discern, since patients are often incapable of accurately sensing the location of the pressure applicator  16  of the wand  12  once inserted. Thus, the user&#39;s doctor or therapist may determine the appropriate depth or depths at which the wand  12  needs to be inserted to access the trigger points  3  on which release will be performed by the patient. With the insertion depth fixed, the user may then identify the trigger point  3  location or locations more easily, since the range of motion of the pressure applicator  16  of the wand  12  is limited by engagement of the adjustable stop  130  with the exterior of the patient&#39;s body. Also, by using the adjustable stop  130 , the maximum depth of insertion of the wand  12  is limited, thereby reducing the risk of patient injury, such as tissue bleeding, damage or internal organ perforation. 
         [0035]    The adjustable stop  130  includes a flange  132  that extends radially outward from a collar  134  that is slidably disposed upon the wand  12 . The flange  132  lies substantially perpendicular to the longitudinal axis of the wand  12 , and is adapted to engage the exterior of the user&#39;s body to restrain the apparatus  110  against further insertion. The collar  134  is substantially tubular, and has an internal diameter complementary to the external diameter of the wand  12 . A positioning element  136 , such as a set screw, extends through a threaded aperture  138 . The positioning element  136  moves between an engaged position, where the positioning element  136  engages the wand  12  to restrain movement of the adjustable stop  230  with respect to the wand  12 , and a disengaged position, where the positioning element  136  does not engage the wand  12  and the adjustable stop  130  is not restrained from moving with respect to the wand  12 . Thus, when the positioning element  136  of the adjustable stop  130  is in the disengaged position, the adjustable stop  130  may be slid along the wand  12  to any desired location on the straight portion  18  or the semicircular portion  20  of the wand  12 . Then, when the adjustable stop  130  is in a desired position, the positioning element  136  may be moved to the engaged position to lock the adjustable stop  130  in the desired position. 
         [0036]    As shown in  FIG. 5 , an apparatus  210  according to a third embodiment of the invention includes a wand  212  having a primary curved portion  220  that is similar to the semicircular portion  20  of the apparatus  10  of the first embodiment, as well as a secondary curved portion  222  that is disposed between the primary curved portion  220  of the wand  212  and a pressure applicator  216 , that is similar to the pressure applicator  16  of the apparatus  10  of the first embodiment. The primary curved portion  220  forms a generally u-shaped curve, and may be substantially semicircular. The apparatus  210  also includes a handle  314  that is connected to a straight portion  218  of the wand  212 , which are similar to the handle  14  and straight portion  18  of the apparatus  10  of the first embodiment. 
         [0037]    The secondary curved portion  222  of the wand  212  is positioned along the wand so that it is disposed internally when the pressure applicator  216  is engaged with a trigger point  3 . The secondary curved portion forms an angle between 45 to 90 degrees with respect to the primary curved portion  220 , and the primary curved portion  220  and the secondary curved portion  222  may cooperate to define a reverse curve. 
         [0038]    By providing the secondary curved portion  222  on the wand  212 , the user may engage the pressure applicator  216  with posterior trigger points  3  (trigger points  3  located toward the back of the body, closer to the back than the belly), such as trigger points  3  on the coccygeus muscles, to perform ischemic compression, milking, or strumming of those trigger points  3 . 
         [0039]    As shown in  FIG. 6 , an apparatus  310  according to a fourth embodiment of the invention includes a pressure sensor (algometer)  322  that is disposed within a pressure applicator  316 . The wand  312 , the handle  314 , and the pressure applicator  316  are similar to the wand  12 , the handle  14 , and the pressure applicator  16  of the apparatus  10  of the first embodiment, respectively. 
         [0040]    The pressure sensor  322  may be any conventional sensor operable to output an electrical signal corresponding to a sensed pressure value, and thus the pressure sensor  322  is operable to detect the pressure applied to the trigger point  3  by the pressure applicator  316  of the wand. To provide information regarding the pressure applied by the pressure applicator  316  to the user, the pressure sensor  322  is electrically connected to a display  324  by a cable  326 . The display  324  is a conventional digital or analog device operable to display a measured value corresponding to the measurement made by the sensor  322 , and thus allows the pressure applied to by the pressure applicator  316  to be monitored by the patient during use of the apparatus  310 . The display  324  may be disposed external to the wand  312  and the handle  314  in a separate housing, and the cable  326  may extend through the wand  312  and out of the handle  314  to the display  324 . Alternatively, the display  324  may be disposed on the straight portion  318  of the wand  312  or on the handle  314 . Provision of the pressure sensor  322  and the display  324  allows the patient to apply the amount of pressure to the trigger point  3  prescribed by the patient&#39;s doctor or therapist, thereby facilitating effective, safe trigger point  3  release. 
