ERGONOMIC CRUTCH

Abstract

Medical devices used to assist walking by helping to support a user's weight comprise a series of elements angled with respect to each other at angles selected to honor certain normal anatomical relationships so as to provide a stable platform for supporting a user's weight while reducing injury. Optional additional elements provide cushioning and stability.

Claims

1. A crutch comprising an arm support, an intermediate shaft segment having a first end and a second end, and a lower shaft segment having a first end and a second end; said arm support connected to the first end of said intermediate shaft segment at a first angle of between approximately 15 to 20 degrees outward and forward at a second angle of approximately 15 to 20 in a plane orthogonal to the plane of said first angle and shaped so as to make contact with the volar surface of a user's forearm muscle belly and the ulnar border of the user's forearm; the second end of said intermediate shaft segment connected to the first end of the lower shaft segment at a third angle of between approximately 20 to 30 degrees outward in a plane orthogonal to the plane of said first angle.

2. A crutch as in claim 1, further comprising a tip connected at the distal end of said crutch and angled outward at an angle of between about 0 and 20 degrees.

3. A crutch as in claim 1, further comprising a handgrip connected to either the intermediate shaft segment or the lower shaft segment at a fourth angle of between approximately 10 degrees upward to 10 degrees downward and 0 to 15 degrees inward.

4. A crutch as in claim 2, further comprising a handgrip connected to either the intermediate shaft segment or the lower shaft segment at a fourth angle of between approximately 10 degrees upward to 10 degrees downward and 0 to 15 degrees inward.

5. A crutch as in claim 3 wherein said handgrip is padded.

6. A crutch as in claim 4 wherein said handgrip is padded.

7. A crutch as in claim 3 wherein the connection between the handgrip and the shaft segment comprises a shock absorbing element.

8. A crutch as in claim 4 wherein the connection between the handgrip and the shaft segment comprises a shock absorbing element.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The foregoing and still other objects of this invention will become apparent, along with various advantages and features of novelty residing in the present embodiments, from study of the following drawings, in which:

[0026] FIG. 1 is a side view of a crutch designed in accordance with the invention.

[0027] FIG. 2 is a top view of a crutch designed in accordance with the invention.

[0028] FIG. 3 is a view illustrating a user using a crutch designed in accordance with the invention.

[0029] FIG. 4 illustrates the upper segment for an alternate embodiment known as a short arm crutch.

[0030] FIG. 5 illustrates one embodiment of the invention from several views.

[0031] FIG. 6 illustrates a short arm embodiment of the inventions.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0032] Referring to the drawings, the invention is a novel crutch comprising a series of elements angled with respect to each other in three orthogonal planes at specified angles or ranges of angles so as to provide a stable platform for supporting a user's weight while reducing injury to the user's axillary and carpal nerves and tendons. A first preferred embodiment of the crutch is shown in overview in FIGS. 1, 2 and 5 and in use in FIG. 3. A second preferred embodiment is shown in FIGS. 4 and 6.

[0033] As illustrated in FIGS. 1 and 5, the invention comprises a crutch having an axillary support (1) at one end designed and angled to fit under a user's axilla as shown in use in FIG. 3, connected at an angle (a) to an upper shaft segment (2) which in turn is connected at an angle (b) to an intermediate shaft segment (3) which in turn is connected to a lower shaft segment (4) at an angle (c); the lower shaft segment terminates in a tip (5) suitable for making contact with the ground; between the axillary support and the tip, a handgrip (6) joins either the intermediate shaft segment or the lower shaft segment at an angle (d). As best seen in FIG. 2, the axillary support is preferably angled at approximately 10 to 15 degrees toward the user's torso so as to encourage support of the user's weight by the user's pectoralis and latissimus muscles rather than the vascular and neural structure of the user's axilla. It is also contoured front and back so as to decrease pressure on the front and back of the user's axilla. The crutch so constructed enables the user to support a portion of his body weight with his torso and shoulder, arm and hand.

