Abstract:
A rotatable shock absorber assembly for a crutch. A guide pin is removably fixable within the upper portion of a support leg. A piston comprises a flange arranged proximate a saddle, comprising a top surface having two or more arcuate rotation grooves defined therein, and a main body defining an elongate slot enabling the guide pin to be inserted therethrough, such that the piston can translate along the elongate axis relative to the guide pin. A joint, can operably couple the piston to the saddle. The joint can rotate about the elongate axis relative to the piston. A biasing mechanism is configured to urge the piston along the elongate axis toward the armpit of the user whereby the saddle can be held stable in the armpit of the user and the support leg can rotate about, and translate along the elongate axis during use.

Description:
RELATED APPLICATION 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 62/365,816 filed Jul. 22, 2016, which is hereby fully incorporated herein by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    This invention pertains to medical devices for ambulatory assistance such as crutches, and more particularly to improvements to the stability and durability of biomechanically and ergonomically designed adjustable crutches. 
       BACKGROUND 
       [0003]    Most crutches are not appropriately designed for either biomechanical considerations (the way in which the crutch supports and transfers loads during operation) or ergonomic considerations (the way in which the crutch fits the anatomy of a user). The biomechanically derived adjustable crutch described in U.S. Pat. No. 7,717,123 to Weber et al. (the disclosure of which is incorporated by reference herein) discloses an adjustable crutch that is both biomechanically appropriate and ergonomically comfortable for the user. This biomechanically derived crutch includes a support leg that is curved both forwardly in a side-view plane and outwardly in a front-view plane with a cantilevered handle angularly offset from both the front-view plane and as horizontal plane. The biomechanically derived crutch further includes an upper portion with a saddle for positioning under the arm that can both pivot from front to back and side to size, and can move vertically. The lower portion has a foot member that is oriented perpendicular to the floor when the crutch is in a resting position. 
         [0004]    Although the design of this biomechanically derived crutch presents a significant advance in terms of both proper functionality and improved comfort of the crutch, the need for the crutch to be adjustable to accommodate different user heights and the moveable nature of the saddle relative to the support leg has presented design challenges in making the crutch both stable and durable, especially over extended periods of use. Accordingly, there is a continuing need for improvements to a biomechanically derived crutch which can address these challenges. 
       SUMMARY 
       [0005]    An improved biomechanical and ergonomic adjustable crutch in accordance with various embodiments enhances the stability and durability of the crutch with various improvements that make the improved crutch quieter, more durable, and more stable. The biomechanical and ergonomic adjustable crutch includes a support leg that is curved both forwardly in a side-view (median/sagittal plane) and outwardly in a front-view (frontal/coronal plane) with a cantilevered handle angularly offset from each of a frontal/coronal plane, a median/sagittal plane, and a transverse/axial plane, and a foot member that is oriented perpendicular to the floor when the crutch is in a resting position. 
         [0006]    In some embodiments, a saddle for positioning under the arm of the user is operably connected to an upper portion of the support leg of the crutch by a rotatable shock absorber assembly that is both horizontally pivotable and vertically moveable on a spring-loaded, internally positioned piston that is entirely inside of an upper portion of the support leg. In various embodiments, the internally positioned piston provides for both greater stability and durability of the shock absorber assembly in response to both vertical and rotation movement. In some embodiments, an upper portion and a lower portion slidingly interface with a middle portion of the support leg. A plurality of apertures and corresponding spring-loaded frusto-conical adjustment pin(s) in the portions may be selectively actuated to adjust a relative height of the portions of the support leg based on the apertures that the adjustment pin(s) engages. The various embodiments, the adjustment pin(s) have a conical angle that provides for less vertical play between the corresponding portions of the support leg and quieter operation, especially in response to a transfer of weight carried by the support leg during use of the crutch. 
         [0007]    Embodiments provide a rotatable shock absorber assembly for a crutch. The shock absorber assembly can comprise a guide pin that is removably fixable within the upper portion of the support leg and extends along an axis orthogonal to the elongate axis. A piston can comprise a flange proximate the saddle with a top surface having two or more arcuate rotation grooves defined therein. In some embodiments, the flange has a size and shape inhibiting the entry of the flange into the upper portion of the support leg. 
         [0008]    The main body of the piston can be slideably arrangable within the upper portion of the support leg define an elongate slot through which the guide pin can be inserted such that the piston can translate along the elongate axis relative to the guide pin. A joint can operably couple the piston to the saddle. The joint can comprise two or more rotation pins, each slidably insertable within a respective one of the two or more arcuate rotation grooves such that the joint can rotate about the elongate axis relative to the piston. In embodiments a piston washer, which can be copper, is arrangable at a bottom face of the joint. 
