Patent Document

CROSS-REFERENCE TO RELATED APPLICATION 
     The present application claims priority to U.S. Provisional Application No. 61/438,509, entitled “Secure Adjustable Orthotic Device,” filed Feb. 1, 2011, the entire contents of which are herein incorporated by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention generally relates to a secure adjustable orthotic device or orthosis (commonly known as a brace or splint) comprising various buckles, straps, and adjustable supports. More particularly, the invention relates to an orthotic device having level moving buckles and secure adjustable supports. 
     BACKGROUND OF THE INVENTION 
     In certain orthosis applications, it is important that buckles and adjustable supports be easy to use while also inhibiting the accidental release, tightening or adjustment of an inserted strap (in the case of a buckle) or bracket (in the case of an adjustable support). For example, a common method of alleviating pain, promoting healing, and preventing further injury in patients who have suffered a back or spine injury (or in post-operative spinal surgery patients) is to stabilize the spine by means of an orthotic device. Among other things, an orthosis can provide stabilization, support, protection, pain reduction and replacement of lost function. Many orthotic devices rely on buckles, belts/straps, adjustable supports, and brackets to allow the donning or doffing of the device, and for adjusting and maintaining the device&#39;s fit/support. 
     There are a large variety of braces available depending on the diagnosis and physical needs of the individual. These devices include a multitude of construction materials and buckling and support designs for fitting the device around the patient&#39;s trunk or peripheral area, such as the cervical and pelvic regions. 
     Such braces are effective in achieving spinal stability if worn properly and consistently. However, most patients have difficulty in manually adjusting the brace&#39;s belts or straps so that the brace fits tightly enough to provide adequate support and stability but not so tight that the brace itself becomes a source of pain or discomfort, or causes the disruption of circulation. This is especially true in the case of post-operative patients who are generally in pain, have a limited range of motion, and frequently lack sufficient strength to make necessary adjustments to the brace by way of the brace&#39;s buckles and straps. 
     U.S. Pat. No. 4,406,043 discloses a belt buckle comprising a frame and pivotable tongue that engages the perforations in a flexible belt. Buckles of this general type can be difficult and uncomfortable to operate, particularly for persons with limited strength or mobility, such as post-operative patients. To secure or release a belt or strap using this type of buckle, the belt must be over-tightened before the pivotable tongue can be inserted into, or removed from, the desired perforation. Further, because each perforation reduces the structural integrity of the belt, buckles of this type are limited to applications not requiring fine adjustments to fit. 
     U.S. Pat. No. 4,688,337 discloses a two-piece clasp comprising a male clasp piece having parallel resilient arms that inset and lock into corresponding slots in a receptacle clasp piece. Straps are threaded through bars on the free ends of each clasp piece. A disadvantage of buckles of this general type is that manual adjustment of the straps through the bars on the freed ends of each clap piece is difficult, particularly for post-operative patients having limited strength and range of motion. 
     U.S. Pat. No. 4,903,381 teaches a fastener that accepts a strap in a receiving channel wherein a spring-loaded arresting member engages a serrated region of the strap thereby preventing the withdrawal of an inserted strap. A disadvantage of fasteners or buckles of this type is that, during a patient&#39;s daily activities, it is possible for a force or pressure to be applied to the strap in the insertion direction, thereby causing the strap to be tightened unintentionally and causing pain, discomfort, or loss of circulation. 
     U.S. Pat. No. 376,055 discloses a buckle comprising a clasp wherein the clasp grips an inserted belt or strap. The strap or belt is released by pulling up on the free end of the clasp. A buckle having similar features is taught in U.S. Pat. No. 5,572,771. A drawback to buckles of this type is that the strap or belt can be accidentally released if the free end of the clasp is pulled open accidentally by the patient&#39;s clothing or in some other way during the patient&#39;s daily activities. 
