Patent Publication Number: US-2018042755-A1

Title: Back brace

Description:
REFERENCE TO RELATED APPLICATIONS 
     This application is based on U.S. Provisional Application No. 62/375,254, filed Aug. 15, 2016, and incorporated by referenced herein along with its appendices. 
    
    
     REFERENCE TO APPENDICES 
     Appendix A, A Passive Brace To Improve Activities Of Daily Living Utilizing Compliant Parallel Mechanisms, and Appendix B, Preliminary Summary Compliant Scoliosis Brace, are hereby incorporated by reference in this application. 
     BACKGROUND 
     Scoliosis is a musculo-skeletal disease that causes a three-dimensional deformity primarily characterized by the curvature of the spine in the frontal plane. In this paper we will focus on adolescent idiopathic scoliosis (AIS), which is the most common form of scoliosis and affects 2 to 3% of adolescents, approximately 10% of which will require medical treatment. Girls are nearly 3 times more likely to have scoliosis than boys. Scoliosis usually affects adolescents during their growth periods between the age of five and eight, and ten until the end of growth. 
     Scoliosis can lead to certain health implications. Most notably, patients with scoliosis that requires bracing or surgery can experience shortness of breath. In addition, scoliosis patients can suffer from heart problems and back pain. Nonphysical health implications include struggling with self-image, an emotional pain. 
     A scoliotic spine contains either an “S” or “C” curve. The degree of scoliosis is generally characterized by the Cobb angle, defined as the angle between the two most tilted vertebrae of a spine segment. Cobb angles less than 25° require biannual checkups but no treatment unless the angle increases. A Cobb angle greater than 40° requires surgery. Cobb angles between 25° and 40° generally require bracing to prevent further progression. 
     Bracing is the most common treatment for AIS. The goal of bracing is not necessarily to correct the curve, but to prevent further progression, though correction can occur. Braces are generally to be worn up to 23 hours a day. It has been recognized that a brace should be designed with regard to the “three C&#39;s” (Comfort, Control, and Cosmetics). Comfort refers to the patient&#39;s ability to perform ADL, control refers to the brace&#39;s ability to apply correction forces of the right directions and magnitudes, and cosmetics refers to the appearance of the brace itself, along with how the patient perceives themselves in the brace. While conventional braces have been able to achieve one or even two of the three Cs, none have been able to achieve all three in the same brace. 
     The most common braces are rigid, although concepts of flexible braces have recently been explored, and a few have been brought to market. Rigid braces include the Milwaukee, Boston, and Cheneau braces. Flexible braces include the SpineCor and the TriaC braces. The rigid braces tend to be more effective and achieve the control goal of the three Cs, while the flexible braces tend to achieve comfort and cosmetic goals at the expense of control. 
     For example, the Milwaukee brace was the first documented brace to prove effective with a 74% success rate. It consists of a steel and leather pelvic base with rods that extend to the throat. However, the ‘superstructure’ of this brace caused lower jaw and dental deformities. The Boston brace, currently most recommended for treatment, consists of a standardized size polystyrene shell, tightened around the torso using straps, with interior foam padding to apply corrective forces and ‘cut-outs’ to provide relief. The Boston brace has up to a 93% success rate. The Cheneau brace, which has many variations, is also a rigid plastic shell, but is customized to each individual patient 
     The most common cause of failure in rigid brace treatment is a lack of patient compliance in wearing the brace. Comfort and aesthetics are the main reasons that patient do not wear braces for the prescribed amount of time each day. Rigid braces limit range of motion, including flexion and rotation, which in turn limits the patient&#39;s ADL. Braces are also bulky and cannot be easily hidden. Oversized clothes must be worn to hide a brace. This can damage self-confidence and have a psychological impact on the young patients who are usually going through puberty at the time of treatment. 
     Flexible braces are designed to address the drawbacks of rigid braces. The SpineCore brace is a flexible brace consisting of elastic bands, a pelvic base, and crotch and thigh bands. This brace allows the patient a much greater range of motion compared to rigid braces, but has a lower success rate according to some sources. Guo, et al found in a study that 5 out of 7 patients who encountered progression of the spinal deformation with the SpineCor brace had no further progression after switching to a rigid brace. The TriaC brace is another flexible brace that consists of two parts—lumbar and thoracic straps that are interconnected by a flexible coupling device. Although the manufacturers of the TriaC brace purport a success rate of 76% success rate, such flexible braces are nevertheless less effective than rigid braces in preventing scoliotic progression. 