         [0041]    As shown in  FIG. 7 , an apparatus  410  according to a fifth embodiment of the invention includes a flexible pressure sensor  422  that is disposed within a straight portion  418  of a wand  412 , adjacent to a handle  414 . The flexible pressure sensor  422  is, for example, a flexible bend sensor that produces a changing output signal, such as resistance, as the degree of bending of the sensor occurs. Thus, the flexible pressure sensor  422  is an elongated body that is disposed within or embedded within the handle  414 . The flexible pressure sensor  422  is electrically connected to a display  424  by a cable  426 , which are similar to the display  324  and cable  326  of the apparatus  310  of the fourth embodiment, respectively. During use of the apparatus  410 , the user places a first hand  2   a  on the handle  414  of the apparatus  410 , and a second hand  2   b  on the straight portion  418  of the wand  412 . Thus, when pressure is applied to the trigger point  3  using the pressure applicator  16  (not shown in  FIG. 7 ), a deflection is induced in the straight portion  418  of the wand  412 . This deflection is measured by the flexible pressure sensor  422  and, since it corresponds to the pressure applied by the pressure applicator  16 , is converted to a pressure reading and output on the display  424 . 
         [0042]    As shown in  FIG. 8 , an apparatus  510  according to a sixth embodiment of the invention includes an electrical stimulation unit  524 . The wand  512 , the handle  514 , and the pressure applicator  516  are similar to the wand  12 , the handle  14 , and the pressure applicator  16  of the apparatus  10  of the first embodiment, respectively. However, the wand  512  of the apparatus  510  is fabricated from a non-electrically conductive material, such as acrylic, while the pressure applicator  516  is fabricated from an electrically conductive material. The electrical stimulation unit  524  is disposed external to the wand  512  and the handle  514 , and is electrically connected to the pressure applicator  516  by a cable  522  that extends through the wand  512  and out of the handle  514 . The electrical stimulation unit  524  is a conventional unit that is adapted to provide electrical current for electrical stimulation of muscles. Thus, the pressure applicator  516  may apply both pressure and electrical stimulation to the trigger point  3  using the electrical stimulation unit  524 . 
         [0043]    As shown in  FIG. 9 , an apparatus  610  according to a seventh embodiment of the invention includes a removable pressure applicator  616 . The wand  512 , the handle  514 , and the pressure applicator  516  are similar to the wand  12 , the handle  14 , and the pressure applicator  16  of the apparatus  10  of the first embodiment, respectively. However, a threaded portion  622  is provided at the distal end of the curved portion  620  of the wand  612 , and a threaded recess  624  is provided on the pressure applicator  616 . Thus the pressure applicator  616  may be threadedly connected and disconnected from the wand  612 . By providing a selectively detachable pressure applicator  616 , a plurality of pressure applicators  616  may be provided having various diameters ranging between nine-sixteenth of one inch in diameter and one and one-quarter inches in diameter. Thus, the patient may utilize the apparatus with a larger diameter pressure applicator  616  when the trigger point  3  is near the surface, and may utilize a smaller diameter pressure applicator  616  when the trigger point  3  is located deep within the patient&#39;s muscles. 
         [0044]    Use of the apparatuses of the second through seventh embodiments is performed in substantially the same manner as described in connection with the first embodiment. Of course, it should be understood that the features of the above embodiments may be combined. For example, an apparatus could be provided having the adjustable stop  130  according to the second embodiment, the primary curved portion  220  and the secondary curved portion  222  as demonstrated in the third embodiment, as well as the flexible pressure sensor  422  and the display  424  of the fourth embodiment. 
         [0045]    While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiments, but to the contrary, it is intended to cover various modifications or equivalent arrangements included within the spirit and scope of the appended claims. The scope is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures as is permitted under the law.