Abstract:
An improved chiropractic adjusting instrument is provided for use in spinal manipulative therapy and for exciting a human spine at preselected resettable frequencies within the range of its natural frequency. The improvement comprises providing a repositionable and resettable shaped mass adjacent to the thrust element; a longitudinally shiftable and rotatable sleeve portion on the shaped mass enables setting the frequency to a predetermined number of preselected settings that are easily and positively fixed so that inadvertent changes in frequency will not occur in use.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to the chiropractic adjustment of musculoskeletal structures, and more particularly concerns an improved chiropractic adjusting instrument for use in spinal manipulative therapy. The present invention is a further refinement of the improved instrument described and claimed in U.S. Pat. No. 5,626,615, issued May 6, 1997 of which applicant of the present invention is a co-inventor. 
     2. Description of the Prior Art 
     The chiropractic art is generally concerned with adjusting misaligned body structures by manually manipulating the various joints in the human body. Of more specific interest in the art, however, is the spinal column which is comprised of several interconnected musculoskeletal structures or vertebrae. Unlike other, less critical body structures, the spinal column must be treated or manipulated with extreme caution because of its link with the central nervous system. 
     The human spine is susceptible to many different pathologic abnormalities including misalignment, miscellaneous trauma and pain, and degeneration as a result of age or disease. By employing various physical therapy techniques, though, a chiropractor, or one skilled in the chiropractic art, one may be able to successfully treat a pathologic spine. Successful treatment will not only relieve any pain or discomfort that the patient might be suffering, but will also improve the overall quality of life of that patient. 
     One common spinal-adjustment technique involves applying thrusts or forces to the afflicted region of the spine. In particular, this technique involves either “mobilizing” the spine (i.e. passively moving the spine with relatively slow cyclic or oscillatory motion), or “manipulating” the spine (i.e. applying an impulsive thrust or force in a well-defined direction to a specific region of the spine). Depending on professional affiliations, this technique is referred to as chiropractic adjustment, osteopathic manipulation, orthopedic manual therapy, and/or spinal manipulative therapy. 
     There are several well known procedures or techniques for “manipulating” or administering impulsive thrusts to a spine. One technique involves applying one or more rapid thumb thrusts to misaligned or afflicted vertebrae. Thumb thrusts, however, tend to be both imprecise in magnitude and location and tiresome to administer. Another technique involves using a manually operated chiropractic adjusting instrument. For instance, U.S. Pat. No. 4,116,235, issued to Fuhr et al. (“Fuhr”) and U.S. Pat. No. 4,498,464, issued to Morgan, Jr., disclose such instruments. 
     The Fuhr device, in particular, is a manually operated, spring-loaded device for delivering an impact force or thrust to a patient&#39;s spine at a rapid speed and in a precise line of drive. Further, although the magnitude of the impact force delivered by the Fuhr device is adjustable, the frequency at which the impact force is delivered is completely arbitrary. As such, the Fuhr device is not mechanically “tuned” to any particular frequency. 
     The ability to “tune” a chiropractic adjusting instrument to a desired frequency, though, offers the chiropractic clinician several significant advantages over the prior art. For instance, a chiropractic adjusting instrument that is “tuned” or “tunable” to the natural frequency of a human spine maximizes the dynamic motion response of the spine while, at the same time, minimize the magnitude of the requisite impact force. Such a chiropractic adjusting instrument not only enhances the overall effectiveness of spinal manipulative therapy, but would also decrease the possibility of damage to the vertebrae during such treatment. The instrument described and claimed in U.S. Pat. No. 5,626,615 does provide such an instrument which is “tunable” within a broad range of frequencies. As a practical matter, however, it is desirable to have an instrument which may be easily set or settable to the most commonly used and effective frequencies. 
     OBJECTS AND SUMMARY OF THE INVENTION 
     The primary object of the present invention is to provide an improved chiropractic adjusting instrument which is “tunable” to and settable to a preselected number of desired frequencies within the optional range of natural frequency. 
     A more specific object of the present invention is to provide an improved chiropractic adjusting instrument which is “tunable” or settable to the natural frequency of a musculoskeletal structure and may be easily resettable to a selected number of frequencies with a range of suitable frequencies. 
     An even more specific object of the present invention is to provide an improved chiropractic adjusting instrument which is “tunable” to the natural frequency of a human spine or a selected number of different frequencies or a range of thrusts. 
     Another object of the present invention is to provide an improved chiropractic adjusting instrument of the foregoing type which is reliable, precise, and convenient to use and readily and reliably resettable. 
     These and other features and advantages of the invention will become apparent upon reading the following description of a preferred exemplified embodiment of the invention, and upon reference to the accompanying drawings wherein: 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side view of an improved chiropractic adjusting instrument according to the present invention having a shaped mass set in one of a selectable number of desired frequencies; 
     FIG. 2 is a side view of the improved chiropractic adjusting instrument having a shaped mass which has a plurality of settings that mechanically tunes the instrument to a desired frequency or amount of thrust; 
     FIG. 3 is a cross-sectional view of the chiropractic adjusting instrument shaped mass portion taken along line  3 — 3  in FIG. 1; 
     FIG. 4 is a cross-sectional view of the improved chiropractic adjusting instrument shaped mass portion taken along line  4 — 4  in FIG. 2; and 
     FIG. 5 is an exploded parts drawing of the shaped mass portion of the instrument. 
