Abstract:
A selectively lockable orthotic joint is provided that in one embodiment includes at least one pressure sensor and an electronic circuit associated with the pressure sensor for generating or providing a control signal indicative of pressure, force or other value sensed by the sensor. A mechanical orthotic joint is provided that has a locking mechanism that can be selectively locked and unlocked in response to the control signal.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This is a continuation of U.S. patent application Ser. No. 09/398,332, filed Sep. 17, 1999, now U.S. Pat. No. 6,517,503, which claims the benefit under 35 U.S.C. §119 (e) of U.S. Provisional Application Serial No. 60/101,084, filed Sep. 18, 1998. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates generally to orthoses for providing assistance in walking. More particularly, the present invention relates to an improved knee joint for such an orthosis. 
     An orthosis is a brace or other orthopedic device that is applied to a segment of a human body for the purpose of assisting in the restoration or improvement of its function. Orthoses can provide assistance in walking to persons having any of several types of walking disability. One known type of orthosis is a knee/ankle/foot orthosis which controls the motion and alignment of a knee and an ankle when a person attempts to walk. Such orthoses can be made of molded plastic materials or of metal and leather parts. Various knee and ankle joints can be added to achieve the desired function. 
     Typical reasons for wearing such an orthosis include stroke, brain injuries, spinal cord injury and post-polio treatment. A person who is not able to move his leg in a functional manner to ambulate, must wear a knee/ankle/foot orthosis to stabilize his leg and allow for ambulation. It has been found that for people with weak knee joints, a locking mechanism is necessary in order to lock a calf supporting orthosis to prevent movement in relation to a thigh supporting orthosis, thereby allowing the person to walk, albeit stiff legged. 
     There are many types of knee joints used on such orthoses. However, all the known joints which lock during ambulation are manual. In other words, when a patient is using the orthosis, he has a choice of walking with his leg locked in extension or in a free swing. If the patient chooses the locked position, he is forced to walk stiff legged. However, for some people, flexing at the knee during walking would result in a buckling of the person&#39;s leg. Therefore, walking stiff legged is much preferable to being not able to walk at all. Of course, a movement of the calf orthosis in relation to the thigh orthosis is necessary when the person decides to sit down. 
     As far as is known, there are no knee joints currently on the market which have the ability to automatically lock and unlock without direct manual patient intervention. 
     Accordingly, it has been considered desirable to develop a new and improved orthosis knee joint which would overcome the foregoing difficulties and others while providing better and more advantageous overall results. 
     BRIEF SUMMARY OF THE INVENTION 
     In accordance with the present invention, there is provided an orthosis for assistance in walking. 
     More particularly in accordance with this aspect of the invention, the orthosis includes an orthosis system which comprises a foot plate including at least one pressure sensor that senses the pressure exerted by a patient&#39;s foot on the foot plate, a circuit connected to at least one pressure sensor in the foot plate and a knee joint which is selectively locked and unlocked by the circuit. To this end, the knee joint is electrically operated. 
     More particularly mechanical orthotic joint of the selectively lockable orthotic joint invention includes an energizable electromagnetic coil, a spring washer deflectable in an axial direction when the electromagnetic coil is energized and an arrangement of first and second plates. The first plate has a face or an operative surface composed of a plurality of spaced teeth. The second plate also has a face or an operative surface having a plurality of spaced teeth that are complementary to the plurality of spaced teeth of the first plate. The second plate is mounted so that it is deflectable in an axial direction such that the plurality of spaced teeth of the second plate can engage the plurality of spaced teeth of the first plate when the electromagnetic coil is energized. The engagement of the first and second plates locks movement of the orthotic joint in at least one direction when the first and second plates are engaged. 
     More particularly, the mechanical orthotic joint of the selectively lockable orthotic joint invention includes an energizable electromagnetic coil, a spring washer is deflectable in an axial direction when the electromagnetic coil is energized and an arrangement of first and second plates. The first plate has a face or an operative surface composed of a plurality of spaced teeth. The second plate also has a face or an operative surface having a plurality of spaced teeth that are complementary to the plurality of spaced teeth of the first plate. The second plate is mounted so that it is deflectable in an axial direction such that the plurality of spaced teeth of the second plate can engage the plurality of spaced teeth of the first plate when the electromagnetic coil is energized. The engagement of the first and second plates locks movement of the orthotic joint in at least one direction when the first and second plates are engaged. 