     Existing orthotic devices, such as described in U.S. Pat. No. 7,371,221, immobilize the head relative to the base using a single support bracket and a single locking pin located at the back of the cervical brace. However, such devices present the problems of being difficult for the user to adjust without assistance, and accidental release of the locking pin and the accompanying loss of support. As discussed above, it is important that adjustable supports be easy to use while also preventing accidental release. 
     The present invention satisfies these and other needs, and provides further related advantages. 
     SUMMARY OF THE INVENTION 
     For purposes of summarizing the disclosure, exemplary embodiments of a secure adjustable orthotic device having one or more locking mechanisms have been described herein. 
     The present invention may be embodied in a locking mechanism for a secure adjustable orthotic device. In one embodiment, the locking mechanism comprises a base member, a locking member and a top member. The base member comprises a base portion, a first side portion and a second side portion that, together, form a longitudinal channel for receiving a free end of a strap. The locking member is pivotally attached to the base member and is pivotable between a locked position and an unlocked position. The locking member comprises a first projection extending in a first direction and a second projection connected to the first projection but extending in a second direction. The first projection of the locking member has a first surface, a second opposite surface and a third surface. The second projection has a surface that engages an inserted strap when the locking member is in the locked position. The top member is slidably attached to the base member and comprises a top portion and one or more protrusions extending toward the locking member. Longitudinal movement of the top member relative to the base member in a first locked direction causes the one or more protrusions of the top member to apply a force to the first and then the third surfaces of the first projection of the locking member, pivoting the locking member to the locked position. Assuming a strap has been inserted into the longitudinal channel, the second projection of the locking member engages the inserted strap, thereby impeding the longitudinal movement of the strap. Longitudinal movement of the top member in a second opposite direction relative to the base member causes the one or more protrusions of the top member to apply a force to the second opposite surface of the first projection of the locking member, pivoting the locking member to the unlocked position and causing the second projection of the locking member to disengage the inserted strap, thereby allowing the longitudinal movement of the strap. 
     In another embodiment, at least one aperture is formed in the base portion of the base member so that the locking mechanism can be attached to other objects or surfaces. For example, the locking mechanisms can be attached to an orthotic device or orthosis (commonly known as a brace or splint). 
     In a further embodiment, a first aperture is formed in the first side portion of the base member, and a second aperture is formed in the second side portion of the base member. The locking member comprises a first protrusion extending in a first direction and a second protrusion extending in a second opposite direction. The first protrusion of the locking member is inserted into the first aperture in the first side portion of the base member. The second protrusion of the locking member is inserted into the second aperture in the second side portion of the base member. The first and second protrusions of the locking member form a transverse axis along which the locking member is free to pivot between the unlocked and locked positions based on the longitudinal movement of the top member relative to the base member. 
     In another embodiment, the first and second protrusions of the locking member are spindles. The first and second protrusions can be formed from the same material as that used to form the locking member. Alternatively, the first and second protrusions can be formed by inserting a support shaft or axle made of metal or other hard substance through the locking member. 
     In yet another embodiment, a first slot is formed in the outer surface of the first side portion of the base member and a second slot is formed in the outer surface of the second side portion of the base member. The first and second slots are parallel to the plane of the base portion of the base member and are located near the top edges of the first and second side portions of the base member. Preferably, the first and second slots terminate prior to the longitudinal ends of the first and second side portions of the base member. In this embodiment, the top member has a first lip extending from a first side edge of the top portion of the top member in a direction perpendicular to the plane of the top portion of the top member and a second lip extending from a second side edge of the top portion of the top member in a direction perpendicular to the plane of the top portion of the top member. A first tongue is formed on the interior surface of the first lip of the top member and a second tongue is formed on the interior surface of the second lip of the top member. The first tongue formed on the interior surface of the first lip of the top member is inserted into the first slot formed in the outer surface of the first side portion of the base member and the second tongue formed on the interior surface of the second lip of the top member is inserted into the second slot formed in the outer surface of the second side portion of the base member, thereby slidably attaching the top member to the base member. Alternatively, multiple short slots can be formed on the outer surfaces of the first and second side portions of the base member and multiple corresponding tongues can be formed on the interior surfaces of the first and second lips of the top member. 
