Patent Publication Number: US-7712478-B2

Title: Ergonomic crutch

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates generally to the field of medical devices, and more specifically, to an ergonomic crutch. 
   2. Description of the Related Art 
   Traditional crutches have stationary armpit pads, a hand grip that is vertically aligned with the armpit pad, and no way of adjusting the angle of the hand grip relative to the armpit pad. In an attempt to make crutches more ergonomic, shock absorbers have been incorporated into crutches to generate a more horizontal plane of travel (as opposed to an arc) of the armpit pad when the crutch is in use. Some prior art designs for crutches have incorporated a vertical tilt to the armpit pad itself to provide for a more comfortable fit between the patient&#39;s underarm and the armpit pad of the crutch. 
   In some crutches currently available on the market, the hand grip has been moved from its traditional location inside of the crutch frame to a position outside of the crutch frame and further away from the body. Various accessories, such as crutch pockets and pouch bags, have been added to crutches to make it more convenient for the patient to carry items while using crutches. All of these innovations in crutch design are intended to make crutches easier and more comfortable to use. 
   None of these prior art crutch designs, however, has solved the particular problem that is addressed by the present invention, and that is, that the angle of a person&#39;s palm in relation to the rest of his or her body when the person&#39;s arm is allowed to hang freely varies from individual to individual. This problem is solved in the present invention by allowing the armpit pad to swivel horizontally so that the patient can achieve the most comfortable position of the hand grip in relation to the armpit pad. 
   The present invention also offers the advantage of being collapsible into three pieces, which can be held together with a strap and carried in a stuff bag for easy portability. These and other advantages of the present invention are discussed more fully below. 
   BRIEF SUMMARY OF THE INVENTION 
   The present invention is an ergonomic crutch comprising an armpit pad assembly; a top tube; a middle tube; a bottom tube; a hand grip; a shock absorber; and a footpad assembly; the armpit pad assembly comprises an armpit pad and means for allowing the armpit pad to tilt vertically and swivel horizontally; the top tube comprises a top end and a bottom end, and the armpit pad assembly connects to the top end of the top tube; the middle tube comprises a top end and a bottom end; the bottom end of the top tube slides into the top end of the middle tube; the bottom tube comprises a top end and a bottom end; the top end of the bottom tube slides into the bottom end of the middle tube; the hand grip is offset laterally from the middle tube; the shock absorber comprises a barrel and a piston; the barrel of the shock absorber is situated inside of the bottom end of the bottom tube, and the piston of the shock absorber protrudes downward from the bottom end of the bottom tube; the footpad assembly comprises a footpad; the piston of the shock absorber comprises a top end and a bottom end; and the bottom end of the piston of the shock absorber connects to the footpad. In a preferred embodiment, the top, middle and bottom tubes are approximately the same length. Preferably, the armpit pad is gel-filled. 
   In a preferred embodiment, the middle tube comprises a top half and a bottom half; the middle tube comprises four series of spirally aligned apertures, two of which are located in the top half of the middle tube, and two of which are located in the bottom half of the middle tube; and the spirally aligned apertures are configured such that each aperture has a corresponding aperture exactly horizontal to it on an opposite side of the middle tube to facilitate securing the top and bottom tubes inside of the middle tube. 
   In a preferred embodiment, the hand grip comprises a cushioned pad and a metal bar; the middle tube comprises a middle; the metal bar is attached to the middle of the middle tube; the metal bar extends from the middle tube in one direction, makes a U turn, and then extends in an opposite direction to a point beyond the middle tube, thereby forming a short arm and a long arm of the metal bar; the cushioned pad is wrapped around the long arm of the metal bar; the cushioned pad comprises a center; the foot pad comprises a center; and the center of the cushioned pad is directly adjacent to the center of the foot pad from the perspective of a top view of the crutch. Preferably, the cushioned pad is gel-filled. 
   In a preferred embodiment, the present invention further comprises a rubber strap; the rubber strap is used to secure the top, middle and bottom tubes together when the crutch is disassembled; the rubber strap comprises a first end and a second end; the first end of the rubber strap is attached to the middle tube at a point directly beneath the point at which the metal bar of the hand grip is attached to the middle of the middle tube; there is a side of the middle tube that faces the patient when the crutch is in use and a side of the middle tube that does not face the patient when the crutch is in use; and the point at which the rubber strap is attached to the middle tube is on the side of the middle tube that faces the patient when the crutch is in use. 
   In a preferred embodiment, the present invention further comprises a clipboard, and the clipboard attaches to the middle tube at a point on the middle tube directly opposite the point at which the rubber strap attaches to the middle tube. Preferably, the clipboard comprises a magnetic strip. 
   In a preferred embodiment, the present invention further comprises a removable beverage holder; the beverage holder comprises a top end and a bottom end; the top end of the beverage holder attaches to the middle tube at a point on the middle tube directly opposite the point at which the rubber strap attaches to the middle tube; and the bottom end of the beverage holder is not attached to the middle tube so that it can swing freely and maintain a vertical orientation when the crutch is in use. 
