Abstract:
A joint hinge and a leg brace having the joint hinge that includes a spring loaded spherical joint for coupling a proximal portion and a distal portion of the joint hinge. The spherical joint includes a dome on one portion coupled to a mating cup on the other portion. A wide-headed pin, typically a shoulder screw, captivates the cup against the sphere. A spring washer may be included to provide a preloading force to mate the cup to the dome. The spherical portion may be pressed or stamped into one portion of the hinge or fabricated separately and attached. In one embodiment, the dome is fabricated of sintered bearing material and may be impregnated with lubricant. The spherical joint functions in conjunction with an adjustable flexion range limiting system that include rods that are threaded and easy to screw in and out as the patient&#39;s range of motion changes.

Description:
BACKGROUND 
   1. Field of the Invention 
   The present invention relates generally to the field of orthotic devices and more particularly to ankle foot orthoses with a flexion control ankle hinge apparatus, system and method. 
   2. Background of the Invention 
   Present ankle joints for leg braces can offer control of plantar flexion and dorsiflection as shown in U.S. Pat. No. 6,929,614 issued Aug. 16, 2005 to Jackovitch, which is incorporated herein by reference. However, these and other prior art ankle joints are often difficult to install, requiring precisely parallel mounting surfaces for medial and lateral joint mechanisms. Without proper mounting the joints may be subject to greater wear, binding, and stress on the leg brace components, leading to cracks and possible failure. Achieving proper installation requires additional shimming or shaping or remaking of the leg brace components, taking extra time for the practitioner and potentially leading to extra complication and cost for the patient. 
   Devices that offer plantar flexion control include devices that are bulky and difficult to fit in the patient&#39;s shoe, and are difficult to adjust due to the fact that they include definite settings that can only be adjusted in increments. Other devices require separate pieces, such as range of motion keys, which must be inserted and replaced as the patient&#39;s range of motion increases or decreases. Often these devices are large and cause additional complications with smaller patients, such as pediatric patients. 
   Thus, there is a need for an ankle joint that can be fitted to a leg brace and automatically accommodates slight misalignment of leg brace components and non parallelism of mounting surfaces while providing for plantar flexion limits. The ankle joint should be compact in size allowing potential use with pediatric patients. 
   BRIEF DESCRIPTION OF THE INVENTION 
   Briefly, the present invention relates to a joint hinge and a leg brace having the joint hinge that includes a spring loaded spherical joint for coupling a proximal portion and a distal portion of the joint hinge. The spherical joint includes a dome on one portion coupled to a mating cup on the other portion. The spherical dome presents a spherical surface for contacting the mating cup, the spherical surface consisting of a portion of a hemisphere less than a full hemisphere. A wide headed pin, typically a shoulder screw, captivates the cup against the sphere. A spring washer may be included to provide a preloading force to mate the cup to the dome. The spherical portion may be pressed or stamped into one portion of the hinge. In one embodiment, the dome is fabricated of sintered bearing material and may be impregnated with lubricant. 
   The spherical joint functions in conjunction with an adjustable flexion range limiting system that include rods that are threaded and easy to screw in and out as the patient&#39;s range of motion changes. In a typical embodiment, a proximal plate rotates about the spherical joint with respect to a distal plate. The spherical joint is generally aligned with the patient&#39;s ankle axis. The range limiting system&#39;s rods screw toward and away from a portion of the proximal plate, thereby limiting the range of the proximal, and therefore, the distal plates. The proximal plate is connected to one portion of the leg brace and the distal plate is connected to the other portion of the leg brace. 
   One aspect of the invention features a flexion joint apparatus incorporated into a leg brace, including a proximal plate having an upper end and a lower end, a distal plate connected to the proximal plate and an anterior-posterior range limiting system, including a tongue connected to the second end of the proximal plate, and two tongue-stops connected to the distal plate at a generally perpendicular orientation, wherein each of the tongue-stops includes a threaded hole through which a threaded rod is connected to the tongue-stops in threaded engagement. 