     In accordance with one embodiment, the first and second plates are complementary and each comprise ratchet plates allowing the orthotic joint to move only in one direction when the joint is in a locked position. More specifically, in one embodiment, when unlocked the orthotic joint is movable in a flexion direction and an extension direction and when the orthotic joint is locked, it is movable only in the extension direction. 
     The first and second plates may comprise a low hysteresis magnetic material. 
     In accordance with another aspect of the present invention, a method for selectively locking and unlocking an orthotic joint is provided. One embodiment locks the orthotic joint to permit movement only in the extension direction. 
     In accordance with the method, an orthotic joint of the type previously described is utilized. Pressure is sensed by the pressure sensor and an electronic control signal is generated with the electronic circuit that is indicative of pressure sensed by the pressure sensor. In response to the electronic control signal, the orthotic joint locks through its locking mechanism. 
     One advantage of the present invention is the provision of a knee joint which allows patients, who are currently walking stiff legged with a locked knee joint in a knee/ankle/foot orthosis, to walk with a more normal gait. 
     Another advantage of the present invention is the provision of an orthosis which will make sitting and standing much safer and easier for any patient forced to manually unlock his knee joint. 
     Still another advantage of the present invention is the provision of an orthosis system which senses the pressure placed by a patient&#39;s foot on a foot plate of the orthosis and can automatically trigger a knee joint of the orthosis to lock and unlock. The knee joint will be locked when pressure is placed by the patient&#39;s foot on the foot plate. It will be unlocked when the patient&#39;s foot no longer exerts pressure on the foot plate. 
     In accordance with another aspect of the invention, a selectively lockable orthotic joint is provided. The selectively lockable orthotic joint includes an electronic circuit for providing at least one control signal indicative of a value. At least one mechanical orthotic joint is provided that includes a locking mechanism that is in communication with the circuit. The locking mechanism can be selectively locked and unlocked in response to the control signal. The control signal provided by the electronic circuit can originate from a variety of sources other than by sensing pressure or weight. For example, the control signal can originate from EMG signals in leg muscles, from EEG signals, from a sensor that detects distance between the ground and the bottom of a shoe or other article, such as a cane, for example. In addition, a controller could be provided for operation by the user, such as a joy stick or other type of switch in order to generate or otherwise provide the control signal for locking and/or unlocking the locking mechanism of the mechanical orthotic joint. 
     Still other benefits and advantages of the invention will become apparent to those of average skill in the art upon a reading and understanding of the following detailed specification. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention may take physical form in certain parts and arrangements of parts, a preferred embodiment of which will be described in detail in this specification and illustrated in the accompanying drawings which form a part hereof and wherein: 
     FIG. 1A is a side elevational view in cross section along line  1 A— 1 A of FIG. 13 of a knee joint according to the present invention in an unlocked condition; 
     FIG. 1B is a side elevational view in cross section of the knee joint of FIG. 1A in a locked condition; 
     FIG. 2A is a top plan view of the toroidally shaped housing of the joint of FIG. 1A; 
     FIG. 2B is a cross-sectional view taken along line  2 B— 2 B of FIG. 2A; 
     FIG. 3A is a top plan view of a bottom ratchet plate of the knee joint of FIG. 1A; 
     FIG. 3B is a side elevational view in cross section along line  3 B— 3 B of FIG. 3A; 
     FIG. 4A is a bottom plan view of a top ratchet plate of the knee joint of FIG. 1A; 
     FIG. 4B is a side elevational view in cross section along line  4 B— 4 B of FIG. 4A; 
     FIG. 5A is a top plan view of the top end portion of the knee joint of FIG. 1A; 
     FIG. 5B is a side elevational view in cross section taken along line  5 B— 5 B of FIG. 5A; 
     FIG. 6 is a top plan view of an inner retaining ring of the knee joint of FIG. 1A; 
     FIG. 6A is a cross-sectional view along lines  6 A— 6 A of FIG. 6; 
     FIG. 7 is a top plan view of the retaining cap of the knee joint of FIG. 1A; 
     FIG. 7A is a cross-sectional view along line  7 A— 7 A of FIG. 7; 