   In a preferred embodiment, the crutch is used by a patient, and the shock absorber is adjustable based on the weight of the patient. Preferably, the footpad comprises a broad rounded underside that allows the foot pad to rock in all directions. 
   In a preferred embodiment, the armpit pad assembly further comprises a primary swivel part, a first washer, a cap, a second washer, a nut, and a shoulder bolt; the armpit pad comprises an underside; the primary swivel part is inserted into the underside of the armpit pad and secured with the shoulder bolt; the primary swivel part comprises a top section, a disc, a bottom extension, and a threaded portion; the shoulder bolt extends through an aperture in the top section of the primary swivel part; the cap comprises a top surface with an aperture and an underside; the first washer is positioned over the bottom extension of the primary swivel part and the bottom extension inserted into the aperture in the top surface of the cap; the second washer is inserted over the bottom extension of the primary swivel part underneath the aperture in the top surface of the cap; the nut is screwed onto the threaded portion of the primary swivel part to secure the primary swivel part on the cap; the cap is affixed to the top end of the top tube; and the disc of the primary swivel part lies flat against the first washer, the first washer lies flat against the top surface of the cap, and the second washer lies flat against the underside of the top surface of the cap, thereby allowing the armpit pad to swivel horizontally in relation to the top tube. 
   In a preferred embodiment, the disc of the primary swivel part comprises a bottom surface; the primary swivel part comprises a bottom extension that extends downward from the bottom surface of the disc and connects to the threaded portion of the primary swivel part; the bottom extension has a height; the first washer, top surface of the cap, and second washer each has a thickness; and the height of the bottom extension is slightly greater than the total thickness of the first washer, the top surface of the cap, and the second washer. 
   In a preferred embodiment, the underside of the armpit pad comprises two angled walls and two shoulders; the top section of the primary swivel part fits in between the two shoulders of the armpit pad; the shoulder bolt extends through an aperture on one side of the armpit pad, through one of the two shoulders, through the aperture in the top section of the primary swivel part, and through the other shoulder; and the shoulder bolt comprises a threaded portion that screws into a side wall of the armpit pad. 
   In a preferred embodiment, the angled walls of the armpit pad allow the armpit pad to tilt vertically when the armpit pad assembly is fully assembled; each angled wall has an angle, and the angle of one angled wall is equal to the angle of the other angled wall; the angle of the angled walls determines how far the armpit pad is capable of tilting vertically; and the angle of the angled walls can be adjusted during manufacture to allow for greater or lesser tilt of the armpit pad. 
   In an alternate embodiment, the present invention is an ergonomic crutch comprising an armpit pad assembly; a top tube; a middle tube; a bottom tube; a hand grip; and a footpad assembly; the armpit pad assembly comprises an armpit pad and means for allowing the armpit pad to tilt vertically and swivel horizontally; the top tube comprises a top end and a bottom end, and the armpit pad assembly connects to the top end of the top tube; the middle tube comprises a top end and a bottom end; the bottom end of the top tube slides into the top end of the middle tube; the bottom tube comprises a top end and a bottom end; the top end of the bottom tube slides into the bottom end of the middle tube; and the hand grip is offset laterally from the middle tube. Preferably, the armpit pad is gel-filled. 
   In a preferred embodiment, the middle tube comprises a top half and a bottom half; the middle tube comprises four series of spirally aligned apertures, two of which are located in the top half of the middle tube, and two of which are located in the bottom half of the middle tube; and the spirally aligned apertures are configured such that each aperture has a corresponding aperture exactly horizontal to it on an opposite side of the middle tube to facilitate securing the top and bottom tubes inside of the middle tube. 
   In a preferred embodiment, the hand grip comprises a cushioned pad and a metal bar; the middle tube comprises a middle; the metal bar is attached to the middle of the middle tube; the metal bar extends from the middle tube in one direction, makes a U turn, and then extends in an opposite direction to a point beyond the middle tube, thereby forming a short arm and a long arm of the metal bar; the cushioned pad is wrapped around the long arm of the metal bar; the cushioned pad comprises a center; the foot pad comprises a center; and the center of the cushioned pad is directly adjacent to the center of the foot pad from the perspective of a top view of the crutch. Preferably, the cushioned pad is gel-filled. 
   In a preferred embodiment, the present invention further comprises a rubber strap; the rubber strap is used to secure the top, middle and bottom tubes together when the crutch is disassembled; the rubber strap comprises a first end and a second end; the first end of the rubber strap is attached to the middle tube at a point directly beneath the point at which the metal bar of the hand grip is attached to the middle of the middle tube; there is a side of the middle tube that faces the patient when the crutch is in use and a side of the middle tube that does not face the patient when the crutch is in use; and the point at which the rubber strap is attached to the middle tube is on the side of the middle tube that faces the patient when the crutch is in use. 
