Abstract:
A stylus and a treatment head for use with a medical device for imparting a force is provided. The stylus allows a practitioner to maintain focus on the treatment location while adjusting placement and force. This is because a light signal is emitted in the vicinity of the distal end of the stylus, proximate the treatment location on the patient. Alternatively, an audible or a tactile signal is employed for feedback. As a safety feature, the stylus is provided with means to allow it to collapse at forces above the accept able limit.

Description:
TECHNICAL FIELD 
       [0001]    The technology relates to a stylus and treatment head for use with a medical device that imparts a force on a patient. More specifically, the technology is a stylus having a point-of-treatment visual output to inform a practitioner of the force imparted through the stylus. 
       BACKGROUND ART 
       [0002]    Numerous medical devices are provided with means to illuminate the working area and the relevant sections of the device. For example, US Publication Number 20060217596 discloses illuminated surgical retractors including at least one retractor blade and a light delivery system. The light delivery system may include an array of lights which may be attached directly to the retractor blade or to a support in the shape of an elongated blade that extends along the length of the retractor blade for illuminating all or a portion of the length of the retractor blade. In one embodiment the light delivery system is in the form of a light rod which emits light at a distal end. 
         [0003]    U.S. Pat. No. 6,739,744 discloses a lighting device that includes an optic light guide having a free end that emits directional light. Surrounding the free end is a sleeve having an aperture through which a beam of light emitted by the free end of the light guide passes. The sleeve may be moved in and out relative to the free end to vary the size of the beam of light passing through the aperture. 
         [0004]    U.S. Pat. No. 6,304,712 discloses a bendable medical, dental and surgical illuminating appliance that includes a light-conducting rod, at least a portion of which is light projecting. The rod is flexible and comprises a self-sustaining shape. The rod also includes a light inlet that is operably engaged with the outlet of a fiberoptic conductor. 
         [0005]    With regard to force sensors, U.S. Pat. No. 7,714,239 discloses a mechanical force switch to be disposed along a longitudinal device axis of a medical device that includes an electrically conductive switching piston to form a first electrical contact of the switch, a hollow body, an end stop, a bias device, and an electrically conductive second contact of the switch electrically insulated from the piston. The piston is movably disposed in the body hollow along the axis to define different switch-making and -breaking positions. The bias device surrounds the piston and imparts bias against it to retain it in one of the two positions until an external axis force overcomes the bias, at which time the switch indicates a state changeover. The switch can be normally open or closed. Electrically coupled to the switch is an indicator light which illuminates in response to one of the two positions, either opened or closed. It is also contemplated that if the force switch is provided with a strain gauge, also referred to as a load cell, then a continuous force output can be displayed to the user in which, for example, a row of light emitting diodes (LEDs) gradually light up dependent upon the amount of force or an LCD or LED numerical field increments numerical values corresponding to the amount of force imparted through the force switch. 
         [0006]    With regard to an applicator having multiple probes or contact points, U.S. Pat. No. 6,585,668 discloses a massage head comprising robot massage hands that are distinctly anthropomorphic. Each robot massage hand comprises an articulated thumb and three articulated fingers, in accordance with a preferred embodiment of the present invention. Robot massage hands can perform finer and more varies motions than robot massage hands. For example, robot massage hands can perform pinching and grasping motions substantially more similar to pinching and grasping motions performed by the human hand than pinching and grasping motions performed by robot massage hands. 
         [0007]    Similarly, U.S. Pat. No. 6,200,282 discloses a machine that comprises a massage unit having a first therapeutic finger for giving tapping massage to the upper part or the upper to frontal part of the shoulder of the user, and a second therapeutic finger for giving tapping massage to the back or the back to the posterior part of the shoulder. The fingers each have a portion to be brought into contact with the user at the forward end of an arm. The arms are pivotally movable independently of each other by respective finger drive means. U.S. Pat. No. 6,190,339 also discloses a massage machine. In this case, the massage device has first and second massage members. The first massage member performs a circulating motion including (i) a massage zone where the member approaches the second massage member in a locus which swells in an outward direction as seen from a massage arm; and (ii) a release zone where the member separates from the second massage member in a locus which is shorter than the massage zone. The second massage member performs a reciprocal rocking motion in synchronization with the first massage member. 
