EP1575474A2

EP1575474A2 - Mobility-aid apparatus and method

Info

Publication number: EP1575474A2
Application number: EP03767280A
Authority: EP
Inventors: Jeremy Gin; Jesus Garza; Richard W. Benner; Jerry Gin
Original assignee: Hessa Medical Inc
Current assignee: Hessa Medical Inc
Priority date: 2002-08-06
Filing date: 2003-08-06
Publication date: 2005-09-21
Also published as: WO2004012641A2; AU2003264024A1; EP1575474A4; WO2004012641A3; AU2003264024A8

Abstract

Apparatuses, e.g., crutches, and methods assist in mobility of a person. For example, a crutch (IB) includes at least two height adjustment points (3, 5, 7) on the crutch for greater range of adjustment, a configuration that avoids triggering security alarms, one or more of various integral features, a wide-angle ground contact piece (44), and a variable-spring-rate shock absorber (49), or other features.

Description

MOBILITY-AID APPARATUS AND METHOD

TECHNICAL FIELD [0001] The present invention relates to mobility aid apparatuses and methods. For example, embodiments of the present invention are especially applicable to crutches or the like.

BACKGROUND OF THE INVENTION [0002] Mobility aids including crutches of various designs have long been used to assist people with injuries or other temporary or permanent disabilities.

[0003] In order to accommodate users having diverse body dimensions, typical commercially available crutches are adjustable in overall height and in the position of a handle along the overall height. A typical commercially produced crutch has body components made of wood (see, e.g., U.S. Patent No. 815,368) or aluminum (see, e.g., U.S. Patent No. 4,838,291). Such body components typically have multiple holes by which they can connect to one another using metal bolts and metal wing nuts. Depending on the particular holes selected for use, overall height and handle position is determined. Typically, there is only one adjustment point for the overall height. [0004] Despite their long history of existence, conventional crutches have problems of being uncomfortable to use due to their rigidity, expensive to produce due to their complexity, and expensive to produce and keep as inventory due to a need for multiple sizes of crutches caused by the limited height adjustability of any one crutch. Another problem is that metal components used in crutches tend to trigger metal detector alarms, for example, at airports.

BRIEF DESCRIPTION OF THE DRAWINGS

[0005] In order to more fully describe specific embodiments of the present invention, including the currently preferred embodiments of the invention and the currently known best mode of the present invention, reference is made to the accompanying drawings. Understand that these drawings are not to be considered limitations in the scope of the invention, but are merely illustrative. [0006] Throughout the views, like reference numerals refer to like parts:

FIG. 1A includes a schematic diagram of an embodiment of the invention; FIG. IB includes an outline diagram of a crutch that embodies the invention; FIGS. 2 A, 2B, and 2C include views of an upper component of the crutch; FIGS. 3 A, 3B, and 3C include views of a middle component of the crutch;

FIG. 3D includes an enlarged, fragmentary view of a portion, of the middle component, that includes the handle of the middle component; FIGS. 4A-4C include views of the handle; FIGS. 5A-5C include views of an adjustment pin for the handle; FIGS. 6A-6C include views of a lower component of the crutch as assembled to the lower portion of the middle component;

FIGS. 7 A and 7B include fragmentary views of only an upper region of the lower component of the crutch;

FIGS. 8A-8C include views of a lower portion of the lower component of the crutch, including a breakout view of the bottom of the lower portion;

FIG. 9 includes a perspective view of a step cap, seen in, e.g., FIGS. 7B and 8A-8C, from the lower portion of the lower component;

FIGS. 10 A- 10C include views of a boot, or footpad, that was seen in FIGS. 6A-6C; FIGS . 11 A- 11 D include views of an example adjustment pin according to an alternative embodiment of the invention;

FIGS. 12A-12C include views of another example adjustment pin according to an alternative embodiment of the invention;

FIG. 13 includes an exploded view of an alternative embodiment of the invention that has a simplified single-post design; FIGS. 14A-C and 15A-B include views of two parts of a particular, two-part implementation of a main body component

FIGS. 16A-C include views of a forearm crutch according to an embodiment of the present invention.

FIGS. 17A-C include views of a cuff of the forearm crutch of FIGS 16A-C. FIGS. 18A-E include views of an upper post 17c of the forearm crutch of FIGS 16A-C.

FIG. 19 includes a schematic diagram of the main body component and mold cores being withdrawn from the molded main body component in directions indicated by arrows.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

[0007] Reference will now be made in detail to the following specific embodiments of the invention, examples of which are illustrated in the accompanying drawings. While the invention will be described in conjunction with the specific embodiments, it will be understood that the described embodiments are not intended to limit the invention specifically to those embodiments. On the contrary, the invention is intended to cover alternatives, modifications and equivalents, which may be included within the spirit and scope of the invention as defined by the appended claims. While the preferred embodiments are presented in the form of an underarm crutch, the invention could be embodied as, or incorporated into, a wide range of mobility assisting devices including, for example, forearm crutches or walkers or the like. For example, a forearm crutch embodiment may differ from an underarm crutch by being shorter overall and by having, not an underarm saddle, but a forearm contact.

[0008] Embodiments of the present invention are (also) discussed in the following commonly-owned U.S. Patent Applications, which are hereby incorporated by reference in their entirety for all purposes:

U.S. Provisional Patent Application No. 60/401,630, filed August 6, 2002, entitled "MOBILITY-AID APPARATUS AND METHOD";

U.S. Patent Application No. 10/364,126 , filed February 10, 2003, entitled "Mobility- Aid Apparatus and Method Using Multiple Height Adjustments"; U.S. Patent Application No. 10/364,605 , filed February 10, 2003, entitled

"Adjustable Mobility- Aid Apparatus That Avoids Triggering Alarms";

U.S. Patent Application No. 10/364,086, filed February 10, 2003, entitled "Mobility- Aid Apparatus and Method Using Members That Resist Rotation";

U.S. Patent Application No. 10/364,180, filed February 10, 2003, entitled "Mobility- Aid Apparatus and Method Using Integrated Tabs"; U.S. Patent Application No. 10/361,977, filed February 10, 2003, entitled "Mobility-Aid Apparatus and Method Using Tabs on Non-Boundary Region";

U.S. Patent Application No. 10/364,059, filed February 10, 2003, entitled "Mobility-Aid Apparatus and Method Having Ground Contact Pad Without Intervening Washer";

U.S. Patent Application No. 10/364,082, filed February 10, 2003, entitled "Apparatus and Method for Maintaining Ground Contact of a Mobility- Aid Apparatus at Varying Angles";

U.S. Patent Application No. 10/364,642, filed February 10, 2003, entitled "Shock Absorbing Apparatus and Method for a Mobility- Aid Device Using Limited

Range of Compression".

U.S. Patent Application No. 10/364,577, filed February 10, 2003, entitled "Mobility- Aid Apparatus and Method with Hollow Cores Having Negative Draft"";

U.S. Patent Application No. 10/364,091, filed February 10, 2003, entitled "Apparatus and Method for Producing a Mobility- Aid Apparatus Having a Hollow

Core";

[0009] FIG. 1A includes a schematic diagram, in elevation view, of an embodiment of the invention. According to the embodiment of the invention, a crutch la includes an upper component 3a, a middle component 5a, a lower component 7a, and a handle 9a that are adjustably interconnected. Three vertical adjustments relative to the middle component allow the crutch to accommodate a large range of user heights and arm lengths. The three adjustments are of the upper component 3a, the handle 9a, and the lower component, respectively. The large range is of advantage to manufacturers, hospitals, and distributors, which otherwise would need to produce, buy, and/or stock several sizes of conventional crutches (typically medium adult, tall adult, child, and small child). Thus the embodiment of the invention replaces several sizes of crutches with a single model. [0010] The embodiment of the invention can be composed mostly or entirely of polymeric material, for example, high strength plastic such as xenoy, nylon, polypropolene, peat, or the like. The plastic can be plastic filled with glass, wood, other strengthening additives, or the like. Furthermore, parts that move relative to each other during crutch use can be lubricated externally or with an additive, for example, silicone, or the like. According to a particular embodiment of the invention, glass filled nylon having about 30% glass content produces good strength and low weight and costs of the crutch. The composition of the crutch, including for example, proportion of glass content, may be changed to accommodate changes in material costs, crutch design, manufacturing procedures, customer preferences, other market forces, or the like.

