Patent Application
20060174459
1. Field of the Invention
This invention relates generally to an adjustable fastener and, more particularly, to an adjustable fastener that can be used to secure the end of a brace strap.
2. Description of Related Art
Various types of buckles, clips, and other connectors that can be used in various orthotic and other types of devices such as to secure one end of a strap either to another portion of the same strap or to some other anchor point in the device are known to those of skill in the art. Some examples of previously disclosed buckles include those described in U.S. Pat. No. 3,112,496; U.S. Pat. No. 3,808,643; U.S. Pat. No. 3,827,107; U.S. Pat. No. 4,005,506; U.S. Pat. No. 4,310,110; U.S. Pat. No. 4,378,793; U.S. Pat. No. 5,201,100; U.S. Pat. No. 5,548,871; U.S. Pat. No. 5,502,843; U.S. Pat. No. 6,131,249; U.S. Pat. No. 6,163,941; U.S. Pat. No. 6,360,410; U.S. Pat. No. 6,631,537; U.S. Pat. No. 6,748,630; U.S. Pat. No. 6,760,958; and U.S. Pat. No. 6,766,532.
Not all types of fasteners are appropriate for any given particular application. In particular, there are special considerations for fasteners that are used to secure and tension straps on medical braces and other orthopedic devices. These fasteners should have an extremely low profile so that they do not interfere with the operation of the brace, hinder normal physiological movement of the body, or become accidentally opened if jarred. They also need to be able to allow the strap to be sufficiently tensioned and be of sufficient strength to withstand such tension force without failure. It is also beneficial if the fasteners are easy to operate so the patient can remove the device and easily returned to its original tension setting when the strap is refastened.
In the field of braces and orthopedic devices, two types of fasteners are prevalent. One of the most common type of fastener used are hook and loop fasteners (i.e. Velcro), often in combination with a D-ring. The D-ring is secured to an anchor point on the device, which may be one end of the strap itself or a brace shell or support. An end of the strap passes through the D-ring and doubles back on itself. The outer surface of the strap is composed of a material that forms the loop portion of the fastening system. At the end of the strap is a section of hooks that form the hook portion of the fastening system. The hook section can be used to secure the end of the strap to any point along the strap itself. By adjusting the location where the strap end is secured to itself, the length of the strap and hence the amount of tension that is applied by the strap can be controlled. If no D-ring is used, one portion of the fastener (e.g. the hook portion) can be located directly on an anchor point, such as a shell on a brace or the other end of the strap, and the other portion can be located on the end of the strap.
Hook and loop fastening systems are able to provide sufficient shear strength to prevent the strap from loosening or coming unfastened, while at the same time allowing the patient or physician to quickly and easily remove the strap and/or adjust the tension of the strap. It also can allow infinite variability in the amount of tension applied to the strap. While this type of fastener makes it easy for a patient to undo the straps to remove the brace when it is not needed, it can be difficult for the patient to refasten the strap with the exact amount of tension that was present when the strap was removed. In addition, hook and loop fasteners tend to wear out over time, especially when they are frequently opened and closed as would occur when a brace is removed daily for such activities as bathing, physical therapy, and/or sleeping. This may require the straps on a brace to be replaced every 3-6 months.
Another common category of fasteners in bracing and orthopedic devices is made up of various types of snap fasteners. While snap fasteners are more durable than the hook and loop fasteners, they are generally difficult to close when a significant amount of tension must be placed on the strap. The user often must place a higher amount of tension on the strap than the strap will provide once closed, while at the same time aligning the snap portions and often applying an additional force to snap the sections together. This is often difficult to achieve, especially for individuals who are weakened or have limited strength, and can result in the patient's skin being pinched between the portions of the snap. Many snap fasteners are also not adjustable. Adjustable fasteners that ratchet, such as are sometimes used in ski boots, have the ratcheting surface on the wide top surface of the strap and are too thick and bulky for use in braces and other orthotic devices. Therefore, there still remains a need for a fastener that is adjustable, easy to operate, and appropriate for use in braces and other orthotic devices.
The invention relates to an adjustable fastener such as one suitable for use in securing straps in a variety of orthotic and other types of devices. The fastener comprises a male portion and a female portion that are each attached to a strap or other desired location on the device with which the fastener is used. The male portion comprises an elongated tab and the female portion comprises a housing and a passage through the housing. The passage allows the elongated tab to slide through the housing in the female portion. An engagement finger in the housing is resiliently biased to engage one or more teeth along an edge of the elongated tab to prevent the elongated tab from sliding further out of the passage. The finger can be selectively disengaged from the teeth to allow the elongated tab to slide further or completely out of the housing. Preferably there are teeth along both edges of the elongated tab and there is a finger in the housing adapted to separately engage each set of teeth. It is additionally preferable that the elongated tab can be ratcheted further into the housing by sliding it without disengaging the engagement finger.