   In another aspect, the apparatus further includes a conduit located on the distal plate and partially surrounding each of the threaded rods. 
   In yet another aspect, the apparatus includes leg brace connection points located on the proximal and distal plates, each leg brace connection point, comprising a generally circular-shaped base surrounding a hole. 
   In another aspect, the invention features a flexion joint apparatus, including a proximal plate having a tongue protruding from an end of the proximal plate, a distal plate having a protrusion connected generally perpendicular to each side of the distal plate, wherein the tongue of the proximal plate overlaps a portion of the distal plate and travels a path along the distal plate, each end of the path terminating in a respective one of the protrusions. 
   In still another aspect, the invention features a flexion joint apparatus, including a body including a proximal plate having a tongue and distal plate having a protrusion on either side of the distal plate and means for limiting the relative motion of the proximal plate with respect to the distal plate. 
   In another aspect, the invention features a method of installing an ankle joint in a leg brace, including pouring the cast, modifying the cast, mounting a dummy ankle joint having fixed range of motion, vacuum forming plastic on the cast, cooling the plastic and removing the brace. 
   One advantage of the invention is that the joint hinge tolerates misalignment and nonparallel mounting surfaces with respect to the leg brace, simplifying and speeding the fabrication and fitting process. 
   A further advantage of the invention is that the ankle joint assembly is compact in length and width and thin in the rotation axis dimension, generating minimal interference with the patient&#39;s shoes and allowing use with smaller patients, such as pediatric patients. 
   Another advantage of the invention is that the range of motion of the joint hinge and therefore a leg brace can be easily set by the patient or practitioner. 
   Another advantage of the invention is that a range limiting system allows the patient or practitioner to set a continuum of settings to meet the individual needs of a patient. 
   Another advantage of the invention is that the threaded rods in the range limiting system are set in the anterior and posterior directions. 
   Other advantages, features, and capabilities of the invention will become apparent from the following description taken in conjunction with the accompanying drawings showing the preferred embodiment of the invention. 

   
     BRIEF DESCRIPTION OF THE FIGURES 
     The present invention is described with reference to the accompanying drawings. In the drawings, like reference numbers indicate identical or functionally similar elements. 
       FIG. 1A-D  illustrate respective front and side views of the constituent components of an embodiment of a flexion control ankle hinge apparatus; 
       FIG. 2  illustrates a front view of an embodiment of a flexion control ankle joint hinge assembly using the components of  FIG. 1A-FIG .  1 D; 
       FIG. 3  illustrates an exploded side view of the assembly of  FIG. 2 . 
       FIG. 4A-FIG .  4 C illustrate the assembled side view and illustrate different bends for the ends of the embodiment of  FIG. 3 . 
       FIG. 5A  illustrates a separate component forming the dome of the cylindrical connection. 
       FIG. 5B  illustrates a formed embodiment for the dome of the cylindrical connection. 
       FIG. 6  illustrates an embodiment of a leg brace having an embodiment of flexion control ankle joint hinge apparatus connected to the brace. 
       FIG. 7A  illustrates a rear view of the embodiment of the leg brace of  FIG. 6  showing a misalignment angle accommodated by the invention. 
       FIG. 7B  illustrates a top view of the embodiment of the leg brace of  FIG. 6  showing a misalignment angle accommodated by the invention. 
       FIG. 8  illustrates a cross section view of a fabrication model showing the conformal shaping of a leg brace. 
       FIG. 9  shows a molding dummy ankle joint for the fabrication model of  FIG. 8 . 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The present invention pertains to an ankle joint providing rigid vertical support, allowing free ankle rotation within adjustable plantar and dorsiflexion limits while allowing angular misalignments that simplify fabrication and adjustment of a leg brace utilizing the ankle joint. The ankle joint results in a compact assembly easily adapted to smaller patients, including pediatric patients. These capabilities are achieved by an ankle joint comprising a proximal and distal plate joined by a spring loaded spherical dome hinge. The spherical dome is formed in one component, typically the distal plate, and a mating recess is formed in the other component, typically the proximal plate. The assembly is held together by a captive screw and spring wave washer. The distal plate further includes a rotation range limiting mechanism including dorsiflexion and plantar flexion limit adjustments. These features may be better understood with reference to the figures. 