[0011] FIG. IB includes an outline diagram, in front elevation view, of an embodiment of the invention, namely, a crutch 1 that embodies the crutch la of FIG. 1A. (In the drawings of the crutch 1, the view shown in FIG. IB is called the "front view", for convenience. It will be appreciated that, when the crutch is held underarm for use by a person, the "front" face of the crutch as seen in FIG. IB will face a direction that is generally sideways of the person and not frontward of the person.) [0012] The crutch 1 includes an upper component 3, a middle component 5, a lower component 7, and a handle 9. For convenience, the just-mentioned components 3, 5, 7 will also be referred to as the underarm component 3, the main body component 5, and the shaft 7, respectively. Of course, it would be, and it is to be, understood that in some other similar embodiments of the present invention, elements corresponding to the underarm component 3 might not be intended to fit "underarm" (e.g., for forearm crutches), and elements corresponding to the shaft 7 might not take the form of a "shaft", and elements corresponding to the main body component 5 might not be considered to be "main". Components 3 and 5 have a junction 11. Components 5 and 9 have a junction 13. Components 5 and 7 have a junction 15. Relative positions of components 3, 5, 7, and 9 can be adjusted such that the junctions 11, 13, and 15 would be at different positions on the components. [0013] FIGS. 2A, 2B, and 2C include, respectively, a front elevation view, a side elevation view, and a front section view of an embodiment of the upper component 3 shown in FIG. IB. FIGS. 3A, 3B, and 3C include, respectively, a front elevation view, a side elevation view, and a front section view of an embodiment of the middle component shown in FIG. IB. [0014] The underarm component 3, as embodied, accommodates a padded underarm saddle pad 16 and includes at least one (two are shown) downwardly extending post 17. The main body component 5 includes a corresponding number of upwardly extending hollow posts 19 (two are shown) that are open at top to accept the downwardly extending posts in telescoping manner. Spring pins 21 are molded into the underarm component 3. The hollow posts 19 have sidewalls that have vertically spaced holes that are configured to receive the spring pins 21. Crutch height is easily adjusted by telescoping the downwardly extending posts 17 into the upwardly extending hollow posts 19 and inserting the spring pins 21 into selected ones of the vertically spaced holes 23 to lock the crutch height. The inclusion of spring pins 21 integrally in the underarm support for locking vertical adjustment simplifies the crutch design, as conventional crutches have traditionally used separate spring pins or separate bolts.

[0015] For ease of manufacturing, the hollows of the hollow posts 19 can be other than perfectly cylindrical. Each of the hollows can be formed to have a taper, to facilitate withdrawal of a core mold from a molded hollow post 19. Generally, more taper means easier manufacturing. For example, a core mold need not be as polished and "non-stick" if it is being withdrawn from a core having a slight, favoring taper. Conversely, less taper, or no taper, can give a more precise feel to the apparatus by reducing looseness. In one embodiment, a taper of no more than about a 1/16 of a degree gives a good, precise feel. In another embodiment, a taper of at least 1/16 of a degree, gives greater ease and economy of manufacture, but preferably the taper is no greater than about 1/4 of a degree of taper, or, no greater than about 1/8 of a degree. In still another embodiment, a taper is greater than 1/8 of a degree, to give even greater ease of manufacture. Still other tapers are possible. [0016] Preferably, the taper is a negative draft with regard to the telescoping downwardly pointing underarm support posts of the underarm component 1. Such a negative draft gives a tighter fit at the mouth of the hollow, and makes the looseness less noticeable to the user, as compared to a hollow with a wider mouth. The negative draft is formed by a core mold for each hollow. The mold core is preferably withdrawn from the main body component in a "downward" direction 25 with respect to the main body component, as shown in FIG. 19. Thus, each hollow has positive draft with respect to its mold core. [0017] Included in the underarm support posts 17 is a set of molded spring supports

27. These spring supports 27 keep the underarm support 3 stable relative to the main body component 5, especially given the negative draft of the hollows of the hollow posts 19, for example, by springing outward to meet the internal sidewalls despite the tapering of the sidewall away from the diameter of the underarm support post 17. The hollow that accepts the support post 17 may have a corresponding channel or keyway 31 into which the spring support 27 fits and against which the spring support 27 would push to help resist any relative rotation between the support post 17 and the hollow that accepts the support post 17. Thus, the spring support 27 is an example of a protuberance that fits into a corresponding keyway to resist rotation. Any other way of resisting rotation between mating components can also or instead be used. For example, other non-cylindrical shaped posts and corresponding receiving hollows may be used. For example, posts and hollows having polygon or star-shaped or ribbed cross sections may be used. [0018] The main body component 5 is preferably a one-piece, all polymeric design (e.g., integrally reinforced plastic) with ribbing 33 to reduce weight while having adequate desired flexural strength. Conventional Finite Element Analysis can be used to select dimensions of the ribbing. The ribbing 33 also protects the snaps 21 in the upper component 3 and similar snaps in the lower component (which will be seen in later drawings) from inadvertent detent. [0019] FIG. 3D includes an enlarged, fragmentary front elevation view of a portion, of the main body component of FIG. 3 A, that includes the handle 9 of the main body component 5. FIGS. 4A-4C respectively include a front elevation view, a top view, and a side elevation view of the handle 9. The handle 9 is preferably adjustable in its height position along the crutch 1. The handle 9 may be ribbed to give strength at an economical weight. According to one embodiment, the crutch 1 includes removable pins for adjustment and placement of a crutch grip into selected ones of vertically spaced support holes 35 (see FIG. 3D) in the main body component 5. FIGS. 5A-5C respectively include a perspective view, a side elevation view, and a rear elevation view of an embodiment 37 of an adjustment pin. The adjustment pin 37 has at least one prong 39 (two are shown and are preferred) and has a crescent-shaped backplate 41. The adjustment pin 37 is configured to snap into place. As shown, the backplate 41 has hooks 43 that snap into place to hold the adjustment pin 37 in place. This particular design allows for independent handle replacement without requiring other parts to be removed or unlocked from the crutch. The pin 37 in a preferred embodiment is molded of polymeric material, but any other suitable material, e.g., metal, may be used. [0020] FIGS. 6A-6C include respectively a front elevation view, a side elevation view, and a front section view of the shaft 7 as assembled to the lower portion of the main body component 5. Only the lower portion of the main body component 5 is shown. The shaft 7 preferably includes a boot 44 at bottom. [0021] The crutch 1 preferably includes a shock absorber. Preferably, the shock absorber is part of the lower component 7.

[0022] FIGS. 7A and 7B include respectively a front elevation view and a side section of only an upper region of the shaft 7. As a way to shrink overall length of the crutch 7 resiliently for shock absorption, the shaft 7 includes an upper shaft portion 45, a lower shaft portion 47, and a shock absorber 49 between the portions 45 and 47. The shock absorber 49 acts as a spring with a spring rate (also known as spring constant) that increases with the amount of weight applied, resulting in a similar shock absorbing feel to the crutch for users of varying weights (note: a spring constant measures the strength of the spring, where a higher value denotes a stronger spring). [0023J For all springs: F = - K • X where F is force applied to the spring, X is the deflection of the spring until the force is equalized by the spring, and K is the spring rate. For music wire and other conventional springs or pneumatic devices used in crutches, K is considered to be about constant, so as F (the weight applied by the crutch user) increases, X, the resulting deflection of the spring, increases about proportionately. This presents a practical problem that different springs are needed for crutch users of differing weights — e.g., if a user weighs too much, the spring will fully compress, whereas if the user doesn't weigh enough the spring will not compress adequately. However, the shock absorber 49 is configured to have a variable spring rate such that as F increases, K increases as well, allowing X to increase substantially less than proportionately with increases in F. For example, the preceding sentence would be true for a weight difference between two typical users of conventional crutches of different sizes (e.g., "medium adult" versus "tall adult", or "child" versus "tall adult", or any other pair of conventional sizes.) [0024] The shock absorber 49 is made of a resilient material, for example, rubber, plastic, or the like, for example, neoprene, that has a cone-like shape. The shock absorber can also have any other shape having a section that increases in thickness from one end to the other. The shock absorber can also be any other type of variable-spring-rate spring, for example, a coil spring having variable coil diameter and/or variable coil density. Due to the nature of the shock absorber 49, the crutch provides similar shock absorbency to users of diverse weights with a single part. Furthermore, the use of a neoprene or other low durometer rubber or plastic with a good structural memory provides further improvement over other shock absorbing mechanisms.