         [0009]    A biasing mechanism can be configured to urge the piston along the elongate axis toward the armpit of the user. In embodiments, the saddle can be held stable in the armpit of the user and the support leg can rotate about, and translate along the elongate axis during use. The extent of the translation of the piston relative to the guide spring can be limited by the length of the slot along the elongate axis. 
         [0010]    In some embodiments, the biasing mechanism comprises a block fixedly arranged within the upper portion of the support leg at a position distal to the saddle relative to the piston and a compression spring arranged between the block and the piston. The block can comprise an upwardly extending spring pin which is receivable within one or more lower coils of the spring. The piston can comprise a downwardly extending block stem receivable within one or more upper coils of the spring. 
         [0011]    In embodiments, the joint is tiltably coupled to the saddle such that the saddle can remain fixed within the armpit of the user while the support leg is pivoted between the front side of the user and the back side of the user. 
         [0012]    In one embodiment, the rotatable shock absorber assembly is incorporated within a crutch having a first side direction generally parallel to a walking direction of a user, a second side direction opposite the first side direction, a third side direction perpendicular to the first side direction and a fourth side direction opposite the third side direction. The crutch can also comprise a saddle, extending in an elongate shape between the first side direction and the second side direction. The saddle can include an inner lobe configured to rest against a torso of the user during use, an outer lobe configured to rest against an arm of the user during use, and a top portion connecting the inner lobe and the outer lobe and forming a U-shaped channel having an curved upper surface configured to fit within an armpit of the user with the U-shaped channel open along at least a portion of a downward facing side. The crutch can have a support leg pivotably connected to the saddle at the a rotatable shock absorber assembly, wherein the joint is disposed within the U-shaped channel. The saddle can be held stable in the armpit of the user and the support leg can rotate about, and translate along the elongate axis during use. 
         [0013]    In one embodiment, the rotatable shock absorber assembly is incorporated within a crutch having a first side direction generally parallel to a walking direction of a user, a second side direction opposite the first side direction, a third side direction perpendicular to the first side direction and a fourth side direction opposite the third side direction. The crutch can also comprise a support leg having a top end and a bottom end. The support leg can also comprise a bottom portion proximate the bottom end, a middle portion disposed to the first side direction of an axis extending between the top end and the bottom end, and disposed to the third side direction of the axis extending between the top end and the bottom end, and a top portion proximate the top end extending along an elongate axis. 
         [0014]    In embodiments, a cantilevered handle can extend in an elongate shape from a fixed end arranged at the middle portion of the support leg to a free end. The crutch can also comprise a saddle coupled to the top end of the support leg by the rotatable shock absorber assembly. 
         [0015]    The above summary is not intended to describe each illustrated embodiment or every implementation of the subject matter hereof. The figures and the detailed description that follow more particularly exemplify various embodiments. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]    Subject matter hereof may be more completely understood in consideration of the following detailed description of various embodiments in connection with the accompanying figures. 
           [0017]      FIG. 1  is an exploded perspective view depicting a crutch, according to an embodiment. 
           [0018]      FIG. 2A  is a front view depicting a pair of crutches in use, according to an embodiment. 
           [0019]      FIG. 2B  is a side view depicting a pair of crutches in use, according to an embodiment. 
           [0020]      FIG. 3A  is a front view depicting a crutch, according to an embodiment. 
           [0021]      FIG. 3B  is a side view depicting a crutch, according to an embodiment. 
           [0022]      FIG. 4A  is a depiction of a button connector selectively positioned within an aperture in the support leg of a crutch, according to an embodiment. 
           [0023]      FIG. 4B  is a depiction of the button connector of  FIG. 4A  selectively positioned within an aperture in the support leg of a crutch, according to an embodiment. 
           [0024]      FIG. 4C  is a front plan view depicting a button connector, according to an embodiment. 
           [0025]      FIG. 4D  is a side plan view depicting a button connector according to an embodiment. 
           [0026]      FIG. 4E  is a front plan view depicting an adjustment button according to an embodiment. 
           [0027]      FIG. 5  is an exploded perspective view depicting a crutch, according to an embodiment. 
           [0028]      FIG. 6A  is a top isometric exploded view depicting a saddle of a crutch, according to an embodiment. 
           [0029]      FIG. 6B  is a bottom isometric exploded view depicting the saddle of a crutch of  FIG. 6A . 
