Abstract:
A dynamic hip stabilizer utilized to reduce the risk of postoperative and recurrent traumatic hip dislocations. The hip stabilizer includes a pelvic girdle, at least one thigh cuff, and one or more elements for generating an elastic tensile force between the girdle and cuff. The girdle has an upper portion configured for defining an upper opening for the wearer&#39;s waist, a lower portion configured for defining a lower opening for the wearer&#39;s hips, and a posterior portion configured for engaging the wearer&#39;s lower back. The hip stabilizer further includes one or more elements for engaging the wearer&#39;s shoulders to limit movement of the girdle toward the thigh cuffs caused by the elastic tensile force, and one or more elements for stiffening the posterior portion of the girdle.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     This is a continuation-in-part patent application of co-pending U.S. patent application Ser. No. 10/604,993, filed Aug. 29, 2003, which claims the benefit of U.S. Provisional Application No. 60/319,519, filed Sep. 4, 2002. The contents of these prior applications are incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     The present invention relates to devices utilized to reduce the risk of postoperative hip dislocations and recurrent traumatic hip dislocations. More particularly, this invention relates to a dynamic hip stabilizer with a combination of components that generate tensile (tensional) forces capable of holding a patient&#39;s thigh to the patient&#39;s pelvis, preferably with enough tension to control excessive adduction, flexion or extension, control excessive internal or external rotation, provide hip stability by controlling and modifying certain hip motions through increasing tension as the extremes of a particular motion are approached, and provide hip stability by constantly maintaining elevated abductor tension across the hip joint.  
         [0003]     There are a variety of techniques currently in use to prevent postoperative hip dislocations, recurrent traumatic hip dislocations, etc., some of which make use of specialized devices. A basic technique is to place a pillow between the thighs of the patient to cause abduction of the hips. A slightly more advanced technique is to secure a foam abduction pillow between the thighs with hook and loop straps to hold the hips in wide abduction. More advanced techniques include the use of single hip spica abduction braces, which generally comprise a thermoplastic waist brace attached to a thermoplastic thigh component by a hinged metal bar. The metal hinge portion allows flexion of the hip within a variable fixed range which can be set by the treatment provider. Single and bilateral hip spica casts, which serve to prevent all hip motions, also have long been used. Another type of device is the hip abduction brace, which generally comprises two curved semicircular plastic plates connected by hinges to a central threaded expansion-contraction device. By turning a central control threaded screw, the semicircular plastic plates spread out. When held between the proximal thighs by hook and loop straps, the device pushes the thighs apart, attempting to maintain abduction of the hips.  
         [0004]     Various shortcomings are associated with the use of the above techniques and devices. Conventional pillows are too moveable and not wide enough to give consistent abduction, and undesirably allow the patient to move about. As a result, a pillow is rarely capable of preventing postoperative dislocation because it does not move with the patient who rolls over, or when the patient sits at the side of the bed or is being transferred to a wheel chair. Foam abduction pillows are clumsy and require considerable nursing effort to roll a patient from side to side. Furthermore, foam abduction pillows must be removed when the patient sits up and when bed-to-chair transfers are required.  
         [0005]     A significant shortcoming of hip spica casts is the risk of prolonged stiffness because of the lack of all motion at the hip for many weeks. While single hip spica abduction braces avoid this concern, they require measurement and fitting by an orthotist and are formed from prefabricated parts of thermoplastic material and metal struts. Though single hip spica abduction braces can be worn in bed and while the patient sits and is being transferred, form-fit plastic abdominal and thigh portions of the brace often do not fit well, and allow many patients to rotate, putting the hip at risk. These braces also often allow some adduction and internal rotation, which is a significant risk to hip stability. Furthermore, this type of brace offers no compression of the femur against the pelvic acetabulum.  
         [0006]     Hip abduction braces work reasonably well for the first days after surgery when the patient is fairly inactive. However, if not maintained in its fully abducted position, this type of brace allows for adduction to neutral and flexion is uncontrolled. The brace is removed for perineal care and when sitting the patient up at bedside. In addition, this type of brace cannot be worn during patient bed-to-wheelchair transfers or during gait training.  