     FIG. 8 is a top plan view of an outer retaining ring of the joint of FIG. 1A; 
     FIG. 9 is a top plan view of a spring washer of the joint of FIG. 1A; 
     FIG. 10 is an exploded perspective view of components of the knee joint of FIG. 1A; 
     FIG. 11 is a circuit diagram of a circuit which is employed with the knee joint of FIG.  1 A and the force or pressure sensor of FIG. 12; 
     FIG. 12 is a perspective view of the force or pressure sensor employed with the joint of FIG. 1A; 
     FIG. 13 is a perspective view of an orthosis in accordance with the invention incorporating the joint of FIG.  1 A and the sensor of FIG. 12; 
     FIG. 14 is a fragmentary perspective exploded view of an alternate embodiment joint in accordance with the invention; and 
     FIG. 15 illustrates a cross-sectional schematic view of a portion of the alternate embodiment of FIG.  14 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings wherein the drawings are for purposes of illustrating a preferred embodiment of the invention only and not for purposes of limiting same, FIGS. 1A and 1B,  10  and  13 , for example, show a knee joint  10  which is used in an orthosis  10 ′ or orthopedic appliance, for example in FIG.  13 . It is evident that two such knee joints would need to be employed for the two legs of a patient, one joint for each leg of the patient. Perhaps, even four knee joints could be used, one on either side of the knee of each leg of the patient. It is to be understood that joint  10  could be used other than as a knee joint, for example. 
     Joint  10  includes a toroidally shaped housing  12 . Toroidally shaped housing  12  is depicted individually in FIGS. 2A and 2B. With reference now to FIGS. 2A and 2B, the toroidally shaped housing  12  has an inner wali  14 , a base wall  16  and an outer wall  18  which together define a cavity  20 . A plurality of spaced teeth  22  protrude upwardly from the inner wall  14 . Preferably, eight such teeth are provided, although any suitable number of teeth can be utilized. A continuous flange  24  extends upwardly from the outer wall  18 . A rib  26  extends radially inwardly from the inner wall  14  into a central opening  28  to form a toroidal ledge  26 ′ approximately half way up the height of the inner wall. 
     With reference again to FIGS. 1A and 1B and  10 , an electromagnetic coil  30  is located in cavity  20 . Electromagnetic coil  30  is formed around a plastic bobbin  32 . Positioned on either side of rib  26  are a first bearing  34  and a second bearing  36 . The bearings can be conventional roller bearings or other suitable bearings, as desired. A bottom ratchet plate  38  is also provided for the knee joint. Bottom ratchet plate  38  is depicted in greater detail FIGS. 3A and 3B. Bottom ratchet plate  38  includes a planar bottom surface  40 , as illustrated in FIG. 3B, and a top face  42  having a plurality of radially extending spaced teeth  44  protruding therefrom. As is evident from FIG. 3A, sixty such teeth  44  are preferably located on the top face  42  with each tooth being spaced from the adjacent teeth by slots, although any suitable number of teeth can be utilized. Preferably, the teeth  44  are cut in a saw tooth pattern radially at a 30 degree slope. A set of eight spaced slots  46  are cut into the bottom ratchet plate  38 . The slots extend radially outwardly from a central opening  48  of the plate  38  as is evident from FIG.  3 A. 
     The joint of FIGS. 1A and 1B is further provided with a top ratchet plate  50 , which is shown in more detail in FIGS. 4A and 4B. Top ratchet plate  50  is preferably constructed of a magnetically soft material, for example a low hysteresis, solenoid quality magnetic stainless steel. Bottom plate  38  may be constructed of similar material. With reference now to FIG. 4A, top ratchet plate  50  includes a top face  52  (FIG. 4B) and a bottom face  54 . A plurality of spaced teeth  56  are cut into the bottom face  54 . Preferably sixty such teeth are provided. As with the bottom plate  38 , the teeth  56  in the top plate are cut in a saw tooth pattern radially at a 30 degree slope such that a tip of each tooth is separated from a tip of each adjacent tooth by 6 degrees. The teeth  56  of the top ratchet plate are meant to be and should be of suitable design and number to engage and mesh with the teeth  44  of bottom ratchet plate  38  when the two ratchet plates are brought into contact with each other. Also provided on top ratchet plate  50  is a slot  58  which circumscribes the teeth  56 . A plurality of spaced apertures  60 ′ extend through top ratchet plate  50 . These apertures are positioned radially outwardly of slot  58 . As is evident from FIGS. 1B and 10, suitable fasteners  60  can extend into the top ratchet plate apertures. 