     FIG. 1A-FIG .  1 D illustrate respective front and side views of the constituent components of an embodiment of a flexion control ankle hinge apparatus  100 . The apparatus  100  typically includes a proximal plate  105  and a distal plate  150 . The distal plate  150  typically includes a dome feature  228  for coupling to the proximal plate  105 . The proximal plate  105  typically includes a recess  224  for receiving the dome  228  of the distal plate  150 . A captive screw  220  and wave washer  222  hold the dome  228  and surface of the recess  224  in contact and insure connection of the proximal  105  and distal  150  plates. 
   The proximal plate  105 , which is comprised of an upper end  106  and lower end  107 , typically includes one or more brace connection points  108  that are used in conjunction with a leg brace as described further below with respect to a flexion control ankle joint hinge system. One of the brace connection points  108  is typically located at the upper end  106  of the proximal plate  105 . Another brace connection point  108  is typically positioned between the upper and lower ends  106 ,  107 . The brace connection points  108  are typically wider than the overall width of the proximal plate  105  and may have a generally circular-shaped base  109 . A hole  110  is also located approximately in the center of each base  109  of the connection points  108 . The proximal plate  105  further includes a distal plate connection point  111  positioned adjacent the lower end  107 . The distal plate connection point  111  includes a recess  224  formed to mate with the dome  228  of the distal plate. The recess  224  includes a through hole  226  to accommodate a shoulder screw  220  and wave washer  222  captive device. 
   The proximal plate  105  also includes a tongue  115  connected to the lower end  107  of the proximal plate  105 . The tongue  115  is a protrusion and is generally narrower than the overall width of the proximal plate  105 . In one embodiment, the tongue is slightly thicker than the remainder of the proximal plate. The tongue  115  is part of the overall range limiting system that is discussed further in the description below. 
   The proximal plate and tongue may include chamfering or contouring of the edges to allow greater range of motion in lateral directions. 
   Referring to  FIG. 1B  and  FIG. 1C , as shown in the side view of the proximal plate  105 , the upper and lower ends  106 ,  107  of the proximal plate  105  are offset from each other due to a gradual curvature of the proximal plate  105 . A portion of the lower end  107  is elevated slightly with respect to the upper end  106 . A bend, causing the overall curvature, in the proximal plate  105  typically achieves this elevation differential. As described further below, when the distal plate  150  and proximal plate  105  are connected, this elevation differential results in the upper end  106  of the proximal plate  105  and the distal plate  150  being oriented in a similar positional plane. 
   The distal plate  150  generally includes an upper end  151  and a lower end  152 . The upper end  151  of the distal plate  150  includes a proximal plate connection point  155 . The proximal plate connection point  155  generally includes a smooth outer curvature  158  that generally follows the resulting path of curvature of the proximal plate  105  with respect to the distal plate  150  when the two are attached and move with respect to one another. The proximal plate connection point  155  generally includes a dome feature  228  raised from the surface of the distal plate  150  in the direction of the proximal plate  105 . The dome feature  228  includes a threaded hole  230  through the top of the dome for receiving the captive screw  220 . The dome  228  may be fabricated as in at least two embodiments, a formed embodiment as shown in  FIG. 1D  and a separate component as described later below with reference to  FIG. 5A . 
   The lower end  152  of the distal plate  150  typically includes two brace connection points  160 . Similar to the brace connection points  108  of the proximal plate  105 , the brace connection points  160  of the distal plate  150  have a generally circular-shaped base  161 . A hole  162  is also located approximately in the center of each base  161  of each brace connection point  160 . 