           [0030]      FIG. 7  is a cross-sectional view depicting a rotatable shock absorber assembly of a crutch, according to an embodiment. 
           [0031]      FIG. 8A  is a perspective view depicting a joint for a rotatable shock absorber assembly, according to an embodiment. 
           [0032]      FIG. 8B  is a top plan view depicting the joint of  FIG. 8A , according to an embodiment. 
           [0033]      FIG. 8C  is a side plan view depicting the joint of  FIG. 8A , according to an embodiment. 
           [0034]      FIG. 8D  is a front plan view depicting the joint of  FIG. 8A , according to an embodiment. 
           [0035]      FIG. 8E  is a cross-sectional view depicting the joint of  FIG. 8A , according to an embodiment. 
           [0036]      FIG. 8F  is a perspective view depicting the joint for a rotatable shock absorber assembly, according to an embodiment. 
           [0037]      FIG. 8G  is a perspective view depicting the joint for a rotatable shock absorber assembly, according to an embodiment. 
           [0038]      FIG. 9A  is a perspective view depicting pistons for the rotatable shock absorber assembly, according to an embodiment. 
           [0039]      FIG. 9B  is a cross-sectional view depicting a piston for the rotatable shock absorber assembly, according to an embodiment. 
           [0040]      FIG. 9C  is a cross-sectional view depicting a piston for the rotatable shock absorber assembly, according to an embodiment. 
           [0041]      FIG. 10A  is a top plan view depicting a piston washer for a rotatable shock absorber assembly, according to an embodiment. 
           [0042]      FIG. 10B  is a perspective view depicting a piston washer for a rotatable shock absorber assembly, according to an embodiment. 
           [0043]      FIG. 11A  is an exploded perspective view depicting a rotatable shock absorber assembly and support leg, according to an embodiment. 
           [0044]      FIG. 11B  is a perspective view depicting the rotatable shock absorber assembly and support leg of  FIG. 11A , according to an embodiment. 
       
    
    
       [0045]    Dimensions provided in drawings are examples only. Unless otherwise stated, dimensions in drawings are provided in millimeters. While various embodiments are amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit the claimed inventions to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the subject matter as defined by the claims. 
       DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0046]    An example of an improved crutch  10 , shown in  FIG. 1 , includes an elongate support leg  12  having a cantilevered handle  14  disposed thereon with a saddle  16  connected to an upper portion  20  of the support leg  12  at a top end  22  of the crutch  10 , and a foot  18  connected to a lower portion  24  of the support leg  12  at a bottom end  26  of the crutch  10 . Crutch  10  is a handed crutch and is configured for optimal use with a particular hand and side of the body. The particular crutch  10  shown is a left-handed crutch, but references to crutch  10  should not be understood as limited to a crutch of a particular handedness. A right-handed crutch is omitted for the sake of simplicity in this figure, but it should be understood that the discussion herein is applicable to right-handed crutches, which are contemplated and which are in a mirror image of their left-handed counterparts as shown, for example, in  FIG. 2A and 2B . Further, the crutches disclosed herein may and often will be packaged in a set including a left-handed crutch and a right-handed crutch. Still further, some embodiments and features are not limited to handed crutches and may be used in conjunction with crutches or other devices that are equally suited to use with either hand. 
         [0047]    The elongate support leg  12  may be understood better with reference to  FIG. 2A and 2B , which are front and side views showing a pair of crutches in use, as well as with reference to  FIG. 3A and 3B  which depict front-views and side views of a single crutch. Support leg  12  may be shaped to accommodate a narrower stance width, which eases mobility in crowded areas and cramped areas. In the embodiment shown, a middle portion  28  of support leg  12  arcs outwardly to the side to accommodate the hip area and then arcs back in to narrow the stance of the crutch  10  at the lower portion  24  that includes the foot  18 . In other words, the middle portion  28  of support leg  12  is curved in the anatomical planes of the user outwardly in a frontal/coronal plane to an outer side of a median/sagittal plane. 
         [0048]    In some embodiments, a crutch axis (shown by phantom line  30 ) extending between the top end  22  and the bottom end  26  of crutch  10  is not perfectly vertical in a resting, neutral position, but is at a small forward angle such that the bottom end  26  of support leg  12  is in front of a frontal/coronal plane relative to an anatomical central axis of the user (shown by phantom line  32 ), with the middle portion  28  of support leg  12  further in front of the bottom end  26 . In other words, the support leg  12  is curved forwardly in a side-view (median/sagittal plane) with the bottom end  26  slightly forward of the top end  22 . In various embodiments, the forward curve of the support leg  12  is such that, in addition to the middle portion  28  being further forward in a side-view (median/sagittal plane), the lower portion  24  is generally oriented perpendicular to the floor when the crutch  10  is in a resting position even though the bottom end  26  at a slight angle and forward of the top end  22  of the support leg  12 . 