         [0008]    While the foregoing examples all attempt to mimic the motion of a human hand giving a massage, other devices simply have multiple probes that provide a repetitive force. In this regard, U.S. Pat. No. 5,447,491 is exemplary. It discloses an anticellulitis massaging device comprising a plurality of massaging elements or fingers located within a body member or casing and susceptible of axial percussion movements and oscillating and/or rotating movements, which are controlled by a motor assembly and via cam actuating means. 
       DISCLOSURE OF INVENTION 
     Technical Problem 
       [0009]    Controlling and monitoring force exerted on a patient during treatment 
       Technical Solution 
       [0010]    When applying a force to a patient, it is important to ensure that the force is within the prescribed limits. As the force applied is often controlled by the relative position of the device and this is often electronically controlled, one can see how easy it would be to position the device such that the force is outside of the desired range. Ideally, therefore, a practitioner would be able to receive feedback with regard to the force being exerted during the positioning step and would not have to shift their gaze between the treatment location and a remote output in order to do so. The present technology provides a stylus that allows a practitioner to focus on the treatment location while positioning the stylus on the patient and adjusting the force. One way to achieve this goal is to have an indicator proximate to the treatment location. Light pipes, fibre optics and lights located at the distal end of the stylus all permit the practitioner to receive feedback in the form of a light signal without removing their gaze from the vicinity of the area to be treated. An alternative approach is to provide the stylus with an audible signal. Yet another approach is a tactile signal, for example, a vibration. These signals identify when the stylus load is too low, is in the appropriate range, and when it is too high, whether in compression or tension. An additional use of the technology is as a measure of tension or compression in relation to preset values. 
         [0011]    In the preferred embodiment, the stylus is a light pipe. At least the tip, which is located at the distal end, scatters light, and therefore is readily visible to the practitioner at the treatment location or very close to the treatment location, regardless of the viewing angle. By using light emitting diodes controlled by a Red Green Blue (RGB) controller, the colour injected into the light pipe switches from blue, which is associated with forces below the desired range, to green, which is associated with forces within the desired range, to red, which is associated with forces greater than acceptable range. The stylus has a load cell at a proximal end that measures the force exerted during treatment. If the load exceeds the acceptable limits, mechanical features in the stylus assembly collapse, thereby preventing excess force from being applied through the stylus. Preferably, this is at a force much higher than the limits used for treatment, in other words, much higher than a force that causes the light to be red. 
         [0012]    In an alternative embodiment, a treatment head for use in medical applications is provided wherein force is applied at a treatment location. The treatment head comprises: 
         [0013]    A treatment head for use in medical applications wherein force is applied at a treatment location, the treatment head comprising: 
         [0014]    i) a distal end; 
         [0015]    ii) a proximal end, the proximal end having a strain gauge; 
         [0016]    iii) a shaft between the distal end and the proximal end, the shaft comprising a rod, an inner sleeve for retaining the rod, an outer sleeve and means for generating a magnetic field therebetween, such that in use, the inner sleeve and outer sleeve are releasably attached to one another until a force limit is reached, at which force, the magnetic field is broken resulting in collapse of the treatment head; 
         [0017]    iv) an applicator located on the rod, the applicator comprising: an at least one tip, the tip being adjustable distally, proximally and orthogonally in relation to the shaft of the rod; and 
         [0018]    v) a signaler in electrical communication with the strain gauge. 
         [0019]    Preferably the rod is a light pipe and the signaler is a light source and a light controller, such that in use, a light signal is emitted in the vicinity of the treatment location in response to a predefined force or a range of predefined forces. 
         [0020]    It is advantageous that the applicator comprises at least two tips and the treatment head is configured to provide the same force at each tip. 
         [0021]    Uses of the stylus and treatment head in force imparting devices are also provided. These devices are preferably medical devices. 