   The distal plate  150  further includes a tongue-stop  170  on each side of the distal plate  150 , located generally between the upper and lower ends  151 ,  152 . The tongue-stops  170  are typically a small plate protrusion generally perpendicular to the overall surface of the distal plate  150 , although other angles are anticipated. Each of the tongue-stops  170  includes threaded holes  171  through which the threaded rod  175  is typically connected in threaded engagement. The threaded rods may include nylon or similar inserts to maintain friction contact to prevent movement of the adjustment once the proper setting is established. Alternatively, a thread locking compound may be used to set the thread position. The tongue-stops  170  are part of the overall range limiting system that is discussed further in the description below. A conduit  180 , if provided, may be located on a portion of the distal plate  150  adjacent the tongue-stops  175 . The conduit  180  is generally oriented to receive the threaded rods  175  as the rods  175  transverse through the holes  171  on the tongue stops  170  as they are screwed into and out of the tongue stops  170 . Since the threaded rods  175  are not typically oriented in opposition, the conduit  180  typically bends, thereby generally changing the direction of the conduit  180 , at an approximate center location of the distal plate  150 . In other embodiments, the threaded rods  175  can be oriented in opposition and, therefore, the conduit  180  can be in a continuous straight line. 
   As shown in the side view of the distal plate  150 , the upper and lower ends  151 ,  152  of the distal plate  150  are offset from each other due to a gradual curvature of the distal plate  150 . A portion of the lower end  152  is curved slightly with respect to the upper end  151 . As described further below, when the distal plate  150  and proximal plate  105  are connected, this elevation differential results in the upper end  106  of the proximal plate  105  and the lower end  152  of the distal plate  150  being oriented in a similar positional plane. 
   The apparatus  100  further includes several screws  190  that can be used to connect the apparatus  100  to a leg brace to form an overall brace system. In general, the screws  190  can be used to engage the holes  110 ,  162  in the brace connection points  111 ,  160  of the proximal and distal plates  105 ,  150  respectively. The holes  110 ,  162  can include threads so that the screws  190  can be in threaded engagement with the screws  190 . The apparatus  100  can further include an external adjustment instrument, such as a hex wrench which can be used to adjust the threaded rods  175  within the holes  171  of the tongue-stops  170  as part of the overall range limiting system. The apparatus  100 , the screws  190  and the adjustment instrument can be included together as an overall leg brace kit. 
     FIG. 2  illustrates a front view of an embodiment of a flexion control ankle joint hinge apparatus  100 . The apparatus  100  generally includes the proximal plate  105  and a distal plate  150  that are pivotally connected to each other. The connected proximal and distal plates  105 ,  150  make up a main body in which the proximal and distal plates  105 ,  150  pivot with respect to each other. The front view shows the connection point connecting the proximal and distal plates allowing rotation while accommodating misalignments. Also shown is the rotation limit tongue and adjustment screws. 
   With the component pieces assembled in this manner, the distal and proximal plates  105 ,  150  remain connected to each other. The plates  105 ,  150  can pivot with respect to each other about an axis generally aligned with the captive screw  220  and the plates may rotate by traversing along the surface of the dome along axes generally perpendicular to the captive screw. The captive screw  220  and spring wave washer  222  maintain contact between the proximal  105  and distal  150  plates and prevents the component pieces from coming disassembled. 