         [0049]    In various embodiments, lower portion  24  can be generally straight, middle portion  28  can exhibit middle bend  64 , and upper portion  20  can exhibit upper bend  66 . 
         [0050]    In an example embodiment, the angles and dimensions of the portions of the support leg  12  are approximately as described below, though other angles and dimensions can be used. Lower portion  24  is generally straight, defining a lower portion axis (phantom line  60 ), and can have a length, in one embodiment, of about 43 cm. As assembled, middle portion  28  can extend above lower portion  24 , along lower portion axis for a length of about 48 cm to middle bend  64 . Above middle bend  64 , middle portion  28  can extend along middle portion axis (phantom line  62 ) for a length of about 24 cm. Upper portion  20  can extend along middle portion axis  62  for a length of about 20 cm, to upper bend  66 . Above upper bend  66 , upper portion  20  can extend along crutch axis  30  for about 10 cm. 
         [0051]    Relative to a median/sagittal plane of the user, middle bend  64  can define an angle between lower portion axis  60  and middle portion axis  62  of about 9 degrees. Relative to a transverse plane of the user, middle bend  64  define have an angle between lower portion axis  60  and middle portion axis  62  of about 2 degrees. 
         [0000]    Relative to a median/sagittal plane of the user, bend  66  can define an angle between middle portion axis  62  and crutch axis  30  of about 170 degrees. 
         [0052]    In various embodiments, one or both of the upper portion  20  and lower portion  24  are both slidably adjustable with respect to the middle portion  28  to fit the crutch  10  to a particular user. In some embodiments, the upper portion  20  may be adjusted first with respect to the middle portion  28  to fit the crutch  10  to an arm of user of a particular length, and the lower portion  24  may be subsequently adjusted to fit the crutch  10  to the height of a user. In various embodiments, the versatility of the crutch  10  is such that a first size of adjustable crutch can accommodate people with heights of 5′0″-6′6″, a smaller, second size of adjustable crutch can accommodate people with heights of 4′0″-5′0″, and a larger, third size of adjustable crutch can accommodate people with heights of 6′0″-7′0″. Other sizes can be provided in embodiments. 
         [0053]    In one embodiment of crutch  10 , the upper portion  20  and the lower portion  24  are telescopically inserted into the middle portion  28 . Alternatively, the middle portion  28  could be telescopically inserted into one or both of the upper portion  20  and/or lower portion  24 . In various embodiments, the cross-sectional shape of these portions may be circular or optionally may be oval, oblong, or other non-circular shape to maintain the orientation of these portions with respect to each other as the relative position of each portion is adjusted. 
         [0054]    In embodiments, such as that shown in  FIGS. 4A-4D , discrete sliding adjustment of the portions  20 ,  24 ,  28  of support leg  12  relative to one another is facilitated by button connector  300 . The outer portion(s) of support leg  12  can present linearly spaced pairs of apertures  301 . Each aperture of each pair of apertures  301  is generally opposite around the perimeter of the outer portion(s) of support leg  12 . The inner portion(s) of support leg  12  can present a single pair of adjustment apertures (not shown). Adjustment apertures can be, for example, about 5 centimeters from the end of the inner portion(s) that will be inserted into the outer portion(s). In the depicted embodiment, middle portion  28  is the outer portion into which upper portion  20  and lower portion  24  are telescopically inserted. The following description adopts this convention, but it will be clear to those of ordinary skill of the art that alternative arrangements are possible. 
         [0055]    Each button connector  300  can be selectively depressed to retract and then released to extend button connector  300  into adjustment apertures in upper portion  20  and lower portion  24  of support leg  12 . Each button connector  300  can further extend into a selected pair of apertures  301  in the middle portion  28  of support leg  12 . When the button connector  300  is extended into a selected pair of apertures  301 , relative movement of the two sections is prevented. The two sections may be adjusted by depressing button connector  300  and sliding one section with respect to another. The support leg  12  may further include one or more fittings such as plastic bushings (not shown) or the like that serve to guide and position the portions of the leg with respect to each other to prevent rattling and provide a solid one-piece feel. 
