Abstract:
A portable traction device suitable for cervical or lumbar traction powered by a pneumatic cylinder. The portable traction device includes a support structure having a longitudinal axis and a carriage slidable along a portion of the support structure parallel to the longitudinal axis. The carriage including restraining mechanism for releasably restraining a portion of a patient&#39;s body to the carriage. A pneumatic cylinder includes a cylinder housing attached to the support structure. The cylinder housing contains a piston and piston rod. The piston rod is attached to the carriage for moving the carriage along the longitudinal axis relative to the support structure when pressurized air is injected into the pneumatic cylinder. The piston has at least one pressure activated seal extending circumferentially around the piston for engagement with an inside surface of the cylinder housing. A bicycle-style hand pump fluidly connected to the pneumatic cylinder is provided for injecting pressurized air into the cylinder.

Description:
The present application claims the benefit of the filing date of PCT/US95/14217, filed Oct. 31, 1995, which is a continuation-in-part of U.S. Ser. No. 08/334,189, filed Nov. 3, 1994. 
    
    
     FIELD OF THE INVENTION 
     The present invention is directed to a portable traction device powered by a pneumatic cylinder. 
     BACKGROUND OF THE INVENTION 
     Traction is widely used to relieve pressure on inflamed or enlarged nerves. While traction is applicable to any part of the body, cervical and lumbar or spinal traction are the most common. When correctly performed, spinal traction can cause distraction or separation of the vertebral bodies, a combination of distraction and gliding of the facet joints, tensing of the ligamentous structures of the spinal segment, widening of the intervertebral foramen, straightening of spinal curvature and stretching of the spinal musculature. Depending on the injury being treated, the traction component of physical therapy may require multiple sessions per week for a prolonged period of time. 
     Cervical traction requires a traction force up to approximately 222 N (50 lbs.). Lumbar traction typically requires force equal to half of the patient&#39;s bodyweight, or about 333-667 N (75-150 lbs.). The equipment necessary for performing traction, however, has typically been expensive and thus only available to a patient in a therapist&#39;s office. 
     Attempts to create a sufficiently low cost portable traction device for home use have thus far produced unsatisfactory results. A number of portable traction devices utilize pneumatic or hydraulic cylinders to create the traction force. Hydraulic cylinders have the disadvantage of the weight of the hydraulic fluid. Pneumatic cylinders with low pressure inputs typically can not maintain an adequate traction force for a sufficient period of time to be effective in a traction device. In an attempt to overcome this deficiency, some of these devices utilize an automatic pumping device triggered by a pressure sensing device to supply additional compressed air so that a constant level of traction force is maintained. These pump and sensor configurations add cost, weight and complexity to the traction device. 
     The air input pumps used on some traction devices also exhibit a number of shortcomings. For example, bulb-type air pumps produce relatively small input pressures. A small female patient can generate only about 483 kPa (7 psi) of pressure using a bulb-type pump. Consequently, small input pressure devices require large diameter cylinders to generate the necessary output traction forces. Larger diameter cylinders, when used with low pressure input devices, are more prone to leak, thereby further complicating the problem of maintaining a constant traction force for a prolonged period of time. 
     Therefore, what is needed is a low cost, light weight portable traction device utilizing a pneumatic cylinder which can maintain a traction force of an adequate magnitude for a prolonged period of time. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a portable traction device powered by a pneumatic cylinder. The present invention is also directed to a pneumatic cylinder suitable for use in traction devices. 
     The portable traction device includes a support structure having a longitudinal axis and a carriage slidable along a portion of the support structure parallel to the longitudinal axis. The carriage including restraining mechanism for releasably restraining a portion of a patient&#39;s body to the carriage. A pneumatic cylinder includes a cylinder housing attached to the support structure. The cylinder housing contains a piston and piston rod. The piston rod is attached to the carriage for moving the carriage along the longitudinal axis relative to the support structure when pressurized air is injected into the pneumatic cylinder. The piston has at least one pressure activated seal extending circumferentially around the piston for engagement with an inside surface of the cylinder housing. A bicycle-style hand pump fluidly connected to the pneumatic cylinder is provided for injecting pressurized air into the cylinder. 