     
    
     
       ADVANTAGEOUS EFFECTS 
       Description of Drawings 
         [0022]      FIG. 1  is a longitudinal mid-section view of the stylus of the present technology. 
           [0023]      FIGS. 2 and 2   a  are longitudinal mid-section views of the shaft of the present technology wherein  FIG. 2  shows the placement of the magnets or magnet and magnetic material for compression and  FIG. 2   a  shows the placement of the magnets for tension. 
           [0024]      FIG. 3  is a longitudinal view of an embodiment of the technology of  FIG. 1 . 
           [0025]      FIG. 4  is a longitudinal mid-section view of an alternative embodiment of the technology of  FIG. 1 . 
           [0026]      FIG. 5  is a longitudinal view of an alternative embodiment of the technology of  FIG. 1 . 
           [0027]      FIG. 6  is an exploded longitudinal view of the tip and distal end of the stylus of  FIG. 1 . 
           [0028]      FIG. 7  is an exploded longitudinal view of an alternative embodiment of the tip. 
           [0029]      FIG. 8  is a longitudinal mid-section view of the treatment head of the present technology. 
           [0030]      FIG. 9  is a longitudinal mid-section view of the shaft of the present technology showing the placement of the magnets or magnet and magnetic material. 
           [0031]      FIG. 10  is a perspective view of a tip in the applicator indicating directions of movement for adjustment. 
           [0032]      FIG. 11  is a longitudinal mid-section view of the applicator with a cover. 
           [0033]      FIG. 12  is a perspective view of an alternative embodiment of the technology of  FIG. 11 . 
           [0034]      FIG. 13  is a longitudinal mid-section view of an alternative embodiment of  FIG. 8 . 
       
    
    
     MODE FOR INVENTION 
     Definitions 
       [0035]    Resistant in the context of the present technology is meant to mean any material that is capable of transferring a force axially. 
         [0036]    Light transmitting material in the context of the present technology is meant to mean a transparent or translucent material. 
         [0037]    Resilient in the context of the present technology is meant to mean any material that is able to be repeatedly deformed and returned to its original form. 
         [0038]    Treatment location in the context of the present technology is meant to mean at or in the vicinity of the location on a patient being treated. 
         [0039]    Signaler in the context of the present technology produces at least one of a tactile, audible or visual signal. 
       DETAILED DESCRIPTION 
       [0040]    As shown in  FIG. 1 , a stylus for imparting a force or measuring a force on a patient is generally referred to as  10 . The stylus  10  is for use with a medical device for imparting a force, either tensile or compressive. The stylus  10  has a tip  14  at a distal end  16 , a strain gauge  18  at a proximal end  20  and a shaft  12  therebetween. The contact area of each tip  114  is preferably about 0.8 cm in diameter to about 1.2 cm in diameter, more preferably about 0.9 cm in diameter to about 1.1 cm in diameter and most preferably 1 cm in diameter. The strain gauge  18  is in electrical communication with a controller  22  and a light controller  24 , the light controller  24  being in electrical communication with a light source  26 . The strain gauge  18  is preferably a load cell. The light source  26  is preferably a light emitting diode (LED) light source. The LED light source is preferably an RGB LED with independent inputs for generating red, green, and blue light. 
         [0041]    As shown in  FIGS. 2 and 2   a , the shaft  12  consists of an inner sleeve  13 , an outer sleeve  15  and a rod  17 . The rod  17  is attached to the inner sleeve  13 , for example by a friction fit, using a pair of positioning screws  19 . The inner sleeve  13  and the outer sleeve  15  are releasably held to one another by electromagnets  21 . As shown in  FIG. 2 , perimeter magnets  21  are located on the inner surface  23  of the outer sleeve  15  and in the vicinity of the end  25  of the inner sleeve  13  when the device is used for compressive forces. Magnets  21  are also located on the inner sleeve  13  in the vicinity of the end  25 . As shown in  FIG. 2   a , when used in tension, the perimeter magnets  21  are located on the inner surface  23  of the outer sleeve  15  distal to the end  25  of the inner sleeve  13 . Magnets  21  are also located on the inner sleeve  13  in the vicinity of the end  25 . A sensor  27  provides electronic feedback to signal when the magnetic connection is broken. 