[0025] The lower shaft portion 47 can slide axially relative to the upper shaft portion

45. The lower shaft portion 47 includes guide pins 51 that slide against guide slots 53 in the bottom edge of the lower sidewall of the upper shaft portion 45. The guide pins 51 and the slot 53, for example, were preferably molded into the molded portions 45 and 47. The guide pins 51 and guide slots 53 resist relative rotation by the upper and lower shaft portions 45 and 47. The guide pins 51 also form a locking mechanism that prevents the upper and lower shaft portions 45 and 47 from unintentionally separating. [0026] The inner wall of the upper shaft portion 45 is dimensioned to closely fit around the upper outer wall of the lower shaft portion 47 in order to provide a tight engagement between the two components, while still allowing sliding movement between parts. The top of the lower shaft portion 47 includes a stepped cap 55 that has an upwardly facing concave indentation, which receives the shock absorber 49 and keeps the shock absorber centered. [0027] As is shown in FIG. 6C, the main body component 4 includes a long downwardly pointing hollow post 57 that accepts the shaft 7. Referring again to FIGS. 7A-7B, the upper shaft portion 45 includes spring pins 59 for vertical adjustment of the crutch height that is in addition to the crutch height adjustment using the underarm component 3. The sidewall of the downwardly pointing hollow post 57 of the main body component 5 includes spaced holes 61 that accept the spring pins 59. [0028] For ease of manufacturing, cavity of the main body component 4 that accepts the shaft can be other than perfectly cylindrical. As discussed above in connection with the hollow posts 19, the cavity can have a taper. Preferably, the taper is a negative draft with regard to the telescoping upwardly pointing shaft. The negative draft is formed by a mold core for the cavity. Referring to FIG. 19, the mold core is preferably withdrawn from the main body component in an "upward" direction with respect to the main body component, as shown by an arrow 63. Thus, the cavity has positive draft with respect to the mold core. In one embodiment of the crutch, a taper of no more than about a 1/16 of a degree gives a good, precise feel. In another embodiment, a taper of at least 1/16 of a degree gives greater ease and economy of manufacture, but preferably the taper is no greater than about 1/4 of a degree of taper, or, no greater than about 1/8 of a degree. In still another embodiment, a taper is greater than 1/8 of a degree, to give even greater ease of manufacture. Still other tapers are possible. [0029] Referring again to FIGS. 7A-7B, the shaft 7 is kept from rotating relative to the main body component 5 (see, e.g., FIG. 6A-6C) by supports 65, which, similarly to feature 27 from FIGS. 2A-2C, have a built-in springiness to provide a tight fit with the main body component 5 while allowing for negative draft of the cavity of the main body component 5 that accepts the shaft 7. The cavity that accepts the shaft 7 may have a corresponding channel or keyway 67 (see FIGS. 6C, 3C) into which the support 65 fits and against which the support 65 would push to help resist any rotation between the shaft and the cavity that receives the shaft. In this way, the support 65 and its corresponding keyway or channel 67 prevents or reduces any rotation-caused stress on pins 51 or 59 or both 51 and 59. Thus, the support 65 is an example of a protuberance that fits into a corresponding keyway to resist rotation. Any other way of resisting rotation between mating components can also or instead be used. For example, the ways discussed in connection with feature 27 of FIGS. 2A-2C can be used.

[0030] Additionally, the upper region of the shaft 7 is designed to prevent complete removal of the entire shaft 7 from the bottom of the main body component 5. The internal keyway 67 in the main body component 5 terminates near the end of the bottom of the main body component 5 (see termination 69, FIG. 3C) such that the upper region of the shaft 7 cannot exit through the bottom of the main body component 5. In this way, tampering, loss of parts, and other damage is avoided.

[0031] Once the upper shaft portion 45 and lower shaft portion 47 are assembled and within the main body component 5, their components are prevented from coming apart due to the close tolerances with each other and the main body component 5.

[0032] FIGS. 8A-8C include respectively, a top view, a side elevation view, and a side section view of the lower portion 47 of the shaft 7 of the crutch 1. As can be seen, the bottom of the lower portion 47 preferably terminates in a closed end 71 that caps (in the sense of closing off, preferably integrally during manufacture) the preferably hollow lower portion 47 of the shaft 7. The closed end 71 provides a larger surface (as opposed to a tubular open end) over which to distribute axial force on the boot 44 (see FIGS. 6A-6C). This prevents excessive wear on the boot 44 and helps to allow the entire boot 44 to be metal free, as traditional boots have used a metal washer embedded in the footpad to serve the function of reducing wear on the traditional boot. [0033] FIG. 9 includes a perspective view of a step cap, seen in, e.g., FIGS. 7B and

8A-8C, from the lower portion of the lower component.

[0034] FIGS. 10A-10C include respectively a side elevation view, a front section view, and a perspective view of the boot 44 (that was seen in FIGS. 6A-6C), which is also referred to as the footpad 44. The footpad 44 differs from its predecessors by being shaped to be "missing" one or more rings 73 of material from the exterior of the footpad 44. This results in an accordion-like function, providing extra cushioning for the crutch user. Additionally, the removed ring (or rings) allows the base of the footpad to remain flush with the ground even when weight is applied during use at large angles from the vertical. The material between the "missing" portions can also act to limit footpad flexibility to prevent buckling. This confers greater traction and stability during crutch use. The footpad can be constructed out of any rubber or other polymeric material, but preferably out of a skid-resistant material that does not wear quickly.

[0035] According to one particular implementation (e.g., embodiment) of the embodiment of the invention, an underarm crutch has height that can be adjusted by amounts within a range of about 15 inches. This compares very favorably with conventional crutches, which tend to have heights that are adjustable within a much smaller range. The range of adjustment of about 15 inches may, for example, include about 9 inches of adjustment at the interface between the lower and the middle components (with less than about 1/4 of a degree of taper in the receiving cavity) and about 6 inches of adjustment at the interface between the upper and the middle components (with less than about 1/8 of a degree of taper in the receiving hollows). For a higher-quality embodiment, the tapers can further be restricted to less than about 1/8 of a degree, and less than about 1/16 degree, respectively. The crutch may be configured such that the range of heights may be, for example, from about 45 inches to about 60 inches or from about 48 inches to about 62 inches. Other ranges may also be used. For example, a range of adjustment of more than about 9 inches, or more than about 12 inches is also useful. Still other ranges may be used. It is to be understood that the present invention need not be tied to any particular numeric range of adjustment. [0036] In an alternative embodiment of the invention, the integral spring pins 21 and their peninsular springs, as seen in FIGS. 2A-2B, do not exist. Instead, the peninsular spring and its integral spring pin 21 are replaced by a mere hole (not shown) at the location of each integral spring pin 21. Then, separate adjustment pins are used. The adjustment pins may be shaped, for example, as shown in FIGS. 11A-1 ID. FIGS. 11A-1 ID include respectively a front elevation view, a side elevation view, a top view, and a perspective view of an example adjustment pin 75. Crutch height is adjusted by telescoping the downwardly extending posts 17 (see, e.g., FIGS. 2A-2C) into the upwardly extending hollow posts 19 (see, e.g., FIGS. 3A-3C) and inserting the separate adjustment pins 75 into selected ones of the vertically spaced holes 23 (see, e.g., FIGS. 3A, 3C) to lock the crutch height. The adjustment pins 75 when removed allow for both of the crutch users' hands to be free to adjust the underarm component 1 to the appropriate height. This height adjustment mechanism does not require the crutch user to apply continuous pressure to depress any spring pins while adjusting the height. A similar adjustment pin (not shown) can be used in adjusting the shaft 7, by similarly replacing the spring pins 59, seen, e.g., in FIGS 7A-7B, according to the alternative embodiment or another embodiment. Separate adjustment pins may be, for example, separately molded from plastic, or the like. Of course, metal pins may also be used, depending on designer preference. [0037] The pin shapes shown in FIGS. 11 A-l ID are just one possible shape. Other shapes can also be used. For example, a pin having a more substantially cylindrical, dowel shape insertion portion can be used to enhance strength both along the length of the pin and transversely. Such a shape would still have snap features that allows locking in the crutch to prevent inadvertent removal. And such a shape would still have a head. Preferably, the head is still configured to fit within ribs. For example, a rectangular shape having two edges that abut rib walls would orient the pin to ensure that the snap feature on the pin engages as designed. Fitting the head within ribs can reduce or eliminate the amount of pinhead that sticks out from the ribbing and thereby reduce opportunity for the pinhead to catch on items of clothing, hair, other objects, and the like. FIGS. 12A-12C include respectively a top view, a side elevation view, and a front elevation view of such another example adjustment pin 75b. [0038] Preferably, the downwardly extending posts 17 and the upwardly extending hollow posts 19 in the alternative embodiment have holes that extend through all material. Thus, each pin 75 (or 75b) can penetrate in from one side of an upwardly extending hollow post 19 and have a distal end of the pin 75 poke out from the opposite side of the upwardly extending hollow post 19.

