ORTHOPAEDIC HIP HINGE PROVIDING ADJUSTMENT FOR ABDUCTION

Abstract: An orthopedic device suitable for controlling hip joints is provided which includes a first hinge means (10, 22, 36) for flexion and extension of the hip and a second hinge means (20, 31) for abduction and adduction of the hip. The orthopedic hip hinge permits a shortening of the overall length of the hinge arm assembly during abduction of the hip and minimizes pistoning of the thigh attachment support. Also included are means for permitting free abduction of the orthopedic hinge within a specified range, while preventing any adduction of the hip. The disclosed device more closely approximates the actual motion of the femoral head in its socket, since the flexion hinge and the abduction hinge employ a common element, and are disposed in a ball-joint arrangement.

Description: This invention relates to orthoses for regulating the movement of an associate body part and, in particular, to orthopaedic hip hinges that permit adjustments to be made to both the abduction-adduction axes and the extension-flexion axes of the hip. Hip joint orthoses have heretofore been employed by orthopaedic professionals for a variety of problems including, Legg Calf Perthes Disease, brittle bone fractures, osteoarthritis, and post-operative therapy for total hip joint replacement. It is well known that hip hinges for casts and orthoses are employed to control abduction and adduction, flexion and extension, and loading of the femur. Most of the known techniques are designed to maintain the femoral head in its correct anatomical location and approximately normal orientation with respect to the acetabulum during the healing process. In most prescribed treatments, the patient is placed in some degree of abduction and the hip orthosis is adjusted to prevent adduction. Caution is taken to prevent adduction because it is known that such motion causes the femoral head to rotate out of its socket, increasing the likelihood of dislocation. Traditionally, hip orthoses have included means for adjusting the flexion-extension axes of the hip joint while preventing lateral motion. See Rolfes U.S: Patent No. 4,481,941. More recent devices have included two axes of motion arranged at right angles to one another. See Young et al, application GB 2163352A, published February 26, 1986. The Young et al orthopaedic hip hinge is equipped with a first flexion-extension axis that can be adjusted for limited motion and a second abduction-adduction axis having an adjustable locking means for setting the abduction at three different angular settings, namely, 0°, 15° and 30°. The second axis of Young et al can also provide free abduction when the shoulder pin is removed from the device. However, since adduction is not blocked, there is a chance that dislocation of the joint will occur, resulting in discomfort to the patient and the likelihood of more surgery. Moreover, the limitation of only three angular settings restricts the available positions for post operative treatment. The Cerebral Palsy Orthosis by Hosmer® is designed to provide adjustable abduction to 25°, with free abduction beyond setting, thereby avoiding the risk of dislocation presented by Young et al. The Post-Op Total Hip Orthotic Joint, also by Hosmer®, has a 45° fixed flexion and abduction axis which can be pre-set to maintain positive medial pressure to the femoral head to prevent accidental dislocation of a prosthesis from the acetabular cup implanted in the ilium. The abduction axis is adjustable to 13° with a small wedge, and to 25° with a large wedge. None of the prior art devices, however, provides for the gradual shortening of the overall length of the side bars, in conjunction with their hinges, referred hereinafter as "arm assembly", as the femoral head rotates and the distance between the hip and the thigh of the patient decreases with abduction. Since these appliances are relatively rigid along the length of the arm assembly, the shortening of the distance between the hip and the thigh causes sliding of the waist band and/or pistoning of the thigh attachment, resulting in discomfort to the patient. Although, Rolfes and others have provided for adjustments to the length of the control arms, these adjustments are fixed and are merely an accommodation for the height of the patient. The object of the invention is to provide an orthopaedic hinge which more closely approximates the movement of the femoral head within the acetabular cavity, and having an arm assembly length that varies with the distance between the hip and thigh during abduction. According to the invention, there is proposed an orthopaedic hip hinge suitable for hip casts and orthoses and including an upper control arm for attachment to a location on a patient's waist, a lower control arm for attachment to a location on a patient's thigh, first hinge means providing angular adjustment between said upper and lower control arms corresponding to flexion and extension of the hip and second hinge means providing angular adjustment between said upper and lower control arms corresponding to abduction and adduction of the hip, said upper and lower control arms and said first and second hinge means forming an arm assembly having an overall length, characterised in that said second hinge means has sliding pivot means for causing a shortening of the overall length of said arm assembly during abduction of the hip. The hinge can be adjusted to lock in the arm assembly at any angle of flexion or abduction within the provided ranges. Moreover, the