Abstract:
A lightweight, foldable device for the partial weight bearing during walking and gait training is provided. The lightweight, partial weight bearing suspension walker is made from two frames that are pivotally attached and can be folded at the pivot point for storage or transport. The apparatus can be adjusted to fit over wide treadmills or wheelchairs and through narrow doors. The apparatus includes two fail-safe lift and support devices to insure patient safety in case of unintentional release by the operator.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   This application is entitled to the benefit and filing date of Provisional Patent Application 60/574,420 filed May 26, 2004. Applicant claims priority to Provisional Patent Application 60/574,420 filed May 26, 2005 pursuant to 35 USC paragraph 119e. 

   STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
   Not Applicable 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a device for gait training for a walking impaired patient. More specifically the instant invention relates to a lightweight, foldable device that can partially support the weight of a patient while walking and can be adjusted wide enough to fit over treadmills or wheelchairs and can be adjusted narrow enough to fit through standard doorways. 
   2. Discussion of Related Art 
   Partial weight bearing gate trainers or unweighting systems are used by medical personnel during physical therapy to improve the mobility of the patient to regain strength and range of motion. These units are generally used over treadmills or on flat surfaces in a medical office. Most of these units use a system of ropes or webbing combined with a harness to lift the patient and lower the amount of weight the patient places upon their legs. The patient can then walk on a treadmill with their weight being partially relieved by the device allowing earlier physical therapy during rehabilitation. These units are most often used in large institutional settings where a dedicated space is available to operate and store the unit. 
   Current units are often large, heavy pieces of equipment designed for institutional use in large medical facilities. The devices are normally used by patients while walking on a treadmill since the weight and the associated rolling friction of the devices makes them difficult to use on a smooth floor. The units that are more mobile still require an assistant to help the unit roll since the weight of the unit plus the patient&#39;s weight make it difficult to roll unaided. The need to constantly guide and assist the patient slows the necessary regaining of the sense of balance for the patient. 
   Those prior art units are difficult to transport and require the complete disassembly of the equipment and transport by truck or van. Moving a unit often requires two or three people to disassemble and carry the parts to the truck and reassemble them at the next facility. Many units are necessarily wide to insure fitting over a treadmill or wheelchair but are often too wide to fit through most standard doorways. 
   Today many rehabilitation facilities are much smaller in size and have the need of a compact unit that can be easily stored and transported between facilities or rooms. Patients are given instructions to do exercises away from the rehabilitation facility, creating the need for a unit that is lightweight, foldable and easy to transport to and from the facility in the back of a minivan or car by one person. 
   What is needed is a lightweight, easily portable device that can be made wide enough to fit over wheel chairs or treadmills yet can made narrow enough to roll through a standard doorway. The unit must be light enough that it can easily roll on smooth floors without momentum effects overpowering the patient. It must be compact when stored yet stable and safe when fully assembled. It should be easy to assemble and disassemble by one person and be light enough to be carried by hand. It also needs to fail-safe when raising or lowering the patient to insure that it is impossible to drop a patient during use of the equipment. 
   BRIEF SUMMARY OF THE INVENTION 
   This invention provides an apparatus that can carry the partial weight of a patient during rehabilitation while walking on a treadmill or while walking on a floor with the device alone. The device is structurally strong enough to lift a patient yet light enough to be carried by one person. The invention folds to a smaller size for storage and transport and can be folded or unfolded by one person. 
   The invention can be used as a partial weight bearing walker due to its low mass and its minimal momentum effects. The device has wheels that can lock as a brake for use when lifting a patient out of a wheelchair or for use over a treadmill. The wheels can be locked to roll in one direction only for added stability when used as a suspension walker alone. The invention has a winch lifting system for lifting the patient to a standing position and for adjusting the amount of weight the patient bears on his/her legs. The preferred embodiment of the invention has a centrifugally activated failsafe mechanism that automatically stops the fall of the patient due to winch or rope failure or operator error while operating the winch. The device is also width adjustable and can be widened or narrowed to fit over treadmills or wheelchairs or through narrow doorways. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an overall view of the partial weight bearing suspension walker. 