[0039] The configuration of pins 75 includes a head 77 and a protrusion 79 and an optional depression 81. The protrusion is compressible to allow entry through the vertically spaced holes of the crutch. The protrusion prevents the pin from being removed from the crutch without firm and concentrated force. A crutch user would apply a force on an end 83 distal from the head to push the pin 75 out slightly to better expose the head 77. The crutch user can then remove the pin 75 by gripping and pulling the head 77. When the pin 75 is secured in the crutch the head preferably rests between ribs 33 (that are seen, e.g., in FIG. 3A) of the main body component 5. [0040] FIG. 13 includes a schematic exploded view of another alternative embodiment lb of the invention that has a simplified single-post design. For simplicity, ribbing is not shown in FIG. 13, even though the alternative embodiment preferably does include ribbing and can include any of the other features discussed in the present document. [0041] FIGS. 14A-C and 15A-B depict views of two parts of a particular, two-part implementation of a main body component. Instead of being integrally molded, the main body component comprises an upper part (FIGS. 14A-C) and a lower part (FIGS. 15A-B, not to same scale as FIGS. 14A-C), which are separately made and then assembled. Having separate parts serves to reduce the size of the mold needed for the main body component, and makes it easier to core the parts in the right direction (such that with taper, the openings in the crutch body fit tightly with sliding parts).

[0042] The upper and lower parts of the main body component can be joined, after molding, with a "snap fit," threading (like a screw), or press fit. An adhesive (for example, epoxy-based or the like) can be applied to increase strength between components. Alternatively, without adhesive, the two-part main body component can allow a crutch user to separate the crutch into two segments on demand for ease of storage and transportation. This same feature can also reduce the space required for shipping and storage of the crutch by distributors and healthcare facilities. A removable pin, for example, a pin similar to the pin 75b of FIGS.12A-C, may be used to secure the two halves when assembled. [0043] The lower part of the main body component (see FIGS. 15A-B) can be also be used as the lower part of a two-part separately-injection molded main body component of a forearm crutch (versus underarm crutch). In this way, commonality of parts between an underarm crutch and a forearm crutch is enhanced, and mold costs and other costs are reduced. In short, a main body component of a forearm crutch would have a different upper part, but the same lower part as the main body component of an underarm crutch). [0044] FIGS. 16 A-B include a front elevation view and a side perspective view of a forearm crutch lc according to an embodiment of the present invention. FIG. 16C includes a top view of the forearm crutch lc, which is preferably made using polymeric materials as a structural basis and to contain substantially no metal. The forearm crutch lc includes a lower leg 89, a grip handle 9c, a forearm post 19c, and a cuff 91. The cuff 91 is connected to the rest of the forearm crutch 1 c via an upper post 17c. The lower leg 89 is adjustable in height, as has been discussed above, for example, in connection with the crutch 1 of FIG. IB. The height position of the cuff 91, relative to the handle 9c, is also adjustable via telescoping of the upper post 17c into a hollow core of the forearm post 19c. Height position of the handle 9c is either fixed, in one embodiment, or is separately adjustable, in another embodiment. The user would contact the forearm crutch lc at the handle 9c and the cuff 91 during use.

[0045] The handle 9c of the forearm crutch lc is preferably supported at both ends, as opposed to being fixed at only one end as on traditional models. Further, the lower leg 89 is positioned such that its vertical axis, if extended imaginarily, would intersect the handle 9c at a point within the grip of a user's gripping hand, for example, near the center of the handle 9c, and/or not at one end of the handle 9c. During use, the shown design spreads pressure throughout the palm of the hand, whereas previous designs concentrated the stress between the thumb and forefinger. The reduction in stress concentration could reduce incidence and severity of Carpal Tunnel Syndrome and other repetitive stress injuries caused by crutch use. From a structural design standpoint, supporting the handle on multiple sides reduces torque on the handle relative to the lower leg of the crutch and focuses stresses along the shaft of the lower leg. The forearm crutch lc is shown as being configured to use a detachable upper pin 75c, but an integral spring pin, or other locking mechanisms, may also be used. The detachable pin 75c may, for example, resemble the detachable pin 75b shown in FIGS. 12A-C.

[0046] The forearm crutch lc is shown as using a modular, detachable, height-adjustable lower leg 89. Thus, as discussed above, commonality of parts between an underarm crutch and a forearm crutch is achieved, because the lower leg 89 can be a common interchangeable part that is also used within an underarm crutch. (See FIGS. 14A-C and 15 A-B.) Furthermore, detaching the lower leg 89 enables more compact storage and transport.

[0047] The forearm crutch lc is preferably configured to consolidate the three traditional forearm crutch models (junior, adult, and tall adult) into two models. Traditional heights from handle to tip for each model are as follows: Junior - 24.5" to 33.5" Adult - 28" to 37" Tall Adult- 35.5" to 41.5." The forearm crutch lc, in contrast, can be embodied in two sizes to cover the same height range. For example, a medium model can be adjustable between about 24.5 inches to about 32 inches, and a tall model can be adjustable between about 32 inches to about 42 inches. Still other ranges may be used. It is to be understood that the present invention need not be tied to any particular numeric range of adjustment. The configuration of the forearm crutch lc for greater adjustability can simplify inventory for healthcare providers and distributors by eliminating the need for a third product and product code.

[0048] FIGS. 17A-C include a top view, a front view, and a side view, respectively, of the cuff 91. FIGS . 18 A-E include a front elevation view, a side elevation view, a rear section view, a front section view, and a top view, respectively, of the upper post 17c into which the cuff snaps. The cuff 91 can easily be manually snapped on and off a post 17c. The cuff 91 can also be pivoted on the post 17c. In contrast, conventional cuffs are bolted, riveted or non-removable. The snap-action detachable connection between the cuff 91 and the rest of the forearm crutch lc allows for easily interchangeable cuffs. Any snapping and pivoting mechanism can be used to connect the cuff 91 and the upper post 17c. The particular mechanism illustrated includes a pivot bar on the cuff 91, and a snap-action receiver on the upper post 17c that receives the pivot bar. [0049] ' Further embodiments of the invention can be made, each by combining any number of, and any of, the features, elements, or embodiments discussed in the present document, including all documents incorporated by reference, with each other and/or with conventional features, elements, or devices, unless the combination is impossible due to contradiction between the specific example features, elements, or embodiments that are being contemplated for combination. [0050] Throughout the description and drawings, example embodiments have been given with reference to specific configurations. It will be appreciated by those of ordinary skill in the present art that the present invention can be embodied in other specific forms without departing from the spirit and scope of the present invention. For example, even though some embodiments of the invention show an upper part telescoping into a lower part, or vice versa, an opposite configuration can also be used—i.e., having a lower part telescoping into an upper part, or vice versa. For another example, even though some embodiments of the invention use a telescoping connection, any other type of adjustable connections may also be used. The scope of the invention is not limited merely to the specific example embodiments of the foregoing description, but rather is indicated by the appended claims. All changes and modifications that come within the meaning and range of equivalents within the claims are intended to be considered as being embraced within the scope of the claims.