         [0056]      FIGS. 4C-4E  depict detailed views of button connector  300 . Button connector  300  can present connector legs  302   a  and  302   b  joined at connector vertex  304 , and presenting buttons  306   a  and  306   b  at respective ends distal to connector vertex  304 . Connector legs  302   a  and  302   b  can be bent such that angle φ between portions of connector legs  302   a  and  302   b  proximate to connector vertex  304  is about sixty five degrees, and angle θ between portions of connector legs  302   a  and  302   b  proximate buttons  306   a  and  306   b  is about 20 degrees. Other angles can be used. Buttons  306   a  and  306   b  can each present notch  316 . Buttons  306   a  and  306   b  can be substantially hollow, or may be filled with an elastomeric or other substance. 
         [0057]    As depicted in further detail in  FIG. 4E , buttons  306   a  and  306   b  can define generally frusto-conical forms, having a first diameter at an outer end  308  that is smaller than a second diameter at connection point  310  at connector leg  302 . This frusto-conical form provides for a more secure fit between the button  306  and the corresponding aperture  301 . In embodiments, first and second diameters are chosen such that the slope of button edge  312  relative to a line (phantom line  314 ) normal to connector leg  302  defines an angle δ that is between one degree and five degrees. In embodiments, δ can be from two degrees to three degrees. In one embodiment, δ is two and one-half degrees. The second diameter at connection point  310  can be chosen to be substantially equivalent to the diameter of each aperture  301 . 
         [0058]    Button connector  300 , in concert with apertures  301  therefore allows adjustment of the working lengths of upper portion  20  and lower portion  24  of support leg  12 , in order to support the varying body geometry of various users. In addition, the structure of buttons  306  reduces the amount of play between buttons  306  and apertures  301 , resulting in a quieter, more secure feeling connection less bothersome “clacking” or wear on upper portion  20 , lower portion  24 , or buttons  306 . 
         [0059]    In an embodiment, discrete adjustment can be provided by a spring loaded adjustment pin (not shown) which can operated in a manner substantially similar to button connector  300 . 
         [0060]    As can be seen in  FIG. 5 , handle  14  is attached to the leg by sliding handle  14  over a cantilevered arm  54  fixed to the leg. It is contemplated that the cantilevered arm  54  provides most of the structural support for the handle  14 , while the handle  14  is made from a non-abrasive resilient closed-cell foam or other suitable material to provide a comfortable grippable surface for the use. 
         [0061]    In various embodiments, the angles of a center line of the handle (shown in phantom at  34 ) relative to the three orthogonal axis of the body of the user are about 16 degrees in the median/sagittal plane, about 60 degrees in the frontal/coronal plane, and about 45 degrees in the transverse/axial plane defined relative to the central axis of the user. Other angles may be used. The handle  14  preferably may include a fastener (not shown) such as a screw or Christmas tree fastener to fix the handle  14  to the cantilevered arm  54 . Cantilevered arm  54  may include a hole (not shown) for receiving the fastener. An opening (not shown) of handle  14  may have an oval or other non-circular cross-section and cantilevered arm  54  of the leg may have a corresponding shape such that the relationship of arm  54  to the opening prevents rotation of the handle  14 . Of course, other stem and cavity configurations that do not have circular profiles may also provide a similar function. Handle  14  may also include tabs on either side that extend at least partially round the sides of the vertical portion of the leg to further oppose rotational force. Handle  14  may be symmetric such that it is equally suitable for use by both a left hand and a right hand. Handle  14  may also be shaped in order to better accommodate a left or right hand. 
         [0062]    The position and angles of handle  14  relative to crutch axis  30  allow the hand of the user to be generally positioned parallel with the crutch axis  30  with the handle angularly offset from each anatomical plane relative to the central axis  23  of the user. In various embodiments, the position and angle of the handle  14  corresponds to a natural position of the hand of the user when hanging in a resting position. This positioning of handle  14  facilitates a more natural balance to reduce effort by the user in keeping the crutch  10  from shifting forward or backward with respect to the shoulder, thereby reducing forearm fatigue and shear stress under the arm in contact with the saddle  16 . 
         [0063]      FIG. 6A and 6B  are exploded views depicting an embodiment of saddle  16 . Saddle  16  may include an elastomeric molded member  42  that may be molded and then expanded to at least partially orient the polymeric molecules of the member  42 . This member may be stretched and attached to a rigid perimeter frame  44  to provide the saddle shape. The member  42  preferably completely encloses the perimeter of frame  44  to isolate the frame from the user. Frame  44  has a hyperbolic paraboloid shape, with one lobe being larger than the other. The elastomeric molded member may include slits or other openings to allow for ventilation through the saddle. Frame  44  can present attachment features enabling attachment of rotatable shock absorber assembly  400 . Other saddles, such as those described in U.S. Pat. Nos. 7,926,498 and 8,418,706 (the disclosures of which are incorporated by reference herein) may also be used. 