     In one embodiment, the portable traction device is configured for use as a portable, cervical traction device. The carriage may include a head support pad to receive a patient&#39;s head and a pair of opposing neck supports contoured and arranged to engage the occipital area of the patient&#39;s head when the head is on the head support pad. The neck supports are adjustably attached to the carriage to permit adjustment of the lateral separation therebetween. A head support strap may be provided for restraining the patient&#39;s head to the support pad. 
     In an alternate embodiment, the portable traction device is configured as a portable, lumbar traction device. The restraining mechanism may include a waist belt for releasably restraining the lower body of the user to the carriage. The support structure preferably includes counter traction restraining mechanism for restraining the upper body of the user to the support structure. Alternatively, the restraining mechanism includes a pair of opposing, laterally adjustable hip gripping supports arranged to engage the superior edge of the user&#39;s pelvis. 
     The piston has a diameter smaller than an internal diameter of the cylinder housing so that a gap is formed therebetween. The pressure activated seal may be a pair of pressure activated seals arranged circumferentially around the piston. The pressure activated seal is a generally V-shaped seal member arranged to expand when the air pressure in the pneumatic cylinder exceeds 13.8 kPa (2 psi). In one embodiment, the pressure activated seal maintains a generally static traction force of greater than 111 N (25 pounds) for a period in excess of 10 minutes without additional pressurized air being injected into the cylinder. In an alternate embodiment, the pressure activated seal maintains a generally static traction force of greater than 200 N (45 pounds) for a period in excess of 20 minutes without additional pressurized air being injected into the cylinder. 
     The hand pump preferably includes a gauge indicating traction force and a pressure relief mechanism to manually release pressure in the pneumatic cylinder. In one embodiment, the operator rotates the gauge relative to the hand pump to release pressure from the cylinder. The cylinder preferably includes a pressure regulator to prevent the pressure in the pneumatic cylinder from exceeding a predetermined value. Alternatively, the pressure regulator may be located on the hand pump. The hand pump is capable of injecting at least 207 kPa (30 psi) of pressure to the pneumatic cylinder. 
     The present invention is also directed to the pneumatic cylinder and hand pump discussed above for use as the traction force generating apparatus on a portable traction device. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side view of a portable traction device; 
     FIG. 2 is a top view of the portable traction device of FIG. 1; 
     FIG. 3 is an end view of the portable traction device of FIG. 1 illustrating a laterally adjustable neck support; 
     FIG. 4 is a side view of a patient utilizing the traction device of FIG. 1; 
     FIG. 5 is a schematic illustration of an exemplary pneumatic cylinder for use with a portable traction device; 
     FIG. 6 is a top view of an exemplary air pump; 
     FIG. 7 is a side view of the exemplary air pump of FIG. 6; 
     FIG. 8 illustrates an exemplary portable, lumbar traction device; 
     FIGS. 9 a - 9   c  illustrate a top, front and end view of an alternate portable lumbar traction device; 
     FIG. 10 illustrates a pneumatic cylinder configuration for use with a portable, lumbar traction device; and 
     FIG. 11 illustrates a hip gripping device for a portable, lumbar traction device. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIGS. 1 and 2 illustrate an exemplary portable, cervical traction device  20  in which a carriage  22  and slide portion  24  are allowed to move freely on a track  26  along a direction “S” (see also FIG.  3 ). The slide portion  24  includes a slide bracket  28  which engages with a piston rod  30  on a pneumatic cylinder  32  mounted underneath the track  26 . A lateral adjustment mechanism  38 , a head support pad  76 , and a pair of V-shaped neck supports  50 ,  52  (see FIG.  3 ), are mounted to the carriage  22 , which will be discussed in detail below. The pneumatic cylinder  32  is attached to the track  26  by an angle bracket  34 . An air line  40  is attached to an air inlet  42  at one end of cylinder  32  for providing pressurized air to the cylinder  32 . An alternate V-shaped neck support structure suitable for use in the present invention is disclosed in U.S. Pat. No. Re. 32,791 issued to Saunders on Nov. 29, 1988, which is hereby incorporated by reference. 
     The angle bracket  34  also serves the purpose of retaining the track  26  at an angle α relative to a support surface  36 . A removable stabilizer bracket  35  may optionally be added to prevent the support bracket  36  from lifting off of the support surface  36  during use. A pad  37  preferably is placed over the support bracket  36  for the comfort of the user. It will be understood that the length of the angle bracket  34  may be adjustable depending on the application of the portable traction device  20 . For example, the angle bracket  34  may be of a telescoping constructions. It will also be understood that the slide portion  24  may engage with the track  26  in a variety of configurations, and that the present invention is not limited to the specific embodiment disclosed herein. The track  26 , carriage  22 , and slide portions  24  are preferably constructed of a lightweight, low cost material, such as, for example, aluminum, steel, high density plastic, or a variety of composite materials. 