     With reference now to FIGS. 1A,  1 B and  10 , a shaft  62  is also provided. As shown in FIGS. 5A and 5B shaft  62  includes a stem portion  64  and an enlarged top end  66  having a set of spaced apertures  68  extending therethrough. Note that in FIGS. 5A and  5 B, the diameter of flange  66  is illustrated smaller than the diameter illustrated in the other figures. A bottom end of the stem portion  64  is provided with a centrally located aperture  70 . Each of these apertures accommodates suitable fasteners  60  and  61 . Referring to FIGS. 1A and 1B, also provided is an inner retaining ring  72 . As detailed in FIG. 6, inner retaining ring  72  has a central aperture  72 ′ for accommodating stem portion  64  and includes a set of apertures  74  extending therein. Each of apertures  74  is also meant to accommodate a suitable fastener  60 . A retaining cap  76  is also provided. As shown in FIGS. 7 and 7A, retaining cap  76  has a centrally extending aperture  78  for accommodating a suitable fastener  61 . Fasteners  60  and  61  can be threaded fasteners or any other suitable type of fastener, for example. 
     Joint  10  is also provided with an outer retaining ring  80 . As shown in FIG. 8 a set of apertures  82  extend through retaining ring  80  to accommodate suitable fasteners  60 . As shown in FIGS. 1A,  1 B,  9  and  10 , a spring washer  84  is further provided. Spring washer  84  is preferably comprised of a plurality of very thin pieces of metal which, when assembled, is very compliant in an axial direction while maintaining a high rigidity in torsion. For example, spring washer  84  may consist of approximately 60 pieces of 0.001 inch thick stainless steel disks. The axial compliance allows the spring washer to be deflected at relatively low electromagnetic forces allowing the upper ratchet plate to mesh with the lower ratchet plate. Spring washer  84 , further depicted in FIG. 9, has a set of outer apertures  86  for accommodating a suitable first set of fasteners  60  and a set of inner apertures  88  similarly for accommodating a suitable second set of fasteners  60 . Spring washer  84  also has a central opening  90  to accommodate stem portion  64  of shaft  62 . 
     Spring washer  84  is very compliant in the axial direction, permitting deflection of upper ratchet plate  50  even with relatively low electromagnetic attraction forces, typically deflecting about {fraction (1/16)} th  of an inch in an axial direction with an electromagnetic force of several pounds. Thus, the significant axial deflection that is obtained with low electromagnetic forces permits operation of joint  10  at low power consumption levels which is important for battery-operated use. Spring washer  84 , however, is strong and stiff in torsion, providing the necessary reaction torque to support the moments required in an orthotic application. Any suitable washer that performs the function of spring washer  84  can be utilized in accordance with the invention. 
     As is evident from FIGS. 1A,  1 B and  10 , shaft  62  is located in central opening  28  of toroidally shaped housing  12 . Retaining cap  76  is fastened to shaft  62  by fastener  61 . In this way, two bearings  34  and  36  can be secured in place in central opening  28  of housing  12 . Bottom ratchet plate  38  is seated on inner wall  14  of housing  12 . To this end, several spaced slots  46  in bottom ratchet plate  38  accommodate several spaced teeth  22  in housing  12 . More particularly, eight slots  46  and eight teeth  22  are provided in housing  12 . It is apparent that no keying is necessary since bottom ratchet plate  38  can be rotated in relation to the housing to any desired extent so long as the slots  46  are aligned with teeth  22 . 
     Top ratchet plate  50  is positioned above bottom ratchet plate  38 . In the condition illustrated in FIG. 1A, top ratchet plate  50  is spaced from bottom ratchet plate  38 . This allows a movement of joint  10  in either rotational direction (flexion or extension). In the position illustrated in FIG. 1B, the teeth of top ratchet plate  50  engage the teeth of bottom ratchet plate  38  to prevent any further rotation of the joint. Preferably, the two ratchet plates are spaced from each other as indicated when in the unactuated state as shown in FIG.  1 A. 