     What is needed is a brace that achieves the three Cs—Comfort, Control, and Cosmetics. The present invention fulfills this need among others. 
     SUMMARY OF INVENTION 
     The following presents a simplified summary of the invention in order to provide a basic understanding of some aspects of the invention. This summary is not an extensive overview of the invention. It is not intended to identify key/critical elements of the invention or to delineate the scope of the invention. Its sole purpose is to present some concepts of the invention in a simplified form as a prelude to the more detailed description that is presented later. 
     The present invention relates to a flexible scoliosis brace designed to provide corrective force in a specific directions and mobility in other directions. The invention also relates to the identification of the problem with the SpineCor and TriaC braces. Specifically, without being tied to a particular theory, Applicants believe these braces lack the ability to be tuned for both compliance and stiffness that compliant mechanisms, described below, can supply. Both the SpineCor and TriaC braces are designed to provide corrective force with varying levels of reported success. This is in contrast to rigid braces which are designed to constrain the spine. This relationship is characterized as force-controlled correction (flexible braces) vs. displacement-controlled correction (rigid braces). The invention uses compliant mechanisms to constrain the spine through tuned stiffness, while permitting specific motions through kinematic design. Compliant mechanisms are used because they can apply the corrective force, but also allow the patients some range of motion. Thus, we seek to improve patients&#39; comfort by designing a brace that improves range of motion, while remaining stiff in the corrective direction. 
     The brace comprises compliant mechanisms, which may or may not be attached to rigid elements. The brace may also include flexible shell elements, flexures, and/or lamina emergent sheets. In one embodiment, the back brace comprises: (a) a pelvic member configured to snuggly wrap around a user such that the pelvic member is essentially immobilized relative to the pelvis of the user; (b) at least one thoracic member configured to snuggly wrap around the user such that the at least one thoracic member is essentially immobilized relative to the ribs of the user; and (c) one or more first compliant connectors between the pelvic member and the at least one thoracic member and configured to impart an urging force between the pelvic member and the at least one thoracic member. 
     In another embodiment, the back brace comprises: (a) a pelvic member configured to snuggly wrap around a user such that the pelvic member is essentially immobilized relative to the pelvis of the user; (b) at least one thoracic member configured to snuggly around the user such that the at least one thoracic member is essentially immobilized relative to the ribs of the user; and (c) least one compliant connector between the pelvic member and the at least one thoracic member, and being configured to allow the pelvic member and the at least one thoracic member to move relative to each other with at least 2 degrees of freedom, but less than 6 degrees of freedom. 
    
    
     
       BRIEF DESCRIPTION OF FIGURES 
         FIG. 1  shows one embodiment of the brace of the present invention. 
         FIG. 2( a )  shows a brace which has a helical pelvic member which wraps entirely around the user. 
         FIG. 2( b )  shows a brace with another embodiment in which the pelvic member does not wrap around the patient, but rather is configured as a pad to apply pressure to a particular point on the user&#39;s hip/pelvis. 
         FIG. 2( c )  shows a brace that has a circular pelvic member which wraps around the user. 
         FIG. 2( d )  shows a brace that has a pelvic member that wraps around the user&#39;s hip but is open in the front. 
         FIG. 2 ( e )  shows a brace where the pelvic member is configured to wrap around most of the body, but remains open in the front as shown. 
         FIG. 3( a )  shows the brace on the torso from the right side view. 
         FIG. 3( b )  shows the brace on the torso from the front. 
         FIG. 3( c )  shows the brace from the left side without being superimposed on the body. 
         FIG. 3( d )  shows the brace from the rear without being superimposed on the torso. 
         FIG. 4( a )  shows the brace which comprises a pelvic member and a thoracic member, and intermediate members. 
         FIG. 4 ( b )  shows the brace as having essentially the same pelvic thoracic and intermediate members, but having different compliant connectors. 
         FIG. 4 ( c )  shows the brace which comprises a pelvic member and thoracic member and an intermediate member. 
         FIG. 5( a )  shows that the brace comprises a pelvic member and a thoracic member with a combination of flexure and shell compliant members connecting the two together. 
         FIG. 5( b )  shows the brace in which the pelvic member is connected to a pair of cartwheel hinges, which, in turn, is connected to a crossed helix. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIG. 1 , one embodiment of the brace  100  of the present invention is shown. The brace  100  comprises a pelvic member  101  configured to be secured to a user&#39;s pelvis such that the pelvic member is essentially immobilized relative to the pelvis of the user, and a thoracic member  102  configured to be secured to a user&#39;s chest such that the thoracic member is essentially immobilized relative to the chest of the user. The brace  100  also comprises at least one compliant connector between the pelvic member and the thoracic member  102  to provide an urging force between the pelvic member and the thoracic member. 
