Abstract:
The ulnar support splint is formed of a continuous spiral having a first end, a midpoint and a second end. The splint can be made of a semi-rigid material being molded to the user&#39;s hand. The splint provides lateral support to a user&#39;s fingers through at least three points of contact, including the ulnar medial side of at least one finger, the web space between the user&#39;s thumb and metacarpophalangeal joint of the user&#39;s index finger and the user&#39;s wrist distal the user&#39;s ulnar styloid. A method for providing lateral support to the fingers using the splint applies pressure at the least three points creating counterbalancing pressure points.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to orthopaedic splint type devices for the hand used to align the proximal phalanges when necessary because of ulnar drift. 
     2. Description of the Prior Art 
     Rheumatoid arthritis is an incurable disease which affects a large number of individuals to varying degrees. In severe cases, the disease is both painful and crippling. Due to the incapacitive nature of the disease, various adaptive equipment and splints exist in the prior art to assist individuals in dealing with the effects of this disease. 
     When the hands become involved in the arthritic disease process, internal forces in the hand and fingers change due to pain, inflammation and swelling. This creates dynamic and static imbalances which result in deformities. Specifically, as the tendons and ligaments around the joint become over stretched and the bone structure of the joint deteriorates due to the disease, the joints become very unstable in all directions through the full range of flexion and extension. Chronic pain and general muscle weakness exacerbate the problem of joint instability to the point of serious loss of function in the rheumatoid hand. 
     When joint instability occurs in the lateral plane, it frequently results in ulnar deviation of the fingers at the metacarpophalangeal joints (ulnar drift). Specifically, ulnar drift results from the degradation due to disease or injury of the structures holding the flexor and/or extensor tendons in normal placement. Following this degradation, the tendons slip from their normal position toward the ulnar side of the hand. During normal grasp and release hand movement, the displaced tendons exert a lateral torque in the ulnar direction about the metacarpophalangeal joints, which results in ulnar medial deviation or ulnar drift of the phalanges. Ulnar drift causes decreased prehension, loss of grip strength and unacceptable cosmesis. 
     Furthermore, when ulnar drift occurs, the head of the second metacarpal bone of the index finger usually protrudes due to atrophy of the interosseous muscle. This bony protrusion must be avoided on the radial side of the hand when splinting, because it is painful when splints and/or straps rest on the protrusion and skin breakdown frequently occurs. 
     Prior art splints have attempted to address the problem of ulnar drift. They are typically palmar or dorsal hand based splints with padding and finger separators, such as disclosed in Barber, &#34;Ulnar Deviation Splint,&#34; U.S. Pat. No. 4,558,694. The &#39;694 patent, from the user&#39;s standpoint, has many drawbacks to the disclosed device. The use of hook and loop material requires more physical grip strength than many arthritis patients have in their fingers. Further the finger separators maintain the user&#39;s fingers in an abducted (separated) position which is awkward for performing normal everyday activities. Furthermore, the straps of the device simply hold the hand in relation to itself. There are no other areas of the hand or arm which are used to stabilize the hand and prevent ulnar drift. Prior to the Barber patent, Czap, &#34;Ulnar Drift Splint,&#34; U.S. Pat. No. 3,299,887, in fact suggests a hinged mechanism to support laterally deviating fingers. Unfortunately, these prior art splints fail to provide sufficient leverage to correct ulnar drift. 
     As discussed above, when ulnar drift occurs, the fingers deviate in a lateral plane, with the axis of deviation being at the metacarpophalangeal joints. To correct this deformity, the splint needs to contact the affected area in three distinct and sufficiently separate areas to allow corrective leverage. 
     Palmar and dorsal hand based splints of the prior art are short, rotating when ulnarly deviating fingers push against the distal end of the splint. As the splint rotates, the distal edge on the radial side of the splint digs into the neck of the metacarpal bone just proximal to the head. This area is frequently recessed due to atrophy of the interosseous muscle, and it is very painful to have a splint either digging in proximal to the head of the metacarpal bone or resting directly on the lateral side of the metacarpal joint. Furthermore, splints resting on, and/or digging into, this area causes pressure sores and skin breakdown. Additionally, prior art splints tend to be bulky, abduct (spread apart) the fingers and have straps which make donning and doffing the splint difficult for individuals with limited hand function and grip strength. The ulnar support splint of the present invention overcomes the deficiencies of the prior art by providing a splint of sufficient overall length to provide corrective forces in the lateral plane. 
