Abstract:
An apparatus comprising: (a) a stationary base; (b) a drive assembly providing a drive member and means for reciprocating the drive member along a fixed linear path; (c) a femoral support extending between a first end connected to the base and a second end; (d) a tibial support extending between a first end connected to the second end of the femoral support and a second end; (e) a rigidly mounted, cantilevered femoral cradle slidably connected to the femoral support; (f) a rigidly mounted, cantilevered tibial cradle slidably connected to the tibial support; (g) a connecting member having an upper end connected to the tibial support second end and a lower end connected to the drive member; (h) a footrest structure mounted forwardly of the tibial cradle; and (i) the above elements arranged such that a person&#39;s leg is cyclically flexed and extended in response to reciprocation of said drive member.

Description:
FIELD OF THE INVENTION 
   The invention relates to an apparatus and method for supporting and continuously flexing a jointed limb; flexing of a leg and its knee joint being used by way of example. 
   BACKGROUND OF THE INVENTION 
   To avoid repetition of information, reference is made to the accompanying Information Disclosure Statement and to the prior art listed therein for background information. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of the apparatus showing cantilevered, slideably attached and rigid cradle supports arranged for receiving a right leg. 
       FIG. 2  is a fragmentary view of the drive portion of the apparatus of  FIG. 1  with the housing cover of the base unit removed to show the motor and associated drive elements of the apparatus. 
       FIG. 3  is an enlarged fragmentary view of the drive elements mounted via an internally threaded nut onto a drive screw. 
       FIG. 4  is a cross sectional view taken in the direction of line  4 - 4  of  FIG. 3  to show the drive elements. 
       FIG. 5  is a top plan view of the apparatus of  FIG. 1  showing the apparatus (in solid lines) when in its fully extended position and with the apparatus set up for flexing a person&#39;s right leg and (in dashed lines) when in its fully extended position with the apparatus set up for flexing a person&#39;s left leg. 
       FIG. 6  is a top plan view of the apparatus of  FIG. 5  when in its contracted position and set up for flexing a person&#39;s right leg. 
       FIG. 7  is a side elevation view of the apparatus of  FIG. 5  showing in dashed lines the placement of a person&#39;s upper and lower right leg in respective corresponding cantilevered cradles when the apparatus is in its fully extended position. 
       FIG. 8  is a side elevation view of the apparatus of  FIG. 6  showing in dashed lines the placement of a person&#39;s upper and lower right leg in respective corresponding cantilevered cradles when the apparatus is in the contracted position. 
       FIG. 9  is a block diagram of the overall control system for the apparatus of  FIG. 1 . 
       FIG. 10  is an enlarged fragmentary plan view of the control panel seen in  FIG. 9  and which in  FIGS. 1 and 5  is shown mounted on the femoral support member of the apparatus. 
       FIG. 11A  is a bottom perspective view of the femoral-cantilevered cradle and slide attachment to the femoral support member and illustrated for use by a person&#39;s upper right leg, and in dashed lines at the start of being rotated to the other side of the femoral support member for receiving a person&#39;s left leg. 
       FIG. 11B  is a bottom perspective view showing the femoral-cantilevered cradle of  FIG. 11A  after being positioned for receiving a person&#39;s upper left leg. 
       FIG. 12A  is a bottom perspective view of the tibial-cantilevered cradle and slide attachment as well as the foot support with swivel attachment and illustrated in position for receiving a person&#39;s lower right leg and right foot. 
       FIG. 12B  is a bottom perspective view of the tibial-cantilevered cradle assembly of  FIG. 12A  illustrating the first stage of the transition of the tibial cradle to the other side of the tibial support member wherein the footplate is rotated downward and the tibial cradle is rotated partway underneath the tibial support member. 
       FIG. 12C  is a bottom perspective view of the tibial-cantilevered cradle assembly of  FIG. 12A  illustrating the second stage of rotation of the tibial cradle during which the tibial cradle is rotated 180 degrees and positioned for receiving a lower left leg and with the foot plate set to swivel 180 degrees to the other side of the tibial cradle. 