     In another embodiment, first and second channels are formed on the inner surfaces of the first and second side portions of the base member. The channels run parallel to the plane of the base portion and are located near the top edges of the first and second side portions. Preferably, the channels terminate prior to the longitudinal ends of the first and second side portions of the base member. In this embodiment, a first side edge of the top portion of the top member is inserted into the first channel formed on the inner surface of the first side portion of the base member, and a second side edge portion of the top portion of the top member is inserted into the second channel formed on the inner surface of the second side portion of the base member, thereby slidably attaching the top member to the base member. 
     In a further embodiment of the locking mechanism, the locking member is juxtaposed to the base member. In this embodiment, a majority of the locking member is located within a well formed in the top surface of the base portion of the base member so that, in the unlocked position, the locking member does not obstruct the longitudinal channel formed by the base member. Alternatively, a majority of the locking member is proximal to the top member so that, when a strap is inserted into the locking mechanism&#39;s longitudinal channel, a majority of the locking member is located between the top member and the inserted strap. 
     The present invention may additionally be embodied in a locking mechanism that inhibits the locking member from pivoting from a locked position to an unlocked position when tension is applied to the strap inserted into the longitudinal channel of the locking mechanism. This embodiment comprises a top member having a protrusion extending away from the plane of the top member and toward the locking member. The protrusion has a first angled surface relative to the plane of the top member and a second parallel surface relative to the plane of the top member. Longitudinal movement of the top member in a first locking direction causes initial contact between the first angled surface of the protrusion of the top member and the first surface of the first projection of the locking member. This initial contact with the first angled surface of the protrusion of the top member applies a force to the first projection of the locking member, the force having a downward vector component relative to the plane of the top member. The downward force causes the first projection of the locking member to move in a direction perpendicular to the plane of the longitudinal channel and toward the base member so that the locking member pivots to the locked position, causing the second projection of the locking member to engage a strap inserted into the longitudinal channel and thereby preventing the withdrawal of strap. Further lateral movement of the top member causes the second surface of the protrusion of the top member that is parallel to the longitudinal movement of the top member to align with a third surface of the first projection. The third surface is parallel to the second surface of the protrusion of the top member. Thus, when the top member is in the fully locked position, contact between the protrusion of the top member and the third surface of the first projection of the locking member is along a plane parallel to the longitudinal movement of the top member. If tension is applied to the strap when the top member is in the locked position, the strap will apply a force to the second projection of the locking member in the direction of the base member. This force will be communicated through the rigid structure of the locking member and its transverse pivot, causing the third surface of the first projection of the locking member to apply a force to the second surface of the protrusion of the top member in a direction away from the base member. Because the planes of the third surface of the first projection of the locking member and the second surface of the protrusion of the top member are substantially parallel to the longitudinal movement of the top member (and the force is in a direction substantially perpendicular to the longitudinal movement of the top member), the top member does not move longitudinally in the unlocking direction and thus prevents the withdrawal of the strap. 
     In another embodiment, the strap that can be inserted into the locking member&#39;s longitudinal channel has a series of transverse teeth on one surface. In this embodiment, the second projection of the locking member forms a pawl that is shaped to engage the transverse teeth of an inserted strap. 