   In a preferred embodiment, the present invention further comprises a clipboard, and the clipboard attaches to the middle tube at a point on the middle tube directly opposite the point at which the rubber strap attaches to the middle tube. Preferably, the clipboard comprises a magnetic strip. 
   In a preferred embodiment, the present invention further comprises a removable beverage holder; the beverage holder comprises a top end and a bottom end; the top end of the beverage holder attaches to the middle tube at a point on the middle tube directly opposite the point at which the rubber strap attaches to the middle tube; and the bottom end of the beverage holder is not attached to the middle tube so that it can swing freely and maintain a vertical orientation when the crutch is in use. 
   Preferably, the footpad comprises a broad rounded underside that allows the foot pad to rock in all directions. 
   In a preferred embodiment, the armpit pad assembly further comprises a primary swivel part, a first washer, a cap, a second washer, a nut, and a shoulder bolt; the armpit pad comprises an underside; the primary swivel part is inserted into the underside of the armpit pad and secured with the shoulder bolt; the primary swivel part comprises a top section, a disc, a bottom extension, and a threaded portion; the shoulder bolt extends through an aperture in the top section of the primary swivel part; the cap comprises a top surface with an aperture and an underside; the first washer is positioned over the bottom extension of the primary swivel part and the bottom extension inserted into the aperture in the top surface of the cap; the second washer is inserted over the bottom extension of the primary swivel part underneath the aperture in the top surface of the cap; the nut is screwed onto the threaded portion of the primary swivel part to secure the primary swivel part on the cap; the cap is affixed to the top end of the top tube; and the disc of the primary swivel part lies flat against the first washer, the first washer lies flat against the top surface of the cap, and the second washer lies flat against the underside of the top surface of the cap, thereby allowing the armpit pad to swivel horizontally in relation to the top tube. 
   In a preferred embodiment, the disc of the primary swivel part comprises a bottom surface; the primary swivel part comprises a bottom extension that extends downward from the bottom surface of the disc and connects to the threaded portion of the primary swivel part; the bottom extension has a height; the first washer, top surface of the cap, and second washer each has a thickness; and the height of the bottom extension is slightly greater than the total thickness of the first washer, the top surface of the cap, and the second washer. 
   In a preferred embodiment, the underside of the armpit pad comprises two angled walls and two shoulders; the top section of the primary swivel part fits in between the two shoulders of the armpit pad; the shoulder bolt extends through an aperture on one side of the armpit pad, through one of the two shoulders, through the aperture in the top section of the primary swivel part, and through the other shoulder; and the shoulder bolt comprises a threaded portion that screws into a side wall of the armpit pad. 
   In a preferred embodiment, the angled walls of the armpit pad allow the armpit pad to tilt vertically when the armpit pad assembly is fully assembled; each angled wall has an angle, and the angle of one angled wall is equal to the angle of the other angled wall; the angle of the angled walls determines how far the armpit pad is capable of tilting vertically; and the angle of the angled walls can be adjusted during manufacture to allow for greater or lesser tilt of the armpit pad. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of a first embodiment of the present invention. 
       FIG. 2  is an exploded view of a first embodiment of the present invention. 
       FIG. 3  is a detail view of the spring pin mechanism of the present invention. 
       FIG. 3A  is a detail view of the rubber strap attached to the middle tube of the present invention. 
       FIG. 4  is an exploded view of the armpit pad assembly of the present invention. 
       FIG. 4A  is an exploded view of the primary swivel part, first washer, second washer and nut of the armpit pad assembly. 
       FIG. 4B  is a side view of the primary swivel part, first washer, second washer and nut installed on the cap of the armpit pad assembly. 
       FIG. 5  is a bottom perspective view of the armpit pad of the present invention. 
       FIG. 6  is a first section view of the armpit pad assembly of the present invention. 
       FIG. 7  is a second section view of the armpit pad assembly of the present invention. 
       FIG. 8  is a partial side view of the present invention with the armpit pad tilted vertically. 
       FIG. 9  is a top view of the present invention showing the armpit pad swiveled horizontally in a first direction. 
       FIG. 10  is a top view of the present invention showing the armpit pad swiveled horizontally in a second direction. 
       FIG. 11  is an exploded view of the footpad section of a first embodiment of the present invention. 
       FIG. 12  is a bottom perspective view of the footpad of the present invention. 
       FIG. 13  is a top perspective view of the footpad of the present invention. 
       FIG. 14  is a partial perspective view of the present invention shown with an optional clipboard attachment. 
       FIG. 15  is a partial perspective view of the present invention shown with an optional beverage holder attachment. 
       FIG. 16  is a perspective view of a second embodiment of the present invention. 
       FIG. 17  is an exploded view of a second embodiment of the present invention. 
       FIG. 18  is an exploded view of the footpad section of a second embodiment of the present invention. 
     