       FIG. 2  is a view of the top of the partial weight bearing suspension walker. 
       FIG. 3  is an overall view of the partially folded partial weight bearing suspension walker. 
       FIG. 4  shows a view of the walker in use. 
       FIG. 5  shows details of a second embodiment of the device. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1  shows a preferred embodiment of the weight bearing suspension walker  100 . The forward frame  1  is pivotally attached to rear frame  2  with fasteners such as bolts at pivoting point  3 . Forward frame  1  and rear frame  2  may also be pivotally attached with ball and socket joints, rods and clevis pins or other means such as are known in the arts to attach frames, tubing or bars in such a manner so to allow them to pivot in the same plane. Forward frame  1  has large diameter braking casters  10  attached to the bottom ends of each leg  1   a ,  1   b  of frame  1 . The braking casters  10  swivel and can be braked to stop all rolling movement of the invention. Rear frame  2  has large diameter directional casters  11  attached to the bottom ends of each leg  2   a ,  2   b  of rear frame  2 . The directional casters  11  swivel and can be locked in any steering direction compared to frame  2 . Both braking casters  11  and directional casters  12  are attached to smaller diameter tubing that slides into forward frame  1  and rear frame  2 , respectively. The directional casters  11  and braking casters  10  are interchangeable and may be attached to forward frame  1  and rear frame  2  in different combinations as required for the patients use in alternate embodiments of the invention. Casters  10  and  11  can be raised or lowered by sliding the small diameter tubing into or out of forward frame  1  and rear frame  2  and then attaching by bolts or pins in place. Forward frame  1  and rear frame  2  are preferred to be made from flexible large diameter anodized aluminum tubing although other materials and shapes may be used. 
   Forward frame  1  can be pivotally attached to left lower frame  4  at left lower pivot joint  13  with bolts as shown in  FIG. 1 . Forward frame  1  can be pivotally attached to right lower frame  5  at right lower pivot joint  21  with bolts. Both left lower frame  4  and right lower frame  5  may be pivotally attached to forward frame  1 . Left lower frame  4  and right lower frame  5  are attached to the lower portion of rear frame  2  with quick release pins as are known in the art, at attachment points  8  and  7 , respectively. Releasing the quick release mechanisms at attachment points  8  and  7  allow the device to fold into a much smaller space.  FIG. 3  shows the invention partially folded with the frames  4  and  5  detached from the rear frame  2 . 
   The forward portions of right lower frame  5  and left lower frame  4 , as shown in  FIG. 1 , are attached to each other with bolts and wing nuts or threaded knobs at attachment points  6  by a plurality of holes through each frame. The plurality of holes through each frame allows the width of the invention to be adjusted to fit over a treadmill or wheelchair or through most doorways. Forward frame  1  and rear frame  2  flex in the width dimension enough so that the width of the device can be changed solely by relative adjustment of the position of right lower frame  5  to left lower frame  4 . The upper portions of the forward  1  and rear frame  2  near the flat guide bar  18  and rear flat attachment bar  19  remain at a constant width that defines the narrowest possible width of the walker  100 . Once the width has been adjusted by changing the position of right lower frame  5  and left lower frame  4  then the frames are locked in position with a bolt through one of the plurality of holes in both frames and a threaded knob. The relative positions may also be locked in position with other means as are known in the art such as a snap pin. Folding bar linkage  9  attaches to the upper portion of forward frame  1  and rear frame  2  just below pivoting point  3 . Folding bar linkage  9  prevents forward frame  1  and rear frame  2  from expanding too far when the invention is taken from a folded position to a fully assembled standing position. Folding bar linkage  9  is designed to keep the positions of forward frame  1  and rear frame  2  in the approximate positions needed to reattach right lower frame  5  and left lower frame  4  to attachment points  8  and  7 , respectively, when unfolding the invention. 