     The present invention may also be embodied in an adjustable orthotic device comprising a first brace portion, a second brace portion, a third brace portion, a bracket portion, and an adjustment tool. The bracket portion interconnects the first brace portion and second brace portion, and is fixedly attached to the first brace portion and slidably attached to the second brace portion. The bracket portion comprises first and second parallel projections, each projection having a plurality of apertures longitudinally spaced along a portion of its length. The second brace portion comprises a body portion and a pair of locking members attached to the body portion and spaced apart from one another. The first and second locking members of the second brace portion each has a top portion having an aperture, a first side portion and a second side portion together forming a longitudinal channel adapted to receive the first and second projections of the bracket portion respectively. Each locking member also has a pin having a diameter smaller than the aperture in the top portion of the locking member. The pin has a first end sized to fit within each of the apertures of the projections of the bracket portion (the pin being slidable in a first locked direction and a second unlocked direction along an axis defined by the longitudinal axis of the pin&#39;s shaft. The pin further has a first projection proximate to the first end of the pin and defining an axis substantially perpendicular to the longitudinal axis of the pin, a second opposite end having a second projection defining an axis substantially parallel to the first projection, and a spring that applies a force to the first projection of the pin in the locked direction. The third brace portion is detachably coupled to the first and second brace portions. The adjustment tool comprises a body portion, a first end portion, and a second end portion. The first and second end portions are spaced apart from one another. The first and second end portions each has a slot defining an axis and a first pair of surfaces adjacent to the slot, wherein surface is tapered in a direction parallel to the axis of the slot. The slots of the first and second end portions of the adjustment tool are oriented to accept the second ends of the pins of the locking members. As the first and second end portions of the adjustment tool are pushed toward the second ends of the pins, the tapered surfaces adjacent to each slot of the adjustment tool apply a force to the lips of the pins. This force is greater than the force applied by the springs, thereby causing the pins to move in the second unlocked direction. When the first and second ends of the adjustment tool are fully inserted under the lips of the two pins of the locking members, the first ends of the pins withdraw from the apertures of the first and second projections of the bracket portion, allowing the bracket portion (and the first brace portion fixedly attached thereto) to be adjusted relative to the second brace portion. 
     The present invention is additionally embodied in a locking mechanism wherein the first brace portion is a mandibular support, the second brace portion is a front sternum plate, and the third brace portion is a occipital-scapular plate. 
     These and other features and advantages of the present invention will be more readily apparent from the detailed description of the embodiments set forth below taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the present invention will now be described, by way of example only, with reference to the following drawings. 
         FIG. 1A  is perspective view of a locking mechanism, in accordance with an embodiment of the present invention. 
         FIG. 1B  is an exploded view of the locking mechanism shown in  FIG. 1A . 
         FIG. 2  is an enlarged perspective view of a base member, in accordance with an embodiment of the present invention. 
         FIG. 3  is an enlarged perspective view of a locking member, in accordance with an embodiment of the present invention. 
         FIGS. 4A and 4B  are enlarged top and bottom perspective views of a top member, in accordance with an embodiment of the present invention. 
         FIGS. 5A through 5C  inclusive are perspective views that show, respectively, (i) a strap prior to insertion into one of the locking mechanisms shown in  FIG. 1 , (ii) the strap inserted into the locking mechanism, wherein the locking mechanism is in the unlocked position, and (iii) the strap inserted into the locking mechanism, wherein the locking mechanism is in the locked position. 
         FIGS. 6A and 6B  are cross-sectional views of the locking mechanisms of  FIGS. 5B and 5C , respectively. 
         FIG. 7  is a perspective view of an orthotic device having secure adjustable supports, in accordance with an embodiment of the present invention. 
         FIG. 8  is a perspective view of a portion of the secure adjustable orthotic device and an adjustment tool, in accordance with an embodiment of the present invention. 
         FIG. 9  is an exploded view a locking member removed from a locking mechanism housing of a second brace portion of the secure adjustable orthotic device shown in  FIG. 8 . 
         FIGS. 10A-10C  are side views of an assembled locking member shown in  FIG. 9 , along with an adjustment tool and a bracket portion of the secure adjustable orthotic device, in accordance with an embodiment of the present invention. 
     
    
    
     Exemplary embodiments and their advantages are best understood by referring to the detailed descriptions that follow. It should be appreciated that like reference numerals are used to identify like elements illustrated in one or more of the figures, wherein showings therein are for purposes of illustrating exemplary embodiments and not for purposes of limiting the same. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to the drawings in detail,  FIGS. 1A and 1B   FIG. 1  show a representative locking mechanism  1  according to the present invention comprising a base member  2 , a locking member  12 , and a top member  3 . 