   The range limiting system is mentioned shortly in the above description with respect to the tongue  115  and the tongue-stops  170 . The range limiting system is now described with respect to the assembled flexion control ankle joint hinge apparatus  100 . In the assembled state, the tongue  115  generally pivots above the surface of the distal plate  150  as the proximal plate  105  is rotated with respect to the distal plate  150 . The range of movement of the tongue  150  generally follows the path of the conduit  180  on the distal plate  150 . By following the general path of the conduit  180 , the tongue  115  is limited in its outward motion by coming into contact with the tips  176  of the threaded rods  175  as they sit in a portion of the conduit  180  when in threaded engagement with the tongue-stops  170 . With the threaded rods  175  removed or screwed outward to a point so that the tips of the rods  175  do not protrude from the inner portion of the tongue-stop protrusions  170 , the tongue  115  generally moves in its widest range of motion. The outer motion of the tongue  115  is limited when its contacts the tongue stops  170 . In this orientation, the maximum outward motion of the apparatus  100  is defined. In an opposite extreme, the threaded rods  175  can be screwed inward to their maximum inward position, in which the tips  176  of both the threaded rods  175  contact the tongue  115  at the same time, thereby allowing no motion of the tongue  115  to occur. The threaded rods  175  can be adjusted slightly to still keep the tongue  115  and therefore the proximal plate  105  from rotating with respect to the distal plate  150  and to allow the proximal plate  105  to be oriented in a fixed position with respect to the distal plate  150 . As shown in the figures, the threaded rods  175  are oriented in the anterior and posterior directions. By being oriented in the anterior and posterior directions, the apparatus  100  can be adjusted easily without having to remove the brace as described further below. In a typical implementation, the threaded rods  175  can be adjusted with an Allen (or hex) wrench. A typical Allen wrench includes a ninety degree angle so that when a user reaches down the forward portion of the Allen wrench is naturally positioned in the posterior and anterior direction. It is further appreciated that each of the threaded rods  175  can be adjusted and optionally fixed so that the proximal plate  105  moves in a fixed direction or is positioned in a fixed angular position with respect to the distal plate  150 . 
   As described further below with respect to the flexion control ankle joint hinge apparatus  100  connected to a leg brace, it is typically desired to allow some range of motion depending on the level of therapy of the patient wearing the brace. Therefore, the threaded rods  175  are typically threaded to a setting that allows the tongue  115  to move with some limited motion, thereby allowing the proximal and distal plates  105 ,  150  to pivot with respect to each other. As can be appreciated by the above description in conjunction with the figures, there is a continuum of positions that are possible by setting the threaded rods  175 . It is further appreciated that this range limiting system allows a patient and practitioner to fine tune settings of the apparatus to meet the many different needs of different patients. 
     FIG. 3  illustrates an exploded side view of the assembly of  FIG. 2 .  FIG. 3  also illustrates the dome being formed by a separate component.  FIG. 3  shows the distal plate, with the dome, the proximal plate with the recess for receiving the dome and the through hole. The shoulder screw  220  is shown aligned with the through hole  226  in the proximal plate and the threaded hole  230  through the top of the dome  228 . The spring wave washer  222  is shown positioned between the head  232  of the shoulder screw  220  and the surface of the proximal plate  105 . 
     FIG. 4A-FIG .  4 C illustrate the assembled side view and illustrate different bends for the ends of the embodiment of  FIG. 3 . The side view of  FIG. 4A  illustrates the relative position of the proximal and distal plates  105 ,  150  with respect to each other showing certain dimensional features. Specifically, as mentioned above, there is an elevation differential between the upper and lower ends  106 ,  107  of the proximal plate  105 . When the proximal and distal plates  105 ,  150  are assembled, the upper end  106  of the proximal plate  105  is generally in the same plane as the lower end  152  the distal plate  150  and the lower end  107  of the proximal plate  105  is located in a plane generally parallel to overall orientation of the distal plate  150 . 
     FIG. 4B  and  FIG. 4C  illustrate additional embodiments wherein the proximal plate  105  is further curved and wherein the lower end  152  of the distal plate  150  is slightly curved. These features allow accommodation of different leg brace interface surfaces. 
     FIG. 5A  illustrates the use of a separate component to form the dome of the cylindrical connection.  FIG. 5A  illustrates the proximal plate  105  and distal plate  150  in a partial cross section side view. The cross section cut is identified in  FIG. 2 . Referring to  FIG. 5A , the distal plate  150  includes the dome component  238  inserted and attached to the distal plate  150 . The dome component  238  is formed with a wide cylindrical base  240 , a slightly narrower cylindrical midsection  242  followed by the dome portion  228  on top. The dome component  238  has a threaded hole  228  in the center to receive the threaded portion  234  of the captive screw  220 . The proximal plate  105  rests on top of the dome  228  with the surface of the matching recess  224  in contact with the spherical dome  228 . The shoulder screw  220  holds the spring wave washer  222  in place to apply a preload pressure to the proximal plate  105  in contact with the dome  228 . A space  244  is provided between the shoulder  234  of the captive screw  220  and the proximal plate  105  to allow movement of the proximal plate  105 . The proximal plate  105  does not normally press against the captive screw  220  unless the proximal plate exceeds the mechanical limits of rotation along the surface of the dome  228  or unless disruptive forces exceed the preload of the spring wave washer  222 , in which case, the captive screw  220  serves to maintain connection integrity of the ankle joint  100 . 