         [0042]    The rod  17  is resistant and light transmitting. In one embodiment it is preferably an acrylic rod that functions as a light pipe. The rod  17  is preferably provided with light scattering segments  30  as shown in  FIG. 3 . In the preferred embodiment, the light scattering segments  30  are facets that provide rings of light spaced along the rod  17 . Light scattering may be provided by etching or by machining or other methods as would be known to one skilled in the art. The tip  14  also preferably scatters light. The tip  14  is preferably releasable to allow for it to be replaced between patients. If the tip  14  is used to impart a force, it is preferably a resilient or resistant material, and may be translucent in and of itself, without further treatment, such as etching. The tip may further be provided with protrusions  28 , dimpling or other surface contouring. If additional strength is required, a slave  32  is placed in parallel with the shaft  12 , either as a core as shown in  FIG. 1  or directly adjacent, as shown in  FIG. 3 . 
         [0043]    As shown in  FIG. 4 , in another embodiment, the rod  17  is a fibre optic conductor  34  encased in a resistant housing  36 . The tip  14 , which preferably releasable, fits over the distal end  16 , and scatters light. If the tip  14  is used to impart a force, it is preferably a resilient material, and may be translucent in of itself, without further treatment, such as etching. 
         [0044]    In another embodiment, the stylus  10  is provided with a light source  26  in the vicinity of the distal end  16 , as shown in  FIG. 5 . The light source  26  is in electrical communication with the light controller  24  and a resistant housing  36  is employed that functions as the rod  17 . 
         [0045]    The tip  14  may be configured to provide tension. In this mode, a releasable locking mechanism  38  retains the tip  14  on the stylus  10 , as shown in  FIG. 6 . This may be any mating pair, such as, but not limited to, a threaded pair, or a key and keyway. The tip  14  is provided with a grip  40  as shown in  FIG. 6 . In alternative embodiments, the grip can be replaced with a loop  42  or tether as shown in  FIG. 7 . When the stylus  10  is used to produce tension, the stylus  10  need not be resistant. Therefore, for example, a bendable housing can be used with fibre optic conductor or electrical cord. Similarly, a bendable, light transmitting polymeric material can be used as the light pipe. Further, the load cell can be configured to measure tension and compression alternately; in other words, the device could measure tension and compression without any changes to hardware. In this case, the light assignments could be changed to reveal polarity of stylus force (blue for compression, red for tension, green for neither, for example, but not limited to) with either light intensity or hue (obtained by colour intensity mixing) corresponding to magnitude. For this case, a combination of the two collapse mechanisms can be used to ensure forces beyond compressive or tensile limits for an application are not exceeded. 
         [0046]    Note too that intensity could be relayed to the operator by flash rate of the LEDs. Humans can generally detect flicker rates up to about 20 Hz, so, for example, but not limited to, DC (steady output) might indicate no applied force; 1 Hz (one flash per second) might indicate 10% of limit, 2 Hz 20%, and so forth, in either direction as indicated by light colour. 
         [0047]    When used with a medical apparatus for imparting a compressive force, the stylus  10  collapses at a force commensurate with an upper limit. The stylus  10  collapses as follows: When the force exceeds the acceptable limit, the magnets  21  are forced apart. Once the magnetic connection (magnetic field) has been broken, the inner sleeve  13  and the outer sleeve  15  lose compliance with one another and are free to move independently. As the magnetic field decreases at a strength that is the square of distance, once the field is broken, the two sleeves  13 ,  15  telescope readily in response to the force. An electronic feedback then can signal to stop movement of the device and further, can signal to retract the device away from the patient, and further, indicate to the controller and ultimately the operator that the maximum force limit was reached. If the stylus  10  is used for impulse treatment, the electronic feedback can also signal to stop the movement of the stylus  10 . The load cell  18  provides an additional feedback to assist in keeping the operating conditions within the acceptable working range. In one example the working range, when the compressive force is for application to bone, will be less than about 5 pounds, more preferably less than about 4 pounds and most preferably less than about 2.5 pounds (about 22 N, about 18 N and about 11 N, respectively) and the upper limit will be about 5 pounds, more preferably about 4 pounds and still more preferably about 3 pounds. When used with a medical device to measure compressive force, the stylus  10  need not be set to collapse at a force commensurate with an upper limit, however, it is preferable to do so. Similarly, when used with a medical device for imparting tension, the stylus  10  is set to collapse at a force commensurate with an upper limit. When used with a medical device to measure tension, the stylus  10  need not be set to collapse at a force commensurate with an upper limit, however, it is preferable to do so. 