       FIG. 12D  is a bottom perspective view of the tibial-cantilevered cradle assembly of  FIG. 12A  showing the third stage of rotation of the tibial cradle to the other side of the tibial support member wherein the footrest attachment member has been rotated 180 degrees to the other side of the tibial cradle to receive a person&#39;s left foot. 
       FIG. 12E  is an enlarged fragmentary perspective view showing the fourth stage of rotation wherein the footrest attachment member has been rotated 180 degrees to the other side of the tibial-cantilevered cradle (not shown) to receive a person&#39;s left foot and the footplate has been rotated upward 180 degrees to receive a person&#39;s left foot. 
       FIG. 13  is an exploded perspective view of the spring mounting arrangement of the footplate adjustment mounting apparatus. 
       FIG. 14  is a side view of the spring mounting arrangement seen in  FIG. 13  with one of its side plates removed. 
       FIG. 15  is a partial section view taken along line  15 - 15  of  FIG. 1  of the slide mechanism for the femoral-cantilevered cradle. 
       FIG. 16  is fragmentary plan view of the tibial-cantilevered cradle and foot plate attachment member showing the adjustability of the foot plate attachment member to swivel from one side of the tibial cradle to the other side as well as the ability of the foot plate and footplate support member to extend in line with the foot plate attachment member during changeover from one side of the apparatus to the other side. 
       FIG. 17  is a fragmentary plan view of the foot plate showing in dashed lines its ability to adjust from side to side. 
       FIG. 18  is a bottom plan view of the apparatus of  FIG. 1  showing the position of the stabilizing arms rotated underneath the base of the apparatus during transport. 
       FIG. 19  is a fragmentary view of the tibial support member and its associated tibial-cantilevered cradle illustrating an alternative embodiment with the addition of a tibial potentiometer. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The apparatus provides means for supporting and continuously flexing a jointed limb of a person for a measured period of time during which the jointed limb is flexed and extended, and is illustrated by way of example with the jointed limb being that of a human leg, which is moved through a plurality of cycles of motion. 
   The apparatus comprises the following principal elements: 
   (a) a rigid femoral cradle slidably supported on, pivotally connected around a single axis, and cantilevered outwardly from the femoral support member and on which rest the femoral portion of the jointed limb being flexed; 
   (b) a rigid tibial cradle slidably supported on, pivotally connected around two axes, and cantilevered outwardly from the tibial support member and on which rest the tibial portion of the jointed limb being flexed; 
   (c) a control arrangement mounted on the femoral support member in a location readily accessible to the user; 
   (d) an adjustable foot support uniquely constructed and mounted on the cantilevered tibial cradle so as to be able to slide lengthwise and rotate around an axis transverse of the tibial support member in coordination with movement of the tibial-cantilevered cradle; 
   (e) an arrangement of pivotal and rotatable mounts which in conjunction with the cradles and foot support referred to above facilitate use of the apparatus on either right or left limbs; and 
   (f) an arrangement which permits the upper and lower portions of a person&#39;s leg to be flexed while the respective leg portions remaining relatively stationary positions on respective slidable rigid cantilevered cradles. 
   Elements other than the principal elements referred to above will be described as the description proceeds. 
   Referring initially to  FIG. 1 , the apparatus  20  includes a main structural support element defined as a base element  21 . The femoral support member  26  has its lower end pivotally mounted by means of a pin  27  to the upper V-shaped end of a femoral base element attachment member  28  whose lower end is fixedly attached to the base element  21 . The upper end of the femoral support member  26  is pivotally linked by means of a pin  29  to the trailing end of tibial support member  34 . The leading end of tibial support member  34  is fixedly mounted by means of pins  35  and  36  onto the upper end of tibial base element attachment member  40 . The lower end of the tibial base element attachment member  40  is in turn formed with a pair of opposed mounting arms  41  and  42  which are pivotally attached via axially aligned pins  43  and  44  to driving element  50 . W 1  is the axis about which the femoral support member  26  rotates in relation to femoral base element attachment member  28 . W 2  is the axis of rotation about pin  29  in the connection between the femoral support member  26  and the tibial support member  34  wherein apparatus  20  extends and contracts. 