         [0007]     Other techniques and braces that pertain to the prevention of hip dislocations, or more generally to supporting or bracing the hip region, include U.S. Pat. No. 976,564 to Goodson, U.S. Pat. No. 1,722,192 to Brokaw, U.S. Pat. No. 2,332,119 Springer, U.S. Pat. No. 4,531,515 to Rolfes, U.S. Pat. No. 4,709,692 to Kirschenberg et al., 4,901,710 to Meyer, U.S. Pat. No. 4,905,678 to Cumins et al., U.S. Pat. No. 4,926,845 to Harris, U.S. Pat. No. 5,267,928 to Barile et al., U.S. Pat. No. 5,286,251 to Thompson et al., U.S. Pat. No. 5,465,428 to Earl, U.S. Pat. No. 5,840,050 to Lerman, U.S. Pat. No. 5,893,367 to Dubats et al., U.S. Pat. No. 5,928,175 to Tanaka, and U.S. Pat. No. 6,039,707 to Crawford et al. Each of Goodson, Brokaw, Barile et al. and  
         [0008]     Earl entail device with a waist portion, thigh portions, and elastic straps that interconnect the waist and thigh portions. Goodson&#39;s straps are limited to the posterior to provide posture support. Brokaw discloses a brace with inelastic anterior straps and elastic posterior straps. Barile et al. disclose a one-piece support garment with elastic anterior and posterior straps and elastic lateral straps, the latter of which may be wrapped in various ways around the thighs or hips of the wearer. Finally, Earl discloses an exercise device whose elastic straps are limited to the posterior side of the device.  
         [0009]     It would be desirable if an improved device was available that was specifically configured to prevent hip dislocations by controlling excessive adduction, flexion and/or extension, controlling excessive internal or external rotation, and increasing hip stability.  
       BRIEF SUMMARY OF THE INVENTION  
       [0010]     The present invention provides a dynamic hip stabilizer capable of reducing the risk of hip dislocations, including postoperative and recurrent traumatic hip dislocations. The hip stabilizer generally comprises a pelvic girdle, at least one thigh cuff, and one or more elements for generating an elastic tensile force between the pelvic girdle and the thigh cuff. The pelvic girdle has an upper portion configured for defining an upper opening for the wearer&#39;s waist, a lower portion configured for defining a lower opening for the wearer&#39;s hips, and a posterior portion configured for engaging the wearer&#39;s lower back when the pelvic girdle is worn by the wearer. The thigh cuff defines lower and upper openings for the wearer&#39;s thigh. The hip stabilizer further includes one or more elements for engaging the wearer&#39;s shoulders to limit movement of the pelvic girdle toward the thigh cuff caused by the elastic tensile force, and one or more elements for stiffening the posterior portion of the pelvic girdle relative to the upper and lower portions of the pelvic girdle.  
         [0011]     According to a preferred aspect of the invention, the elastic tensile force generated between the pelvic girdle and thigh cuff is operative to hold the wearer&#39;s thigh to the wearer&#39;s pelvis with sufficient tension to control excessive adduction, flexion or extension, provide hip stability by controlling and modifying certain hip motions through increasing tension as the extremes of a particular motion are approached, and provide hip stability by constantly maintaining elevated abductor tension. The stability and proper positioning of the girdle is enhanced by the action of the one or more elements that limit movement of the girdle toward the thigh cuff, and by the one or more stiffening elements that also provide support to the lower back of the wearer.  
         [0012]     Other objects and advantages of this invention will be better appreciated from the following detailed description. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]      FIGS. 1, 2  and  3  represent anterior, lateral and posterior views, respectively, of a patient wearing a pelvic girdle and two thigh cuffs that cooperate to form a dynamic hip stabilizer in accordance with a preferred embodiment of the invention.  
         [0014]      FIGS. 4 and 5  are plan views of the exterior and interior surfaces, respectively, of the pelvic girdle and thigh cuffs shown in  FIGS. 1, 2  and  3 .  
         [0015]      FIG. 6  is an enlarged view of a D-shaped ring for attaching an elastic cable that interconnects the pelvic girdle to a thigh cuff of the preceding Figures. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0016]      FIGS. 1 through 5  show a dynamic hip stabilizer  10  in accordance with the present invention. The hip stabilizer  10  is shown as including a pelvic girdle  12  and two thigh cuffs  14 . The girdle  12  is shown as being elastically interconnected to each thigh cuff  14  with elastic cables  16 . The cables  16  are shown connected to the girdle  12  and the thigh cuffs  14  so that, when the hip stabilizer  10  is worn, the cables  16  cooperate to generate an elastic tensile force between the girdle  12  and the cuffs  14 . As will be discussed in more detail below, a preferred aspect of the invention is that this elastic tensile force serves to hold the wearer&#39;s thigh to the wearer&#39;s pelvis with sufficient tension to prevent hip dislocations by controlling excessive adduction, flexion and/or extension, control excessive internal or external rotation, and promote hip stability by controlling and modifying certain hip motions through increasing tension as the extremes of a particular motion are approached, and through constantly maintaining elevated abductor tension. In some patients, the above capabilities may be sufficiently achieved with only one of the thigh cuffs  14  in place.  