       
         
           
               
             
               
                   
               
               
                 REFERENCE NUMBERS 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
            
               
                 1 
                 Armpit pad 
               
               
                 2 
                 Top tube 
               
               
                 3 
                 Middle tube 
               
               
                 4 
                 Bottom tube 
               
               
                 5 
                 Hand grip 
               
               
                 6 
                 Foot pad 
               
               
                 7 
                 Shock absorber 
               
               
                 8 
                 Cushioned pad 
               
               
                 9 
                 Metal tube (of hand grip) 
               
               
                 10 
                 Spirally aligned apertures (on middle tube) 
               
               
                 11 
                 Spring pin 
               
               
                 12 
                 Adjustment knob (on shock absorber) 
               
               
                 13 
                 Piston (of shock absorber) 
               
               
                 14 
                 Barrel (of shock absorber) 
               
               
                 15 
                 Rubber strap 
               
               
                 16 
                 Clipboard 
               
               
                 17 
                 Beverage holder 
               
               
                 18 
                 Armpit pad assembly 
               
               
                 19 
                 Nut 
               
               
                 20 
                 Bolt 
               
               
                 21 
                 Foot pad assembly 
               
               
                 22 
                 Knob (on spring pin) 
               
               
                 23 
                 Aperture (on top tube) 
               
               
                 24 
                 Knob (on rubber strap) 
               
               
                 25 
                 Apertures (in rubber strap) 
               
               
                 26 
                 Primary swivel part 
               
               
                 27 
                 First washer 
               
               
                 28 
                 Cap 
               
               
                 29 
                 Second washer 
               
               
                 30 
                 Nut 
               
               
                 31 
                 Shoulder bolt 
               
               
                 32 
                 Aperture (in top section of primary swivel part) 
               
               
                 33 
                 Threaded portion (of primary swivel part) 
               
               
                 34 
                 Aperture (in cap) 
               
               
                 35 
                 Disc (of primary swivel part) 
               
               
                 36 
                 Angled wall (of armpit pad) 
               
               
                 37 
                 Shoulder (of armpit pad) 
               
               
                 38 
                 Top section (of primary swivel part) 
               
               
                 39 
                 Threaded portion (of shoulder bolt) 
               
               
                 40 
                 Nut 
               
               
                 41 
                 Bolt 
               
               
                 42 
                 Extension (on barrel of shock absorber) 
               
               
                 43 
                 Aperture (in bottom tube) 
               
               
                 44 
                 Threaded recess (in foot pad) 
               
               
                 45 
                 End piece 
               
               
                 46 
                 Magnetic strip 
               
               
                 47 
                 Threaded extension (of end piece) 
               
               
                 48 
                 Aperture (in armpit pad) 
               
               
                 49 
                 Bottom extension (of primary swivel part) 
               
               
                   
               
            
           
         
       
     
   