         [0064]    In an embodiment, saddle  16  is fixedly connected to rotatable shock absorber assembly  400 .  FIG. 7  is a section view depicting a rotatable shock absorber assembly  400 , according to an embodiment. Rotatable shock absorber assembly  400  can comprise joint  402 , piston  500 , and block  600 . Rotatable shock absorber assembly  400  can maintain the saddle in position in the armpit of a user to help support the user and move with the user during operation while the rest of the crutch is moved back and forth with respect to the user&#39;s body. Shock absorber assembly  400  can extend along an elongate axis  36  (represented by dotted line), which can be parallel to central axis  23 , crutch axis  30 , or at an angle relative to both in embodiments. A radial plane, normal to elongate axis  36  can be defined by major axis  38  (represented by solid line) and minor axis  40  (represented by dashed line depicted in  FIG. 11A ), which are orthogonal to each other. 
         [0065]      FIGS. 8A-8E  are perspective views and plan views depicting an embodiment of joint  402 . As can be seen in  FIG. 8B , a frontal plane (parallel to elongate axis  36  and major axis  38 , denoted as line  450 ) divides joint  402  into mirrored front and back portions. Similarly, a median plane (parallel to elongate axis  36  and minor axis  40 , denoted as line  460 ) divides joint  402  into mirrored side portions. As seen in  FIG. 8C , joint  402  includes generally rectangular bottom face  406 , elongated along line  450 . Joint  402  further includes generally cylindrical head portion  420 , elongated along line  460 . Head portion  420  can be sloped at front and rear faces  422 . Head portion  420  includes centrally located circular aperture  424 . Sloped side faces  408  can slope from head portion  420  towards rectangular bottom face  406 . In embodiments, sloped side faces can meet vertical side faces  416 . Joint  402  can present one or more rotation pins  410 , which can protrude from bottom face  406 . Joint  402  can further present centrally located joint bore  412 . As can be seen in  FIG. 8E , joint  402  can further present one or more tilt spring holders  414 , which can be pins embedded into depressions within sloped side faces  408 . 
         [0066]    Additional views of joint  402  can are provided in  FIGS. 8F and 8G , which are perspective views of an embodiment. Joint  402  can comprise hard plastic, rubber, metal, or other materials. In embodiments, joint  402  can comprise resins or other polymers and can be glass fiber reinforced. Joint  402  can be cast, injection molded, 3D printed, or fabricated via other methods known in the art. 
         [0067]    One or more tilt springs  404  (depicted in  FIGS. 7 and 11A-11B ) can be positioned to interact between joint  402  and saddle  16 , enabling saddle  16  to tile, or pivot, on minor axis  40 . In the embodiment of  FIGS. 11A and 11B , two tilt springs  404   a  and  404   b  are shown, though more or fewer tilt springs can be included in embodiments. Tilt springs  404  can be compressed as saddle  16  is tilted and be configured to urge saddle  16  to a neutral position. This tilting action can allow the saddle to rock about minor axis  40  during use to reduce or eliminate scrubbing action of the saddle against the user&#39;s chest and arms. In embodiments, joint  402  can enable tilting as described while being fixed or adjustably fixed about elongate axis  36 . 
         [0068]      FIGS. 9A-9C  are perspective and plan views depicting an embodiment of piston  500 , according to an embodiment. The main body of  502  of piston  500  can have a generally elliptical cross section, and extend along elongate axis  36 . A bottom surface  502  can define an ellipse, elongated along major axis  38 . A flange  504  can be arranged at an upper end of main body  502  and define a rectangle elongated along major axis  38  having rounded extensions  506 . Extensions  506  can extend further along major axis  38  than main body  502 . Piston  500  is slidably insertable into upper portion  20  of support leg  12 , with the exception of flange  504 . Joint stem  508  can be centrally located on flange  504  and extend upward along elongate axis  36 . Joint stem  508  can have a diameter that enables insertion into joint bore  412 . In embodiments this diameter can be about 7 mm. Joint stem  508  can further present screw bore  510 . In embodiments, screw  518  and washer  522  (as shown in  FIGS. 7A and 7C ) can fixably connect piston  500  to joint  402 . 