Claims

What is claimed is:

1. A crutch, the crutch having a height, the crutch comprising: a first member; a second member slidably and lockably connected to the first member to permit, when not locked, substantially linear movement of the first and second members relative to each other, hereinafter referred to as first relative movement, wherein the first relative movement provides a first change of the height of the crutch to help accommodate body height of a user; a third member slidably and lockably connected to the second member to permit, when not locked, substantially linear movement of the second and third members relative to each other, hereinafter referred to as second relative movement, wherein the second relative movement provides a second change of the height of the crutch to help accommodate the body height of the user, and wherein the first and second changes are distinct from one another.

2. A crutch according to claim 1, wherein: each of the first, second, and third members comprises an upper end and a lower end; the first and second members are configured for one of the lower end of the first member and the upper end of the second member to telescope into the other of the lower end of the first member and the upper end of the second member; and the second and third members are configured for one of the lower end of the second member and the upper end of the third member to telescope into the other of the lower end of the second member and the upper end of the third member.

3. A crutch according to claim 2, wherein the first, second, and third members are configured to permit total adjustment of the height of the crutch by amounts including an amount that is at least about twelve inches.

4. A crutch according to claim 3, wherein the first and second members are configured that the first change of the height of the crutch can be no greater than about nine inches.

5. A crutch according to claim 1, wherein the first, second, and third members are configured to permit adjustment of the height of the crutch to heights including a height between about 48 to about 50 inches and a height between about 58 to about 60 inches.

6. A crutch according to claim 1 , wherein at least the first and second members include plastic as a structural basis.

7. An apparatus for helping to support weight of a person during ambulation, the apparatus having a length, hereinafter referred to as apparatus length, along a direction of the apparatus, the apparatus comprising: a first stage; a second stage adjustably connected to the first stage, the adjustably connected first and second stages together spanning a length, hereinafter referred to as first sub-length, along the direction of the apparatus, wherein the first and second stages are adjustably connected to permit change in position of the adjustably connected first and second stages relative to each other to alter the first sub-length, a portion of the first sub-length accounting for a first portion of the apparatus length; and a third stage adjustably connected to the second stage, the adjustably connected second and third stages together spanning a length, hereinafter referred to as second sub-length, along the direction of the apparatus, wherein the second and third stages are adjustably connected to permit change in position of the adjustably connected second and third stages relative to each other to alter the second sub-length, a portion of the second sub-length accounting for a second portion of the apparatus length, the second portion being distinct from the first portion of the apparatus length; wherein the first, second, and third stages are configured that the apparatus length is adjustable by altering the first and second sub-lengths; and wherein altering the first sub-length is capable of contributing a first adjustment to the apparatus length, and altering the second sub-length is capable of contributing a second adjustment to the apparatus length, the first adjustment being other than the second adjustment.

8. An apparatus according to claim 7, wherein the first, second, and third stages are configured and arranged that some weight of the person during use is to be transmitted from the person to the first stage, then from the first stage to the second stage, then from the second stage to the third stage, and ultimately to ground.

9. An apparatus according to claim 7, wherein at least the second and third stages are substantially composed of injection-molded plastic.

10. An apparatus according to claim 7, wherein the first adjustment may be made without the second adjustment having also to be made.

11. An apparatus for assisting in mobility of a person, the apparatus comprising: a crutch having a length along an axis; and at least two adjustment points on the crutch, wherein the length, hereinafter referred to as crutch length, is adjustable at the adjustment points, whereby the crutch is customizable for accommodating body dimensions of an intended user; wherein the adjustment points include a first and a second adjustment point, and the first adjustment point is configured to, at least occasionally, contribute an adjustment to the crutch length that is not merely an adjustment that is being contributed by the second adjustment point.

12. An apparatus according to claim 11, wherein the crutch comprises: an upper end and a lower end that define the crutch length; and a grip to be held by a hand of the intended user, distance between the upper end and the grip being hereinafter referred to as grip offset; at least a third adjustment point, wherein the grip offset is adjustable at the third adjustment point, whereby the grip distance is customizable for accommodating length of at least a portion of a limb of the intended user; wherein the third adjustment point is configured to be adjustable, at least occasionally, to contribute an adjustment to the grip offset that is not merely an adjustment that is being contributed by the first or second adjustment point.

13. An apparatus according to claim 12, wherein the crutch comprises at the third adjustment point a plurality of receptors, and the crutch comprises at least one removable pin, wherein the grip is configured to engage the at least one removable pin, and wherein the grip offset is fixed by positioning the grip, engaging the grip with the at least one removable pin, and inserting the at least one removable pin into at least a selected one of the plurality of receptors.

14. An apparatus according to claim 11 , wherein the crutch is an underarm crutch.

15. An apparatus according to claim 11 , wherein the crutch and the adjustment points are configured to permit total adjustment of the crutch length by amounts including an amount that is at least about twelve inches.

16. An apparatus according to claim 11 , wherein the crutch includes plastic as a structural basis.

17. A crutch, the crutch having a height when positioned vertically, the crutch comprising: an underarm saddle at an upper end of the crutch that engages a person underarm; a multipart body coupled to the underarm saddle, the multipart body configured to permit adjustment of height of the crutch to heights including a height that is less than about 50 inches and a height that is more than about 59 inches.

18. A crutch according to claim 17, wherein the multipart body includes plastic as a structural basis.

19. A crutch according to claim 17, wherein the multipart body includes a first, second, and third part, the first part adjustably connected to the second part, the second part adjustably connected to the third part, adjustment between the first and second parts capable contributing a first adjustment of the height of the crutch, adjustment between the second and third parts contributing a second adjustment of the height of the crutch, the first and second adjustments being distinct from one another.

20. A method for producing a mobility-assistance device, the mobility-assistance device having a device length, the method comprising the steps of: providing a first member; providing a second member; providing a third member; slideably connecting the first member to the second member, wherein sliding between the first and second members alters the device length by a first adjustment contribution; and slideably connecting the third member to the second member, wherein sliding between the third and second members alters the device length by a second adjustment contribution, the first and second adjustment contributions together contributing an adjustment adjustment of the device length that is greater than either one of the first and second adjustment contributions.

21. A method according to claim 20, wherein: the step of providing the first member comprises molding the first member; the step of providing the second member comprises molding the second member; the step of providing the third member comprises molding the third member.

22. A method according to claim 21 , wherein: the step of providing the second member comprises molding the second member of plastic.

23. A method according to claim 20, wherein the mobility-assistance device is a crutch.

40. A mobility-assistance device produced according to the method according to claim 35.

24. A mobility-assistance device according to claim 20, wherein the mobility-assistance device is a crutch.

25. A method for adjusting longitudinal length of a mobility-assistance device, wherein the mobility-assistance device includes a multi-part body and at least a first and a second adjustment point on the mobility-assistance device, wherein the longitudinal length, hereinafter referred to as device length, is adjustable at the first and second adjustment points, whereby the mobility-assistance device is customizable for accommodating body dimensions of an intended user, the method comprising adjusting the mobility-assistance device at the first adjustment point to obtain a first adjustment to the device length; and adjusting the mobility-assistance device at the second adjustment point to obtain a second adjustment to the device length, wherein the first and second adjustments together contribute a total adjustment that is not merely either of the first and second adjustments alone.

26. A method according to claim 25, wherein: the mobility-assistance device comprises an upper end and a lower end that define the device length and a grip to be held by a hand of the intended user, distance between the upper end and the grip being hereinafter referred to as grip offset; the method further comprises adjusting the grip offset without thereby adjusting the device length.

27. An underarm crutch, comprising: an underarm support that is placed underarm of a person during use; and at least one elongated member that bears weight and that includes a polymeric material as a structural basis, wherein the underarm support is coupled to the at least one member to help support weight of the person; wherein the underarm crutch has height during use, a substantial portion of which height is contributed by the at least one elongated member; and wherein the underarm crutch comprises substantially no metal, whereby the underarm crutch is capable of not triggering an alarm by an airport metal detector.

28. An underarm crutch according to claim 27, wherein the underarm crutch is configured to comprise no metal during intended use.