   DETAILED DESCRIPTION OF INVENTION 
     FIG. 1  is a perspective view of a first embodiment of the present invention. As shown in this figure, the present invention is a crutch comprised of an armpit pad  1 , a top tube  2 , a middle tube  3 , a bottom tube  4 , a hand grip  5  and a foot pad  6 . In this embodiment, the crutch further comprises a shock absorber  7 . The armpit pad  1  is preferably gel-filled and ergonomically shaped so as to keep pressure off of the sensitive nerve areas of the armpit. As shown in subsequent figures, the armpit pad  1  both tilts vertically and swivels horizontally. 
   The hand grip  5  is welded onto the middle tube  3  and preferably comprises a gel-filled cushioned pad  8  for ease of grip. The present invention is not limited to any particular type of cushioned pad; the cushioned pad could be made of rubber or foam, for example. The hand grip  5  further comprises a metal bar  9  that extends in one direction from the middle tube  3 , makes a U turn, and then extends in an opposite direction to a point beyond the middle tube  3  (this is also shown more clearly in  FIG. 2 ) so that the side of the U-shaped metal bar with the cushioned pad  8  is longer than the side without the cushioned pad. The cushioned pad  8  is preferably situated on the metal bar  9  so that the center of the cushioned pad  8  is directly adjacent to the center of the foot pad  6  from the perspective of a top view of the crutch (see  FIGS. 9 and 10 ). 
   The middle tube  3  preferably comprises four series of spirally aligned apertures  10 , two situated underneath the hand grip  5  on the middle tube  3  and two situated above the hand grip  5  on the middle tube  3 . These apertures  10  are aligned spirally to avoid the weakness in the middle tube  3  that would result if they were vertically aligned, and also to provide greater flexibility in terms of positioning the top and bottom tubes  2 ,  4  inside of the middle tube  3  (see  FIG. 2 ). In addition, each aperture has a corresponding aperture on the opposite (horizontal) side of the middle tube  3  so that the spring pin  11  can hold the two tubes (either the top and middle tubes or the middle and bottom tubes) together (see  FIG. 3 ). 
   The shock absorber  7  absorbs some of the weight of the patient and allows the patient to maintain a horizontal plane at the level of the armpit pad  1  when using the crutch as compared to the arc-shaped path of travel of the armpit pad  1  on a crutch without a shock absorber  7 . Combined with the vertically tilting armpit pad  1 , the shock absorber  7  allows the armpit pad  1  to stay horizontal and in contact with the patient&#39;s armpit throughout the walking cycle. This results in a forward motion that is more fluid, level, and comfortable for the patient. It also allows the patient to rely more heavily on the armpit pad to carry her weight as opposed to the patient having to carry all of her weight with her arms. 
   The shock absorber  7  is designed to fit into the inner diameter of the bottom tube  4  and is fastened to the bottom tube  4  with a nut and bolt (see  FIG. 11 ). The tension of the shock absorber  7  is preferably adjustable to accommodate the weight of the patient. The tension of the shock absorber is adjusted via an adjustment knob  12  that extends from the barrel  14  of the shock absorber  7  (see  FIG. 11 ) through the bottom tube  4 . Preferably, the two shock absorbers  7  together (one on the right-hand crutch and one on the left-hand crutch) can be adjusted to accommodate patients weighing from 80 to 300 pounds (i.e., each shock absorber  7  will handle between 40 and 150 pounds). 
   In a preferred embodiment, the piston  13  of the shock absorber  7  extends below the bottom tube  4  and has a stroke of approximately three inches. The diameter of the barrel  14  of the shock absorber  7  is slightly less than the inside diameter of the bottom tube  4 . 
   As shown in  FIG. 1 , the present invention preferably comprises a rubber strap  15  that is attached to the middle tube  3  with a nut and bolt (see  FIG. 2 ). Alternately, the rubber strap can be attached to the middle tube  3  with a rivet (not shown). The present invention is not limited to any particular method of attaching the rubber strap to the middle tube. The purpose of the rubber strap  15  is to hold the three tubes  2 ,  3 ,  4  together when they are disassembled for easy transport of the crutch. The rubber strap  15  is preferably attached to the middle tube  3  at a point directly underneath the hand grip (see  FIG. 3A ) on the inside of the crutch (i.e., the side of the crutch that is adjacent to the patient&#39;s body). The purpose of this positioning is so that the bolt (or rivet) that attaches the rubber strap  15  to the middle tube  3  can also be used to attach the clipboard  16  and beverage holder  17  to the middle tube  3  (see  FIGS. 14 and 15 ). 