     Referring to  FIGS. 1A and 2 , the base member  2  is formed by a base portion  4 , a first side portion  5  and a second side portion  6  that form a longitudinal channel  7  for receiving a free end of a strap  31  (shown in  FIGS. 2A through 2C ). In this embodiment of the base member, at least one aperture  8  is formed in the base portion of the base member to allow the locking mechanism to be attached to other objects, such as an orthotic device. A first aperture  9  is formed in the first side portion  5  of the base member, and a second aperture  8  is formed in the second side portion  6  of the base member. A well  11  is formed in the top surface of the base portion of the base member to accommodate the locking member  12 . A plurality of slots  10  are formed in the outer surfaces of the first and second side portions of the base member. The slots are parallel to the plane of the base portion  4  of the base member and terminate prior to the longitudinal ends of the first and second side portions of the base member. 
     As shown in  FIGS. 1B and 3 , the locking member  12  comprises a plurality of first projections  15   a ,  15   b , and  15   c  extending in a first direction and a second projection  16  connected to the plurality of first projections but extending in a second direction. The first projection  15   a  of the locking member has a first surface  17  and a third surface  19 . The first projections  15   b  and  15   c  have second opposite surfaces  18 . The second projection  16  has a surface  20  capable of engaging an inserted strap  31  (shown in  FIGS. 2A through 2C ) when the locking member  12  is pivoted to, or is in, the locked position. A first finger  13   a  of the locking member shown in  FIG. 3  extends in a first direction and a second finger  13   b  extends in a second opposite direction. The first and second protrusions of the locking member form a transverse rotational axis. 
     In order to pivotally attach the locking member  12  to the base member  2 , the first finger  13   a  of the locking member is inserted into the first aperture  9   a  in the first side portion  5  of the base member, and the second finger  13   b  of the locking member is inserted into the second aperture  9   b  in the first side portion  5  of the base member. The first and second protrusions of the locking member form a transverse axis along which the locking member is free to pivot between an unlocked and a locked position. 
       FIGS. 4A and 4B  show a top member  3  having a top portion  25 , a first lip  21  extending from a first side edge  26   a  of the top portion of the top member in a direction perpendicular to the plane of the top member and a second lip  22  extending from a second side edge  26   b  of the top portion of the top member in a direction perpendicular to the plane of the top member. A plurality of first tongues  23  are formed on the interior surface of the first lip  21  of the top member, and a plurality of second tongues  24  are formed on the interior surface of the second lip  22  of the top member. 
       FIG. 4B  shows the bottom surface of top member  3 . A first protrusion  27   a  and a second protrusion  27   b  are formed on the inner surface of the top portion of the top member. The first protrusion  27   a  has an angled first surface  28  (relative to the plane of the longitudinal movement of the top member), a second surface  29  that is parallel to the plane of the longitudinal movement of the top member, and a third surface  30 . The first and second protrusions each also has a strap alignment surface  37 . 
     According to the embodiment shown in  FIG. 1 , in order to slidably attach the top member  3  to the base member  2 , the first tongues  23  formed on the interior surface of the first lip  21  of the top member are inserted into the plurality of first slots  10   a  formed in the outer surface of the first side portion  5  of the base member. The second tongues  24  formed on the interior surface of the second lip  22  of the top member are inserted into the plurality of second slots  10   b  formed in the outer surface of the second side portion  6  of the base member. 
     In another embodiment, first and second channels are formed on the inner surfaces of the first and second side portions of the base member. The channels run parallel to the plane of the base portion and are located near the top edges of the first and second side portions. Preferably, the channels terminate prior to the longitudinal ends of the first and second side portions of the base member. In this embodiment, a first side edge of the top portion of the top member is inserted into the first channel formed on the inner surface of the first side portion of the base member, and a second side edge portion of the top portion of the top member is inserted into the second channel formed on the inner surface of the second side portion of the base member, thereby slidably attaching the top member to the base member. 