29. An underarm crutch according to claim 27, wherein the at least one member is substantially composed of injection molded plastic.

30. An apparatus for helping to support weight of a person, the apparatus comprising: a crutch that is substantially composed of injection molded plastic and that includes no metal; wherein the crutch, when viewed using x-ray, has appearance that differs from appearance of a metal crutch.

31. An apparatus according to claim 30, wherein the crutch is a height-adjustable underarm crutch.

32. An apparatus according to claim 30, wherein the crutch is substantially composed of glass filled nylon.

33. A device for assisting in ambulation, the device having a longitudinal axis, the device comprising: a lower body portion that includes an elongated, weight-bearing first member at top of the lower body portion when the device is positioned substantially vertically to support weight of a user, the lower body portion having no other elongated, weight-bearing member at top of the lower body portion parallel to the first member when the device is positioned substantially vertically; and an upper body portion that includes an elongated second member at bottom of the upper body portion, the second member being adjustably connected to the first member, adjustment of the connection for adjustment of device height; wherein each of the first and the second members is integrally shaped to oppose relative rotation between the second member and the first member around the longitudinal axis.

34. A device according to claim 33, wherein: an elongated portion of one of the first and second members telescopes along the longitudinal axis into a compatibly shaped passage defined by the other of the first and second members, during adjustment, amount of telescoping regulating device height; and the elongated portion is externally shaped not merely as a cylinder, and the compatibly shaped passage is shaped not merely as a cylindrical bore, and relative rotation between the second member and the first member around the longitudinal axis is opposed by the elongated portion and the passage.

35. A device according to claim 34, wherein: the elongated portion includes an external surface, and the passage includes an internal sidewall; and one of the external surface and the internal sidewall includes a protrusion, and the other of the external surface and the internal sidewall includes a channel into which the protrusion is disposed and along which the protrusion slides when the elongated portion telescopes into the passage.

36. A device according to claim 35, wherein the elongated portion comprises a plurality of ribs on the external surface, and the passage comprises a plurality of corresponding channels on the internal sidewall to accept the ribs.

37. A device according to claim 34, wherein the elongated portion is shaped to have a polygonal exterior cross section perpendicular to the longitudinal axis, and the passage is shaped to interface with the elongated portion to oppose the relative rotation around the longitudinal axis.

38. A device according to claim 33, wherein the device is an underarm crutch.

39. A method for producing an apparatus for enhancing mobility of a physically-impaired person, the apparatus having a longitudinal axis, the method comprising: forming a lower body portion that includes an elongated first member that is to bear weight and be at top of the lower body portion when the apparatus is positioned substantially vertically to support weight of a user, the lower body portion having no other elongated, weight-bearing member at top of the lower body portion parallel to the first member when the apparatus is positioned substantially vertically; and forming an upper body portion that includes an elongated second member at bottom of the upper body portion, the second member being adjustably connected to the first member, adjustment of the connection for adjustment of apparatus height; wherein the forming steps comprise integrally shaping each of the first and the second members to oppose relative rotation between the first and second members around the longitudinal axis.

40. A method according to claim 39, wherein: the forming steps comprise forming one of the first and second members to include an elongated portion to telescope into the other of the first and second members along the longitudinal axis into a compatibly shaped passage defined by the other of the first and second members, amount of telescoping regulating apparatus height; and the elongated portion is externally shaped not merely as a cylinder, and the compatibly shaped passage is shaped not merely as a cylindrical bore, and relative rotation between the second member and the first member around the longitudinal axis is opposed by the elongated portion and the passage.

41. A method according to claim 39, wherein: the method comprises forming a pin-and-recess lock that locks the first and second members from mutually sliding along the longitudinal axis, to fix the apparatus height; and opposing of relative rotation between the first and second members around the longitudinal axis due to integral shape of the first and second members at least partially avoids force on the pin-and-recess lock that would otherwise result from relative rotation between the first and first members around the longitudinal axis.

42. An apparatus produced using the method according to claim 39.

43. An apparatus for assisting in ambulation, comprising: a first member; a second member adjustably connected to the first member, wherein the first and second members together span an adjustable height; and at least one tab, integrally formed on the first member, that, when engaged, opposes adjustment of the adjustable height.

44. An apparatus according to claim 43, wherein the at least one tab is formed integrally on the first member of injection-molded plastic.

45. An apparatus according to claim 43, wherein the apparatus is a crutch.

46. An apparatus according to claim 43, wherein: the second member includes a wall that defines an open cavity; the first member is configured to telescope into the cavity, wherein extent of telescoping regulates the adjustable height; the tab includes a protrusion; the wall includes a plurality of irregularities configured to interface with the protrusion to oppose telescoping motion.

47. A crutch, the crutch comprising: a multipart body having an adjustable overall axial length, wherein the multipart body comprises at least a first part and a second part, and axial positioning of the first and second parts relative to each other contributes to adjustment of the overall axial length; and at least one stop, integral with the first part, that, when engaged, fixes relative axial position between the first and second parts, wherein the stop is not merely a bore through the first part.

48. The crutch according to claim 47, wherein the at least one stop comprises a tab that is formed integrally with the first part.

49. The crutch according to claim 47, wherein the first part comprises a wall external to a cavity, and the tab is defined by a generally U-shaped hole in the wall.

50. The crutch according to claim 47, wherein: the tab includes a protruding lock pin; the second part includes a plurality of holes in which the lock pin may be selectively disposed to fix the relative axial position between the first and second parts.

51. The crutch according to claim 50, wherein: an elongated portion of the first part is configured to telescope into the second part, wherein the elongated portion includes the tab; the lock pin is configured to protrude outward through one of the plurality of holes in which the lock pin is disposed; and the tab flexes to enable manual adjustment of the lock pin into another of the plurality of holes and provides a return force to maintain the lock pin in a hole, post adjustment.

52. A method for producing an apparatus for assisting in mobility of a physically-impaired person, the method comprising: forming a first member including integrally forming a stop on the first member, wherein the stop is not merely a bore through the first member; providing a second member; and adjustably connecting the second member to the first member, wherein the first and second members together span an adjustable height, and wherein the stop is configured as capable of being engaged to oppose relative motion against the second member to thereby oppose adjustment of the adjustable height.

53. The method according to claim 52, wherein the stop comprises a tab that is of a same material as remainder of the first member.

54. An apparatus produced using the method according to claim 52.

55. An apparatus produced using the method according to claim 52, wherein the apparatus is an underarm crutch.

56. An apparatus for assisting in ambulation, the apparatus comprising: a first member that includes an exterior, wherein the first member is made using a mold that includes at least a first form unit that forms a first portion of the exterior and a second form unit that forms a second portion of the exterior, there being at least one boundary, not necessarily visibly marked, on the exterior between the first and second portions of the exterior; a second member adjustably connected to the first member, the first and second members together spanning an adjustable axial length; and a lock that, when engaged, fixes the adjustable axial length against at least one of contraction or expansion, wherein the lock engages, or exists on, the first member not on the at least one boundary on the exterior of the first member.

57. An apparatus according claim 56, wherein the lock comprises a pin on the first member, the second member comprises a plurality of receptacles into which the pin may be disposed, and the pin is on only one of the first and second portions of the exterior of the first member.

58. An apparatus according claim 57, wherein the first and second members include plastic as a structural basis.

59. An apparatus according claim 58, wherein the apparatus is a crutch.

60. An apparatus according claim 56, wherein: the mold is hereinafter referred to as first mold, and the exterior of the first member is hereinafter referred to as first exterior; the second member includes an exterior, hereinafter referred to as second exterior; the second member is made using a second mold that includes at least a third form unit that forms a first portion of the second exterior and a fourth form unit that forms a second portion of the second exterior, there being at least one boundary, not necessarily visible, on the second exterior between the first and second portions of the second exterior; and the lock does not engage, and does not exist on, the at least one boundary on the second exterior between the first and second portions of the second exterior.

61. A method for producing an apparatus for assisting in mobility of a physically-impaired person, the method comprising: molding a first member using a mold that includes at least a first form unit that forms a first portion of the exterior and a second form unit that forms a second portion of the exterior, there being at least one boundary, not necessarily visibly marked, on the exterior between the first and second portions of the exterior; providing a second member to adjustably connect to the first member, the first and second members together spanning an adjustable axial length; and providing a lock that, when engaged, fixes the adjustable axial length against at least one of contraction or expansion, wherein the lock engages, or exists on, the first member not on the at least one boundary on the exterior of the first member.