     FIG. 2 , showing the drive mechanism with housing cover  51  removed, illustrates driving element  50  mounted via an internally threaded nut  52  onto drive screw  53 . Driving element  50  is designed to move in both directions along the linear path of drive screw  53 , by operation of reversible motor  54 , in accordance with programmed input. The rotary motion of the drive screw  53  as generated by the motor  54  leads to both linear displacement of nut  52  and movement of driving element  50  along its linear path. Drive screw  53  is part of a drive mechanism that comprises both drive screw  53  and reversible motor  54 . Drive screw  53  is mounted for rotation about its longitudinal axis at the posterior end of the apparatus  20  by a rear bearing support  61  and at the anterior end of the apparatus by a forward bearing  62 . The drive screw  53  is linked through a flexible coupling  65  to reversible motor  54 . Reversible motor  54  is supported at one end by motor support  55  and also by its mounting to the base element  21 . 
     FIGS. 3 and 4  show the drive mechanism as contained within the housing cover  51 , and in the embodiment as illustrated in  FIG. 1  with a slotted brush screen  68  which allows the driving element  50  to move along the length of drive screw  53 . W 6  is the axis of rotation about which tibial base element attachment member  40  and its mounting arms  41  and  42  rotate in their connection with driving element  50  during contraction and extension of apparatus  20 . 
     FIGS. 5 and 6  illustrate, in top plan views of the apparatus, the transition from a fully extended position as in  FIG. 5  to a contracted position as in  FIG. 6 . The solid lines in  FIG. 5  for the femoral-cantilevered cradle  70  and the tibial-cantilevered cradle  80  illustrate the set-up for receiving a person&#39;s right leg and the dashed lines illustrate the set-up when the femoral-cantilevered cradle  70  and the tibial-cantilevered cradle  80  are rotated 180 degrees to the other side of the apparatus  20  for receiving a person&#39;s left leg. Also illustrated in  FIGS. 5 and 6  are the stabilizing arms  72  and  76  which are mounted so as to be able to rotate 180 degrees to the other side of the apparatus  20  depending on which side the femoral-cantilevered cradle  70  and tibial-cantilevered cradle  80  are located. Stabilizing arms  72  and  76  are shown in  FIG. 5  in solid lines for supporting the apparatus  20  when it is positioned for receiving a person&#39;s right leg and are shown in dotted lines in  FIG. 5  when they are rotated to the other side in correspondence with the apparatus being positioned for supporting a person&#39;s left leg.  FIG. 5  also shows a graduated scale  85  located on the top of the tibial support member  34 . The graduated scale  85  is used for measurement of the length of a person&#39;s leg and based on the gradation number  86  being for example 6 (see  FIG. 9 ) and corresponding to the person&#39;s leg size, that gradation number  86  ( FIG. 9 ) is input as one of a set of input control numbers ( FIG. 9 ) into the control panel  90  which is displayed on the top of the femoral support member  26 , as seen in  FIGS. 5 and 6 . 