       FIGS. 5A through 6B  show an assembled embodiment of the locking mechanisms  1  as it relates to a strap  31 .  FIGS. 5A and 5B  show the strap  31  prior to, and following, insertion into the longitudinal channel  7 , wherein the top member  3  is in the unlocked position. The strap  31  is generally planar in shape, having first  34  and second  35  opposed major surfaces. The first major surface  34  of the strap  31  includes a series of longitudinally spaced transverse locking teeth  32 (see  FIGS. 6A-6B ).  FIG. 5C  shows the strap inserted into the longitudinal channel  7  and the top member  3  in the locked position. 
       FIG. 6A  shows a longitudinal cross-sectional view of the embodiment of the locking mechanism shown in  FIG. 5B . Specifically, longitudinal movement of the top member  3  relative to the base member  2  in the “unlocked” direction  38  causes the third surface  30  of the first protrusion  27   a  of the top member to apply a force to the second opposite surfaces  18  of the first projections  15   b  and  15   c  of the locking member  12 . The force applied to surfaces  18  causes the locking member to pivot about its transverse axis, defined by fingers  13   a  and  13   b , to the unlocked position, wherein the second projection  16  pivots into the well  11  in the bottom portion  4  of the base member  2  so that the second projection  16  does not inhibit the insertion or adjustment of the strap  31  in the longitudinal channel  7 . 
     As shown in  FIG. 6B , which is a longitudinal cross-sectional view of the embodiment of the locking mechanism and strap shown in  FIG. 5C , longitudinal movement of the top member  3  relative to the base member  2  in the “locked” direction  36  causes the first protrusion  27   a  of the top member to apply a force to the first surface  17  of the first projection  15   a  of the locking member, pivoting the locking member to the locked position. In the locked position, the pawl  20  of the second projection  16  of the locking member engages the inserted strap  31  and the strap alignment surfaces  37  of the first and second protrusions of the top member  3  prevent the strap from deflecting away from the pawl  20  thereby impeding the withdrawal of the strap. Specifically, longitudinal movement of the top member in the locked direction  36  causes initial contact between the angled first surface  28  of the first protrusion  27   a  and the first surface  17  of the first projection  15   a  of the locking member  12 . Continued movement of the top member in the locked direction  36  causes the first surface  28  of the protrusion to apply a force to the first projection  15   a  of the locking member. Due to the angle of the first surface  28 , the force applied to the first projection  15   a  has a downward vector component (toward the base member). The applied force causes the locking member to pivot to the locked position, causing the second projection  16  of the locking member to engage a strap  31  inserted into the longitudinal channel  7 , thereby preventing the withdrawal of strap. In the embodiment of the locking mechanism shown in  FIG. 6B , the second projection  16  of the locking member  12  forms a pawl having a free end  20  shaped to fit the longitudinal spaces  33  between the transverse locking teeth  32  on the first surface  35  of the strap  31 . When the locking member pivots from the unlocked to the locked position following the insertion of a strap, the free end enters the longitudinal space between adjacent transverse locking teeth, thereby obstructing the withdrawal of the strap. 
       FIG. 6B  also illustrates that the present invention may be additionally embodied in a locking mechanism that inhibits the accidental movement or release of the strap  31  when the top member  12  is in the fully locked position because the application of a longitudinal force to the strap in either direction will not cause the top member to move in the unlocked direction  35 . Specifically, when the top member in the fully locked position, the second surface  29  of the first protrusion  27   a  aligns with the third surface  19  of the first projection  15   a  of the locking member. The aligned surfaces  29  and  19  are parallel to one another and parallel to the plane of the longitudinal movement of the top member  12 . Therefore, attempting to withdraw or insert the strap  31  while the locking mechanism is in the fully locked position creates a force that does not result in movement at surfaces  29  and  19  because the generated force is in a direction perpendicular to the longitudinal movement in which the top member is free to engage. 
