Abstract:
A knee orthosis includes two parts, upper and lower, each provided with at least one attachment means linking supporting parts, suitable for attaching said upper and lower parts respectively to a thigh and to a leg. Both parts are linked via bi-centric articulation means suitable for enabling each of said parts to pivot about a common axis between the ends of the supporting parts and an intermediate part forming a connection rod. A cord linking links the common axis between the connection rod connecting an articulation means to the upper portion of the orthosis, with the distal end of an arm forming one of the supporting parts of the lower portion of the orthosis.

Description:
BACKGROUND 
       [0001]    The present invention relates to an active knee orthosis comprising two parts which are articulated with respect to each other and which, being each provided with at least one attachment means, are fixed respectively to a thigh and to a leg of a lower limb of a person or patient in order, on the one hand, to externally strengthen the knee, maintain the joint in place and alleviate the osteoarticular pathologies, and, on the other hand, to correct an abnormal lateral deviation of the curvature of the lower limb, for example of the valgus or varus type, hence the term active. 
       SUMMARY 
       [0002]    The technical field is the production and the use of such an orthosis or external orthopedic appliance for the knee, which can be fitted in place by the actual wearer. 
         [0003]    Many appliances are known in this field, most of them having been the subject of filed patent applications. For example, mention may be made of FR 2 872 205 which was filed by the company Axmed and which describes an orthosis, of which the parts articulated with respect to each other each have lateral rigid side supports connected to each other by a rigid frame, and of which at least one of the side supports is adjustable in length such that, with the side supports thus being able to have different lengths, the corresponding part of the orthosis has a lateral deviation able to correct a valgus-varus. 
         [0004]    The patent application UK 2 136 294 filed by the company Northern Scient Equipment also describes an orthosis for a person who suffers from knock knees, comprising a telescopic device arranged on one side of the knee and combined with straps which surround the knee from the other side and thus force the latter toward the telescopic device in order to correct the abnormal deviation of the knee. 
         [0005]    Although all of these appliances, and indeed others, allow knee problems to be corrected or alleviated, they are either uncomfortable, especially in the flexion position, or their action is only partial and/or they may even cause side effects that damage the joint. 
         [0006]    The problem addressed is therefore to produce an orthopedic appliance or knee orthosis which corrects abnormal lateral deviations of the knee, while at the same time strengthening the joint, and which alleviates the interosseous crushing pressure between the bones of the knee in the extension position, which is comfortable for the patient, especially in the flexion position, and whose corrective and strengthening action on the knee is as complete as possible without causing side effects. 
         [0007]    A solution to the problem addressed is a knee orthosis comprising two parts, the first being the upper part and the second being the lower part, said parts each being provided at least with an attachment means which links support components and is suitable for fixing said parts respectively to a thigh and to a leg of a lower limb of a person presenting an abnormal initial lateral deviation, and having a circular general shape that is adaptable respectively to said thigh and to said leg and with the same axis respectively as those, and such that they thus follow the movement of this thigh and of this leg; said two parts are connected via bi-centric articulation means which are intended to be positioned laterally on each side of the knee and are designed to allow the upper part and lower part to each pivot about a common axis between the ends of the support components thereof and an intermediate component forming a connection rod of the corresponding articulation means; according to the invention, said orthosis has a cable linking the common axis, between the connection rod of the articulation means, corresponding to the side of the orthosis opposite the initial deviation, and the upper part of the orthosis, to the distal end of an arm forming one of the support components of the lower part of the orthosis and arranged in a direction almost parallel to the axis thereof: the length of the cable is determined such that it exerts a given traction on the attachment points of its two ends when the upper part and lower part are pivoted in relation to each other in the sense of tending toward the alignment of their axes and, by contrast, is untensioned when the upper part and lower part are pivoted in the opposite sense. 
         [0008]    In a preferred embodiment, a first articulation means, corresponding to the side of the orthosis toward which the initial deviation inclines, on the one hand spaces apart the two common axes, between its connection rod and the support components of the upper part and lower part, when these are pivoted in the sense of tending toward the alignment of their axes, and, on the other hand, brings these two common axes together when said upper and lower parts are pivoted in the sense of increasing the relative angle between their axes. 
         [0009]    In a particular embodiment, the second articulation means, corresponding to the side of the orthosis opposite the initial deviation, has a pusher component which advances toward the first articulation means, situated on the other side of the orthosis, when the upper part and lower part are pivoted in the sense of tending toward the alignment of their axes, and which moves away from this first articulation means when said upper part and lower part are pivoted in the sense of increasing the relative angle between their axes. 