     FIGS. 7 and 8  illustrate side views of the apparatus  20  supporting and flexing a person&#39;s right leg  22 , which is shown in dotted lines. As illustrated in  FIGS. 7 and 8 , both the femur and tibia of the patient are firmly held on the rigid femoral-cantilevered and tibial-cantilevered cradles  70  and  80  respectively, through the use of a soft covering such as sheepskin cushions  23  and the foot is held in place similarly with the use of a sheepskin cushion.  FIG. 7  shows the apparatus  20  at full extension and  FIG. 8  shows the apparatus  20  when contracted. In both figures it should be noted that the axis of rotation about the person&#39;s knee joint, illustrated by an “x” in both  FIGS. 7 and 8 , does not need to coincide with the pivotal axis of the apparatus  20 , which is the pivotal connection of the femoral support member  26  and the tibial support member  34  located at pin  29 . Once a patient&#39;s limb is set according to the appropriate gradation number  86 , for example 6 as in  FIG. 9 , the microprocessor  91  ( FIG. 9 ) ensures that this relationship of the patient&#39;s limb to the apparatus  20  is kept constant throughout its operation. In this way, the patient&#39;s knee is not compelled to follow the pivot of the apparatus  20  but instead follows its natural pivot point, and thereby avoids undue resistance and residual stress on the jointed limb. Apparatus  20  initially starts in its extended position as depicted in  FIG. 7  and from such position driving element  50 , during flexion, initially is driven towards motor  54 . This produces an increasingly acute angular rotation, herein referred to as “negative rotation,” of tibial support member  34  as shown in  FIG. 8 , and consequently also of tibial-cantilevered cradle  80 . Simultaneously, this negative rotation of tibial support member  34  produces a positive rotation, of the femoral support member  26 , and consequently of femoral-cantilevered cradle  70 . This in turn causes both an upward force to be applied to the upper leg and a downward force to be applied to the lower leg simultaneously and thereby the jointed limb flexes. When moving towards extension, as shown in  FIG. 7 , the reverse occurs; wherein the tibial support member  34  is positively rotated while the femoral support member  26  is negatively rotated. Appropriately, when apparatus  20  is moving towards limb extension, negative rotation of the femoral-cantilevered cradle  70  and positive rotation of the tibial-cantilevered cradle  80  causes both downward force on the upper leg and upward force on the lower leg to occur simultaneously and thereby the jointed limb extends. It should be noted that rendering upward force on the femoral-cantilevered cradle  70  and simultaneously rendering downward force on tibial-cantilevered cradle  80  while allowing femoral-cantilevered cradle  70  to slide as necessary along tracks  31   a  ( FIG. 1) and 31   b  (hidden in  FIG. 1 ) and allowing tibial-cantilevered cradle  80  to both slide along tracks  32   a  ( FIG. 1) and 32   b  (hidden in  FIG. 1 ) and rotate about a pivot axis as necessary in order to achieve limb flexion avoids the possibility of applying forces to the tibia that would cause it to move in an anterior direction relative to the femur (or anterior tibial translation), and thereby prevents undue stress on the anterior cruciate ligament (ACL). 
     FIG. 9  is the block diagram of the control system for the apparatus  20 . The contemplation of the present invention can involve a variety of electronics to provide input to the motor  54 . However, it is to be understood that this programmed input and the related electronics necessary for its use can be of any type that is capable of causing the drive screw  53  to rotate in a specified direction at a specified speed in coordination with controlling the amount of time the apparatus  20  operates, the degree of extension and contraction and according to the size of the leg of the person using the apparatus  20 . The electronic control system  92  illustrated by way of example consists of a user interface which in the preferred embodiment is a control panel  90  with user push button input and LED display, located on the top wall of femoral support member  26 . Control panel  90  allows the user to input various control options which are then sent to microprocessor  91 . In the control system  92 , being used by way of example, the user can set the following input controls on control panel  90 : time  93 , speed  94 , extension angle  95  and flexion angle  96 . In addition, two start/stop buttons  97   a  and  97   b  allow multiple access and control to start or stop the apparatus  20 , as well as a home button  98  to direct the apparatus  20  to fully extend and an extension pause button  106  to pause the apparatus  20  during the contraction or extension phase of its cycle. Microprocessor  91  monitors motor shaft encoder  99  to detect motor speed, motor current to detect load, and a potentiometer resistance to detect flexion angle  96  and extension angle  95 . A femoral angle input potentiometer  100 , mounted in the pivotal connection between femoral support member  26  and attachment member  28 , provides a resistance signal which is used to control the angle of contraction or flexion angle  101  of apparatus  20  (i. e., the angle measured by the extension of femoral support member  26  to the tibial support member  34 , as seen in  FIG. 8 ). Microprocessor  91  controls motor speed by varying the duty cycle of a 20 kilohertz, 5 volt pulse sent to motor controller  102 . Microprocessor  91  also controls direction by sending a high (i.e., +5 volt) or low (i.e., 0 volt) signal to motor controller  102 , which changes the direction of driving element  50  at the appropriate time by monitoring the potentiometer resistance from the femoral angle input potentiometer  100 . Microprocessor  91  also keeps time for the session and can be used, in the preferred embodiment, in a count down mode, but in alternate embodiments it can keep time in a count up mode. In the count down mode microprocessor  91  will stop the motion when time reaches zero. Electronic control system  92  is powered by power supply  103  which supplies power to motor controller  102 , motor shaft encoder  99 , reversible motor  54  and microprocessor  91 . In an alternate embodiment, tibial angle input potentiometer  152  (see  FIGS. 9 and 19 ) sends a signal to microprocessor  91  based on the rotation of cradle  80  around axis W 9  corresponding to the patient&#39;s knee angle. Tibial angle input potentiometer is added as an alternate means of calculating the knee angle as opposed to inputting the patient&#39;s leg size as measured on graduated scale  85  (see  FIG. 6 ). 