       FIG. 7  shows an orthotic device  36  having secure adjustable supports according to the present invention. The orthotic device comprises a first brace portion  38  forming a mandibular support, a second brace portion  40  forming a front sternum plate, and a bracket portion  42  fixedly attached to the first brace portion and slidably attached to the second brace portion. The first brace portion  38  and second brace portion  40  each comprises a cushioned pad  39  and  41  respectively. The second brace portion  40  further comprises a body portion  44 , and a pair of locking members  46  spaced apart from one another. The bracket portion  42  comprises a first projection  48  defining an axis and a second projection  52  spaced apart from the first projection and defining an axis that is parallel to the axis defined by the first bracket  42 . The first projection  48  and second projection  52  of the bracket portion  42  each has a plurality of apertures  50  longitudinally spaced along a portion of their length. 
       FIG. 8  is a perspective view of a portion of the second brace portion  40 , the first and second projections of the bracket portion  42 , and an adjustment tool  84 . The second brace portion includes the pair of locking members  46 . Each locking member comprises a housing  53  and a locking portion  55 . The housing  53  of each locking member comprises a top portion  54  having an aperture  56 , a first side portion  58  having a first end  60  attached to the body portion  44  of the second brace portion and a second opposite end  62  attached to the top portion  54  of the locking member, and a second side portion  64  having a first end  66  attached to the body portion  44  of the second brace portion and a second opposite end  68  attached to the top portion  54  of the locking member. The top portion  54 , first side portion  58 , and second side portion  64  of each locking portion housing  53  form a longitudinal channel  70  configured to receive one of the first projection  48  or second projection  52  of the bracket portion  42 . 
     The adjustment tool  84  comprises a body portion  86  having a first end portion  88  and a second end portion  90  that is spaced apart from the first end portion. The first and second end portions of the adjustment tool  84  each has a slot  92  defining an axis  94 , and a pair of surfaces  96  adjacent to the slot. The surfaces  96  are tapered in a direction parallel to the axis  94 . And because the first projection  50  and second projection  52  of the bracket  42  secure the first brace portion  38  to the second brace portion  40  at two independent locking members  46 , adjustment requires the use of the adjustment tool  84 , thereby reducing the chance of accidental movement of the first brace portion relative to the second brace portion. 
       FIG. 9  is an exploded view of a locking portion  55  extracted from the housing  53  of a locking member  46  of the second brace portion  40  shown in  FIGS. 7 and 8 . Each locking portion  55  comprises a pin  72 , a coiled spring  74 , an annular disc  76 , a cap  78 , and a body portion  79 . The pin  72  comprises a first end  80 , a second opposite end  82 , and an annular lip  83  wherein the annular lip has an outer diameter larger than the inner diameter of the coiled spring  74 . The first end  80  of the pin is sized to fit within the apertures  50  of the projections  48  and  52  of the bracket portion  42 . The cap  78  has an aperture  77  formed in the center of its top and the body portion  79  has an aperture  81  formed in the center of its base. The second end  82  of the pin  72  has a diameter smaller than the diameter of the aperture  77  formed in the center of the top of the cap  78 . 
     When assembled, the second end  82  of the pin  72  is positioned within the coiled spring  74  with the coiled spring abutting the annular lip  83  of pin  72 . The second end of the pin is inserted through the aperture  77  in the top of the cap  78  and the annular disc  76  is coupled to the second end  82  of the pin  72 . The body portion  79  is then fixedly attached to the cap  78 . The first end  80  of the pin  72  is allowed to project through the aperture  81  in the center of the base of the body portion  79 . thereby enclosing the coiled spring and majority of the pin  72 . The second end  82  of the pin  72  is positioned within the fixedly attached within the aperture of the second annular disc  78  so that the second annular disc is positioned between the first end  80  and the second end  82  of the pin. The pin  72  of each locking portion is positioned through the aperture  56  formed in the top portion  54  of the housing  53 . The pin is slidable between a first locked position and a second unlocked position along a longitudinal axis defined by the shaft of the pin  72  and substantially perpendicular to the plane of the top portion  54  of the housing  53  of the locking member  46 . When the locking portion  55  is contained within the housing  53  of the locking member  46 , and the pin  72  is in the locked position, its first end  80  extends into the longitudinal channel  70  of the housing  53 . When the pin  72  is in the unlocked position, its first end  80  is retracted from the longitudinal channel  70  of the housing. The coiled spring  74  resists compression between the annular lip  83  of the pin  72  and the cap  78  thereby applying a force to the pin  72  in the locked position. 