     SUMMARY OF THE INVENTION 
     A spiral splint is disclosed for providing lateral support for a user&#39;s fingers, such as in cases where the tendons of the hand slip from the metacarpophalangeal joints resulting in ulnar medial deviation. The spiral of the splint contacts the ulnar and radial areas of the hand and comprises at least one finger support member, each of which can conform to the contour of the finger and in contact with the finger&#39;s medial side. The finger supports can encircle the finger, with one or more of the supports being padded at the point of contact. A palmar support, curved to conform to the user&#39;s hand, engages the user&#39;s palm directly under the metacarpophalangeal joints. A radial arc conforms to, and engages, the radial area of the user&#39;s hand distal to the thumb and proximal the metacarpophalangeal joint of the index finger. A curved dorsum support angles across the hand&#39;s dorsum to a proximal arc which engages the ulnar side of the hand distal the ulnar styloid. A wrist support engages the user&#39;s forearm proximal the wrist and thumb carpometacarpal joint. The splint should avoid any contact with the radial side of the metacarpophalangeal joint of the index finger. 
     In one embodiment the splint is one contiguous piece of semi-rigid material, such as plastic or metal covered with a resilient material. Alternatively, the splint can be manufactured from two or more pieces which are affixed to one another at their ends. A hinged member can be attached to the wrist support and to engage the forearm. Additional securing straps can be provided extending from one of the finger supports member to the dorsum support. 
     Lateral support is provided for the fingers by contacting at least three points of the hand. These three points include one or more of said finger&#39;s ulnar medial sides; the web space between the thumb and the metacarpophalangeal joint of the index finger, and the wrist distal to the ulnar styloid. This placement allows the lateral force created by the fingers to be countered by contact of the splint at the web space. The lateral force created by the web space is then countered by contact of the splint at the ulnar styloid. These points of contact distribute the force required to support the fingers along the hand and wrist. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 illustrates the curved splint ready to be placed on the user&#39;s hand; 
     FIG. 2 is a view of the back of the user&#39;s hand wearing the splint of FIG. 1; 
     FIG. 3 is a view of the palmar area of the user&#39;s hand wearing the splint of FIG. 1; 
     FIG. 4 is a plan view of the pattern used to make the splint of FIG. 1; 
     FIG. 5 is a front view of the back of the user&#39;s hand wearing a splint incorporating an additional support strap; and 
     FIG. 6 is a front view of the back of the user&#39;s hand wearing the disclosed splint incorporating an alternate support strap. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The disclosed invention overcomes the problems associated with the foregoing prior art patents and miscellaneous devices by providing a device which allows the hand and wrist to provide additional support and leverage to the deviating fingers. The three areas of leverage are the ulnar medial side of one or more fingers, the web space between the thumb and the radial side of the metacarpophalangeal joint of the index finger and the wrist distal to the ulnar styloid. By contacting the affected area at these three distinct and sufficiently separate areas, a lateral corrective force can by applied which holds the fingers in proper alignment. The splint is light in weight, low in cross-sectional profile, does not have straps and can be donned and doffed without tools by spiraling around the arm. It is unobtrusive, easy to wear and allows the wearer to use finger and wrist splints in conjunction the ulnar support splint when necessary. Possibly most importantly, the disclosed splint can be worn while performing everyday tasks, such as driving, typing, writing, etc. 
     As discussed above, when ulnar drift occurs, the fingers deviate in a lateral plane, with the axis of deviation being at the metacarpophalangeal joints. To effectively correct this deformity, the splint needs to contact the affected area in three distinct and sufficiently separate areas to allow corrective leverage. 
     As illustrated in FIGS. 1-3, the ulnar support splint 10 is comprised of a contiguous band or strip of thermoplastic or metal material which has been spiraled to wrap around the hand and wrist. Although in the illustrated embodiment, the splint 10 is a single piece of material, for ease of description the splint 10 has been divided in sections, finger supports 14 and 16; palmar support 20; dorsum support 22; and wrist support 24. At one end of the body 12, finger supports 14 and 16 are formed which contact the ulnar medial side of the little finger, and one or more additional fingers. In the illustrated embodiment, only the little finger and the adjacent ring finger are provided with supports. It should be noted, however, that separate lateral support may be provided for any one finger or for all fingers of the splinted hand, however in the preferred embodiment, lateral supports are provided for the ring and little fingers only. Research has shown that the index and middle fingers are sufficiently supported in the lateral plane by laying against the supported ring and little fingers and the resulting splint is less bulky and restrictive of normal hand movement. It has also been found that to provide maximum support, the little finger support 16 must be included. From the finger supports 14 and 16, the body 12 continues to a palmar support 20, proceeds around the hand to the dorsum support 22 and ends at the wrist support 24. 
     The finger supports 14 and 16 are formed to provide lateral support to the affected finger(s) by being positioned and held comfortably and firmly, but not forcefully, against the ulnar medial side of the proximal phalanx(s). The finger support 16 should have sufficient width to provide support and comfort. If any of the finger supports are too narrow, they will tend to dig into the user&#39;s hand, therefore being quite uncomfortable, and will provide little support to prevent ulnar drift. To provide optimum support, the placement of the little finger support 16 must be such that the distal edge of the support 16 must extend past the MCP joint of the small finger. The remaining finger supports 14 must fall distal to the web space between the fingers. Preferably, the supports do not extend to, or beyond, the proximal interphalangeal (PIP) joint of the supported finger(s) so that flexion of the PIP joints is not impeded. 