     With reference again to FIG. 1A, spring washer  84  is fastened to flange  66  of shaft  62  via inner retaining ring  72 . Spring washer  84  is also fastened to top ratchet plate  50  and outer retaining ring  80  by fasteners  60 . In this way, top ratchet plate  50  is normally spring-biased away from bottom ratchet plate  38 . However, top ratchet plate  50  is pulled into contact with bottom ratchet plate  38  when electromagnetic current is flowing through electromagnetic coil  30 . 
     With reference now to FIG. 11, a circuit  100  which includes an integrated circuit  100 ′, which can be a Microchip Model No. PIC16C715, is employed to control the operation of joint  10 . The integrated circuit is preferably powered by a pair of 3 volt batteries  102  and  104 . Electromagnetic coil  30  is preferably powered by a pair of 1.5 volt batteries  106  and  108 . 
     With reference now to FIG. 12, an insole pressure or foot force sensor  110  is also used in connection with the joint  10 . More particularly, a set of output lines  112  lead from a set of sensors  114  in the insole to circuit  100 . Batteries  102  and  104  provide a reference signal for the sensors. A pair of output lines  116 ′ from circuit  100  extend to the electromagnetic coil  30 . The pair of 1.5 volt batteries  106  and  108 , which are of relatively higher power than the power of the 3 volt batteries, are meant to power the electromagnetic coil. 
     Insole pressure sensor  110  is preferably provided with five sensors which detect pressure by a voltage drop across very thin resistors, for example the foot force sensor provided by Cleveland Medical Devices, Inc. It should be apparent to one skilled in the art that more or less sensors may be used. The insole is slipped inside a patient&#39;s shoe. The signal from the insole is translated through wires  112  to circuit  100 . Integrated circuit  100 ′ also contains a programmable microprocessor. Any suitable microprocessor can be utilized. The processor determines a threshold level and sends a signal to the joint  10  attached to a knee joint as depicted in FIG.  13 . However, the joint need not be limited to a knee joint, but may also be an ankle, wrist or elbow joint. Any suitable pressure or force sensor can be used in accordance with the invention. 
     With the orthosis of the present invention, when a person puts his foot on the floor, the sensors  114  in insole sensor  110  sense a pressure and can trigger the joint  10  to lock by energizing electromagnetic coil  30  thereby bringing the top ratchet plate  50  down into contact with bottom ratchet plate  38  engaging respective teeth  56  and  44 . Preferably, this action prevents any further rotation of the joint in one rotational direction, however, this may lock the joint entirely from rotating. More particularly, top ratchet plate  50  and shaft  62  cannot rotate via bearings  34  and  36  in relation to bottom ratchet plate  38  and housing  12  toward a bent knee position. Preferably, when the teeth of the upper and lower ratchet plates are engaged, the joint allows incremental slip (ratcheting) in a joint extension. However, when no more pressure is sensed by sensors  114  of the insole sensor  110 , circuit  100  will unlock the knee joint by ceasing the flow of electric current in the electromagnetic coil. 
     Once this occurs, spring washer  84  will pull top ratchet plate  50  out of engagement with bottom ratchet plate  38 . This will allow a rotation of the knee joint in both directions. In particular, top ratchet plate  50  and shaft  62  are again capable of rotating in relation to bottom ratchet plate  38  and housing  12 . Thus, the joint is unlocked when pressure of the patient&#39;s foot is no longer exerted on the insole sensor  110 . This invention will allow a user who is currently wearing stiff legged knee/ankle/foot orthoses to walk with a more normal gait. In addition, it will make sitting and standing safer and easier for any user currently forced to manually unlock their knee joint. 
     When a threshold level is reached, a magnetic field is generated by electromagnetic coil  30  to pull top ratchet plate  50  into engagement with bottom ratchet plate  38 , no longer allowing the two ratchet plates to rotate freely in relation to each other. This locks the knee joint and prevents it from bending into flexion. However, the joint will still allow extension. As an example, if the patient is attempting to stand and gets stuck halfway up, the joint will block flexion and prevent the patient&#39;s knee from buckling. But, it will still ratchet into extension and allow the patient to continue moving vertically. Thus, a very important advantage of the present invention is the provision of a knee joint in which flexion is prevented when the top ratchet plate  50  meshes with bottom ratchet plate  38  but extension is still allowed. This is accomplished due to the orientation of the meshing teeth  44  and  56  of the bottom and top ratchet plates  38  and  50 . 