     FIG. 3 is an end view of the lateral adjustment mechanism  38  on the carriage  22 . Left and right neck supports  50 ,  52  form a V-shaped neck support structure that generally follows the contour of the base of the user&#39;s skull. The neck supports  50 ,  52  are attached to a pair of corresponding lateral slides  54 ,  56  on the carriage  22 . The lateral slides  54 ,  56  are engaged with the threaded shaft  58  by a pair of coupler nuts  60 ,  62 . The portion of the shaft  58  proximate coupler nut  60  has left-hand threads and the portion proximate coupler nut  62  has right-hand threads. The lateral position of the V-shaped neck supports  50 ,  52  is adjusted by turning the left and right knobs  70 ,  72 . The neck supports  50 ,  52  are ideally positioned around the patient&#39;s head so that they contact and follow the contour of the occipital bone at the base of the patient&#39;s skull, while the back of the patient&#39;s skull rests on the head support pad. 
     FIG. 4 illustrates a patient  78  utilizing the portable traction device  20  on a support surface  36 . It will be understood that the present portable traction device  20  may be used on a variety of support surfaces, such as for example, a floor, a table, or any other suitable surface. It will also be understood that the support surface  36  does not necessarily have to be horizontal and that it may be desirable to have an angled support surface for some types of traction. A support strap  77  may optionally be used to restrain the patient&#39;s head to the head support pad  76  during traction. 
     FIG. 5 is a schematic illustration of a single-acting pneumatic cylinder  32  for use with a present portable traction device. Piston  80  has a diameter “P” which is slightly smaller than the inside diameter “C” of the cylinder  32  so that a small gap  82  is formed between the piston  80  and inner surface  84  of cylinder wall  86 . A pair of slots  88 ,  90  extending around the outside perimeter of the piston  80  contain a pair of pressure activated seals  92 ,  94 . The seals  92 ,  94  are pre-shaped to form seal cavities  98 ,  100  facing upstream of the piston rod  30 . It will be understood that the seals  92 ,  94  and seal cavities  98 ,  100  may be a variety of shapes. 
     The seals  92 ,  94  are arranged so that as pressurized air  91  enters the air inlet  42 , and input chamber  97  is pressurized, a seal cavities  98 ,  100  are pressurized and the pressure activated seals  92 ,  94  are forced into engagement with the inside surface  84  of the cylinder wall  86 . In the exemplary embodiment disclosed herein, approximately 13.8 kPa (2 psi) is required to engage the seals  92 ,  94  with the inside surface  84 . Seal  94  is intended to capture blow-by air that passes the first seal  92 . The small gap  82  between the cylinder wall  86  and the piston  80  permits generally uniform circumferential pressurization of the seals  92 ,  94  against the inside surface  84  around the entire circumference, thereby enhancing sealing capabilities. The pressure activated seal of the present pneumatic cylinder  32  is capable of maintaining a static traction force of greater than 111 N (25 lbs.) for a period in excess of 10 minutes, and preferably, a static traction force of greater than 200 N (45 lbs.) for a period in excess of 20 minutes, without the need to supply additional pressurized air. 
     When the pressure in input chamber  97  is released, the seals  92 ,  94  disengage from the inside surface  84  and the piston  80  is allowed to move freely within the cylinder  32 . The pneumatic cylinder  32  may include spring or other resilient compression member  102  around the piston rod  30  to urge the piston  80  back toward the air inlet  42  when the compressed air  91  is released. Alternatively, a spring (not shown) may be positioned between the slide portion  24  and the track  26 . The compression member  102  preferably has a low spring forces so as to minimize the amount of force needed for the patient to activate the cylinder. 
     FIGS. 6 and 7 illustrate an exemplary air pump  120  for use with the present portable traction device  20 . The air pump  120  has a T-handle  122  attached at one end by a pivot point  124 . The T-handle  122  configuration offers ergonomic advantages over a standard straight pump handle. Alternatively, a straight handle may be substituted for the T-handle. An adjustable pressure regulator  126  may optionally be included in the pump  120  or cylinder  32  (see FIG. 1) so that over-pressure situations can be prevented. The other end of the air pump  120  includes a gauge  128 , which preferably is calibrated to read the actual amount of traction force being provided to the patient, rather than pounds per square inch. The pump, handle and gauge may be formed as a singled piece by an injection molding process. 