         [0010]    The result is a novel active knee orthosis which solves the problem addressed, on the one hand by correcting the abnormal lateral deviations of the knee and by alleviating the interosseous crushing pressure, which may even involve contact between the bones of the knee, in the extension position of the joint, and, on the other hand, by relaxing the forces used for these corrective and alleviating actions in the flexion position of the joint, which ensures comfortable use for the patient wearing the orthosis. 
         [0011]    Moreover, the combination of the three different devices described above, and set out in detail in the description below, permits a corrective, strengthening and pressure-alleviating action which is more complete and more effective than in all the orthoses known to date: and as has been indicated above, these three devices in combination play their role in the extension position of the knee only between 0 and approximately 35°, and they relax their pulling and pushing forces beyond this, allowing the knee to recover a position that is comfortable for the patient in its flexion position. 
         [0012]    The advantages mentioned above thus prove the interest of this novel orthosis or knee brace, of which the description and the attached figures provide an illustrative embodiment. 
         [0013]    Other embodiments are possible, however, within the scope of the present invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]      FIG. 1  is a front cross-sectional view of a knee in the extension position, in which, as a consequence of osteoarticular deficiency, one side of the femoral condyle is in contact with the tibial plateau, creating a lateral imbalance and an abnormal deviation of the joint and causing pain. 
           [0015]      FIGS. 2  are cross-sectional views of the knee from  FIG. 1  equipped with an orthosis according to the invention, on the one hand in the extension position, corrected by virtue of the prosthesis, and, on the other hand, in the flexion position. 
           [0016]      FIGS. 3  are side views and a perspective view of an illustrative embodiment of a first bi-centric lateral articulation means of the orthosis according to the invention, able to move the upper and lower parts thereof away from each other, in the extension position of the knee. 
           [0017]      FIGS. 4  are perspective views of an illustrative embodiment of a second bi-centric lateral articulation means of the orthosis according to the invention, able to push against the knee in the extension position thereof. 
           [0018]      FIGS. 5  are side and profile views of an illustrative embodiment and of the use of a lateral traction cable of the orthosis according to the invention, in the extension position and flexion position of the knee. 
           [0019]      FIGS. 6  are front views of an orthosis according to the invention, in an enlarged representation and in the same positions as in  FIGS. 2 . 
           [0020]      FIGS. 7  are side and profile views of another illustrative embodiment and of the use of a lateral traction cable of the orthosis according to the invention, in the extension position of the knee. 
       
    
    
       [0021]    As defined above, the aim of the present invention is to correct the abnormally large initial lateral deviation of angle γ, as shown by way of example in  FIG. 1  and representing what is called a bow leg  3 , between the axis X 1  of the thigh or of the femur  1  and that X 2  of the leg or of the tibia  2 , in the extension position of the knee without orthosis, and to alleviate the pressure, here arising from contact, between the bones of the knee, or between the femoral condyle  4  and the tibial plateau  5 . 
         [0022]      FIG. 2A  shows the same knee equipped with the orthosis according to the invention and straightened by the latter from its abnormal lateral deviation y, after rotation  13 , albeit shown in an exaggerated manner in this figure for better comprehension. In the flexion position, as shown in  FIG. 2B , the relaxation of all the actions of the orthosis on the articulation affords the patient the desired comfort. 
       DETAILED DESCRIPTION 
       [0023]    For this purpose, the knee orthosis comprises two parts  6 ,  7 , the first  6  being the upper part and the second  7  being the lower part, said parts each being provided with at least one attachment means such as bases  8 ,  9  which link support components  25 ,  25 ′ and are suitable for fixing said parts  6 ,  7  respectively to the thigh and to the leg of a lower limb of the person or patient who presents an abnormal lateral deviation γ, as in  FIG. 1 ; these attachment means have a circular general shape that is adaptable respectively to said thigh and to said leg and with the same axis respectively X 1  and X 2  as those; as is depicted schematically in  FIG. 6B , this circular general shape is shown by the axial view of the attachment means, which can be a strap  8  on and around the thigh (not shown in this figure) and which is in the flexion position with respect to the leg on which the lower part of the prosthesis is fixed by the two attachment means  9 . 
         [0024]    Thus, these upper and lower parts  6 ,  7  of the orthosis according to the invention follow the movements of this thigh and of this leg, and said two parts  6 ,  7  are connected by bi-centric articulation means  10 ,  11 , which are intended to be positioned laterally on each side of the knee and are designed to allow the upper part  6  and lower part  7  to each pivot about a common axis  16 ,  16 ′ for a first articulation means  10  and an axis  17 ,  17 ′ for the second articulation means  11 , between the ends  24 ,  24 ′ of the supports  25 ,  25 ′ thereof and an intermediate component forming a connection rod  14 ,  15  of the corresponding articulation means  10 ,  11 . 