         [0017]     The girdle  12  and thigh cuffs  14  preferably comprise a flexible but firm outer layer  18  of fabric material sewn or adhered to an inner lining material  20  that is preferably soft and nonirritating to the skin. The outer layer  18  is preferably relatively stiffer than the inner lining material  20  to provide support to the lining material  20 . The inner lining material  20  preferably has a high skin friction equivalent, i.e., resists slippage against the skin, a particularly suitable example of which is a synthetic fleece fabric commercially available from Maiden Mills Industries, Inc., under the name POLARFLEECE®. A suitable material for the outer layer  18  is a plastic-molded polyester mesh.  
         [0018]     As evident from  FIGS. 1 through 5 , the girdle  12  is narrower at an upper opening defined by its upper extent  22  (corresponding to the waist level of the wearer) and wider at a lower opening defined by its lower extent  24  (corresponding to the pelvic-hip level of the wearer), so as to have a frustroconical shape. As shown, the inner lining material  20  may project beyond the upper extent  22  of the girdle  12  for added comfort to the wearer. Similar to the girdle  12 , each of the thigh cuffs  14  is frustroconical-shaped, though inverted relative to the girdle  12  so as to be wider at an upper opening defined by its proximal-top extent  32  and narrower at a lower opening defined by its inferior-bottom extent  34  in accordance with the shape of the human thigh. With this arrangement, the girdle  12  and thigh cuffs  14  are inhibited from moving toward each other under the elastic tensile force generated by the cables  16 . The girdle  12  and the thigh cuffs  14  are preferably closable with hook-and loop-closures  30  (or another suitable releasable fasteners), so that the upper and lower openings of the girdle  12  and thigh cuffs  14  can be appropriately sized for the wearer. The closures  30  of the thigh cuffs  14  are preferably located over the inside of the wearer&#39;s thighs when the stabilizer  10  is worn.  
         [0019]     As noted above, the cables  16  are intended to reduce the risk of hip dislocations by generating an elastic tensile force between the girdle  12  and thigh cuffs  14  that is sufficient to hold the wearer&#39;s thigh to the wearer&#39;s pelvis. While a wide variety of elements and materials a capable of providing this tensioning function, a preferred configuration for the cables  16  is a round tubing formed of a rubber material. The desired tensile forces to be generated by the cables  16  will depend on the particular lengths, widths/diameters, and materials of the cables  16 , and can be ascertained with minimal trial and error by those skilled in the art. It is believed that a combined elastic tensile force of at least 40 N between the girdle  12  and thigh cuffs  14  is preferred to notably reduce the risk of hip dislocations. It is further believed that a particularly effective hip stabilizer  10  can be achieved with the use of about two to about four cables  16 , each generating a tensile force of about 10 to about 20 N to produce a combined elastic tensile force of about 40 to about 60 N between the girdle  12  and thigh cuffs  14 .  
         [0020]     Extensions  26  of the inner lining material  20  are shown as projecting below the outer layer  18  at the lateral portions of the girdle  12  to extend distally along the midlateral of each thigh, preferably for about three to about five inches (about eight to about thirteen cm) below the outer layer  18 . The extensions  26  are represented as being releasably connected to the thigh cuffs  14  with zippers  28 , though other releasable fasteners are also within the scope of this invention, as is permanent attachment of the extensions  26  to the thigh cuffs  14 . The extensions  26  serve to inhibit slippage and motion between the wearer and the stabilizer  10 , inhibit hip flexion, limit rotation of the thigh cuffs  14  when under elastic rotational tension, and help maintain the distance relationship between the girdle  12  and cuffs  14 .  