     FIG. 10  is an enlarged fragmentary plan view of control panel  90  which a patient or attendant can use to program various input parameters to adjust apparatus  20  to the patient&#39;s needs via touch pad controls. Other means of inputting the data are also envisioned for use on the apparatus  20 . Input parameters, by use of example, include time  93  in units of h:mm, extension angle  95  in degrees, flexion angle  96  in degrees, and speed  94  in terms of degrees/minute. Control panel  90  also has a leg size touch pad  104  for inputting the patient&#39;s leg size according to the gradation number  86  (for example  6  as shown in  FIG. 10 ) corresponding to the patient&#39;s leg size as measured against the graduated scale  85  on the top side of femoral support member  26  ( FIG. 5 ). Also included in this embodiment of the control panel are dual start/stop touch pads  97   a  and  97   b  to permit the patient or attendant to start or stop the apparatus  20  as well as a extension/flex pause touch pad  105  to direct the apparatus  20  to pause in the extension/flex direction and also a home touch pad  98  to cycle the apparatus  20  to assume the home position, which is the fully extended position. With each unique patient, the actual angular relationship between the tibia and the femur during operation may differ from the corresponding angular relationship between the femoral support member  26  and the tibial support member  34 . Therefore, in operation of apparatus  20 , it is necessary to know the relationship between these two angles, herein defined as flexion angle  101  so that a limiting angle may be specified in the programmed input. Flexion angle  96  is the angle created from the imaginary line drawn from the extension of the femoral support member, measured to the tibial support member  34  and is illustrated in  FIG. 8 . 
     FIGS. 11A and 15  illustrate how femoral-cantilevered cradle  70  for upper limb support is attached to the femoral support member  26  by means of a pivot and attachment assembly  110  via bolt  101 , nut  102  and washer  103 , allowing femoral-cantilevered cradle  70  to rotate 180 degrees about axis W 7  to the other side of femoral support member  26 . Axis W 7  is perpendicular to the plane of the bottom surface of femoral support member  26 . Femoral-cantilevered cradle  70  also is attached via the pivot and attachment assembly  110 , bolt  101  nut  102  and washer  103  to femoral slide mechanism  115 . Femoral slide mechanism  115  slides along tracks  31   a  and  31   b  by means of bolts  116   a ,  116   b  (not seen)  116   c ,  116   d  (not seen), and nuts  117   a ,  117   b  (not seen),  117   c , and  117   d  (not seen), allowing femoral-cantilevered cradle  70  to slide lengthwise alongside of and along a path parallel to and outwardly of femoral support member  26 .  FIG. 11A  illustrates the femoral-cantilevered cradle  70  for receiving a right upper limb and its dashed lines illustrate how femoral-cantilevered cradle  70  can start its rotation of 180 degrees clockwise about axis W 7  to the other side of femoral support member  26 , shown in  FIG. 11B , where it is set to receive a left upper limb. Femoral cradle stops  118  and  119  stop the rotation of femoral-cantilevered cradle  70  from rotating freely around 360 degrees of rotation.  FIG. 11B  illustrates femoral-cantilevered cradle  70  of  FIG. 11A  after rotation 180 degrees about axis W 7  and in place for receiving a left upper leg. 