The preferred embodiments of the apparatus of the invention are further described and explained in relation to the following figures wherein:
The following description will describe the structure and function of the claimed fastener in terms of the preferred embodiments. In discussing the various embodiments of the current invention, corresponding structure will be identified using the same reference numerals. Preferably the parts of the fastener are formed from a polymeric material and most preferably from ST801 Nylon, however those of skill will recognize that many other materials can be appropriate for use in all or portions of the disclosed fastener. Various parts may include up to about 13% glass fibers in the ST801 Nylon, which improves its stiffness and dimensional stability. The inclusion of glass fibers is especially desirable for engagement fingers 54 and leaf springs 66 to help provide the desired strength and spring tension.
Those of skill in the art will recognize the many purposes for which the fastener of the current invention can be used. Preferably, the fastener is adapted for use in securing and tensioning straps of a brace or other orthotic device to assist in holding the brace or device in the desired position on the patient's body and/or applying the desired therapeutic forces. For example, the fastener can be used in conjunction with the Dynamically shiftable counter shear force knee brace disclosed in U.S. Pat. No. 4,955,369 to secure one or more of the various straps used to secure the brace in place on the leg and apply the necessary therapeutic forces. The fastener can also be used in conjunction with hook and loop fasteners to secure the end of an adjustable length strap to the shell of a brace, such as the one in the Muscle Powered Dynamic Knee Brace disclosed in U.S. application Ser. No. 10/774,657, filed by applicant on Feb. 5, 2004. In this case, fastener 10 can be used to replace the D-ring and web attachment portion used in conjunction with straps 46 and 60 on that brace, with one portion of the fastener secured to the strap and the other portion secured to the shell of the brace. Likewise, the disclosed fastener can be used in many other types of orthotic and other types of devices.
Referring to
As shown in
Attachment point 20 on female portion 14 shows alternative structure that allows female portion 14 to be attached to anchor point 28 through the use of a connector such as connector 38. Attachment point 20 contains a hole 36 through which a connector 38 can be used to secure female portion 14 to anchor point 28. If desired, connector 38 can be used to provide a pivotal attachment between female portion 14 and anchor point 28. A pivoting attachment point 20 allows the end of strap 26 to pivot to the correct angle, which may vary based upon the individual patient or even based upon the current position of the limb to which the orthotic device is secured. If desired attachment point 20 can be formed integrally with base 22 as opposed to extending out from base 22 and housing cover 24 as is shown in the figures. In such case, hole 36 can be located directly in base 22, providing a more compact female portion 14. When hole 36 is located in base 22, it will generally be desirable to further include an access hole in housing cover 24 to allow female portion 14 to be secured to anchor point 28 after female portion 14 has been fully assembled.
As shown in
As depicted in
As can be seen more clearly in
As shown in
Arms 68 of engagement fingers 54 each extends outside of housing 24 and allow an individual to manually disengage engagement teeth 64 of each engagement finger 54 from track teeth 48. As seen in
Track teeth 48 and engagement teeth 64 are shaped so that when engaged they allow the ratcheting of the fastener further into passage 60 to tighten strap 26 while preventing it from being loosened by sliding further out of passage 60. Shoulders 50 and 72 contact each other and prevent elongated tab 18 from sliding further out of passage 60, thereby loosening the tension on strap 26 or opening fastener 10. However, if elongated tab 18 is slid further into passage 60, inclined planes 52 and 74 contact each other. The angle of inclined planes 52 and 74 is such that the end of engagement finger 54 containing engagement teeth 64 is rotated away from passage 60 so that inclined plane 74 can ride up inclined plane 52. When finger tooth 64 reaches the high point of inclined plane 52 of one tooth, further sliding elongated tab 18 into passage 60 will result in the biasing action of leaf springs 66 pushing finger tooth 64 down into the notch formed by shoulder 72 of one tooth and inclined plane 52 of the next adjacent tooth. Shoulders 50 and 72 will prevent elongated tab 18 from sliding further out of passage 60 and back to its original position. As a result, elongated tab 18 can be ratcheted further into passage 60 without disengaging engagement finger 54, thereby tightening the tension on strap 26 in discrete but small increments without having to apply forces 76 to arms 68 and risking fastener 10 opening or loosening up. On the other hand, elongated tab 18 cannot be slid further out of passage 60, either to loosen the tension on strap 26 or to open fastener 10 without applying forces 76 to disengage engagement fingers 54 from tracks 46 on elongated tab 18 due to the contact of shoulder 50 on track teeth 48 and shoulder 72 on engagement teeth 64. Further, when two engagement fingers are used, as in the preferred embodiments, forces 76 must both be simultaneously applied to arms 68 to disengage both engagement fingers 54 from track teeth 48 in order to be able to slide elongated tab 18 further out of passage 60 to loosen strap 26 or completely open fastener 10.