         [0021]     As evident from  FIGS. 1 through 4 , the girdle  12  and thigh cuffs  14  are equipped with one or more series of loops  36 . A single transverse row of loops  36  is shown as located near the upper extent  22  of the girdle  12 , extending around nearly the full circumference of the girdle  12  while avoiding the hook-and-loop closure  30  ( FIG. 1 ). The transverse loops  36  of the girdle  12  are preferably spaced apart about every two and one-half inches (about six cm).  FIGS. 1 through 4  show each thigh cuff  14  as being provided with three rows of the transverse loops  36  vertically spaced apart in the longitudinal direction of the stabilizer  10 , with each row extending about three quarters of the circumference of each thigh cuff  14  to avoid the hook-and-loop closures  30  located at the inner thigh. While the girdle  12  is shown with a single transverse row of loops  36  and the thigh cuffs  14  are shown with three transverse rows of loops  36 , any number of rows and loops  36  could be used. In particular, the lower row of loops  36  on the cuffs  14  are believed to be optional, as under certain conditions a cable  16  attached to a loop  36  near the lower extent  34  of a cuff  14  may cause the cuff  14  to curl toward the girdle  12 . Finally, the loops  36  of the girdle  12  and cuffs  14  need not be aligned in rows.  
         [0022]     As also evident from  FIGS. 1 through 4 , the girdle  12  is further equipped with a series of channel loops  38 , shown as being arranged in longitudinal rows that are aligned with the transverse loops  36  and extend toward the lower extent  24  of the girdle  12  and thigh cuffs  14 . The channel loops  38  can be formed of fabric to be of any suitable size, e.g., one and one-eighth inches (about 2.8 cm) wide and one and one-quarter inches (about 3.2 cm) long. While shown as raised loops, other channel-type configurations could be used, including more rigid tubes attached to the girdle  12  or channels recessed into or beneath the surface of the girdle  12 . Each of the elastic cables  16  is attached to one of the transverse loops  36  of the girdle  12  and to one of the transverse loops  36  of the thigh cuffs  14 , passing therebetween through one of the longitudinal rows of channel loops  38  on the girdle  12  so as to be guided and controlled by the channel loops  38 .  
         [0023]     A variety of connector devices can be used to connect the ends of the elastic cables  16  to the transverse loops  36  of the girdle  12  and thigh cuffs  14 . In  FIGS. 1 through 3 , C-shaped rings  40  are shown as connecting the proximal ends of the elastic cables  16  to the transverse loops  36  of the girdle  12 , whereas quick links  42  are shown connecting the distal ends of the cables  16  to the transverse loops  36  on the thigh cuffs  14 . The quick links  42 , well known and commercially available from a variety of sources, are preferably covered with neoprene tubes that act as metal covers.  FIG. 6  shows a preferred connector  44  for connecting the cables  16  to the loops  36  of the girdle  12  and thigh cuffs  14 . The connector  44  is a D-shaped ring having an arcuate portion  46  and two parallel arms  48 . The connector  44  is preferably a zinc oxide-plated steel material, with suitable dimensions being about 16 by 23 mm. The parallel arms  48  are preferably separated by a gap of about 3 mm, which enables the connector  44  to be installed on one of the loops  36  by passing one of the arms  48  under the loop  36 , twisting and rotating the connector  44  ninety degrees, and then passing the second arm  48  under the same loop  36 . This procedure is believed to be less complicated than what is possible with the C-shaped rings  40  and quick links  42 . The preferred D-shaped connector  44  is also potentially stronger and less deformable than comparable C-shaped rings  40 .  
         [0024]     As evident from  FIGS. 1 through 3 , the channel loops  38  control the paths of the cables  16 , directing the tension generated by the cables  16  along paths beneficial to the wearer. Simultaneously, the loops  38  prevent the cables  16  from moving in directions transverse to the longitudinal direction of the stabilizer  10 , which would likely cause discomfort to the wearer. For example, the loops  38  are able to prevent the cables  16  rolling and snapping over the wearer&#39;s buttocks or catching in the gluteal cleft. In practice, a single transverse row of channel loops  38  near the lower extent  24  of the girdle  12  has been shown to be adequate, such that the row of channel loops  38  nearest the loops  36  can be considered as optional.  
         [0025]     As evident from  FIGS. 1 and 3 , respectively, cables  16  can be routed between the anterior portion  50  of the girdle  12  and the anterior side of the cuffs  14 , and between the posterior portion  52  of the girdle  12  and the posterior side of the cuffs  14 . As represented in  FIG. 2 , cables  16  can also be routed from the posterior portion  52  of the girdle  12  to the anterior or lateral sides of the thigh cuffs  14 . Beneficial effects associated with the ability to selectively establish different routes for the cables  16  include the capability of applying internal or external rotational forces. Anterior hip dislocations require an internal rotation and flexion force, while posterior dislocations require external rotation and an extension force. Lateral abductor deficiencies require an abduction force, which can also be generated by appropriately routing one or more cables  16 . By varying the tensions and lengths of the cables  16 , greater and lesser flexion or extension forces can be created.  