     FIG. 12A  illustrates how tibial-cantilevered cradle  80  is attached to tibial support member  34  by means of pivot and attachment assembly  120  via bolt  121  and nut  122  allowing the cradle to rotate 180 degrees about axis W 8  to the other side of tibial support member  34  as shown in  FIGS. 12A through 12E . Axis W 8  is perpendicular to the plane of the bottom surface of tibial support member  34 . In addition, pivot and attachment assembly  120  allows tibial-cantilevered cradle  80  to pivot about axis W 9 . Axis W 9  is parallel to the plane of the bottom surface of tibial support member  34 . In  FIG. 12A , the tibial-cantilevered cradle  80 , footplate  125  and related assembly are positioned for receiving a patient&#39;s lower right leg and foot. Tibial-cantilevered cradle  80  is attached via pivot and attachment assembly  120 , bolt  121  and nut  122  to tibial slide mechanism  81  allowing rigid tibial-cantilevered cradle  80  to slide lengthwise alongside of and along a path parallel to and outwardly of tibial support member  34  along slide tracks  32   a  and  32   b . Bolts  82   a ,  82   b ,  82   c  (not shown), and  82   d  (not shown) and nuts  83   a ,  83   b ,  83   c , and  83   d  (not shown) position the tibial slide mechanism  81  within tracks  32   a  and  32   b  which allows for unrestricted reciprocal movement of the tibial-cantilevered cradle  80  along slide track  32   a  and  32   b . This mounting and sliding mechanism while not illustrated is like that illustrated in  FIGS. 11A and 15  for rigid femoral-cantilevered cradle  70 . Tibial-cantilevered cradle  80  is rotatably attached to pivot and attachment assembly  120  via coupling  46 , bolt  47  and spacer  48  and rotates about axis W 9 . This rotating attachment of tibial-cantilevered cradle  80  about axis W 9  allows for infinite adjustment of the patient&#39;s lower leg during contraction and extension. When a patient puts their lower leg into tibial-cantilevered cradle  80 , apparatus  20  allows for adjustment of footplate  125  by rotatably moving footplate support member  126  around a 360 degree arc around axis W 4 . By pulling plates  130  and  131  away from the ratcheting cog assembly  132  by a spring loaded mechanism (illustrated in  FIGS. 12E ,  13  and  14 ) the patient or attendant is able to rotate footplate support member  126  and footplate  125  in a 360 degree arc around axis W 4 . This allows for adjustment of the forward-rearward angle of the patient&#39;s foot/ankle. Another adjustment of the foot/ankle area is accomplished by adjusting the side-to-side position of the foot/ankle by moving the footplate  125  onto various footplate openings  132  around axis W 5  and then locking the selected opening onto screw  135 . Once the proper angle of footplate  125  is situated to the satisfaction of the patient, one can then release plates  130  and  131 , thereby locking the adjustment in place on the appropriate ratchet position of ratcheting cog assembly  132 . In summary, the tibial-cantilevered cradle  80  and associated footplate attachment member allow for infinite adjustment of the patient&#39;s lower leg by the following mechanisms: (1) slideably allowing for differences in dimension of a person&#39;s lower leg and adjustments during contraction and extension through tibial slide mechanism  81 ; (2) rotatably adjusting about axis W 9  for variations in supporting a person&#39;s lower leg during contraction and extension via pivot and attachment assembly  120 ; (3) rotatably adjusting about axis W 4  for various forward-rearward foot/ankle angles via ratcheting cog assembly  132 ; and (4) adjusting for various side-to-side foot/ankle angles by adjusting footplate  125  about axis W 5  onto various footplate openings  125   a  and locking the selection onto screw  135 . 
     FIG. 12B  illustrates how tibial-cantilevered cradle  80  is pivotally linked to sliding mount  81  via pivot and attachment assembly  120  so that tibial-cantilevered cradle  80  is able to rotate clockwise 180 degrees around the axis of pivot and attachment assembly  120  and nut  127  and bolt  121  and stop via tibial cradle stops  107  and  108 . Footplate  125  and footplate support member  126  are rotated 180 degrees downward so that they can clear tibial support member  34  during the  180  degree rotation of tibial-cantilevered cradle  80  to the other side of tibial support member  34 . 