   Winch  12  is attached to the right lower third of rear frame  2  in  FIG. 1 . Winch  12  is preferred to be a hand crank model for weight savings with a safety pawl that will stop the winch movement when the operator releases the handle. Such manual winches are known in the art and are used where the danger of unintentional release of a winch is hazardous. Rope  15  is wound around winch  12  and attached to left rope  23  and right rope  22  using swages designed for rope. The ropes could also be attached with knots or by other methods as are known in the art. Though described here as rope it will be understood that cable would also work instead of rope. 
     FIG. 2  shows the preferred embodiment of the topmost portion of the invention. Left rope  23  leads through left rear pulley  24  then through left front pulley  26  and is attached to left carabineer  16 . Right rope  22  leads through right rear pulley  17  then through right front pulley  27  and is attached to right carabineer  25 . Left rear pulley  24  and right rear pulley  17  are attached to the right corner of rear flat bar  19 . Rear flat bar  19  is attached to rear frame  2  at the topmost portion of frame  2 . Left front pulley  26  and right front pulley  27  are attached to the topmost opposite corners of front frame  1 . Left centrifugal seat belt mechanism  14  is mounted on the left corner of rear flat bar  19 . Right centrifugal seat belt mechanism  29  is mounted on the right corner of rear flat bar  19 . Left webbing  20  runs from left centrifugal seatbelt mechanism  14  over the top of forward frame  1  and between forward frame  1  and front flat bar  18 . Right webbing  30  runs from right centrifugal seatbelt mechanism  29  over the top of forward frame  1  and between forward frame  1  and front flat bar  18 . Front flat bar  18  is attached to the left and right corners of forward frame  1  with spacers to allow webbing to feed between forward frame  1  and front flat bar  18 . The distal ends of left rope  23  and left webbing  20  are attached to carabineer  16 . The distal ends of right rope  22  and right webbing  30  are attached to carabineer  25 . The patient is placed in a harness, H ( FIG. 4 .), such as are known in the art, and attached to the invention at carabineer  16  and carabineer  25 . 
   Cranking the winch handle  31 , in  FIG. 1 , offloads the weight of the patient by increasing the tension in rope  15 , left rope  22  and right rope  23  shown in  FIG. 2 . Left centrifugal seat belt mechanism  14  and right centrifugal seat belt mechanism  29  insures that if the winch  12  should fail then the patient&#39;s weight would be picked up by left webbing  20  and right webbing  30 . The centrifugal seat belt mechanisms  14  and  29  normally allow belts  20  and  30  to wind onto or to be drawn off reels  14   a  and  29   a  to lower the harness H, but if the winch  12  fails the belts  20  and  30  will begin to pull out rapidly as the patient begins to fall. This rapid belt  20 , 30  motion will cause centrifugal force in said reels  14   a  and  29   a , which will cause the reels  14   a  and  29   a  to stop. Centrifugal sensing mechanisms such as pawls or clutches are well known in winding a reeling and so are not shown here. 
   It is further pointed out that the invention is very lightweight and is easy to roll due to the efficient design. Forward frame  1  and rear frame  2  comprise the structural supports that both support the patient and lead to wheels that carry the offloaded weight to the ground. Forward frame  1  and rear frame  2  are both the structural lifting supports and the rolling base frame and eliminate the need for a separate base frame to carry the offloaded weight. The elimination of a separate base frame lowers the weight of the device, decreasing rolling friction and momentum. Decreased friction and momentum makes the invention easier to use for a physically impaired patient while undergoing gate training. This lighter weight and lower momentum make the invention available for use as a partial weight bearing walker over the floor alone or over a treadmill. 