[0034] While the invention's construction will be described with respect to assembly of discrete elements attached to each other at specified angles, it will be appreciated that the invention could be constructed by creating the discrete elements then welding or otherwise attaching them together in the described configuration, it could also be implemented by molding or casting the elements as a unitary piece, or various elements could be molded or cast as multiple unified pieces and the resulting unified pieces assembled to produce a crutch with the specified angles. In addition, a crutch could be manufactured of a thermoplastic material or other material capable of being deformed then hardened and the specified angles created in that manner. Optionally, the connection between the handgrip and the shaft segment may be provided with a shock absorbing mechanism to reduce repetitive impact to the user's wrist during use. An example of a suitable such mechanism would be a universal joint provided with springs and a set of stops to prevent overrotation of the handgrip. Optionally, one or more adjustable elements may be incorporated for adjusting to a user's height, arm length, leg length or other characteristic. Other methods of producing a crutch having the specified angles will occur to those of ordinary skill in the art and are encompassed by the invention, which includes the specified configurations regardless of the manner of manufacture.

[0035] The preferred lengths of the specified elements and the preferred angles between the elements will vary from user to user. The following describes the technique for determining those lengths and angles for a particular user. The elements could be connected by adjustable means in order to permit producing a crutch which could be customized for a particular user. For example, the elements could be attached to each other using a wing nut which could be loosened in order to establish the desired angle between the elements, then tightened. Alternatively, the elements could be connected by a defonnable/settable material, for example a thermoplastic. A range of lengths and angles suitable for wide ranges of users is provided. Instructions are also provided herein which would pennit fine-tuning the angles to produce a customized crutch for a specific user.

[0036] The basic objective is to provide a crutch which matches the contour of the arm as it flexes forward when it is in a supporting position. The natural position of the arm for strength in supporting weight is pronated relative to the user's ulna at an angle of about 15 to 20 degrees. Prior art crutches force the arm to be too extended, the handle forces the hand to be radially deviated or flexed and therefore does not allow natural pronation, and the top of the crutch will dig into the chest. These are all uncomfortable positions. They force the user's hand, elbow and shoulder to assume non-anatomic positions for support of the user's weight. In broad concept, the device is a crutch comprising a supportin the case of one embodiment, an axillary support, and in the case of another embodiment a forearm supportconnected to shaft segments each having a first end and a second end and connected at angles described herein. Optional additional features include padding, shock absorbing segments located between components, and tips for contact with the ground.

[0037] In the first preferred embodiment, the axillary support (1) is contoured to grab the user's thorax from anterior to posterior under the axilla. Optionally, there may be some anterior to posterior contour as well but the main contour is to grab the thorax below the axilla. In order to honor the carrying angle of the elbow, angle (b) is approximately equal to the angle of the user's elbow in the proper carrying position, that is, bent forward approximately 20 to 30 degrees and outward approximately 0 to 20 degrees, and upper shaft segment (2) joins intermediate shaft segment (3) at angle (b) at approximately the user's elbow.

[0038] To customize a crutch for a particular user, angle (a) should approximate 10 to 15 degrees toward the user's torso (relative to the long axis), and the length of the upper shaft segment should approximate the distance between the user's shoulder and elbow. For most adult male users, 13 to 14.5 inches is a suitable range of values for the length of the upper shaft segment, with a preferred value of approximately 14 inches. For most adult female users, 11 to 13 inches is a suitable range of values for the length of the upper shaft segment, with a preferred value of approximately 12 inches. For pediatric users, the length of the upper shaft segment will depend on the individual user and can be determined using the above customization guidelines.

[0039] To customize a crutch for a particular user, angle (b) should approximate the complex angle of the user's elbow in a relaxed carrying position, i.e., approximately 15 to 20 degrees outward (in the sagittal plane) and approximately 15 to 20 degrees forward (in the coronal plane), and the length of the intermediate shaft segment should approximate the distance from the user's elbow to the user's knuckles. For most adult male users, 13 inches to 14.5 inches is a suitable range of values for the length of the intermediate shaft segment, with a preferred value of approximately 13.75 inches. For most adult female users, 11.5 inches to 13 inches is a suitable range of values for the length of the intermediate shaft segment, with a preferred value of approximately 12 inches.

[0040] The lower shaft segment of the crutch angles outward at angle (c) to the side away from the midline so as to increase the distance between the crutch tips in use, thereby increasing stability. To customize a crutch for a particular user, angle (c) should be designed to result in a sufficient tip to tip distance to provide a stable platform while allowing the user to maintain the upper end, of the crutch close to the torso. A suitable angle for most users would be outward at an angle of about 20 to 30 degrees.