         [0048]    The LED light source  26  is preferably controlled by a red green blue (RGB) LED light controller  24  or any other additive light controller  24 . This allows for a variety of colours, modes and intensities as the light signal. 
         [0049]    When used in the compressive force mode, the upper limit is set and the stylus  10  is located on the patient as needed. The force to be applied is controlled by the controller  22 . As the practitioner increases the force, the LED light source  26  emits light to indicate the force level. In one embodiment, the light signal is a flashing signal having a decreasing or increasing period, with either ‘on’, ‘flashing’ or ‘off’ indicating the working load. In another embodiment, light intensity is used to indicate the load. In another embodiment the colour is used to indicate the load. In yet another embodiment, any combination of light intensity, colour, or pulse can be indicative of the force. Should the force exceed the set upper limit, the stylus  10  collapses. Preferably, collapse of the stylus  10  triggers the controller  22  to retract the medical device, thereby retracting the stylus  10  from the patient. 
         [0050]    When used to measure a compressive force, the upper limit is set and the stylus  10  is located on the patient as needed. The force to be applied is controlled by the patient and measured by the load cell. As the force increases, the LED light source  26  emits light to indicate the force level. In one embodiment, the light signal is a flashing signal having a decreasing or increasing period, with either ‘on’, ‘flashing’ or ‘off’ indicating the working load range. In another embodiment, light intensity is used to indicate the load. In another embodiment the colour is used to indicate the load. The light emitted is preferably blue at low force, green at an acceptable predetermined force or range of predetermined forces, and red at any force above the acceptable range. For example, for the treatment of cervical vertebrae, blue light will be emitted when the force is less than about 4 ounces (1.11 N) and more preferably less than about 2 or 3 ounces (0.556 N or 0.834 N) and most preferably less than about 1 ounce (0.278 N). Green light will be emitted when the force is between about 4 and 6 ounces (1.11 N and 1.668 N), more preferably between about 2 or 3 ounces (0.556 N or 0.834 N) and 5 ounces (1.39 N) and most preferably between about 1 and 3 ounces (0.278 N and 0.834 N). Red light will be emitted when the force is more than about 6 ounces (1.668 N, more preferably more than about 5 ounces (1.39 N) and most preferably more than about 3 ounces (0.834 N). In yet another embodiment, any combination of light intensity, colour, or pulse can be indicative of the force. Should the force exceed the set upper limit, the stylus  10  collapses. 
         [0051]    When used in the tension mode, the upper limit is set and the tip is releasably attached to the patient as needed. The force to be applied is controlled by the controller  22 . As the practitioner increases the force, the LED light source  26  emits light to indicate the force level. In one embodiment, the light signal is a flashing signal having a decreasing or increasing period, with either ‘on’, ‘flashing’ or ‘off’ indicating the working load. In another embodiment, light intensity is used to indicate the load. In another embodiment the colour is used to indicate the load. In yet another embodiment, any combination of light intensity, colour, or pulse can be indicative of the force. Should the force exceed the set upper limit, the stylus  10  collapses. 
         [0052]    When used to measure tension, the upper limit on the load cell  18  is set and the tip is releasably attached to patient as needed. The force to be applied is controlled by the patient and measured by the load cell. As the patient increases the force, the LED light source  26  emits light to indicate the force level. In one embodiment, the light signal is a flashing signal having a decreasing or increasing period, with either ‘on’, ‘flashing’ or ‘off’ indicating the working load. In another embodiment, light intensity is used to indicate the load. In another embodiment the colour is used to indicate the load. In yet another embodiment, any combination of light intensity, colour, or pulse can be indicative of the force. Should the force exceed the set upper limit, the stylus  10  collapses. 