   The crutch shown in  FIG. 1  and in  FIG. 16  can be used on either the left-hand or the right-hand side of the patient. The present invention also covers the mirror image of the crutch shown in  FIG. 1 . 
     FIG. 2  is an exploded view of a first embodiment of the present invention. This figure shows the armpit pad assembly  18 , which is shown in greater detail in  FIG. 4 . It also shows the spring pins  11  that hold the top tube  2  inside of the middle tube  3  and the bottom tube  4  inside of the middle tube  2 . Also shown are the nut  19  and bolt  20  that hold the rubber strap  15  onto the middle tube  3  in one embodiment (in another embodiment the rubber strap is attached to the middle tube  3  with a rivet) and the foot pad/shock absorber assembly  21 , which is shown in greater detail in  FIG. 11 . 
   As this figure illustrates, the top, middle and bottom tubes  2 ,  3 ,  4  are preferably approximately the same length. The outside diameter of the top and bottom tubes  2 ,  4  is slightly less than the inside diameter of the middle tube  3  so that the top and bottom tubes can slide into the middle tube for assembly of the crutch and out of the middle tube for disassembly and storage or transport. 
     FIG. 3  is a detail view of the spring pin mechanism of the present invention. The spring pin  11  is one mechanism of attaching the top and bottom tubes  2 ,  4  to the middle tube  3 , but the present invention is not limited to any particular mechanism of attachment. In this embodiment, the spring pin  11  comprises two knobs  22 . The spring pin  11  is inserted into the top tube  2  and the knobs  22  extended through two horizontally aligned apertures  23  (only one of which is visible in  FIG. 3 ) directly opposite each other on the bottom end of the top tube  2 . The spring pin  11  is then manually compressed so that the knobs  22  do not extend beyond the outer surface of the top tube  2 , and the top tube  2  is inserted into the middle tube  3 . The length of the crutch can be adjusted by moving the top tube  2  either farther down or farther up on the middle tube  3 . To stabilize the top tube  2  in the middle tube  3 , the spring pin  11  is decompressed (by lifting the pressure on the knobs  22 ), and the knobs  22  are allowed to extend through apertures  10  on the middle tube  3 . The bottom tube  4  is inserted into the middle tube  3  in the same manner. 
   In a preferred embodiment, each spirally aligned series of apertures  10  (there are two on the top half of the middle tube  3  and two on the bottom half of the middle tube  3 ) is labeled either with numbers or letters (shown with letters in  FIG. 3 ) so that, for example, the “A” in the first series of spirally aligned apertures  10  is horizontally aligned with the “A” on the second series of spirally aligned apertures. (The first and second series of spirally aligned apertures are both shown on the top half of the middle tube  3  in  FIG. 3 .) Similarly, on the bottom half of the middle tube  3 , the number “1” in the third series of spirally aligned apertures  10  is horizontally aligned with the number “1” on the fourth series of spirally aligned apertures. In this manner, patients can refer to their preferred crutch length as “A1,” B4, “C5,” etc. In a preferred embodiment, each series of spirally aligned apertures  10  comprises ten individual apertures aligned in a spiral. 
     FIG. 3A  is a detail view of the rubber strap attached to the middle tube of the present invention. As shown in this figure, the rubber strap  15  comprises a knob  24 . To strap the three tubes  2 ,  3 ,  4  together, the crutch is disassembled, the tubes are held parallel to each other, and the rubber strap  15  is wrapped around the tubes. To secure the strap around the tubes, the knob  24  is inserted into and through one of the apertures  25  on the bottom end of the rubber strap  15 . This is one way of securing the strap, but the present invention is not limited to this particular method. For example, a hook-and-loop-type fastener could be used as well. 
     FIG. 4  is an exploded view of the armpit pad assembly of the present invention. The armpit pad assembly  18  comprises the armpit pad  1 , the primary swivel part  26 , a first washer  27 , a cap  28 , a second washer  29 , and a nut  30 . It also comprises a shoulder bolt  31 . When the armpit pad assembly  1  is fully assembled, the primary swivel part  26  is inserted into the underside of the armpit pad  1  (see  FIGS. 5-7 ) and secured with the shoulder bolt  31 . The shoulder bolt  31  extends through an aperture  32  in the top section  3   8  of the primary swivel part  26 . The first washer  27  is then positioned over the bottom extension  49  (see  FIG. 4A ) of the primary swivel part  26 , and the bottom extension  49  is inserted into an aperture  34  in the cap  28 . The second washer  29  is then inserted over the bottom extension  49  of the primary swivel part  26  underneath the aperture  34  in the cap  28 , and the nut  30  is screwed onto the threaded portion  33  of the primary swivel part  26  to secure the primary swivel part on the cap  28 . The cap  28  is then welded onto or slid over (without welding) the top of the top end of the top tube  2  (see  FIG. 6 ). Although the armpit pad assembly  18  is shown with two washers, the present invention is not limited to any particular number of washers as long as one washer is on top of the top surface of the cap and another is on the underside of the top surface of the cap. 