   In one embodiment, the dome component  238  is fabricated from a bearing type material, for example, sintered bronze. Sintered bronze may be impregnated with a lubricant. Other bearing type materials may be substituted. The dome component may be affixed by press fitting, brazing, welding, swaging, threading, adhesive, or other means appropriate to the material. As shown, the dome component  238  has a threaded through hole. In an alternative, the hole may be closed at the bottom end (not shown). 
   The distal and proximal plates and dome component may be medical grade stainless steel, or titanium, although other materials including composites and certain high strength plastics may also be used. 
     FIG. 5B  illustrates a formed embodiment for the dome  228  of the cylindrical connection.  FIG. 5B  shows the distal plate  150  portion of  FIG. 5A  using the cut section shown in  FIG. 2 . Referring to  FIG. 5B , the dome portion  228  is formed from the distal plate material by press forming, forging, casting, milling, or other methods. The threaded hole  230  is provided for the captive screw  220 . 
   More generally stated and applicable generally to  FIG. 5A  or  5 B, the captive screw may be a captive stud or pin having a shank portion passing through the through hole in the mating cavity surface, the captive pin having an enlarged cap portion  232  incapable of passing through the through hole in the mating cavity surface. The captive pin may be affixed by other means than by threading, such as by press fitting, swaging, brazing, welding, gluing or other means known in the art for affixing studs. Alternatively, the cap portion  232  may screw onto or otherwise be attached to the stud  234  for holding the wave washer. 
     FIG. 6  illustrates an embodiment of a leg brace  200  having an embodiment of flexion control ankle joint hinge apparatus  100  connected to the brace  200 . The brace  200  is generally manufactured with dies that are pre-contoured to a particular patient. In another embodiment, the brace  200  can be prefabricated. In general, the brace  200  includes the apparatus  100  as described above. Typically, the brace  200  includes an upper or proximal portion  205  and a lower or distal portion  210 . The proximal plate  105  is fixed to the proximal portion  205  of the brace  200  through the brace connection points  108  and screws  190  as described above. The distal plate  150  is fixed to the distal portion  210  of the brace  200  through the brace connection points  160  and screws  190  as also described above. In another implementation, if the patient requires that their ankle remained pointed in one direction, dorsal or plantar, then only one threaded rod can be used, either on the posterior or anterior side. 
   As described above, the anterior-posterior adjustment of the system provides several advantages. If a practitioner is observing, for example, the gait of a patient wearing the brace  200 , the practitioner can make easy adjustments by setting the threaded rods  175  without the patient having to doff the brace  200 . Either the practitioner or the patient can easily adjust the level of control, say the dorsal and plantar flexion. As is further appreciated in the description below, the brace  200  can be custom contoured to the patient then fitted with the apparatus  100  to allow a custom fit for each individual patient. 
   Furthermore, some patients require free plantar flexion, that is, the ankle can be bent so that the foot points downward, yet no dorsiflexion, that is, bending the ankle so that the foot points upward. The range limiting system as described above allows this type of setting to be attained by the patient. The range limiting system allows the degree of plantar flexion to be easily set. In addition, the ankle joints can be reversed so that there is free dorsiflexion. 