     As a second example, a user, when he takes a step, will have the insole read the floor contact and lock the knee for the user. The knee remains locked through the step and then unlocks when the user initiates swing through, i.e. takes the pressure off the first leg and puts the pressure on the second leg. The knee joint will then lock again at the next initial floor contact. 
     Sensors  114  could be wired in series or in parallel for the signal which is sent through wires  112  to circuit  100 . Preferably, the output of all of sensors  114  is summed together. If a set point is reached, electromagnetic coil  30  is triggered and the knee joint is locked. However, the logic of the chip on the integrated circuit could be programmed to differentiate between, e.g. a heel strike and a toe strike of the foot plate. The logic of the circuit may also provide that given patterns of pressure, for example placing pressure on only inner or outer pressure sensors, detected by the sensors could disengage the teeth in the joint permitting an individual to sit. 
     Joint  10  according to the present invention can be attached to any conventional knee/ankle/foot/elbow/wrist orthosis or any knee brace as long as the brace is fabricated to the joint size specification. A person skilled in the art should realize that the orthotic joint of the present invention supports passive locking arrangements wherein the joint is locked until the coil is magnetized which unlocks the joint as opposed to the active locking embodiment of the joint as described above. 
     FIGS. 14 and 15 illustrate an alternate embodiment of an electronically controlled orthotic joint according to the present invention. This embodiment as shown in FIGS. 14 and 15 provides an electromagnetic coil  118  located within a housing  120 . Actuating portion  122  is provided as well as opposing teeth inserts  124  and  126 . Engagement of the teeth inserts  124  and  126  is actuated by energizing coil  118 . The coil is energized under control of a microprocessor (not shown) as in the above embodiment. Energizing the coil produces an axial force on actuating portion  122  which forces teeth insert  124  into engagement with teeth insert  126 . In this embodiment, a passive spring (not shown) causes the teeth of teeth inserts  124  and  126  to disengage upon interruption of current through coil  118 . This embodiment can also provide for incremental slip in a single rotational direction as desired. Further, teeth inserts  124  and  126  are constructed of non-magnetic material so that they may be made of a more durable material, for example tool steel. This embodiment also provides a spline interface (not shown) between outer support ring  130  and actuating element  122 . This spline interface is on the internal surface of outer support ring  130  and the external surface of actuating element  122 . This spline interface permits axial translation of actuating element  122  while enabling large torques to be transmitted from outer support ring  130  to actuating element  122 . This arrangement permits application of large torques from outer support ring  130  to the opposite outer support ring  128  as follows. Torques are transmitted from element  130  to element  122  via the spline interface. Torques are thus transmitted from actuator element  122  to teeth insert  124 , which is fastened rigidly to element  122 . When engaged due to actuation (axial translation of element  122 ), teeth insert  124  meshes with teeth insert  126  enabling transmission of torques that oppose knee flexion. Teeth insert  126 , rigidly fastened to housing  120 , transmits torques to housing  120  via its fasteners. Finally, housing  120 , which is rigidly fastened to outer support ring  128 , transmits torque to outer support ring  128  via fasteners (not shown). In this manner, torques can be transmitted from support arm  132  of outer support ring  130  to support arm  134  of the opposite outer support ring  128 . Support arms  132  and  134  provide a convenient structure to mechanically interface the locking mechanism to orthotic bracing. One skilled in the art should recognize that an equal and opposite torque is transmitted to outer support ring  128  and support arm  134  in a similar manner. 
     FIG. 14 depicts how joint  117  is integrated into an orthotic device. Outer support rings  128  and  130  house joint  117 . As shown in FIG. 14, joint  117  is comprised of an electromagnetic coil  118 , housing  120 , actuating portion  122 , and teeth inserts  124  and  126 . The outer support rings are constructed of non-magnetic metallic material. Outer support ring  130  has an attached support arm  132  which attaches to a limb portion of a patient. Similarly, outer support ring  128  has a support arm  134  that attaches to the same limb portion of a patient as support arm  132 , but joint  117  is aligned with the patient&#39;s joint which is to be supported. 
     While the invention has been described with respect to certain preferred embodiments, as will be appreciated by those skilled in the art, it is to be understood that the invention is capable of numerous changes, modifications and alterations that are within the scope of the appended claims.