         [0053]    In an alternative embodiment, there is an audio feedback using a speaker, such as a piezoelectric speaker, in communication with the load cell. This allows for the practitioner to remain focused on the treatment location without having to check outputs remote to the patient. It also addresses the case where the practitioner is colour-blind, or blind altogether. 
         [0054]    In another alternative embodiment, there is a tactile feedback whereby vibration is used to indicate the force and therefore a vibrator is in communication with the load cell. Again this allows the practitioner to remain focused on the treatment location without having to check outputs remote from the patient. The vibration may also be detected as an audible signal. 
         [0055]    In yet another embodiment as shown in  FIG. 8 , a head for imparting a force at more than one point on a patient is generally referred to as  110 . The head  110  is for use with a medical device for imparting a force, either tensile or compressive. The head  110  has from two to five tips (contact points)  114  at a distal end  116 , a strain gauge  118  at a proximal end  120  and a shaft  112  therebetween. The contact area of each tip  114  is preferably about 0.8 cm in diameter to about 1.2 cm in diameter, more preferably about 0.9 cm in diameter to about 1.1 cm in diameter and most preferably 1 cm in diameter. The strain gauge  118  is in electrical communication with a controller  122  and optionally a light controller  124 , the light controller  124  being in electrical communication with a light source  126 . The strain gauge  118  is preferably a load cell. The optional light source  126  is preferably a light emitting diode (LED) light source. The LED light source is preferably an RGB LED with independent inputs for generating red, green, and blue light. For two tips  114 , blue light will be emitted when the force is less than about 8 ounces (2.22 N) and more preferably less than about 4 or 6 ounces (1.22N or 1.668N) and most preferably less than about 2 ounces (0.556 N). Green light will be emitted when the force is between about 8 and 12 ounces (2.22 N and 3.336 N), more preferably between about 4 or 6 ounces (1.22 N or 1.668 N) and 10 ounces (2.78 N) and most preferably between about 2 and 6 ounces (0.556 N and 1.668 N). Red light will be emitted when the force is more than about 12 ounces (3.336 N, more preferably more than about 10 ounces (2.78 N) and most preferably more than about 6 ounces (1.668 N). For three tips, the values will be half again as much. In yet another embodiment, any combination of light intensity, colour, or pulse can be indicative of the force. Should the force exceed the set upper limit, the stylus  10  collapses. 
         [0056]    As shown in  FIG. 9 , the shaft  112  consists of an inner sleeve  113 , an outer sleeve  115  and a rod  117 . The rod  117  is attached to the inner sleeve  113 , for example by a friction fit, using a pair of positioning screws  119 . The inner sleeve  113  and the outer sleeve  115  are releasably held to one another by electromagnets  121 . As shown in  FIG. 9 , perimeter magnets  121  are located on the inner surface  123  of the outer sleeve  115  and in the vicinity of the end  125  of the inner sleeve  113 . Magnets  121  are also located on the inner sleeve  113  in the vicinity of the end  125 . As would be known to one skilled in the art, the magnets on one surface may be replaced with a magnetic material—what is required is a magnetic field. A sensor  127  provides electronic feedback to signal when the magnetic field is broken. The force required to break the magnetic field is dependent upon the number of tips. For two tips, the force will be about 44N to about 36 N to about 22N, for three tips, about 66N, to about 54N to about 33 N and so on. 