Straps in braces and other orthotic devices must be secured with sufficient tension to hold the brace or device in its intended place. Insufficient tension on straps 26 will allow the brace or device to shift or come off, reducing its benefit or even becoming counterproductive. On the other hand, excess tension will often cause discomfort with the patient, restrict circulation, and may lead to the patient not wearing the brace as often as is recommended. Obtaining the appropriate amount of tension each time the patient secures the strap is even more important when the amount of tension on a particular strap in part regulates the amount of therapeutic force that is being applied by the device.
The presence of multiple track teeth 48 on each edge of elongated tab 18 allows fastener 10 to provide a way of adjusting the tension on the strap in a repeatable manner in addition to operating as a fastener for the strap. A number of track teeth 48 sufficient to provide the desired range of adjustability for the particular strap can be provided on each edge of elongated tab 18. Alternatively, other means may be used to provide the approximate amount of tension required and sufficient track teeth 48 are included on each edge of elongated tab 18 to provide the necessary range of fine-tuning adjustment and accommodate any fluctuations in the desired amount of tension that may occur. For example, the attachment of fastener 10 to the device through either attachment point 16 or 20 can be adjustable to provide the desired approximate adjustment. One way of accomplishing this, as shown in
Fastener 10 avoids the tensioning and closure problems often associated with snap-type fasteners by allowing the individual to close fastener 10 at a lower tension level and then adjusting the tension up to the desired amount in small discrete amounts by sliding the elongated tab further into passage 60, without having to reopen fastener 10. This is accomplished by providing an elongated tab 18 with sufficient track teeth 48 so that the first track tooth 48 engages the engagement teeth 64 on engagement finger 54 with a relatively low amount of tension. At this point fastener 10 is closed and male portion 12 and female portion 14 are fixed relative to each other. Elongated tab 18 can then be further slid into passage 60 to ratchet engagement teeth 64 sequentially to track teeth 48 along elongated tab 18, thereby adjusting fastener 10 in discrete increments to tighten strap 26 without opening fastener 10.
A particularly preferred embodiment of fastener 10 combines male portion 12 with D-ring 30 where one end of strap 26 is looped through slot 32 in D-ring 30 and secured back on itself using hook and loop closures, i.e. Velcro, in place of stitches 34. The use of hook and loop closure on strap 26 allows for an infinitely variable adjustment to the length of strap 26, thereby adjusting its tension. Once initially set, the hook and loop fasteners are left in place and fastener 10 is used to release strap 26 when necessary to remove the device as well as to provide any slight adjustment to the tension on strap 26 that is required. The use of fastener 10 in connection with hook and loop fasteners on strap 26 allows the patient to repeatedly duplicate the amount of tension previously placed on strap 26 by either the user or a medical professional as well as fine tune the amount of tension on strap 26 simply by counting the “clicks” made as engagement finger 54 sequentially engages each track tooth 48. Fastener 10 also prevents the hook and loop from wearing out over time due to repeatedly opening and closing of strap 26.
One of skill in the art will recognize that the dimensions of track teeth 48 on elongated tab 18, engagement teeth 64, and the thickness of elongated tab 18 will depend upon the strength required for the particular application and any size limitations for using fastener 10 in a particular brace or orthotic device. For example, increasing the thickness of elongated tab 18 and engagement fingers 54 will increase the thickness of track teeth 48 and engagement teeth 64 and thus the contacting surface area of shoulders 50 and 72, thereby increasing the strength of fastener 10. The use of track teeth 48 along both edges of elongated tab 18 can also be used to effectively double the surface area of shoulders 50 and 72 contacting each other when compared to the use of track 46 on only one edge of elongated tab 18, thereby increasing the strength of fastener 10 without requiring any additional thickness to fastener 10. The use of track teeth 48 along both edges of elongated tab 18 also helps prevent the unintentional opening of fastener 10. When fastener 10 has two sets of track teeth 48 and two engagement fingers 54, forces 76 must be applied to both arms 68 at the same time before fastener 10 can be opened. The fact that the two forces 76 are in opposite directions in the preferred embodiment makes it much less likely that both engagement fingers can be disengaged through accidental contact, such as when the wearer of the orthotic is engaged in sporting activities.
The use of multiple engagement teeth 64 on each engagement finger 54 also increases the strength of fastener 10 without an increase in the overall size of fastener 10. This is achieved because shoulder 72 on multiple engagement teeth 64 are simultaneously engaged with shoulders 50 on track teeth 48, thereby increasing the contacting surface area and the amount of tension that can be sustained by fastener 10. By adjusting the dimensions and configuration of fastener 10, failure strengths of over 150 pounds can be achieved for fastener 10 of the current invention, while still maintaining the slim profile of fastener 10 as shown in
The above descriptions of certain embodiments are made for the purposes of illustration only and are not intended to be limiting in any manner. Other alterations and modifications of the preferred embodiments will become apparent to those of ordinary skill in the art upon reading this disclosure, and it is intended that the scope of the invention disclosed herein be limited only by the broadest interpretation of the appended claims to which the inventor is legally entitled.