     A manual pressure relief mechanism  130  is also located proximate the gauge  128  for relieving the pressure in the pneumatic cylinder  32  when the treatment period is completed. Alternatively, the pressure relief mechanism (not shown) may be operated by rotating the gauge  128 . Air tube  40  is connected to the air pump  120  opposite the gauge  128 . A variety of pressure regulator configurations may be used in the present invention. For example, the pressure gauge  128  may include an internal pressure regulator. 
     To use the portable, cervical traction device  20 , it is placed on a suitable support surface  36 . The left and right knobs  70 ,  72  are rotated to allow the neck of the user to fit easily between the left and right neck supports  50 ,  52 . The slide portion  24  is moved down on the track  26  as far as possible by depressing pressure relief mechanism  130  (see FIG. 7) until cylinder  32  is at atmospheric pressure. 
     The back of the user is placed on the support surface  36  so that the neck is cradled by the neck supports  50 ,  52 . The neck supports  50 ,  52  should initially contact the user in the mid cervical region, midway between the tip of the earlobe and the top of the shoulder. The knobs  70 ,  72  are turned until the neck supports  50 ,  52  are moved firmly against both sides of the neck. The user&#39;s head is secured to the head support pad  76  by the support strap  77 . With the head support pad  76  under the shoulders, the user&#39;s head should be nearly aligned with the spine. 
     The user then slowly pumps air into the cylinder  32  using the air pump  120 . The configuration of the pump  120  permits a patient to simultaneously view the gauge  128  and operate the pump, while inclined in the portable traction device  20 . The gauge  128  allows the user to stay within the pressure/traction force guidelines provided by the health care provider. The patient increases the traction force by manually operating the pump  120  or decreases the traction force by manually pressing the pressure relief mechanism  130 . The neck supports  50 ,  52  are properly positioned when there is solid contact at the base of the head and the supports  50 ,  52  are positioned near the tip of the ear lobes. When the treatment is complete, the traction force is released by pressing and holding the pressure relief mechanism  130  on the air pump  120 . 
     FIG. 8 illustrates a portable, lumbar traction device  140  in which the pneumatic cylinder  32  is attached to a portable traction device  140 . The portable, lumbar traction device  140  includes a frame  150  retaining a support surface  152 . In a first embodiment, a pelvic belt  142  retains the patient&#39;s pelvis to a sliding portion  154 , which slides along track  156 . The pneumatic cylinder  32  mounted to the frame  150  is coupled to the sliding portion  154  so that the sliding portion  154  moves along the track  156 , creating a traction force “F” when the cylinder  32  is pressurized. A counter traction belt  148  provides a passive counter traction force on the patient&#39;s lower rib cage. The pneumatic cylinder  32  preferably maintains a static traction force of greater than 445 N (100 lbs.) for a period in excess of 10 minutes, and preferably, a static traction force of greater than 890 N (200 lbs.) for a period in excess of 20 minutes, without the need to supply additional pressurized air. It will be understood that two cylinders may be necessary to achieve a static traction force in excess of 445 N. 
     In a second embodiment, pelvic belt  142  is engaged with the pneumatic cylinder  32  by a cable  144  and pulley  146  configuration mounted at the foot of the portable traction device  140 . Counter-traction belt  148  provides a passive counter traction force on the patient&#39;s lower rib cage to restrain the patient in a fixed position relative to the portable traction device  140 . When the patient activates the pneumatic cylinder  32  as discussed above, the cable  144  is retracted, creating a traction force “F” on the waist belt  142  and the patient&#39;s pelvic region. In either of the above embodiments, the counter traction belt  148  may also be coupled to the pneumatic cylinder  32  to provide an active counter traction force in a direction opposite to “F” on the patient. 
     FIGS. 9 a - 9   c  illustrate an alternate embodiment of a portable, lumbar traction device  200  positioned directly on the support surface  36 . Upper body support platform  202  includes a frame  204  supporting a support surface  206 . A moveable head rest  208  is positioned on the surface  206 . Lower body support platform  210  has a support surface  214  slidably engaged with frame  212 . The surface  214  on the lower body support platform  210  slides in a direction “M” preferably about 0.15 meters under the force of a pair of pneumatic cylinders  32 ′ (see FIG.  10 ). The upper and lower body support platforms  202 ,  210  are connected by a hinge  215  to facilitate shipping and storage of the lumbar traction device  200 . 