   The primary swivel part  26  comprises a disc  35  that lies flat up against the first washer  27  when the armpit pad assembly  18  is assembled. The nut  30  is screwed tightly enough to hold the assembly in place but not so tight as to preclude the disc  35  from rotating on the first washer  27 . Because the threaded portion  33  of the primary swivel part  26  is fixedly connected to the nut  30 , the nut  30  rotates on the second washer  29  at the same time and to the same degree that the disc  35  of the primary swivel part  26  rotates on the first washer  27 . The cap  28  is stationary during rotation of the primary swivel part  26  because it is fixedly attached (but not necessarily welded) to the top end of the top tube  2 . 
   Because of the primary swivel part  26  and the manner in which it is attached to the cap  28  and then armpit pad  1 , the armpit pad  1  can swivel horizontally to accommodate the most comfortable position for the patient using the crutch. In particular, the horizontal swivel allows a patient to achieve the best angle of the hand grip  5  in relation to the armpit pad  1  for maximum comfort. This principle is illustrated in  FIGS. 9 and 10 . 
     FIG. 4A  is an exploded view of the primary swivel part, first washer, second washer and nut of the armpit pad assembly. As shown in this figure, the primary swivel part  26  comprises a bottom extension  49  that extends downward from the bottom surface of the disc  35  and connects to the threaded portion  33  of the primary swivel part  26 . Preferably, the total height of the bottom extension (i.e., the distance from the bottom of the disc  35  to the top of the threaded portion  33 ) is slightly greater than the thickness of the first washer  27 , the top of the cap  28 , and the second washer  29  (see  FIG. 4B ). 
     FIG. 5  is a bottom perspective view of the armpit pad of the present invention. As shown in this figure, the underside of the armpit pad  1  preferably comprises two angled walls  36  and two shoulders  37 . The top section  38  of the primary swivel part  26  fits securely in between the two shoulders  37  of the armpit pad  1 , and the shoulder bolt  31  extends through an aperture  48  on the outside of the armpit pad  1 , through one of the two shoulders  37 , through the aperture  32  in the top section  38  of the primary swivel part  26 , and through the other shoulder  37 . The threaded portion  39  of the shoulder bolt  31  screws into the side wall (not to be confused with the “sloping wall” on the underside of the armpit pad) of the armpit pad  1  (see  FIG. 6 ). 
   The angled walls  36  of the armpit pad  1  allow the armpit pad to tilt vertically when the armpit pad assembly  18  is filly assembled (see  FIGS. 7 and 8 ). The angle of the angled walls  36  determines the degree to which the armpit pad  1  will be capable of tilting before the cap  28  hits the angled wall  36 , thereby preventing any further vertical tilt of the armpit pad  1 . Referring to  FIG. 7 , a lesser angle to the angled walls (i.e., more gradually sloping walls) would allow the armpit pad  1  to tilt to a greater degree, whereas a greater angle to the angled walls (i.e., steeper walls) would restrict the degree to which the armpit pad  1  could tilt. In this manner, the present invention can be engineered so as to permit the desirable range of tilt of the armpit pad  1 . The arrow on  FIG. 7  indicates the direction of vertical tilt. 
     FIG. 8  is a partial side view of the present invention with the armpit pad tilted vertically. The mechanism that allows the armpit pad  1  to tilt vertically is described above in connection with  FIGS. 4-7 . The vertical tilt of the armpit pad  1  makes it easier for patients to get onto and off of the armpit pad  1  and maintains constant contact between the patient&#39;s armpit and the armpit pad  1  throughout the walking cycle. 
     FIG. 9  is a top view of the present invention showing the armpit pad swiveled horizontally in a first direction.  FIG. 10  is a top view of the present invention showing the armpit pad swiveled horizontally in a second direction. As explained above, the purpose of the horizontal swivel is to allow the patient to achieve the most comfortable angle of the armpit pad  1  in relation to the hand grip  5 , as shown in these two figures. These two figures also illustrate that the center of the cushioned pad  8  is preferably lined up with the center of the foot pad  6 , as noted above. 