     FIG. 7A  illustrates a rear view of the embodiment of the leg brace of  FIG. 6  showing a misalignment angle accommodated by the invention. Referring to  FIG. 7A , the proximal portion of the leg brace  205  is connected to the distal portion  210  using two spherical dome ankle hinges  100  in accordance with the present invention. Typical fabrication processes may leave imprecise mounting surfaces or out of square alignments to be accommodated by the practitioner, either by modification or by re-fabrication; however, these errors may be accommodated by the spherical dome hinge  100 , saving the time and effort of modification or refabrication.  FIG. 7A  shows a gravity line axis  270  and a square lateral axis  272 . Ideally the hinges should line up along the square lateral axis  272 ; however the hinges shown are off by axis  274 . The mounting surfaces should also line up (perpendicular) to the square lateral axis and should be parallel to one another. However, as shown, the proximal portion  205  has a mounting surface angle  250  and the associated distal portion  210  has a mounting surface angle  252 . The difference angle  254  may otherwise cause rubbing and wear issues in a prior art hinge and stress flexing and cracking issues in the leg brace parts; however, the spherical dome hinge accommodates this angle by allowing the proximal plate to find the correct location on the mating surface of the dome. 
     FIG. 7B  illustrates a top view of the embodiment of the leg brace of  FIG. 6  showing a misalignment angle accommodated by the invention. In a similar manner to the mounting surface misalignments of  FIG. 7A , the mounting surfaces of  FIG. 7B  may be misaligned as viewed from above.  FIG. 7B  shows the perpendicular axis  272  and a forward axis  278  along the foot. The ankle joints may be offset from the perpendicular axis  272  along axis  276 . Also, the top may be at angle  260 , the bottom at angle  262 , generating a difference angle  264 . Again, the spherical dome hinge  100  accommodates this angle by allowing the proximal plate to find the correct location on the mating surface of the dome. 
     FIG. 8  illustrates a cross section view of a fabrication model showing the conformal shaping of a leg brace. First, a comparison is made relative to a prior design ankle joint as described in U.S. Pat. No. 6,929,614 incorporated by reference above. A typical prior metal ankle joint is squared before plastic is added. If squaring is not precise, the misalignment can cause premature wearing. If the ankle joint is not square the ankle joints wear out in the medial and lateral directions, that is, the brace may widen or narrow at the level of the ankle. In a typical implementation, the ankle axis is first located on a negative cast. The cast is drilled at this location and a squaring rod is inserted. The hole is sealed so that there is no subsequent leakage. Then the cast is poured. After the cast has set, then the squaring rod is removed. The resultant cast is a positive cast of the patient&#39;s leg with a hole through the ankle axis. The cast is then modified, that is, it is built up in the ankle. A rod that is used to hold square with the ankle is inserted through the hole. At this point, plastic is vacuum formed. Once the plastic has cooled, it is removed from the cast. The plastic is cut all around and the brace is removed. Since the squaring rod is in the way, the hole is cut. The brace is generally removed easily at this point. 
   Without the spherical hinge, the steps are:
         1) making a shell casting of the leg;
           a) adding a pilot squaring rod at the ankle hinge point;   
           2) making a plaster copy of the leg using the shell casting, including the squaring rod;
           a) removing the pilot squaring rod;   b) inserting hinge holder in hole vacated by squaring rod in plaster;   
           3) building up a joint mount on the plaster cast;
           a) mounting hinge on hinge holder;   
           4) mounting the hinge holder and ankle joint on the built up part of plaster   5) wrapping and forming softened plastic around the leg copy and ankle joint;   6) cooling and remove plastic; and   7) trimming plastic and mounting ankle joint on plastic.       

   In accordance with the invention, a leg brace may be fabricated by:
         1) making a shell casting of the leg;   2) making a plaster copy of the leg using the shell casting;   3) building up a joint mount on the plaster cast;   4) mounting a molding dummy ankle joint on the built up part of plaster;   5) wrapping and forming softened plastic around the leg copy and ankle joint;   6) cooling and remove plastic; and   7) trimming plastic and mounting ankle joint on plastic.       

   Thus, steps 1a, 2a, 2b, and 3a pertaining to the squaring rod and mounting devices are eliminated. Thus, the hinge of the present invention may save a significant amount of time in the fabrication of a leg brace, resulting in a potentially lower cost product. The elimination of misalignment problems further improves life of the leg brace. Details of the new process may better be understood with reference to  FIG. 8 . 