         [0025]    The first articulation means  10 , corresponding to the side of the orthosis toward which the initial deviation γ of  FIG. 1  inclines, is on the side of the knee which can be described as concave and which is that of the pinching of the articulation, where the tibial plateau  5  is too close to or even in contact with the femoral condyle  4 . This first articulation means  10 , as shown in  FIGS. 2 and 3 , on the one hand spaces apart the two common axes  16 ,  16 ′, between its connection rod  14  and the support components  25   1 ,  25 ′, of the upper part  6  and lower part  7 , when these are pivoted in the sense of tending toward the alignment of their axes X, and X 2  and, on the other hand, brings these two common axes together when said upper and lower parts are pivoted in the sense of increasing the relative angle α+β between their axes X, and X 2 : the angle α is to be considered between the axis X, of the support component  25   1  and the axis X 10  of the connection rod  14 , and the angle β between the axis X 2  of the support component  25 ′ 1  and the axis X 10  of this connection rod  14 . 
         [0026]    According to the embodiment in these  FIGS. 3 , the connection rod  14  has an internal seat which is equipped at least with a rack  20  and in which two toothed wheels  21  cooperating with this rack are guided and turn, said toothed wheels being fixed and each rigidly connected to the end  24 , and  24 ′ 1  of a support component  25 ,  25 ′ 1  respectively of the upper part  6  and lower part  7  of the orthosis. 
         [0027]    Thus, as is shown in  FIG. 3A  in the extension position of the knee, the support components  25 , and  25 ′, are spaced apart from each other to the maximum extent by a maximum spacing “d e ” of the axes  16  and  16 ′, whereas, in the position of flexion or semi-flexion as in  FIG. 3B , this distance between the axes  16  and  16 ′ decreases “d f ” through the rotation of the toothed wheels  21  along the rack  20 , thus bringing the support components  25   1  and  25 ′ 1  closer together and thereby relieving the joint. 
         [0028]    Thus, by way of example, the difference in spacing between the axes  16  and  16 ′ (d e −d f ) is from 4 to 8 mm in order to obtain an osseous spacing d 2  (according to  FIG. 2A ), between the edges of the tibial plateau  5  and of the femoral condyle  4 , of 2 to 4 mm taking into account the distraction of the “soft” parts such as the skin and muscles. 
         [0029]    In another embodiment not shown in an attached figure, the connection rod  14  can have an internal seat equipped with two cavities, in each of which is guided and turns a cam which is fixed and rigidly connected to the end  24   1 ,  24 ′ 1  of a support component respectively of the upper part  6  and lower part  7  of the orthosis, each cam bearing on the internal shape of its ramp-shaped cavity makes it possible, during its rotation, to obtain the same effects of spacing apart and bringing together as in the embodiment in  FIGS. 3 . 
         [0030]    The second articulation means  11 , which is positioned on the side of the orthosis opposite the initial deviation γ of  FIG. 1 , is on the other side of the knee in relation to the side on which the first articulation means  10  is arranged, that is to say on the convex side of the knee corresponding to the spacing apart of the joint where the tibial plateau  5  is too far from the femoral condyle  4 . This second articulation means has a pusher component  18  which advances toward the first articulation means  10 , situated therefore on the other side of the orthosis, when the upper part  6  and lower part  7  are pivoted in the sense of tending toward the alignment of their axes X 1  and X 2 , i.e. in the position of extension of the knee, and which moves away from this first articulation means when said upper part  6  and lower part  7  are pivoted in the sense of increasing the relative angle α+β between their axes X 1  and X 2 , i.e. in the flexion position of the knee: the angles α and β are those already defined above, between the axis X 11  of the connection rod  15  of this second articulation means  11  and respectively the axes X 1  and X 2  of the upper part  6  and lower part  7 , or corresponding support components  25   2  and  25 ′ 2 , as shown in  FIGS. 4A and 4B . 
         [0031]      FIGS. 4A and 4B  show an illustrative embodiment of this second articulation means  11  in which the pusher component  18  forms the connection rod  15  of the articulation: the surface of this connection rod  15  is of helicoidal shape over at least a quarter of its surface  22   1 ,  23   1  around these two axes  17 ,  17 ′, which shapes  22 ,  23  constitute ramps which bear on and cooperate with ends  24   2 ,  24 ′ 2  of the support components  25   2 ,  25 ′ 2  fixed respectively to the upper and lower parts of the orthosis and of likewise helicoidal shape  22   2 ,  23   2  likewise forming a ramp of the same pitch and with the same common axis  17 ,  17 ′; said ends  24   2 ,  24 ′ 2  of the support components each having a portion of a toothed ring  26 ,  26 ′ of the same axis  17 ,  17 ′, which cooperate with each other. 