hinge can be adjusted for free abduction motion up to the preferred 30° arc, while at the same time, preventing adduction. Thus, an orthopaedic hinge is provided with a greater availability of settings for fixing the abduction axis. More importantly, the hinge of this invention provides for the gradual receding of the lower control arm within the abduction hinge means during adduction to prevent sliding of the waistband or pistoning of the thigh attachment. The abduction-adduction and flexion-extension axes of this invention are designed to overlap so that the hinge can closely approximate the behavior of the femoral head in its socket. By preventing adduction and through closer tracking of the hip joint, less discomfort will be experienced by patients utilizing this device. The invention will now be described further, by way of example only, with reference to the accompanying drawings illustrating one embodiment thereof and in which:- Fig. 1 is a front elevational view of the orthopedic hinge of the invention in a locked position for both the flexion and abduction axes: and Fig. 2 is a transverse, cross-sectional view of the orthopedic hinge of Fig. 1 taken on line 2-2 thereof. An orthopaedic hip hinge has an upper control arm, not shown, for attaching the device of the invention to a location on a patient's waist and a lower control arm, not shown, for attaching the device to a location on a patient's thigh. The orthopaedic device includes a first hinge means for providing a range of rotation to the lower arm during flexion and extension and a second hinge means for providing a range of rotation to the lower arm during abduction and adduction of the hip. The upper and lower control arms and the first and second hinge means form an arm assembly having an overall length. As the distance between a fixed point on the thigh and a fixed point on the patient's waist gets shorter during abduction, the second hinge means, through a sliding pivot means, permits a shortening of the overall length of the arm assembly. The device further provides free abduction of the hip from about zero degrees to about ninety degrees, preferably from about zero degrees to about thirty degrees, save when an abduction locking means is in position. As shown in the drawings, the first hinge means includes a flexion hinge arm 10 having an extended portion 11 thereof for connecting the device 100 to the upper control arm. The lower hinge arm 10 also includes an internal track portion 24, as depicted in Fig. 2. The lower hinge arm 10 includes an aperture 37 therethrough for receiving a flexion swivel means 36, which provides an axis for flexion and extension for the device 100. The hip hinge of this invention provides for movement which corresponds closely to the motion of the femoral head within its socket. This is accomplished by positioning the flexion and abduction axes on top of one another, as opposed to stacking them vertically on the arm assembly, see Young et al, supra. This feature is facilitated by the sliding pivot means which includes a pivot head means 22 rotatably mounted to the flexion hinge arm 10 through said swivel means 36. The pivot head means 22 is designed with an outwardly-facing convex surface for acting as a bearing for the axis of abduction-adduction and a flat smooth surface for sliding against the flexion hinge arm 10 to provide the axis of flexion-extension. The pivot head means 22 in combination with the abduction setting member 20 provide a "ball-and-socket-surface" for the second hinge means which provides a range of motion during abduction of the hip. This arrangement provides the shortening of the arm assembly and greatly facilitates simultaneous motion in both the abduction and flexion planes. As shown in Fig. 2, the pivot head means 22 has a threaded aperture 26 therein spaced laterally from the swivel means 36. This aperture 26, as will be discussed below, provides a means for fixing the abductive motion of the hip. The pivot head means 22 of the invention further comprises an integral abduction sleeve portion 27 having a concave surface disposed above and parallel to said convex surface, as shown in Fig. 2. The concave and convex surfaces of the pivot head means 22 form an abduction track 31. The sliding pivot means of this invention further comprises an abduction setting member 20 disposed at least partially within said track 31 and slidably engaged with said convex surface of said pivot head means 22. Upon abduction of the hip, the abduction setting member 20 slides over the pivot head means 22, thereby shortening the overall length of the arm assembly. The abduction setting member 20 is also slidably engaged with the concave surface of the abduction sleeve portion 27 for accurately guiding abduction movement. An important feature of this invention includes a slotted aperture 40 provided in the abduction setting member 20. To regulate abduction movement, an abduction locking means extending through said slotted aperture 40 engages the aperture 26 of the pivot head means 22. The abduction locking means is designed to limit the degree of free abduction movement provided by the device 100, and in the arrangement illustrated comprises a threaded screw 15. As described to this point, the hinge device 100 of the invention can provide free rotation about the flexion axis and limited free rotation about the abduction axis; the latter providing from about zero to ninety degrees of free motion, preferably zero to thirty degrees of free motion. For locking the abduction axis, an abduction