     The finger supports 16 should be thin enough to fit comfortably between the fingers without abducting the fingers, while sufficiently thick to provide slightly yielding, but basically firm, support of the fingers while the hand and fingers are being used for normal activities of daily living. Each of the finger support(s) 14 and 16 should extend from the attachment point on the palmar support 20 between the fingers and toward the back of the hand a sufficient distance to provide lateral support for each finger. In the preferred embodiment, each of the finger supports 14 and 16 extend far enough to comfortably cradle the fingers. The supports 14 and 16 are preferably semi-circular to match the round curvature of the finger, extending partially around each finger. 
     The palmar support 20 is slightly bowed to match the palmar arch and rests comfortably and firmly against the palm of the hand directly under the MCP joints. The MCP joints of hands where ulnar deviation is occurring are typically subluxed (dislocated). When the subluxed MCP joints are supported by the palmar support 20 of the splint, they tend to be pushed back into alignment from their subluxed position which decreases the pain associated with subluxation and allows the hand to look and function more normally. 
     The radial arc 26 contacting the hand between the thumb and the radial side of the MCP joint of the index finger is extremely important in both function and placement and serves as the fulcrum point of the splint 10. The finger supports 14 and 16 support and align the fingers by providing a radial force which counters the fingers tendency to ulnarly deviate. This force is transmitted by the design of the splint 10 to the fulcrum point at the arced band 26, where the radial force counters the ulnar force applied by the fingers. The force, or pressure, is further transmitted to the proximal arc 28 of the splint 10 where a radial force subsequently countered by the contact of the splint with the wrist distal the ulnar styloid. 
     Angling and placement of the radial arc 26 is critical as the splint 10 should contact the hand in the web space between the thumb and the metacarpophalangeal joint (MCP) of the index finger, then dorsum support 22 diagonally crosses the dorsum of the hand to the proximal arc 28. The proximal arc 28 preferably lies on the medial side of the wrist distal to the ulnar styloid; to allow for comfort and maximum freedom of movement. The splint 10 finally is formed around and in contact with the wrist support 24 lying on the arm proximal to the wrist. Care should be taken to avoid contact between the radial arc 26 and the radial side of the MCP joint and head of the metacarpal bone. This achieved by angling the dorsum support 22 and radial arc 26 diagonally away from the joint. 
     The dorsum support 22 falls diagonally across the back of the hand, comfortably following the curvature of the hand until it passes around the wrist on the ulnar side, distal the ulnar styloid. Finally, the wrist support 24 lies on the volar surface of the forearm, partially encircling of the arm and ending just proximal to the carpometacarpal (CMC) joint of the thumb. 
     When fitted for use by an ordinary patient, the splint will spiral around the hand, fit flush against the skin and provide comfortable and unobtrusive support for the fingers by holding the supported fingers in a normal and cosmetically acceptable position. The supported fingers are maintained in alignment while at rest and during normal activities. Such support improves prehension and grip strength while reducing pain and fatigue. 
     FIG. 4 illustrates the ulnar support splint pattern prior to being custom fitted for the patient. The curved pattern 50 is a design which can be utilized with various thermoplastic or metal materials to delineate a one dimensional shape which can be formed into the ulnar support splint of the general design and function disclosed here. A flat sheet of material, when cut out in the pattern disclosed here, may be formed through the use of heat and/or pressure into the shape of the ulnar support splint. 
     The component parts of the splint pattern 50 are similar to those described in the preferred embodiment, although they are necessarily flat in the pattern. The little finger support 16, finger support 14, the palmar support 20, the radial arc 26 which proceeds around the radial side of the hand between the thumb and the metacarpophalangeal joint (MCP) of the index finger, the dorsum support 22 and proximal end which wraps around as the wrist support 24 are shown to be able to be fabricated from a single flat sheet of material. 
     Although the embodiment illustrated herein is manufactured from a single piece of material, multiple sections can be used which are connected through means which are convenient to the type of material used, i.e., hot melt glue, rivets, etc. Each of the splints should be molded to the specific user&#39;s hand to obtain maximum support and comfort. In some instances, additional straps 40 and 42 may be desired which can be added on either a permanent or temporary basis, as illustrated in FIGS. 5 and 6. The additional straps can be affixed to the splint 10 through use of hook and loop material. The illustrated straps are two examples of possible configurations and should, in no way, limit the scope of the invention. Although the support would not be as beneficial, the disclosed design can be manufactured from a combination of hook and loop material, fabric and semi-rigid inserts which are placed to provide the compression and extension required to achieve the three point support disclosed heretofore. 
     Various modifications of the invention regarding the placement of supports, contact areas, material types and widths may be necessary for individual patients by those skilled in the art of splinting or orthotics.