   The redundant fail-safe mechanisms insure the patient&#39;s weight cannot be unintentionally released causing the patient to fall. Winch  12  has a pawl that will stop it from moving when it is released. Furthermore, centrifugal seat belt mechanisms  29  and  14  will stop downward motion when the speed of belts  20  and  30  are fast enough to engage the centrifugal clutch. The combination of the safety release on winch  12  and centrifugal seat belt mechanisms  29  and  14  insures that if the operator of the invention were to release the winch and the safety pawl were to fail then the patient&#39;s downward motion would be stopped by centrifugal seat belt mechanisms  14  and  29 . Ropes  22 ,  23  and  15  normally carry the offloaded weight of the patient. In the unlikely failure of either rope  15 ,  22  or  23 , then centrifugal seat belt mechanisms  14  and  29  would activate and belts  20  and  30  would carry the offloaded weight of the patient. This double redundancy is a novel feature not present in other gate training devices. 
   Disconnecting left lower frame  4  and right lower frame  5  from rear frame  2  allows the invention to be folded into a compact space. No tools are required to fold the invention for transport or storage or expand the invention for use. The novel use of forward frame  1  and rear frame  2  as both the patient load carrying part of the device and the base frame eliminates the need for a large and heavy base frame. The simple but unique arrangement of forward frame  1  and rear frame  2  allows the walker  100  to be folded into a small package without assembling a separate base frame. Furthermore, the walker  100  is very stable during expansion for normal use from a folded position. Folding bar linkage  9  limits the amount that forward frame  1  and rear frame  2  may spread during assembly and keeps the walker  100  in the approximate correct position for the attachment of quick release pins at attachment points  7  and  8 . 
   The width of the invention may be expanded or contracted as needed. Left lower frame  4  and right lower frame  5  may be moved inboard or outboard and bolted with wings nuts or threaded knobs at a single attachment point  6 . Forward frame  1  and rear frame  2  flex in the width dimension enough so that the width of the device can be changed solely by relative adjustment of the position of right lower frame  5  to left lower frame  4 . Once the width has been adjusted by changing the position of right lower frame  5  and left lower frame  4  then the frames  4  and  5  are locked in position with a bolt through one of the plurality of holes in both frames and a threaded knob. The ability to quickly change the width of the invention at will lets the invention be used over a larger range of conditions than other devices. The invention can be expanded to fit over wide wheelchairs or treadmills. It can be placed over a wide wheelchair or bed to raise the patient into an upright position yet made narrow enough so the patient can walk through a doorway under his or her own power. This novel width adjustment feature is very important for home use where one unit would be required to do a variety of tasks during the rehabilitation of a patient. 
     FIG. 4  shows the walker  100  in use with a patient harness H attached to carabineers  16  and  25 . The generally ‘U’ shaped forward frame  1  has been spread out such that the distance between each of the front wheels  10  is greater than the width of a treadmill T. The distance between the rear wheels  11  is also adjustable. The forward frame  1  width is adjusted by changing the attachment point  6  to achieve a wider setting of lower right 5 and left 4 frames. The forward frame  1  and rear frame  2  are sufficiently flexible to allow for the single point of adjustment. This single attachment point  6  adjustment is helpful if a patient must use a treadmill several times a day and yet may require the walker  100  to be set to the narrower setting to get through a door for example. The flexibility of the tube frames  1  and  2  allow for the use of a single point to adjust the width and yet provide a structure rigid enough to support the weight of a patient. The upper width of the walker at flat bars  18  and  19  remains constant. The center of gravity of the patient&#39;s weight, X, is below the flat bars  18  and  19  and can be adjusted using the winch  12  to raise or lower the center of gravity X. 
     FIG. 5  shows the winch  212  portion of a second embodiment of the walker  200 . The walker  200  is the same as the first embodiment walker  100  except that the winch  212  is motorized. A motor  202  can control the cable  215  to control the harness H position. The motor  202  can raise or lower the harness H by coiling or uncoiling cable  115  from a shaft  217 . A switch  219  can control the direction of rotation of the motor  202  and shaft  217 . The motor  202  can include a locking brake  204  that will prevent motion of the cable  215  when the motor  202  is not turning and anytime power is lost to the motor  202 . 
   It will be obvious to those skilled in the art that modifications may be made to the embodiments described above without departing from the scope of the present invention as defined by the appended claims and their equivalents.