     An adjustable rib gripping belt  216  is attached to the upper body support platform  202  to provide a passive counter traction force in a direction “C”. A pair of laterally adjustable hip gripping supports  218 ,  220  are connected to the surface  214  so that they move in the direction “M” with the surface  214 . The hip gripping supports  218 ,  220  are independently adjustable and curved to generally correspond to the shape of the user&#39;s waist, as will be discussed in connection with FIG.  11 . 
     FIG. 10 illustrates a segment of the frame  212  of the lower body support platform  210 . The piston rods  30 ′ of the pneumatic cylinders  32 ′ are engaged with the frame  210 . Cylinder heads  31 ′ are attached to sliding support structure  222  that supports surface  214 . Introduction of pressurized air through the air inlet  42 ′ moves the sliding support structure  222  and support surface  214  in the direction “M”. The operation of the cylinders  32 ′ is substantially as discussed above in connection with FIGS. 5-7. The pair of cylinders  32 ′ maintain a static traction force of at least 890 N (200 lbs.) for a period in excess of 20 minutes, without the need to supply additional pressurized air. 
     FIG. 11 illustrates a hip gripping device  230  for use with the portable, lumbar traction devices  20 ′ and  200  of the present invention. The hip gripping supports  218 ,  220  are shown in both the maximum and minimum lateral positions. In the exemplary embodiment illustrated in FIG. 11, the maximum and minimum lateral positions correspond to a distance of 0.50 m and 0.29 m, respectively. However, it will be understood that the hip gripping device may be modified to accommodate larger and smaller users. 
     The hip gripping supports  218 ,  220  include rigid curved members  234 ,  236  covered with padding material  232  for the comfort of the user. The curves generally follow the contour of the waist of the human body. Suitable padding material include high density foam, rubber or a variety of elastomeric materials. The rigid curved members  234 ,  236  include a pin  238  positioned to engage with receiving slots  244  on the top of the track  242  and a pin  240  positioned to engage with the bottom surface  241  of the track  242 . To adjust the hip gripping device  230 , the user rotates one or both of the hip gripping supports  218 ,  220  in the direction “R” so that the pin  238  disengages from the slots  244 . While in the rotated position, the hip gripping supports  218 ,  220  may be moved laterally along the track  242  to the desired location. Rotating the hip gripping supports  218 ,  200  in the direction opposite to “R” will engage the pin  230  with one of the slots  244 . The hip gripping supports  218 ,  220  may be completely disengaged from the track  242  by moving the pin  240  past the ends  246  of the track  242  near the cylinders  32 ′ and lifting the supports  218 ,  220  upward. It will be understood that the waist belt  142  of FIG. 8 may be substituted for the hip gripping device  230 . 
     To use the portable, lumbar traction device  200 , it is placed on a suitable support surface  36 . The hip gripping supports  218 ,  220  are positioned to firmly, but comfortably, engage the waist of the user. The support surface  214  of the lower body support platform  210  is moved upward toward the upper body support platform  202  as far as possible by depressing the pressure relief mechanism  130  (see FIG. 7) until cylinders  32 ′ are at atmospheric pressure. 
     The back of the user is placed on the support surface  206  so that the waist is cradled by the hip gripping supports  218 ,  220 . The hip gripping supports should initially contact the user midway between the bottom of the rib cage and the top of the pelvis. The user&#39;s chest is secured to the support surface  206  of the upper body support platform  202  by the rib gripping belt  216 . The head rest  208  should be placed under the user&#39;s head. The user then slowly pumps air into the cylinders  32 ′ using the air pump  120 , as discussed in connection with the portable, cervical traction device  20 . The hip gripping supports  218 ,  220  are properly positioned when there is solid contact with the top of the pelvis. 
     The present invention has now been described with reference to the several embodiments thereof. It will be apparent to those skilled in the art that many changes can be made in the embodiments described without departing from the scope of the invention. Thus, the scope of the present invention should not be limited to the structures described herein, but only by structures described by the language of the claims and the equivalents of those structures. For example, the present portable traction device may be arranged in a variety of configurations to facilitate traction to any part of the body.