         [0069]    Flange  504  can further present rotation grooves  512 , which can be apertures or depressions in the top surface. Rotation grooves  512  can have a width sufficient to enable insertion of rotation pins  410  of joint  402 . Rotation grooves  512  can define total or partial arcs, enabling rotation pins  410  to move relative to piston  500 , creating a rotation of joint  402  and saddle  16  relative to piston  500  around elongate axis  36 . The extent of rotation may be 15, 20, 22, 25, 30, or 35 degrees or another suitable rotational extent. In one embodiment, this rotational extent is 44 degrees. This horizontal rotation allows the angular position of the saddle to be adjusted with respect to the rest of the crutch and in particular the handle, to allow the crutch to better adapt to various unique user body shapes (the armpit-to-hand angle varies between people). In another suitable embodiment joint  402  can be rotationally fixed relative to piston  500  so as to allow a user to customize the orientation of the saddle  16  with respect to the support leg  12 . 
         [0070]    Piston  500  can present piston slot  516 . Piston slot  516  is elongated in a direction parallel to the main body of piston  500  through flattened faces  502 . In embodiments, piston slot  516  allows passage of guide pin  518  through piston  500  from front to back. In other embodiments, piston slot  516  can define depressions in piston  500 , without allowing through passage of a guide pin  518 . Piston slot  516  can have a length suitable for allowing the desired amount of vertical (relative to the piston) movement of saddle  16 . In embodiments, this length can be about 26.7 mm. Piston  500  can present centrally located block stem  514 , on bottom surface. Block stem  514  can present vertical ridges. 
         [0071]    Piston  500  can comprise hard plastic, rubber, metal, or other materials. In embodiments, joint  402  can comprise resins or other polymers and can be glass fiber reinforced. Piston  500  can be cast, injection molded, 3D printed, or fabricated via other methods known in the art. 
         [0072]    Piston spring  520  can be a spring, metal bellows, or other appropriate store of mechanical energy. In embodiments, piston spring  520  is a metal spring with an inner diameter sufficient to enable the insertion of block stem  514 . 
         [0073]    Block  600  is generally cylindrical or elliptical with cross-section suitable for insertion into upper portion  20  of the support leg  12 . As depicted in  FIG. 7C , block  600  can present block bore  602  which can include spring pin  604 . Block bore  602  can have a diameter sufficient to enable insertion of piston spring  520 , and spring pin can have a diameter sufficiently small to enable insertion into piston spring  520 . 
         [0074]      FIGS. 9A and 9B  are plan and perspective views of optional piston washer  800  that can be provided in embodiments. Piston washer  800  can have an elongate shape similar to flange  504  of piston  500 . Piston washer can be relatively flat along the elongate axis with a height of between about 0.5 mm to about 2 mm. Piston washer  800  can define a centrally arranged joint aperture  802 , which can be sized, shaped, and position to allow joint stem  508  to pass therethrough. Piston washer  800  can further define pin apertures  804 , which can each be sized, shaped, and positioned to allow rotation pins  410  to pass therethrough. Piston washer  800  can comprise copper, aluminum, steel, other ferrous or non-ferrous metals, or elastomeric substances. 
         [0075]    Piston washer  800  can facilitate more even rotation of joint  402  (and therefore saddle  16 ) about elongate axis  36  relative to piston  500  and support leg  12 . The sliding action of the relatively smooth plastic outer surfaces of joint  402  and piston  500  can cause undesirable sticking in some instances. Piston washer  800  can mitigate this sticking by acting as a buffer between the two surfaces. In addition, wear of the plastic surfaces between joint  402  and piston  500  can lessen rotational tension over time, resulting in an undesirably loose rotation of saddle  16 . Piston washer  800  mitigate the effects of this wear, and maintain the rotational tension of joint  402  (and therefore also saddle  16 ) relative to piston  500 . 
         [0076]      FIG. 11A  is an exploded perspective view depicting a rotatable shock absorber assembly  400  according to an embodiment.  FIG. 11B  is a perspective view depicting an assembled embodiment. Guide pin  518  can be a two-piece barrel (or post-and-screw) bolt, in which a screw can be threaded into a barrel shaped flange. In other embodiments, other fasteners or combinations of fasteners of sufficient length to pass through upper portion  20  of support leg  12  used. For example, guide pin  518  can comprise a carriage bolt and a nut. Guide pin  518  can be insertable through a pair of apertures  704  defined within upper portion  20  of support leg  12 . In embodiments, more than one pair of apertures  704  can be provided, enabling adjustment of the location of guide pin  518  (and therefore, the travel of piston  500 ). 