lock limiter 18 is disposed around the threaded screw 15 and engaged with the abduction setting member 20 when the threaded screw 15 is tightened. The abduction lock limiter 18 comprises locking teeth for engaging the abduction setting member 20, and more preferably both the abduction lock limiter 18 and the abduction setting member 20 comprise teeth for fixing the degree of abduction of the hip. As used herein, the teeth associated with the abduction setting member 20 are referred to as "setting teeth" 17. As in the case with the flexion hinge arm 10, the abduction setting member 20 also preferably comprises an extended portion 28 for attachment to the lower control arm. The structure additionally comprises means for fixing the degree of movement provided by the flexion axis. Pursuant to this object, a first flexion limiter 30 is disposed on the track portion 24 in the path of movement of the abduction sleeve portion 27 thereby to limit the degree of flexion and extension of the hip. The flexion limiter 30 comprises an adjustment screw 33 for fixing the flexion limiter 30 at a location on the flexion hinge arm 10. Although a single flexion limiter 30 has thus far been disclosed, the structure will ordinarily include a second flexion limiter 32 in spaced angular disposition relative to the first flexion limiter 30, for providing a means for fixing the degree of flexion of the hip. As in the case of the first flexion limiter 30, the second flexion limiter 32 comprises an adjustment screw 39 and is disposed on the track portion 24. This limiter 32 is also in the path of movement of the abduction sleeve portion 27 and is positioned at that side of sleeve portion 27 remote from the first flexion limiter. The first and second flexion limiters 30 and 32 provide a range of flexion and/or extension for the hip and can be adjusted to give an angle of flexion and/or extension at any point within a desired range. This range preferably is less than 180°, and more preferable is less than 140°. The above-mentioned elements of this invention preferably are fabricated by conventional investment casting techniques using stainless steel raw materials, preferably AISI 303 stainless steel. The adjustable screws used herein are preferably machined from stainless steel stock. Although the upper and lower control arms are not illustrated, they are preferably attached to the flexion hinge arm 10 and the abduction setting member 20 using fasteners applied through apertures 43, as is well known in the art. This is not a requirement, however, and it is anticipated that the upper control arm and flexion hinge arm 10 can be fabricated as one piece. Similarly, the lower control arm and the abduction setting member 20 can also be fabricated in one piece. In these embodiments, the first and second hinge means become integral with control arms. The preferred control arms should be made from a stainless steel, more preferably a stainless steel of the type commonly used for orthotic hinge arms. The hinge device 100 of this invention can be easily adjusted to control the flexion axis by inserting a preferred allen key into the adjustment screws 33 and 39 having allen heads. These screws can be turned counter-clockwise until they are loose. The first flexion limiter 30 and/or the second flexion limiter 32 can then be adjusted angularly of the track portion 24 and then tightened by locking the screws 33 and 39 by turning them clockwise. For locking the flexion axis, the above procedure can be followed, however, both the first and second flexion limiters 30 and 32 must contact the pivot head means 22 simultaneously at the desired locked setting. For locking the abduction axis, the allen key is inserted into the threaded screw 15 and turned counter-clockwise until it is loose. Then the abduction lock limiter 18 is lifted and the abduction setting member 20 is positioned as required. The locking teeth of the abduction lock limiter 18 are then engaged with the setting teeth 17 of the abduction setting member 20 and the threaded screw 15 is tightened by turning it clockwise. To provide free abduction motion to the hinge device 100, the allen key is inserted into screw 15 and turned counter-clockwise until the screw is loose and can be removed from the device 100. Having done so, the abduction lock limiter 18 can be removed. By replacing the threaded screw 15 and tightening it by turning it clockwise, the slotted aperture 40 will permit free abduction motion in the preferred range of about zero to about thirty degrees. The use of this device 100 can be greatly facilitated by providing indicator means on the surfaces of the flexion hinge arm 10 and the abduction sleeve portion 27 representing degrees of setting for abduction and flexion-extension. Preferably, 5° abduction increments can be represented by markings provided on the abduction sleeve portion 27 and 5° flexion-extension increments can be provided on the flexion hinge arm 10. From the foregoing it can be realized that this invention provides an improved orthopaedic device suitable for hip casts and orthoses. This device provides better tracking of the hip joint and reduces pistoning of the support thigh attachment by continuously varying the length of the arm assembly during free abduction. Although various embodiments have been illustrated, this has been for the purpose of describing, but not limiting the invention. Various modifications, which will become apparent to one skilled in the art, are within the scope of this invention described in the attached claims.