     FIG. 11  is an exploded view of the footpad section of a first embodiment of the present invention. As shown in this figure, the shock absorber  7  comprises a piston  13  and a barrel  14 . An adjustment knob  12  on the barrel  14  allows the tension of the shock absorber to be adjusted to the weight of the patient. The outside diameter of the barrel  14  of the shock absorber  7  is slightly smaller than the inside diameter of the bottom tube  4  so that the barrel  14  can be inserted into the tube  4 . The piston  13  extends downward from the base of the tube  4  (see  FIG. 1 ) and screws into the foot pad  6 . The barrel  14  is secured to the bottom tube  4  with a nut  40  and a bolt  41  that extends through an aperture (not shown) on one side of the bottom tube  4 , through an extension  42  at the top of the barrel  14 , and through an aperture  43  on the opposite side of the bottom tube  4 . 
     FIGS. 12 and 13  are bottom perspective and top perspective views, respectively, of the footpad of the present invention. In a preferred embodiment, the foot pad  6  is shaped as shown in  FIGS. 12 and 13  with a relatively broad rounded underside. This shape allows the foot pad to rock in all directions, as necessary, to accommodate the movement of the patient and the horizontal swivel of the armpit pad  1 . The top side of the foot pad  6  comprises a threaded recess  44  into which the piston  13  of the shock absorber  7  or the end piece  45  (see  FIG. 18 ), whichever the case may be, is screwed. 
   In addition to affording the advantageous features described above, namely, the horizontally swiveling and vertically tilting armpit pad, the offset hand grip, the gas shock, the optimally shaped foot pad, and the three-part tubing, the present invention is also designed to accommodate accessories, such as clipboards and beverage holders, to make it even more convenient for the patient on crutches to function. 
     FIG. 14  is a partial perspective view of the present invention shown with an optional clipboard attachment. The clipboard  16  is preferably attached to the middle tube  3  directly beneath the hand grip  5 . The clipboard  16  is attached to the middle tube  3  with the same bolt  20  and nut  19  (or, in an alternate embodiment, rivet) that secure the rubber strap  15  to the middle tube  3 . In a preferred embodiment the clipboard  16  comprises a magnetic strip  46  with which writing instruments or other metal objects can be held. 
     FIG. 15  is a partial perspective view of the present invention shown with an optional beverage holder attachment. The beverage holder  17  is preferably attached to the middle tube  3  directly beneath the hand grip  5 . The beverage holder is attached to the middle tube  3  with the same bolt  20  and nut  21  (or, in an alternate embodiment, rivet) that secure the rubber strap  15  to the middle tube  3 . The beverage holder  17  is preferably attached to the middle tube  3  at only this single point so that the beverage holder will rock from side to side when the crutch is in use, thereby maintaining the bottle in a constant vertical orientation relative to the ground. 
     FIG. 16  is a perspective view of a second embodiment of the present invention. This embodiment is identical to the first embodiment except that the crutch does not include a shock absorber (and, for that reason, the bottom tube  4  may be longer than it was in the first embodiment). This embodiment would provide a horizontally swiveling and vertically tilting armpit pad  1 , but it would not eliminate the problem (described above) of the armpit pad  1  traveling in an arc-shaped path as opposed to a horizontal line when the crutch is in use. It may, however, be less expensive to manufacture than the first embodiment. 
     FIG. 17  is an exploded view of a second embodiment of the present invention. This embodiment is identical to the first embodiment except for the foot pad assembly  21  (compare to  FIG. 2 ). In this embodiment, because there is no shock absorber, the bottom tube  4  is longer than it is in the first embodiment (alternately, if the bottom tube is not longer, the end piece  45  would have to be longer), and it screws directly into the foot pad  6 . As shown in  FIG. 18 , an end piece  45  with a threaded extension  47  is welded into the bottom end of the bottom tube  4  or inserted and held in place with a nut and bolt, and the threaded extension  47  screws into the recess  44  in the foot pad  6 . 
   Although the preferred embodiment of the present invention has been shown and described, it will be apparent to those skilled in the art that many changes and modifications may be made without departing from the invention in its broader aspects. The appended claims are therefore intended to cover all such changes and modifications as fall within the true spirit and scope of the invention.