    
    
     While the invention will be described and disclosed in connection with certain preferred embodiment and procedures, it is not intended to limit the invention to the specific embodiment. Rather it is intended to cover all such alternative embodiments and modifications as fall within the spirit and scope of the appended claims. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to the drawing FIGS. 1 and 2, the instrument as disclosed in U.S. Pat. No. 5,626,615 is a manually operated chiropractic posterior-anterior adjusting instrument  10 . It broadly comprises thrust element  20 , a shaped mass thrust portion  25 , a removable body contact  28 , a main body  30 , an end cap  35 , a first handle member  40 , and a second handle member  45 . Internally (not shown), a spring means propels the body thrust element outwardly; and a trigger means actuates the spring means to impart a thrust to the thrust element  20 . 
     The device  10  also incorporates a calibration means for controlling the amount that the shank portion of the thrust element  20  retracts within the main body  30  when the first and second handle portions  40 ,  45  are squeezed together, for controlling the amount of potential energy imposed on the spring means, and, more particularly, for adjusting the amplitude of the input force delivered to the musculoskeletal structure. 
     In accordance with certain objects of the present invention, the device has been improved such that the input force delivered by the chiropractic adjusting instrument  10  is now “tuned” or is “tunable” to the natural frequency of the musculoskeletal structure being examined and resettable to a number of preselected alternatives which are commonly useable for chiropractic adjustments. These objects are achieved by altering the amount of thrust delivered from the trigger mechanism to the thrust element. 
     A preferred embodiment of a mechanically tuned chiropractic adjusting instrument  10  is illustrated in FIG.  2 . In particular, this embodiment generally comprises a shaped mass generally  25  positioned on the thrust element  20  and disposed between the main body  30  and the removable body contact member  28 . In the illustrated embodiment, the shaped mass  25  is a multi-part arrangement with a frustoconical shaped collar  26 , an elongated sleeve  27  and tightening collar  29 , as shown in FIGS. 3 and 4. It will be readily apparent to those skilled in the art, however, that the shaped mass  25  could be positioned on the thrust element  20  in other ways. 
     As best shown in FIGS. 3 and 4, the shaped mass  25  has collar  26  fixed to the body  30  by a set screw  31  and the sleeve portion  27  has an upper cylindrical portion and a lower portion that tapers inwardly from the sleeve cylindrical portion. Moreover, the shaped mass  25  is arranged on the thrust element  20  such that the sleeve portion  26  faces the first handle member  40  while the generally conical portion  27  faces the removable body contact member  28 . It will be appreciated, however, that both the configuration and the orientation of the shaped mass  25  could be modified from the specific embodiment disclosed herein. 
     In keeping with an important aspect of the present invention, the preferred embodiment of the chiropractic adjusting instrument  10  is mechanically tuned to the natural frequency of most human spinal columns. More importantly, though, the frequency at which the chiropractic adjustment instrument  10  is mechanically tuned to can be adjusted—between a range of about 1 hertz to about 60 hertz—simply by moving the sleeve portion  27  downwardly with respect to collar  26  and rotating the sleeve to one of a number of preselected positions radially, and then moving the sleeve  27  upwardly to lock it in another position relative to the collar  26 . In addition, once the chiropractic adjusting instrument  10  is “tuned” to the natural frequency of a particular spine at one of the preselected positions, the spine can then be excited at its natural frequency. Thus, in spinal manipulative therapy, the dynamic output response of the spine is maximized while the magnitude of the impact force delivered to the spine is minimized. This not only increases the overall effectiveness of spinal manipulative therapy but also significantly reduces the risk of vertebrae damage. 
     As shown in FIGS. 3 and 5, the thrust member  20  threadably attaches to a plunger member  32  and with an intermediate spring  33  is held in place by lower collar  29  that threadably attaches to sleeve  27 . The arrangement is such that the thrust member is pre-spring loaded so it must be pushed inwardly against a surface or body to position the upper head of the plunger  32  where it will be struck by piston  35  that receives the thrust from the trigger means within the body down through the trigger rod  37  when the handles are squeezed together. The trigger rod  37  is threadably attached to the upper threaded portion of piston  35  and a cushioning spring  38  is provided where the assembly is held by barrel  39  that is fixedly held by sleeve  27 . The threaded portion  40  of barrel  39  receives the internal threaded end of the main body  30  and rotation of the sleeve when in its pulled down position (FIG. 4) allows the mass  25  to be radially repositioned through piston  41  that acts through barrel  39 . A pin  42  on the sleeve  27  (FIGS. 2 and 5) allows the sleeve to be positioned in a preselected number of preselected radial positions with respect to collar  26 . In the present instance positions  1 - 3  have been shown where the instrument may be tuned to three different thrust frequencies. It will be appreciated that more or less of such positions may be provided. Preferably, the positions do provide the most common thrust frequencies used in a typical chiropractic practice. Since the sleeve  27  does “lock” into place at each of the selected positions, it is not apt to be rotated inadvertently thereby insuring a delivery of the same thrust frequency for a setting until it is intentionally reset. 
     In accordance with another feature of the invention, an O-ring resilient member  34  (FIG. 5) is seated on the top of plunger  32  so striking by the piston  35  is lightly cushioned and quieter in operation, thereby avoiding a metal to metal contact and its attendant sound.