     Each of these elements is described below in more detail and in connection with selected alternate embodiments. 
     The pelvis and thoracic members  101 ,  102  function to secure the brace to the user&#39;s pelvis (hip) and thorax (chest), respectively, and to transmit the force applied between them by the compliant\ connector(s) to the user&#39;s body at the pelvis and thorax. To this end, the members generally, although not necessarily, comprise a rigid or semi-rigid material to resist deformation from the force of the compliant connector. The type of material used and its thickness will depend on the expected forces and the physical configuration of the pelvic and thoracic members, which can vary as described below. One skilled in the art will readily understand how optimize the materials and their thickness to ensure the pelvic and thoracic members have the requisite stiffness to absorb the stresses imposed by the compliant connectors and translate those forces to the user&#39;s body. Suitable material include, for example, carbon fiber composite, fiberglass composite, and plastics such as Acrylonitrile butadiene styrene (ABS), acetal, polycarbonate (PC), and polypropylene (PP). 
     The pelvic and thoracic members may also comprise belts or additional apparatus to make the brace&#39;s attachment to the body more secure. Such apparatus is well known to those of skill in the art, and, thus, is not described herein in detail. 
     The compliant connectors  103  serve to connect the pelvis and thoracic members and provide a resilient force among the components. The force generation approaches of the compliance connectors are described in detail in Appendix B, Chapter 4. Generally, the compliance connectors are configured to provide one or more of force mechanisms selected from shell mechanisms, such as cross helix, helical strip, single curve, hyperbolic paraboloid, double paraboloid, single corrugated and double corrugated, or flexure mechanisms, such as cartwheel hinge, parallel beam, cross pivot hinge, cross beam, LET outside, LET inside, or S-beam. In one embodiment, the compliance connectors are configured to generate at least 30N, 40N or 50N of force between the pelvic and thoracic members. 
     The compliance connectors may be configured to achieve the desired stiffness between the pelvic and thoracic members while still allowing for primary motions. Generally, the primary motions involve sagittal bending, twisting, and lateral bending. Modeling the brace to balance desired stiffness while maintaining primary motions is described, for example, in Appendix B, generally, and Chapters 3, 5, 6, 8, and 9 in particular. In one embodiment, the compliance connectors are configured to allow for at least 13° in the sagittal direction, 10° in twist, and 9° in lateral bending. In one embodiment, the compliant connectors are configured to allow the pelvic member and the at least one thoracic member to move relative to each other with at least 2 degrees of freedom, but less than 6 degrees of freedom. In another embodiment, the compliant connectors are configured to allow the pelvic member and the thoracic member to move relative to each other with at least 2 degrees of freedom, but less than 5 degrees of freedom. In still another embodiment, the compliant connectors are configured to allow the pelvic member and the thoracic member to move relative to each other with at least 2 degrees of freedom, but less than 4 degrees of freedom. 
     As with the pelvic and thoracic members, the materials used for the compliance connectors will depend on the desired forces and brace configuration. For example, in some embodiments, the compliance connectors comprise the same material as the pelvic and thoracic members. In such embodiments, the compliance connectors may be integral with the pelvic and thoracic members. In other embodiments, the compliance connectors are discrete and comprise elastic materials such as ABS, PP, PC, or acetal and stiffer materials such as titanium, stainless steel, and aluminum. 
     The brace may be configured in different ways, with alternative pelvic members, thoracic members and compliance connector configurations being used to achieve different design objectives as described in detail Appendix B, Chapter 7. For example, referring to  FIG. 2 , a number of alternative designs are shown. (It should be noted that brace  205  in  FIG. 2( e )  is the same as brace  100  in  FIG. 1 .) As mentioned above, the compliant connector(s) may be discrete or they may be integrated with the pelvic and thoracic members. For simplicity, the illustrations in  FIGS. 1 and 2  show essentially homogenous material used for the pelvis/thoracic members and the complaint connectors. 