     FIG. 8  is a top view cross section through the plane of the ankle joint hinge. Shown are the plaster casting  280  of the leg, a plaster build up  284  for the ankle joint, a molding dummy  290  in place of the ankle joint, and the leg brace plastic  282 . The objective of the assembly is to wrap heated and softened leg brace plastic sheet  282  around the fabrication model and vacuum form the plastic to the shape of the fabrication model. The plastic is typically polypropylene, although other plastics may be used. The plaster casting  280  of the leg is made by fabricating a shell casting around the leg, which is cut, removed from the leg, reassembled, and filled with plaster. The plaster build up  284  is added to insure separation of the ankle joint from the leg so that the ankle joint will not rub on the leg. A molding dummy ankle joint  290  is used in place of an actual ankle joint  100  during fabrication to insure that the plastic is set with the ankle joint in a predetermined (centered) position, since the ankle joint may flex in any direction under the stresses encountered during vacuum forming of the plastic. The molding dummy may be essentially an ankle joint which is fixed in the proper orientation, i.e., centered in the plane of the ankle joint and adjusted for proper bias, if any. A molding dummy may be made as a single unit resembling an ankle joint in outer dimension, but held in fixed position, not able to twist or rotate. The molding dummy may be made from any suitable material including plastics and may be molded from low cost plastic. In one embodiment, the molding dummy may be a single piece molded part. Alternatively, a molding dummy may be made by modifying an ankle joint as shown in  FIG. 9 . 
     FIG. 9  shows a molding dummy ankle joint for the fabrication model of  FIG. 8 .  FIG. 9  shows the proximal  105  and distal  150  plates. The wave washer  222  is replaced with a solid washer  292  allowing the shoulder screw  220  to tighten against the proximal plate  105 , holding the proximal plate  105  parallel to the distal plate  150 . Alternatively, a different screw (shorter)  220  may be used to hold the proximal plate  105  directly without the need for a washer  292  to fill the space of the wave washer  222 . The molding dummy  290  may be adjusted for any plantar flexion or dorsiflection angle desired by adjusting the threaded rods  175 , although the typical adjustment would be for straight alignment, i.e. the alignment of  FIG. 2  would be set by adjusting the threaded rods  175  for the centered position shown, but without any range of motion. 
   The molding dummy may then be attached by screws or other methods to the built up portion of the plaster fabrication model. The plastic sheet is then heated and wrapped, vacuum formed and allowed to cool. The cooled plastic is then trimmed to shape and removed from the plaster. Holes may be drilled in the plastic for the hinge by placing the hinge in the recess formed by the molding dummy and using the hinge holes to guide the drill. Screws may then be inserted to mount the ankle joint. 
   Thus, the leg brace may be fabricated without installation of a squaring rod and without undue attention with the squaring process because of the ankle joint&#39;s tolerance of misalignments. Since the squaring process is a time consuming part of prior fabrication, the new ankle joint results in saving of significant time and effort. Further, the leg brace is expected to wear better and longer, especially compared to prior type units that are marginally or poorly squared during the manual fabrication process. 
   Variations 
   Although the ankle joint is shown with the dome on the distal plate and mating depression on the proximal plate, the dome and depression may be reversed, with the dome on the proximal plate and mating depression on the distal plate. As a further variation, the dome may face inward, toward the ankle or outward, as shown in the figures. As a further variation, the leg brace may be configured in reverse, with the proximal plate to the lower side and the distal plate to the upper side. The components may be fabricated of any suitable material including stainless steel, steel, titanium, aluminum, brass, bronze, plastic, re-enforced plastic or any other suitable material or combination of materials. Accordingly, component fabrication may be by stamping, casting, forging, molding or other techniques appropriate for the material. 
   One should understand that numerous variations may be made by one skilled in the art based on the teachings herein. While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example only, and not limitation. Thus, the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.