         [0077]    As assembled, piston washer  800  can be arranged between flange  504  of piston  500  and bottom face  406  of joint  402 , such that joint stem  508  protrudes through joint aperture  802  and is arranged within joint bore  412  and rotation pins  410  protrude through pin apertures  804  and are arranged within rotation grooves  512 . Tilt springs  404  are inserted into tilt spring holders  414 . Screw  518  and washer  522  can fasten joint  402  to piston  500 . Block  600  is arranged within upper portion  20  of support leg  12 . Piston spring  520  is compressed between block  600  and piston  500  such that coils of piston spring  520  are at least partially wrapped around block stem  514  and spring pin  604 . Guide pin  518  is inserted through apertures  704  of upper portion and piston slot  516 . 
         [0078]    In operation, embodiments of rotatable shock absorber assembly  400  described above can function to provide walking assistance to a patient. In embodiments, joint  402  provides one degree of rotational freedom oriented so that support leg  12  pivots back and forth with respect to the saddle along a path parallel to that of the user. In embodiments, joint  402  rotates relative to piston  500  in a plane normal to crutch axis  30 , enabling support leg  12  to move along an outwardly arced path. 
         [0079]    In embodiments, movement of saddle  16  upwards or downwards along crutch axis is facilitated by piston  500 , guide pin  518 , and piston spring  520 . In operation, pressure can be asserted on joint  402  which will urge piston  500  deeper into upper portion  20 , compressing piston spring  520 , until guide pin  518  engages with the top edge of piston slot  516 . When the pressure is released, piston spring  520  can urge piston  500  upwards, until guide pin  518  engages with the bottom edge of piston slot  516 . 
         [0080]    Embodiments of the present disclosure provide numerous improvements over conventional devices, including those mentioned here. For example, guide pin  518  is a separate component from piston  500 . Guide pin  518  can therefore be manufactured independently of piston  500  and consist of a material with higher strength, such as steel bolts. In addition, because guide pin is fixed at a vertical position in support leg  12 , support leg  12  does not need to present elongated external slots, which can be more susceptible to wear. The fixed guide pin  518  also avoids the risk of catching and/or abrading the users skin and/or clothing. Saddle  16 , therefore, does not have to incorporate additional flaps or tabs to cover guide pin  518 . 
         [0081]    Wear can also be reduced by spreading the force of contact across the width of piston  500 . In conventional exposed pin designs the full force of the pins contacting the slots is borne by the slots defined in the hollow support leg. Because the leg is optimally lightweight, it is often constructed of a material, such as aluminum, having thing walls. Excessive wear can therefore occur at the tops and bottoms of the slots. In contrast, piston slot  516  spans the width of piston  500  in disclosed embodiments. The contact pressure between the slot  516  and pin  518  is therefore spread across the width. This internal piston design can protect the piston and the bolt, and inhibit wear in comparison with other designs in which slots are presented as apertures in the crutch leg. 
         [0082]    Various embodiments of systems, devices, and methods have been described herein. These embodiments are given only by way of example and are not intended to limit the scope of the claimed inventions. It should be appreciated, moreover, that the various features of the embodiments that have been described may be combined in various ways to produce numerous additional embodiments. Moreover, while various materials, dimensions, shapes, configurations and locations, etc. have been described for use with disclosed embodiments, others besides those disclosed may be utilized without exceeding the scope of the claimed inventions. 
         [0083]    Persons of ordinary skill in the relevant arts will recognize that the subject matter hereof may comprise fewer features than illustrated in any individual embodiment described above. The embodiments described herein are not meant to be an exhaustive presentation of the ways in which the various features of the subject matter hereof may be combined. Accordingly, the embodiments are not mutually exclusive combinations of features; rather, the various embodiments can comprise a combination of different individual features selected from different individual embodiments, as understood by persons of ordinary skill in the art. Moreover, elements described with respect to one embodiment can be implemented in other embodiments even when not described in such embodiments unless otherwise noted. 
         [0084]    Although a dependent claim may refer in the claims to a specific combination with one or more other claims, other embodiments can also include a combination of the dependent claim with the subject matter of each other dependent claim or a combination of one or more features with other dependent or independent claims. Such combinations are proposed herein unless it is stated that a specific combination is not intended. 
         [0085]    Any incorporation by reference of documents above is limited such that no subject matter is incorporated that is contrary to the explicit disclosure herein. Any incorporation by reference of documents above is further limited such that no claims included in the documents are incorporated by reference herein. Any incorporation by reference of documents above is yet further limited such that any definitions provided in the documents are not incorporated by reference herein unless expressly included herein. 
         [0086]    For purposes of interpreting the claims, it is expressly intended that the provisions of 35 U.S.C. § 112(f) are not to be invoked unless the specific terms “means for” or “step for” are recited in a claim.