     In one embodiment, the pelvic members may wrap around entirely around the body or just a portion of the body. For example, referring to  FIG. 2( e )  brace  205 , the pelvic member  218  is configured to wrap around most of the body, but remains open in the front as shown. Likewise,  FIG. 2( d )  brace  204  has a pelvic member  219  that wraps around the user&#39;s hip but is open in the front. Such an embodiment may also require additional apparatus, such as a belt or strap, to secure the pelvic member to the user. Alternatively, the pelvic member may fully wrap around the user. For example,  FIG. 2( c )  brace  203  has a circular pelvic member  212  which wraps around the user. Similarly,  FIG. 2( a )  brace  201  has a helical pelvic member  206  which wraps entirely around the user. 
       FIG. 2( b )  brace  202  shows another embodiment in which the pelvic member does not wrap around the patient, but rather is configured as a pad  209  to apply pressure to a particular point on the user&#39;s hip/pelvis. Such an embodiment may also require additional apparatus, such as a belt or strap, to secure the pelvic member to the user. 
     Like the pelvic member, the thoracic member may be configured in different ways. In one embodiment the thoracic member wraps around the user&#39;s body. For example, braces  201  and  205  have circular thoracic members  207 ,  229 , which wrap around the user&#39;s upper chest. Brace  205  also has an additional pad  229   a  extending from the thoracic member  229  for additional contact surface to spread the load from the compliant connectors as discussed below. Such embodiments may be preferred to provide specified force to particular areas of the spine. Likewise, braces  203  and  204  have crossed helix thoracic members  213 ,  216 . Such embodiments may be preferred to provide larger ranges of motion in sagittal bending. Alternatively, the thoracic member may be open as with brace  202 . Thoracic member  220  of brace  202  just partially wraps around the user&#39;s upper chest. Such embodiment may be preferred for Scoliotic curves with an apex opposite member  223 . Such an embodiment may also require additional apparatus, such as a belt or strap, to secure the thoracic member to the user. 
     A variety of different compliant connector configurations are possible to connect and bias the thoracic member and pelvic member. The braces in  FIG. 2  use a variety of different compliant connectors, including helix members, cross helix members, single curve members, and single/double corrugated members. For example, braces  201 ,  202 ,  204  and  205  each use a helix member  222 ,  210 ,  215 ,  231 , respectively, as one of several compliant connectors. Helixes may be used to impart a torsional constraint force between the pelvic member and thoracic member, while allowing motion in the sagittal and lateral directions. In braces  201  and  206 , the helix member  222 ,  215  is integrated with the pelvic member  206 ,  219 , respectively, while braces  202  and  205  have a discrete helix member  210 ,  231  positioned proximate the lower thorax of the user. Braces  201 ,  202 ,  203 , and  205  also use single/double corrugated members  208 ,  231 / 223 ,  214 ,  230 / 233  as compliant connectors. Single/double corrugated members may be used to impart lateral bending force between the pelvic member and thoracic member. Braces  201  and  205  both use single/double corrugated members  208 ,  233  in the back of the brace to connect the thoracic member to an intermediate compliant connector, in the case helix members  222 ,  231 . Likewise, brace  202  uses single/double corrugated member  223  to connect thoracic member  220  to helix member  210 . Using single/double corrugated members to connect to the thoracic member may be preferred to permit twisting while applying sagittal bending forces 
     Single/double corrugated members may also be used to connect to the pelvic member. For example, braces  203 ,  205  use two single/double corrugated members  214 ,  230  to connect to the pelvic member  212 ,  218 . Using symmetrical single/double corrugated members may be preferred for permit twisting and in-plane bending while providing lateral bending force. Likewise, brace  202  uses one single/double corrugated member  211  to connect to the pelvic member  209 . Using single/double corrugated members to connect to the pelvic member may be preferred to permit sagittal bending while providing limited force in the lateral bending direction. 
     In yet other embodiments, braces  203 ,  204  use a curved member  224 ,  217  as intermediate compliant connectors. Using curved members as intermediate compliant connectors may be preferred for permitting sagittal bending while applying lateral bending and twisting force. 
     The various thoracic members, pelvic members, and compliant connectors described in connection with  FIGS. 2( a )-( e )  may be mixed and matched to form different embodiments. Still other embodiments involving mixing and matching these different components will be obvious of those of skill in the art in light of this disclosure. 