62. A method according claim 61 , wherein the lock comprises a pin on the first member, the second member comprises a plurality of receptacles into which the pin may be disposed, and the pin is on only one of the first and second portions of the exterior of the first member.

63. A crutch produced using the method according claim 62.

64. A method according claim 61, wherein the second-member providing step comprises molding the second member of a material that includes plastic as a basis.

65. A method according claim 61 , wherein: the mold is hereinafter referred to as first mold, and the exterior of the first member is hereinafter referred to as first exterior; the second member includes an exterior, hereinafter referred to as second exterior; the step of providing a second member comprises molding the second member using a second mold that includes at least a third form unit that forms a first portion of the second exterior and a fourth form unit that forms a second portion of the second exterior, there being at least one boundary, not necessarily visible, on the second exterior between the first and second portions of the second exterior; and the lock does not engage, and does not exist on, the at least one boundary on the second exterior between the first and second portions of the second exterior.

65. A crutch produced using the method according claim 61.

66. A crutch comprising: a body having an upper end and a lower end, the body comprising a strut at the lower end, the strut terminating in a lower tip, the lower tip being integral with and of a same material as the strut; and an end cap that attaches to the body at the lower tip not via overmolding, the end cap engaging the ground during use of the crutch, the end cap integrally made of a resilient material, wherein the end cap is attached to the strut without any intervening washer or baseplate, the intervening washer or baseplate not being integral with and not being integrally formed with either the strut or the end cap.

67. A crutch according to claim 66, wherein the lower tip is without any substantial flange.

68. A crutch according to claim 66, wherein the strut is hollow, and the lower tip is substantially closed.

69. A crutch according to claim 66, wherein the lower tip is closed.

70. A crutch according to claim 66, wherein: the tip is without any substantial flange; a longitudinal axis is associated with the strut; and the body transfers weight to the end cap via at least one substantially downward-facing surface of the lower tip, overall area of the at least one substantially downward-facing surface is not substantially smaller than exterior-defined area of a cross section of the strut perpendicular to the longitudinal axis.

71. A crutch according to claim 66, wherein: a longitudinal axis is associated with the strut; the strut is hollow; and the body transfers weight to the end cap via at least one bottom surface of the lower tip, wherein overall area of the at least one bottom surface is substantially greater than area of non-empty regions of a cross section of the strut peφendicular to the longitudinal axis at a position that is at least two inches above the lower tip.

72. A crutch according to claim 66, wherein the end cap defines an cavity, and the end cap attaches to the lower tip by accepting the lower tip into the cavity, the end cap thereby being stretched over the lower tip and being held to the lower tip by friction.

73. A mobility assistance device comprising: a body having an upper end and a lower end, the body comprising an elongated member at the lower end, the elongated member terminating at the lower end in a lower tip, the lower tip being formed integrally with the elongated member and being without any substantial flange, the lower tip having at least one bottom surface; the elongated member being elongated along a longitudinal axis; and a resilient ground contact that attaches to the body at the lower tip, the ground contact engaging the ground during use of the crutch; wherein the body transfers weight to the ground contact axially via the at least one bottom surface of the lower tip, and overall area of the at least one bottom surface is substantially greater than non-empty area of a cross section of the elongated member peφendicular to the longitudinal axis.

74. A mobility assistance device according to claim 73, wherein the ground contact comprises an end cap that defines a cavity, and the end cap attaches to the lower tip by accepting the lower tip into the cavity, the end cap thereby being stretched over the lower tip.

75. A mobility assistance device according to claim 73, wherein the ground contact comprises an end cap that attaches to the lower tip without any intervening solid material that protects the end cap from potential damage by the at least one lower surface of the lower tip.

76. A mobility assistance device according to claim 73, wherein the mobility assistance device is a crutch.

77. A method for producing a crutch, the method comprising: forming a body having an upper end and a lower end, the body comprising a strut at the lower end, the strut terminating in a lower tip, the lower tip being integral with and of a same material as the strut; providing an ground-contact piece that is made of a resilient material; and attaching the ground-contact piece to the body at the lower tip not via overmolding and without any intervening washer or baseplate, the attached ground-contact piece for engaging the ground during use of the crutch.

78. A method according to claim 77, wherein the lower tip is closed.

79. A method according to claim 77, wherein: the tip is without any substantial flange; a longitudinal axis is associated with the strut; and the body transfers weight to the ground-contact piece via at least one substantially downward-facing surface of the lower tip, overall area of the at least one substantially downward-facing surface is not substantially smaller than exterior-defined area of a cross section of the strut peφendicular to the longitudinal axis.

80. A crutch produced using the method according to claim 77.

81. A ground contact article for connecting onto a bottom tip portion of a mobility assistance device, the ground contact article comprising: a body that includes a resilient material as a structural basis and that includes a top end and a bottom surface, the bottom surface for engaging ground, the body for receiving weight of the mobility assistance device from above; wherein the body is configured to include at least one collapsing region positioned between the top end and the bottom surface, the at least one collapsing region being configured to permit a peripheral portion of the body to collapse more readily than a central portion of the body to thereby permit the bottom surface to remain flush with the ground even when the mobility assistance device is moved such that angle between the mobility assistance device and the ground is changed substantially, relative to an initial angle.

82. A ground contact article according to claim 81, wherein the body has a periphery relative to a central vertical axis, the body having at least one cavity at its periphery at one or more positions between the top end and the bottom surface, wherein the at least one collapsing region comprises the at least one cavity.

83. A ground contact article according to claim 82, wherein the at least one cavity is open at the periphery.

84. A ground contact article according to claim 83, wherein the lower portion of the body above the bottom surface is made of a substantially uniform resilient material.

85. A ground contact article according to claim 82, wherein the mobility assistance device is a crutch.

86. A crutch comprising the ground contact article according to claim 82, and further comprising a height-adjustable crutch body connected to the ground contact article.

87. A ground contact article according to claim 81, wherein the body is shaped to have an intermediate portion between the top end and the bottom surface that is substantially cylindrical or substantially like base of a cone, but with at least two annular regions of material absent from the intermediate portion.

88. A ground contact article according to claim 81, wherein: the body includes a first vertical level, a second vertical level lower than the first vertical level, and a third vertical level lower than the second vertical level, each of the first, second, and third vertical levels having a respective average radius with respect to a vertical axis centered in body; the average radius of the first vertical level exceeds the average radius of the second vertical level; and the average radius of the third vertical level exceeds the average radius of the second vertical level.

89. A method for producing a ground contact article for connecting onto a bottom tip portion of a mobility assistance device, the method comprising: molding a body of a resilient material, the body including a top end and a bottom su «rface, the bottom surface for engaging ground, the body for receiving weight of the mobility assistance device from above, the molding step including: configuring the body to include at least one collapsing region positioned between the top end and the bottom surface; and configuring the at least one collapsing region to permit a peripheral portion of the body to collapse more readily than a central portion of the body to thereby permit the bottom surface to remain flush with the ground even when the mobility assistance device is moved such that angle between the mobility assistance device and the ground is changed substantially, relative to an initial angle.

90. A method according to claim 89, wherein the body includes a periphery relative to a central vertical axis, and the molding step comprises shaping the body to have at least one cavity at its periphery at one or more positions between the top end and the bottom surface, wherein the at least one collapsing region comprises the at least one cavity.

91. A crutch, comprising: a crutch body having an upper end and a lower end, the lower end for engaging the ground during ambulation; and a variable-spring-rate spring coupled to the crutch body to provide shock absoφtion for the crutch, wherein the spring provides greater spring rate with increased compression of the spring.

92. A crutch according to claim 91, wherein the spring is capable of being compressed to allow fluctuation in height of the crutch during crutch use by amounts including an amount of at least about three millimeters.

93. A crutch according to claim 92, wherein the crutch body comprises a first body segment and a second body segment, and the spring is coupled to the crutch body to transmit physical force between the first and second body segments.

94. A crutch according to claim 93, wherein the crutch body defines a cavity, and the spring is disposed within the cavity.