       FIGS. 10A-10C  are side views of an assembled locking portion  55  extracted from the housing  53  of a locking member  46  of the second brace portion  40  shown in  FIGS. 7-8 .  FIG. 10A  shows the locking portion  55  with the annular disc  76  and pin  72  in the locked position with a second end portion  90  of the adjustment tool  84  approaching the locking portion from the left of the figure (it should be apparent that all depictions of the second end portion  90  of the adjustment tool  84  are equally representative of the first end portion  88  of the adjustment tool). Also shown in  FIG. 10A  is a longitudinal cross section of the second projection  52  of the bracket portion  42  to illustrate the plurality of apertures  50  longitudinally spaced along a portion of the second projection&#39;s length (it should be apparent that all depictions of the second projection  52  of the bracket portion  42  are equally representative of the first projection  48  of the bracket portion). 
       FIG. 10B  shows the annular disc  76  and pin  72  of the locking portion  55  in the unlocked position. Due to the angle of the tapered surface  96  of the second end portion  90  of the adjustment tool  84 , insertion of the adjustment tool between the annular disc  76  and the cap  78  exerts a force on the bottom of the annular disc  76  that has an upward component. When the upward component of the force applied to the annular disc  76  (and the pin  72  to which the annular disc is coupled) by the insertion of the adjustment tool  84  overcomes the opposite force that the coiled spring  74  applies to the annular lip  83  of the pin  72  (and the annular disc  76  to which it is coupled) due to the coiled spring&#39;s resistance to compression, the annular disc  76  and pin  72  slide to the unlocked position. As shown in  FIG. 10B , when the annular disc  76  and pin  72  are in the unlocked position, the first end  80  of the pin retracts. When the locking portion  55  is contained within the housing  53  of the locking member  46  and the pin  72  is in the unlocked position, the first end  80  of the pin  72  is retracted from the longitudinal channel  70  of the housing  53 . With the first end  80  of the pin  72  retracted from the longitudinal channel  70 , the second projection  52  of the bracket portion  42  can be inserted into, or adjusted within, the longitudinal channel  70 . 
       FIG. 10C  shows the second end portion  90  of the adjustment tool  84  removed from between the annular disc  76  and the cap  78  of the locking portion  55 . With the adjustment tool removed, the force applied by the compressed coiled spring  74  to the annular lip  83  of the pin  72  causes the pin to return to the locked position. When the locking portion  55  is contained within the housing  53  of the locking member  46 , and the pin  72  returns to the locked position, its first end  80  extends into the longitudinal channel  70  of the housing  53 . With the second projection  52  of the bracket portion  42  positioned within the longitudinal channel, the first end  80  of the pin  72  can enter one of the plurality of apertures  50  longitudinally spaced along a portion of the second projection  52  of the bracket portion  42  thereby preventing the accidental movement of the bracket portion  42  (and the first brace portion  38  to which it is fixedly attached) relative to the second brace portion  40  as show in  FIG. 7 . 
     The present invention has been described above in terms of presently preferred embodiments so that an understanding of the present invention can be conveyed. However, there are other embodiments not specifically described herein for which the present invention is applicable. Therefore, the present invention should not to be seen as limited to the forms shown, which are illustrative rather than restrictive.

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