         [0057]    The rod  117  is resistant and optionally light transmitting. In one embodiment it is preferably an acrylic rod that functions as a light pipe. The rod  117  is preferably provided with light scattering segments (see  FIG. 3  for equivalent structure  30 ). In the preferred embodiment, the light scattering segments are facets that provide rings of light spaced along the rod  117 . Light scattering may be provided by etching or by machining or other methods as would be known to one skilled in the art. The distal end  116  also preferably scatters light. As shown in  FIG. 1 , an applicator  152  is attached to the distal end  116 . In the preferred embodiment, the applicator  152  is in threaded engagement with the distal end  116 , however, the applicator  152  and rod  117  may be a single unit or may be releasably attached to one another in any number of ways, as would be known to one skilled in the art. The applicator  152  retains the tips  114 . As shown in  FIG. 1 , if additional strength is required, a slave  132  is placed in parallel with the shaft  112  (see  FIG. 3  for equivalent structure  32  shown directly adjacent). As would be known to one skilled in the art, the features shown in  FIGS. 4 and 5  may similarly be found in the rod  117 . 
         [0058]    As shown in  FIG. 10  at least one of the tips  114  is adjustably located in apertures  154  in the applicator  152  to allow the practitioner to adjust the distance between the tips  114  prior to treatment i.e. orthogonal to the shaft. A rack and pinion or other suitable linear actuator allows for the adjustment. The tips do not approach one another or move away from one another during the treatment—they function to impart repetitive force impulses a set, but adjustable distance from one another. The tips  114  can also be adjusted proximally and distally using an adjustment screw  156 . This allows the tips  114  to be placed accurately on the treatment location and to provide same force to the treatment area. The relative length of the tips  114  and the rod  117  is variable. The rod  117  may be shorter than the tips  114 , the same length as the tips  114  or longer than the tips  114 , thereby imparting variable force to the treatment area if the treatment area is flat, or the same force if the treatment area is contoured. An aperture  170  is for releasably retaining the distal end  116  of the rod  117 , as described above. 
         [0059]    As shown in  FIG. 11 , the tips  114  may be housed in a cover  158 . The cover  158  may cover the entire tip  114  or part of the tips  114 . A flexible layer  160 , such as a gel or plastic polymer may be enveloped by the cover  158 . This allows any force to radiate concentrically from the tips  114 . As shown in  FIG. 12 , Velcro® or another suitable closure  162  allows the cover  158  to function as a wrap that can be placed around a joint or appendage. 
         [0060]    In another embodiment, shown in  FIG. 13 , the applicator  152  is releasably located on the stylus  10  of  FIGS. 1-5  such that the distal end  16  of the rod  17  extends through the applicator  152 . In this embodiment, the applicator  152  has a central bore  170  for accepting the rod  17  and an adjustment screw  172  for releasably affixing the applicator  152  to the rod  117 . Again, the tips  114  on the applicator can be adjusted laterally, proximally and distally, as shown in  FIG. 12 . The applicator  152  can be placed such that the distal end  116  of the rod  117  may impart force on the patient, or may transfer the force to the tips  114  via the applicator  152 . 
         [0061]    The foregoing is a description of the technology. As would be known to one skilled in the art, variations are contemplated that do not alter the scope of the technology. For example, feedback can be based on colour, intensity, light duration, colour sequence (flashing) or any combination thereof i.e. alternating colours. Light scattering may be effected by varying the light pipe diameter or by machining or etching or otherwise causing an alteration in the surface that results in light scattering. The light pipe, segments or distal end of the pipe may be emit light. If the light is visible at the end of the stylus, then the tip need not diffuse the light. The mechanism for allowing the stylus to collapse need not be confined to a magnetic field created by magnets on each of the outer and inner sleeve, but could, for example, be a magnetic field created by a magnet on one sleeve and a magnetic material on the other sleeve. Alternatively a friction fit could be employed. 
         [0062]    Note that in the case of pulsed light audio feedback or vibration, a single colour, tone or vibration is all that is required to display either tension or compression ranges. In the case of audio feedback, the frequency of sound or other variants of sound could be used to indicate changes in measured force. Similarly, the frequency of vibration could be used to indicate changes in measured force. 
         [0063]    While the foregoing is directed to a stylus, as would be known to one skilled in the art, any shape that can impart a force is contemplated, for example, paddles and hammers. Similarly, the force may be exerted by a cutting implement such as a scalpel or other medical device. 
       INDUSTRIAL APPLICABILITY 
     Sequence List Text 
       [0064]