95. A crutch according to claim 92, wherein the spring comprises a resilient body that comprises a resilient material.

96. A crutch according to claim 95, wherein thicknesses of multiple points along a segment of the resilient body are progressively thicker in a direction along an axis of compression, to provide spring rate that is variable with increased compression of the spring.

97. A device for assisting ambulation, the device comprising: a first member; a second member; and a resilient body, comprising an elastomeric material, coupled to the first and second members to transmit physical force between the first and second members to provide shock absoφtion for the device.

98. A device according to claim 97, wherein the resilient body is capable of being compressed by amounts including an amount of at least about three millimeters along an axis of compression in ordinary weight-supporting use of the device.

99. A device according to claim 98, wherein a segment of the resilient body has form of a segment of a conical shape to provide variable spring rate that varies with amount of compression of the resilient body.

100. A device according to claim 99, wherein the first and second members define a cavity, and the resilient body is disposed within the cavity.

101. A device according to claim 97, wherein the device is an underarm crutch.

102. An apparatus for assisting in mobility of a physically-impaired person, the apparatus comprising: at least one member that supports some weight of the disabled person in the course of using the apparatus; and a material of lower durometer than the at least one member, the material coupled to the at least one member to provide shock absoφtion for the apparatus, wherein the material, at each of multiple points along an axis of compression, has thickness peφendicular to the axis of compression, the thicknesses of the multiple points being substantially non-equal to one another, whereby spring rate of the material is substantially different depending on amount of compression.

103. An apparatus according to claim 102, wherein the material is capable of being compressed by amounts including an amount of at least about three millimeters during ordinary use.

104. An apparatus according to claim 103, wherein the thicknesses of the multiple points, along a segment of the material, are progressively thicker in a direction along the axis of compression.

105. An apparatus according to claim 103, wherein the at least one member comprises a first member and a second member, and the first and second members are coupled at least partially via the material, wherein force along the axis of compression is transferred between the first and second members at least partially via the material.

106. A method for producing a crutch, comprising: providing a crutch body having an upper end and a lower end, the lower end for engaging the ground during ambulation; and coupling a variable-spring-rate spring to the crutch body to provide shock absoφtion for the crutch, wherein the spring provides greater spring rate with increased compression of the spring.

107. A method according to claim 106, wherein the spring is capable of being compressed to allow fluctuation in height of the crutch during crutch use by amounts including an amount of at least about three millimeters.

108. A method according to claim 107, wherein the crutch body comprises a first body segment and a second body segment, and the spring is coupled to the crutch body to transmit physical force between the first and second body segments.

109. A crutch produced using the method according to claim 107.

110. A method for producing an apparatus for assisting ambulation of a person, the method comprising: providing at least one member that supports some weight of the person in the course of using the apparatus; and forming a material of lower durometer than the at least one member, wherein the material, at each of multiple points along an axis of compression, has thickness peφendicular to the axis of compression, the thicknesses of the multiple points being substantially non-equal to one another, whereby spring rate of the material is substantially different depending on amount of compression; and coupling the material to the at least one member to provide shock absoφtion for the apparatus.

111. A device for enhancing mobility of a physically-impaired person, the device comprising: a first member that comprises an elongated portion; and a second member that is configured to slidably receive the elongated portion of the first member and to have negative draft relative to the elongated portion of the first member.

112. A device according to claim 111, wherein the elongated portion includes a spring support that presses against the second member to resist play by the first member relative to the second member, despite the negative draft.

113. A device according to claim 112, wherein the second member comprises plastic as a basis.

114. A device according to claim 112, wherein the second member defines a cavity that slidably receives the elongated portion of the first member along an axis of sliding, the cavity including an opening that receives the elongated portion of the first member, wherein internal diameter of the cavity becomes progressively greater with increasing depth along a segment of the cavity along the axis of sliding.

115. A device according to claim 114, wherein the negative draft is at least an eighth of a degree from being parallel to the axis of sliding along the segment of the cavity.

116. A device according to claim 115, wherein there are at least two achievable depths of insertion of the elongated portion of the first member into the cavity, the two possible depths differing from one another by at least six inches.

117. An apparatus for helping to support weight of a person during ambulation, the apparatus comprising: a first stage that includes an elongated portion; and a second stage that defines a cavity that slidably receives the elongated portion of the first stage along an axis of sliding, the cavity having an opening that receives the elongated portion of the first stage, the second stage including an internal sidewall facing the cavity, at least a portion of the internal sidewall being tapered relative to the axis of sliding, wherein a first point on the internal sidewall deviates more, from the axis of sliding as envisioned centrally in the cavity, than does a second point on the internal sidewall, the first point on the internal sidewall being deeper in the cavity along the centrally-envisioned axis of sliding than the second point on the internal sidewall.

118. An apparatus according to claim 117, wherein the second stage comprises plastic as a structural basis.

119. A method for producing an apparatus for assisting in ambulation, the method comprising the steps of: providing a first member that comprises an elongated portion; and providing a second member, including: forming a recess in the second member for slidably receiving the elongated portion of the first member; and tapering the recess to have negative draft relative to the elongated portion of the first member.

120. A method according to claim 28, wherein the step of providing a second member comprises molding the second member of a plastic-based material.

121. A mold for molding a portion of a device for assisting in ambulation, the portion hereinafter referred to as first member, the device further to include a second member that includes an elongated portion, the first member to include a cavity and an exterior, the cavity to include at least a first external opening, the cavity to accept the elongated portion of the second member through the first external opening along an axis of insertion, the axis of insertion having a direction of insertion of the second member and an opposite direction of withdrawal of the second member, the mold comprising: a form configured to shape the exterior of the first member; and a core configured to shape the cavity of the first member; the core being configured and disposed to separate from the first member in a direction other than the direction of withdrawal of the second member.

122. A mold according to claim 121, wherein the mold is an injection-molding mold for plastic.

123. Arnold according to claim 122, wherein: the core is configured and disposed to withdraw from the first cavity of the first member substantially in the direction of insertion of the second member; and the cavity is to include a second external opening through which the core is to be withdrawn from the first member.

124. A mold according to claim 123, wherein: the cavity is hereinafter referred to as first cavity the axis of insertion is hereinafter referred to as first axis of insertion; the core is hereinafter referred to as first core; the device is further to include a third member that includes an elongated portion; the first member is to include a second cavity that includes at least a third external opening, the second cavity for accepting the elongated portion of the third member through the third external opening along a second axis of insertion, the second axis of insertion having a direction of insertion of the third member and an opposite direction of withdrawal of the third member; and the mold further includes a second core for shaping the second cavity of the first member.

125. A mold according to claim 124, wherein the second core is configured and disposed to separate from the first member in a direction other than the direction of withdrawal of the third member.

126. A method for molding a portion of a mobility-assistance device, the portion hereinafter referred to as first member, the device further to include a second member that includes an elongated portion, the first member to include a cavity and an exterior, the cavity to include at least a first entryway, the cavity to accept the elongated portion of the second member through the first entryway along an axis of insertion, the axis of insertion having a direction of insertion of the second member and an opposite direction of withdrawal of the second member, the method comprising the steps of: molding the first member including defining the cavity using a mold core; and withdrawing the mold core from the first member in a direction other than the direction of withdrawal of the second member.

127. A method according to claim 126, wherein the molding step comprises injection-molding the first member of a plastic material.

128. A method according to claim 127, wherein the first entryway is a first external opening to the cavity, the withdrawing step leaves a second external opening to the cavity through which the mold core was withdrawn from the first member, and the withdrawing step direction other than the direction of withdrawal of the second member is substantially in the direction of insertion of the second member.

129. A method according to claim 128, wherein: the axis of insertion is hereinafter referred to as first axis of insertion; the mold core is hereinafter referred to as first mold core; the device is to include a third member that includes an elongated portion; the first member is to include a second cavity that includes at least a third external opening, the second cavity for accepting the elongated portion of the third member through the third external opening along a second axis of insertion, the second axis of insertion having a direction of insertion of the third member and an opposite direction of withdrawal of the third member; the molding step further includes defining the second cavity using a second mold core; and the method further includes withdrawing the second mold core from the first member in a direction other than the direction of withdrawal of the third member.