Claims: An orthopaedic hip hinge suitable for hip casts and orthoses and including an upper control arm for attachment to a location on a patient's waist, a lower control arm for attachment to a location on a patient's thigh, first hinge means (10, 22, 36) providing angular adjustment between said upper and lower control arms corresponding to flexion and extension of the hip and second hinge means (15, 20, 22) providing angular adjustment between said upper and lower control arms corresponding to abduction and adduction of the hip, said upper and lower control arms and said first and second hinge means forming an arm assembly having an overall length, characterised in that said second hinge means (15, 20, 22) has sliding pivot means (20, 22) for causing a shortening of the overall length of said arm assembly during abduction of the hip. An orthopaedic hinge as claimed in Claim 1, wherein said second hinge means (15, 20, 22) is adapted selectively to locate or to permit abduction of the hip within limits between about zero degrees to about ninety degrees. An orthopaedic hinge as claimed in Claim 1 or 2, wherein said first hinge means (10, 22, 36) comprises a flexion hinge arm (10) having an extended portion (11) thereof for connection to said upper control arm, said flexion hinge arm (10) having a track portion (24) disposed thereon extending transversely thereof selectively to receive flexion limiter means (30, 32) into engagement therewith. An orthopaedic hinge as claimed in Claim 3, wherein said flexion hinge arm (10) comprises an aperture (37) therethrough, the device further comprising flexion swivel means (36) disposed through said aperture, said flexion swivel means (36) providing an axis for flexion and extension. An orthopaedic hinge as claimed in Claim 4, wherein said sliding pivot means (20, 22) comprises pivot head means (22) disposed on said flexion swivel means (36) and rotatably mounted to said flexion hinge arm (10) through said swivel means (36), said pivot head means (22) having an outwardly-facing convex surface. An orthopaedic hinge as claimed in Claim 5, wherein said pivot head means (22) comprises an abduction sleeve portion (27), said sleeve portion (27) having a concave surface disposed above said convex surface, said concave and convex surfaces forming an abduction track (31). An orthopaedic hinge as claimed in Claim 6, wherein said sliding pivot means (20, 22) further comprises an abduction setting member (20) disposed at least partially within said track (31) and slidably engaged with said convex surface of said pivot head means (22), whereby an abduction movement of the hip causes said abduction setting member (20) to slide over said pivot head means (22) thereby shortening the overall length of said arm assembly. An orthopaedic hinge as claimed in Claim 7, wherein said abduction setting member (20) is also slidably engaged with said concave surface of said abduction sleeve portion (27). An orthopaedic hinge as claimed in Claim 7 or 8, wherein said abduction setting member (20) comprises a slotted aperture (40), the device further comprising abduction locking means (15) disposed through said slotted aperture (40) of said abduction setting member (20) and engaged with said aperture of said pivot head means (22), said abduction locking means (15) limiting the degree of free abduction provided by said device. An orthopaedic hinge as claimed in Claim 9, further comprising an abduction lock limiter (18) disposed around said abduction locking means (15), said abduction lock limiter (18) engaging said abduction setting member (20) when said locking means (15) is tightened. An orthopaedic hinge as claimed in any one of Claims 6 to 10, further comprising a first flexion limiter (30) disposed on said track portion (24) in the path of movement of said abduction sleeve portion (27), thereby limiting the degree of flexion and extension of the hip. An orthopaedic hinge as claimed in Claim 11, wherein said first flexion limiter (30) is movably mounted on said track portion (31) and is selectively positionable thereon. An orthopaedic hinge as claimed in Claim 11 or 12, further comprising a second flexion limiter (32) disposed on said track portion (24) in the path of movement of said abduction sleeve portion (27), said first and second flexion limiters (30, 32) being provided at respective opposite sides of said abduction sleeve portion (27) to give a range of permitted flexion and extension for the hip.

Inventors: BORIG, DONALD ALLEN, HARRIS GODFREY, KORNGOLD, GARY PAUL
Applicants: HOLLISTER INCORPORATED
Application year: 1988
Main classification: A61F5
IPC codes: A61F5