         [0032]    Thus, in the flexion position of the knee as shown in  FIG. 4B , the helicoidal shapes or ramps of the connection rod  15  are entirely imbricated in those of the support components  25   2 ,  25 ′ 2 , and the connection rod  15  is thus in a position closest to the ends  24   2  and  24 ′ 2  of these support components; whereas in the view in  FIGS. 4A , in the extension position of the knee joint, the support components  25   2  and  25 ′ 2  having pivoted with respect to the connection rod  15 , the helicoidal shapes, bearing on each other by turning as if one were unscrewing them from each other, space apart the connection rod  15  from the ends  24   2 ,  24 ′ 2  of the support components to the maximum extent: this spacing translates into a pushing effect against the knee, since the support components  25   2 ,  25 ′ 2  are fixed on the thigh and the leg and cannot move away from each other, and it is therefore the connection rod  15  that plays the role of the pusher component  18 , as is shown in  FIGS. 2A and 6A . 
         [0033]    In addition to the combination of the two articulation means  10 ,  11  as have been described above, the orthosis according to the invention has a cable  12  linking the common axis  17 , between the connection rod  15  of the articulation means  11  and the support component  25   2  of the upper part  6  of the orthosis, to an attachment point  30  fixed on the distal end  29  of an arm  19  forming one of the support components  25 ′ 2  of the lower part  7  of the orthosis and arranged in a direction almost parallel to the axis X 2  thereof. 
         [0034]    As is shown in  FIGS. 5A ,  5 A′,  6 A and  7 , the length “L” of the cable  12  is determined such that it exerts a given traction on the attachment points of its two ends when the upper part  6  and lower part  7  are pivoted in relation to each other in the sense of tending toward the alignment of their axes X 1 , and X 2 , that is to say when the knee joint is in the extension position, and, by contrast, as is shown in FIGS.  5 ′A,  5 ′B and  6 B, it is untensioned when the upper part  6  and lower part  7  are pivoted in the opposite sense, that is to say when the knee joint is in the flexion position: by way of example, if I 2 , which is the distance between the two common axes  17 ,  17 ′ of the connection rod  15  and I 1  the distance between the common axis  17 ′ of the connection rod to the other attachment point  30  of the cable  12 , this can have a length L=147.5 mm, for I 2 =50 mm and I 1 =100 mm; the difference of 2.5 mm between L and I 1 +I 2  creates a tensile force in the arm  19  in the extension position: this then moves away from its rest position in order to compensate for this difference, i.e. with the values above, by a distance “d” at its distal end corresponding to an angle δ of about 7°. 
         [0035]    According to the embodiments in  FIGS. 5 and 6 , the arm  19  is made of resilient material with a thinner cross section at its proximal end  28  than at its distal end  29 , and its proximal end  28  is integrated in the second articulation means  11  in which it is fixed and pivots around their common axis  17 ′ with the connection rod  15  when the knee flexes as shown in  FIG. 5B ; in this position, the length L 2  between the two attachment points  17 ,  30  of the cable  12  is less than the length L of the latter which is then untensioned, relaxing its stress on the orthosis and thus on the knee. 
         [0036]    In another embodiment as shown in FIGS.  7  and  7 ′ in a profile view and a side view, the arm  19  is rigid and articulated about an axis  27  perpendicular to the common axis  17 ′ of the connection rod  15  with the end  24 ′ 2  of the support component  25 ′ 2 : this component is thus composed itself of two parts, the part constituting the arm  19  then having its proximal end  28  distinct from the end  24 ′ 2  and pivoting with the whole of the arm in order to move a pusher component  18  which advances toward the first articulation means  10  situated on the other side of the orthosis, in fact against the knee, when the upper part  6  and lower part  7  are pivoted in the sense of tending toward the alignment of their axes X 1 , X 2 , as has been described above for other embodiments, and which moves away from this first articulation means when said upper and lower parts are pivoted in the sense of increasing the relative angle α+β between their axes X 1  and X 2 : thus, in this embodiment according to FIGS.  7  and  7 ′, the cable  12  not only performs the function of traction force on the orthosis and thus on the side of the knee, as in the embodiment in  FIGS. 5 and 6 , but also the function of pushing the second articulation means  11 , of which the pusher component  18  forms part. 
         [0037]    Whatever the embodiments of the three devices for acting on the knee as described above, the combination of the effects of these three devices, which are only active in the extension position of the knee, i.e. when α+β varies from 0 to 35°, on the one hand ensures the correction of the initial lateral deviation and, on the other hand, alleviates the interosseous crushing pressure on the side at which the knee is pinched and which actually causes the deviation. These three devices relax their spacing-apart, pulling and pushing actions beyond 35°, i.e. in the position of flexion, allowing the knee to recover a more comfortable position for the patient. 
         [0038]    The combination of these three effects through the complementary nature of the three devices described above, and shown by way of example in the attached figures, ensures maximum efficacy in the straightening of the knee joint, either of the valgus or the varus type.