     FIG. 12C  illustrates how footplate attachment member  134  is rotated 180 degrees on axis W 3  around tibial-cantilevered cradle  80  so that it can be in position for receiving a patient&#39;s left foot after the transition to the other side. Tibial-cantilevered cradle  80  is now locked in position via tibial cradle stops  107  and  108 . 
     FIG. 12D  illustrates the positioning of footplate support  134 . It has now been rotated 180 degrees about axis W 3  to the other side of tibial-cantilevered cradle  80 .  FIG. 12E  illustrates how spring-loaded plates  130  and  131  are pulled back to allow upward rotation of footplate support member  126  and footplate  125  about axis W 4 . Plates  130  and  131  are then released locking footplate support member  126  and footplate  125  in place on the ratcheting cog assembly  132 . Footplate  125  can be adjusted side to side about axis W 5   
     FIG. 13  is an exploded view of spring-loaded plates  130  and  131 . Plates  130  and  131  are joined by bolts  136 ,  137 ,  138 , and  139  (hidden) and nuts  140 ,  141 ,  142  and  143 . Rollers  144 ,  145 ,  146  and  147  allow plates  130  and  131  to slide forward and backward on footplate attachment member  134 . Pins  148 ,  149 , and  150  align plates  130  and  131  and pin  149  provides compression of spring  151  when the assembly is pulled backward.  FIG. 14  illustrates how pin  150  locks in place in the ratcheting cog assembly  132  and thereby locking in place footplate  125  and footplate support member  126 . 
     FIG. 15  is a partial section view of the slide mechanism for the femoral-cantilevered cradle  70 . Femoral slide mechanism  115  slides along tracks  31   a  and  31   b  via bolts  116   a ,  116   b  (hidden),  116   c , and  116   d  (hidden) and nuts  117   a ,  117   b  (hidden),  117   c  and  117   d  (hidden). 
     FIG. 16  is a fragmentary plan view of the tibial-cantilevered cradle  80  and foot plate attachment member  134  showing the adjustability of the foot plate attachment member  134  to swivel from one side of the tibial-cantilevered cradle  80  to the other side as well as the ability of the foot plate  125  and footplate support member  126  to extend in line with the foot plate attachment member  134  during changeover from one side of the apparatus  20  to the other side. 
     FIG. 17  is a fragmentary plan view and illustrates how footplate  125  is able to adapt to different foot configurations and can be fixed at various angles of rotation about axis W 5  perpendicular to tibial-cantilevered cradle  80  by adjusting screw  135  in one of the various footplate openings  125   a.    
     FIG. 18  is a bottom plan view of apparatus  20  and illustrates how the stabilizing arms  72  and  76  can be positioned for transport. Stabilizing arms  72  and  76  can be rotated 180 degrees around base element  21  by means of pivots  73  and  77  respectively to provide support during CPM of either a right or left leg. Stops  74   a  and  74   b  stop the rotation of stabilizing arm  72  and stops  78   a  and  78   b  stop the rotation of stabilizing arm  76 . Bumper pads  75   a ,  75   b  and  79   a  and  79   b  provide cushioning stability when the apparatus  20  is positioned on a supporting surface. 
     FIG. 19  is a fragmentary bottom view of the tibial support member and its associated tibial-cantilevered cradle illustrating an alternative embodiment with the addition of a tibial angle input potentiometer  152 . Tibial angle input potentiometer  152  is added as an alternate means of calculating the knee angle, as opposed to the use of the graduated scale  85  (see  FIG. 6 ). In the first embodiment, graduated scale  85  is used to determine the patient&#39;s leg size, which is then input as one of the data elements into the control panel  90  (see  FIG. 9 ) so that microprocessor  91  can adjust the movement for the size leg supported by apparatus  20 . In the alternate embodiment, tibial angle input potentiometer  152  works in conjunction with femoral angle input potentiometer  100  to input to microprocessor  91  for direct calculation of the user&#39;s leg size without needing the user to input such data.