       FIGS. 3( a )-( d )  show one embodiment of the brace  300  of the present invention superimposed on a human torso  340 .  FIG. 3( a )  shows the brace  300  on the torso  340  from the right side view.  FIG. 3( b )  shows the brace  300  on the torso  340  from the front,  FIG. 3( c )  shows the brace from the left side without being superimposed on the body and  FIG. 3( d )  shows the brace from the rear without being superimposed on the torso. This embodiment, like the embodiments described above, comprises a pelvic  301  and a thoracic  302  with compliant connectors  303  connecting the pelvic member  301  to the thoracic member  302  and providing a resistive force between them. In this particular embodiment, the compliant connectors comprise a helical member  303 ( a ), a corrugated member  303 ( b ), a curved member  303 ( c ), a curved member  303 ( d ), and a cantilevered member  303 ( e ). It should be understood, that the type of compliant connector  303 , its configuration, and its placement relative to other complaint connectors and the pelvic and thoracic members provides the characteristic corrective forces of a particular brace. Those of skill in the art will understand that modifying the compliant connector type, its material and its position within the brace, will affect the corrective forces. 
     In one particular embodiment of the brace  300 , helix  303   a  was constructed with 12 layers of carbon fiber a layer thickness of 0.305 mm. The carbon was laid directly on top of the mold and the entire mold was vacuum bagged. This 12 layer helix had thickness varying from 3.8 to 4.1 mm. The force generators  303   c  and  303   d  were all produced using vacuum forming using PLA. The thickness varied between 1.8 mm to 3.0 mm for  303   c  and  303   d.    
       FIG. 4  shows an alternative embodiment of the brace of the present invention which uses flexure connections. Using flexure mechanisms as complaint connectors provides for corrective forces as described for example in Appendix A generally and Appendix B, Chapter 4.  FIGS. 4( a ) through ( c )  show braces  401 ,  402  and  403 , respectively, each using flexure mechanism for corrective forces. Specifically, referring to  FIG. 4( a ) , the brace  401  comprises a pelvic member  410  and a thoracic member  411 , and intermediate members  412 . Various fixture mechanisms interconnect the various members. Specifically, a pair of cartwheel hinge complaint connectors  413  connects the pelvic member  410  with intermediate member  412 . Intermediate members  412  are connected by a pair of single beam compliant connectors  414 . And finally, the thoracic member  411  is connected with intermediate member  412  using a CT joint complaint connector  415 . 
     Referring to  FIG. 4B , brace  402  is shown having essentially the same pelvic thoracic and intermediate members  420 ,  421 ,  422 , but having different compliant connectors. Specifically, like brace  401 , the pelvic member  420  is connected to intermediate member  422  using a pair of cartwheel hinge complaint connectors  423 . The intermediate members  422  are interconnected by a single cartwheel hinge complaint connector  424 . Likewise, the thoracic member  421  and the intermediate member  422  is also connected by a single cartwheel hinge complaint connector  424 . Referring to  FIG. 4C , brace  403  comprises a pelvic member  430  and thoracic member  431  and an intermediate member  432 . The pelvic member  430  and the intermediate member  432  are connected by a pair of cross pivot hinge complaint connectors  433 . The thoracic member  431  is connected to intermediate member  432  using single cartwheel hinge complaint connector  434 . 
     The various thoracic members, pelvic members, and flexure compliant connectors described in connection with  FIG. 4 , or anywhere else in this disclosure including the appendences, may be mixed and matched to form different embodiments. Still other embodiments involving mixing and matching these different components will be obvious of those of skill in the art in light of this disclosure. 
     Referring to  FIGS. 5( a ) and 5( b ) , alternative embodiments of the brace of the present invention is shown in which a combination of flexure and shell compliant connectors is used. Specifically, referring to  FIG. 5( a ) , brace  501  comprises a pelvic member  511  and a thoracic member  512  with a combination of flexure and shell compliant members connecting the two together. Specifically, a pair of cartwheel hinges  513  is connected to the pelvic member. A helical strip is connected to the cartwheel hinges  513  and is integral with the thoracic member  512 . Referring to  FIG. 5( b ) , brace  502  is shown in which the pelvic member  521  is connected to a pair of cartwheel hinges  523 , which, in turn, is connected to a crossed helix  524 . The crossed helix  524  is connected to the thoracic member  522  by corrugated member  524 . It should be understood that, in addition to these two embodiments, the various flexure and shell mechanisms disclosed in the patent application and attached appendences can be mixed and matched to form of variety of different brace configurations having different corrective forces which can be tailored for a particular patient. 
     It should be understood that the foregoing is illustrative and not limiting and that obvious modifications may be made by those skilled in the art without departing from the spirit of the invention. Accordingly, the specification is intended to cover such alternatives, modifications, and equivalence as may be included within the spirit and scope of the invention as defined in the following claims.