         [0026]     In addition to the above features, the hip stabilizer  10  shown in  FIGS. 1 through 5  as being equipped with straps  54  attached to the anterior and posterior portions  50  and  52  near the upper extent  22  of the girdle  12 . In use, the straps  54  are preferably crossed at the back of the wearer before being passed over the wearer&#39;s shoulders. To accommodate wearers of different sizes, the straps  54  are preferably adjustably attached to the anterior  50  of the girdle  12 , such as by passing the straps  54  through rings  56  at the upper extent  22 , and then folding the straps  54  back onto themselves using, for example, a hook-and-loop attachment (not shown). Each strap  54  is also shown as having a sliding cushioned pad  60  of sufficient length to protect the wearer&#39;s shoulders from the pressure of the straps  54 . As a result of the shoulder straps  54 , the girdle  12  is inhibited from migrating distally toward the thigh cuffs  14  under the influence of the elastic cables  16 .  
         [0027]      FIGS. 4 and 5  also shown the hip stabilizer  10  as being equipped with an insert  62  that increases the stiffness of the posterior portion  52  of the girdle  12 . The insert  62  is preferably sufficiently firm to support the wearer&#39;s low back so that stresses from wearing the stabilizer  10  do not result in lower back pain. A suitable insert  62  can be formed of a sheet of firm polymeric material, such as a 3/16 inch (about 5 mm) thick polyethylene sheet. The insert  62  is shown as being received in a pocket  64  (shown partially removed to expose one end of the insert  62 ) defined on the interior of the girdle  12 . A suitable pocket  64  can be formed of the inner lining material  20 , and is preferably sized to extend from the upper extent  22  to the lower extent  24  of the girdle  12 , and from the mid-lateral line on the left of the wearer, around the back of the girdle  12 , to the mid-lateral line on the right of the wearer. The insert  62  is also preferably shaped to be wider (higher) at its ends, allowing a gentle curve over the central gluteal cleft.  
         [0028]     The dynamic hip stabilizer  10  as described above is able to solve various problems, shortcomings and disadvantages of the prior art. The stabilizer  10  eliminates motion between the wearer&#39;s skin and the stabilizer  10  by using a custom-fitting girdle  12  and thigh cuffs  14  equipped with a soft, high-friction inner lining material  20 . With the closures  30 , the sizes/circumferences of the girdle  12  and thigh cuffs  14  can be individually tailored to allow for individual abdominal-thigh size variations. The cuffs  14  can then be individually attached to the girdle  12  (e.g., with the zippers  28 ), thereby inhibiting slippage and motion between the wearer and the stabilizer  10 . The elastic cables  16  can be provided in multiple lengths and generate any number of different tensional loads in multiple directions to provide the stabilizing forces required by the wearer&#39;s condition. In particular, the cables  16  can be routed between the girdle  12  and the thigh cuffs  14  so that the wearer&#39;s thigh is held to the pelvis with enough tension to control excessive adduction, flexion, and/or extension, control excessive internal or external rotation (by passing one or more cables  16  from back to front), provide hip stability by controlling and modifying certain hip motions through increasing tension as the extremes of a particular motion are approached, and provide hip stability by constantly maintaining elevated abductor tension and hip joint compression.  
         [0029]     With the dynamic hip stabilizer  10  of this invention, the wearer can be allowed a full range of motion against an increasing tension, which increases strength and institutes proprioceptive feedback to create a muscle contraction throughout the range, thereby aiding the abductor muscles in keeping the hip in place. The constant tension and full range of motion should allow the wearer to move about in bed, sit safely at the side of the bed, and transfer safely to a wheelchair or commode. Unlike various other devices that are commercially available, the stabilizer  10  does not need to be removed for motion or activities. Furthermore, the open groin and buttock areas allow for urination and defecation without having to remove or adjust the stabilizer  10 . Finally, the constant and adjustable tension generated by the cables  16  acts as a progressive resistive strengthening device to aid in postoperative rehabilitation.  
         [0030]     While the invention has been described in terms of a preferred embodiment, it is apparent that other forms could be adopted by one skilled in the art. For example, the pelvic girdle  12  and thigh cuffs  14  could be formed of a variety of different materials, used alone or in combination. Furthermore, the tension-generating function of the cables  16  can be achieved with elements having a variety of forms, including other tubular-shaped elements, flat elements such as straps, etc. In addition, the 12 girdle could be in the form of a compression or plain pair of shorts with some form of tension-generating elements attached, and the extensions  26  could be eliminated. Therefore, the scope of the invention is to be limited only by the following claims.