[0041] The handgrip is located at approximately 85% to 90% of the distance from the user's axilla to the user's knuckles with the user's arm fully extended; alternatively, the location can be determined by measuring the distance from the user's axilla to the user's hand when the elbow is flexed 15-20 degrees. For most adult males, a suitable range would be within a range of approximately 26 to 29 inches from the axillary support, with a preferred value of approximately 27.5 inches. For most adult females, a suitable range would be within a range of approximately 22 to 26 inches from the axillary support, with a preferred value of approximately 24 inches. The handgrip is ideally slightly internally rotated similarly to the user's forearm, that is about 30-45 degrees pronated and neutral with the 2nd metacarpal of the user's hand lined up longitudinally in parallel to the radius bone of the user's arm, and angled slightly so as to accommodate a normal grip, that is a grip which is pronated at about a 10 degree angle. There should be very little radial deviation of the wrist relative to the forearm. To customize a crutch for a particular user, angle (d) is a complex angle which is largely a matter of user comfort. For most adult users, an angle of 10 degrees upward to 10 degrees downward, with a preferred value of approximately 10 degrees downward, and 0 to 15 degrees inward, with a preferred value of approximately 10 degrees inward is a suitable range of values for angle (d). Likewise, the length of the handgrip is a matter of personal preference, depending largely on the size of the user's hand. Typically, the handgrip would be between 4 and 8 inches. For pediatric users, the angles and dimensions will depend on the individual user and can be determined using the above customization guidelines.

[0042] For some applications, an alternate embodiment known as a short arm crutch may be preferred. A short arm crutch, similar to a standard length crutch, allows the upper extremities to provide weight bearing assistance to a lower extremity that is meant to have less than full weight bearing. The short arm crutch relies on hand grips as well as an area of support along the forearm. In the current invention, having the forearm support placed along the forearm flexor muscle mass (medial surface of the forearm) as well as the more traditional posterior aspect of the forearm (along the ulna) provides the user more comfort. The invention also increases the area of contact on the forearm above the hand grip and this increased area of contact decreases the force per unit area which makes for a more comfortable and stable crutch. FIGS. 4 and 6 illustrate the short arm crutch segment of the invention, which would replace the axillary support and upper shaft segments of the previously described embodiment, would have an arm support (7) at one end and would connect to the intermediate shaft segment (3) at the other end, and would incorporate a handgrip. The arm support should be of a length and contour that would allow a user's arm to rest comfortably within the support and the handgrip should be located at a position which would allow the user to reach it comfortably. Current short-arm crutches contact the user's arm along the posterior side of the user's forearm along the ulna. Better support and comfort is provided by instead providing support along the medial flexor mass below the user's elbow. Preferably it would be shaped so as to make contact with the volar surface of a user's forearm muscle belly and the ulnar border of the user's forearm. Cushioning material may be placed on the arm support so as to increase comfort and provide better contact between the arm support and the user's arm. Further sharing of the weight bearing on the volar muscle mass will also be more comfortable for the user. In this embodiment, arm support (7) is connected, in place of axillary support (1) and upper shaft segment (2), to intermediate shaft segment (3); the crutch is the same in all other respects.

[0043] For pediatric users, the dimensions depend on the individual user and can be determined using the above customization guidelines.

[0044] Optionally, a tip may be connected at the distal end of the crutch, designed to contact the ground. It may be padded or made of a material providing non-slip properties for stability. Stability may also be increased by angling the crutch outward from the user's midline so as to provide a greater base, in which case stability may be further increased by angling the tip outward at an angle of between about 0 and 20 degrees, thereby increasing ground contact.

[0045] In a custom application, each of the angles provided may be adjusted within the ranges provided, to a comfortable angle in response to the user's subjective evaluation of comfort.

[0046] It will be appreciated that other anthropomorphic measurements will be equivalent to the ones described above. For example, calculating the distance from the user's axilla to the user's elbow is equivalent to calculating the user's height at the axilla and subtracting the user's height at the elbow.

[0047] The critical dimensions of the invention are summarized in the following chart:

TABLE-US-00001 Element Custom/Pediatric Adult Male Adult Female Axillary Support (1) sufficient to provide a bearing 8-10 inches 8-10 inches surface against the user's torso Axillary Support (1) to approximately equal to angle approximately equal to approximately equal to Upper Shaft segment of 10 to 15 degrees toward angle of 10 to 15 angle of 10 to 15 degrees (2) angle (a) user's torso degrees toward user's toward user's torso torso Upper Shaft segment approximately equal to length within range of within range of (2) from user's shoulder to user's approximately 13 to approximately 11 to 13 elbow 14.5 inches; preferred inches; preferred value value of approximately of approximately 12 13.75 inches inches. Upper Shaft segment approximately equal to a approximately equal to approximately equal to a (2) to Intermediate complex angle of 0 to 10 a complex angle of 0 to complex angle of 0 to 10 Shaft segment (3) degrees outward (in the 10 degrees outward (in degrees outward (in the angle (b) [or in the sagittal plane) and the sagittal plane) and sagittal plane) and case of a short-arm approximately 15 to 20 approximately 15 to 20 approximately 15 to 20 crutch, arm support to degrees forward degrees forward degrees forward Intermediate Shaft segment segment angle] Intermediate Shaft approximately equal to length within range of within range of segment (3) from user's elbow to user's approximately 13 to approximately 11.5 to 13 knuckles 14.5 inches; preferred inches; preferred value value of approximately of approximately 12 13.75 inches inches Intermediate Shaft approximately equal to an approximately equal to approximately equal to segment (3) to Lower angle of 20 to 30 degrees an angle of 20 to 30 an angle of 20 to 30 Shaft segment (4) outward (away from the user's degrees outward (away degrees outward (away angle (c) midline) from the user's midline) from the user's midline) Lower Shaft segment approximately equal to length within range of within range of (4) from user's elbow to the user's approximately 40 to 47 approximately 37 to 43 foot inches; preferred value inches; preferred value of approximately 43.5 of approximately 40 inches inches Handgrip (6) to shaft approximately equal to an approximately equal to approximately equal to segment (3 or 4) angle angle of 10 degrees upward to an angle of 10 degrees an angle of 10 degrees (d) 10 degrees downward, with a upward to 10 degrees upward to 10 degrees preferred value of downward, with a downward, with a approximately 10 degrees preferred value of preferred value of downward, and 0 to 15 degrees approximately 10 approximately 10 degrees inward, with a preferred value degrees downward, downward, and 0 to 15 of approximately 10 degrees and 0 to 15 degrees degrees inward, with a inward inward, with a preferred value of preferred value of approximately 10 degrees approximately 10 inward degrees inward Handgrip (6) located at a point which allows within range of within range of the user to grip it with elbow approximately 26 to 29 approximately 22 to 26 slightly bent, typically inches from the axillary inches from the axillary approximately 85% to 90% of support; preferred support; preferred value the distance from the user's value of approximately of approximately 24 axilla to the user's knuckles 27.5 inches inches with the user's arm fully extended. Preferably slightly internally rotated similarly to the user's forearm, that is about 30-45 degrees pronated and neutral with the 2nd metacarpal of the user's hand lined up longitudinally in parallel to the radius bone of the user's arm, and angled slightly so as to accommodate a normal grip, that is a grip which is pronated at about a 10 degree angle. customize a crutch for a particular user, angle (d) is a complex angle which is largely a matter of user comfort. For most adult users, an angle of 10 degrees upward to 10 degrees downward, with a preferred value of approximately 10 degrees downward, and 0 to 15 degrees inward, with a preferred value of approximately 10 degrees inward is a suitable range of values for angle (d).

[0048] An alternative embodiment, known as a short-arm crutch, terminates at the upper end of the intermediate shaft segment (3). Such a crutch may be made in accordance with the invention using the dimensions and angles described for all components except the axillary support and upper shaft segment, and providing a suitable support for the user's foreaflll at the upper end of intermediate shaft segment (3). The top part of the short arm crutch should contact the volar surface of the forearm muscle bellies for support as well as the ulnar border of the forearm. These muscle bellies form a sort of triangular form from the wrist to the elbow and can be used to dissipate the forces of weight bearing. The position of the grip relative to the lower shaft segment of the crutch should be the same as previously described.

[0049] The use of the invention is the same as the use of conventional crutches, as previously described. Thus a user who is already familiar with the use of prior art crutches may use the invention and obtain its benefits without the disadvantage of needing to learn a new technique.

[0050] Thus, there has been described a novel a crutch comprising a series of shaft segments angled with respect to each other in three orthogonal planes so as to provide a stable platform for supporting a user's weight while reducing injury to the user's axillary and carpal nerves and tendons that has a number of novel features, and a manner of making and using the invention.

[0051] While a specific embodiment of the invention has been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles and that various modifications, alternate constructions, and equivalents will occur to those skilled in the art given the benefit of this disclosure. Thus, the invention is not limited to the specific embodiment described herein, but is defined by the appended claims.