prefabricated knee orthoses in general are designed to stabilise frontal axis movements . because of the nature of these designs they can control flexion and extension up to a certain extent . if for any reason correction of knee alignment in the frontal plane is required , a custom brace or a brace with a total different design is needed . if besides flexion , adjustments by the sagittal axis are needed to unload the medial or lateral compartment , joints and frame need different functions . changing the uprights to accommodate for valgus or varus , the use of a second joint becomes difficult , because of the lengthening and shortening of the uprights . besides these practical reasons , a unilateral joint can be aligned far more easier and the appearance could also benefit . since these types of braces are mainly used to support the treatment of osteoarthritis and therefore used to minimise pain and to protect the knee joint , the movement of the joint should follow the natural movement as close as possible in order to prevent unnecessary friction between the articulating joint surfaces . the function for the thigh and shin cuffs is to divide pressure and to maintain the proper position on the extremity . due to the biomechanical nature of the knee joint it is only possible to change alignment of the knee from 30 ° flexion until full extension . fortunately also the unloading is wanted in that range of motion . even if we realize that the use of osteoarthritis valgus or varus knee braces is not yet scientifically proven ; in a great number of cases we actually can minimise the pain and maintain mobility of the knee joint for a longer period of time . the knee brace of the invention consists of a knee joint , a thigh cuff and a shin cuff . during extension the knee brace is able to correct the position of the knee into valgus or varus . it is biomechanically impossible to keep the knee in the adjusted position during full flexion . for pain relief or to take away the load from the medial or lateral compartment of the knee this is also not needed . from approx . 30 ° of flexion to full extension the brace will correct the adjusted valgus or varus position . the knee of an osteoarthritis patient is sensitive to all kind of friction or forces ; so non - physiological movement must be prevented . for this reason a knee joint with a “ natural movement ” was designed . this so - called four - axes knee joint begins flexion with an anterior movement followed by rotation in a c - shaped joint motion path . in full extension the rotation axis is located 15 cm above the tibial plateau and dorsally of the joint . the anterior translation of the proximal upright is 11 mm . the joint comprises a tilting mechanism which allows for sagittal adjustments as is described more in detail below . although the joint is not designed to prevent hyperextension , an extension stop is present ( not shown ). in fig1 and 2 , the knee brace is shown attached to the leg ( right and left , respectively ) of a patient . the thigh cuff 1 , constructed out of composite is designed to achieve a grip on the femur bone by surrounding the soft tissue . the distal end reaches until the condyles for stabilizing the knee joint . the thigh cuff 1 has rigid areas to achieve proper function ; a lateral strut 10 and a proximal 8 and distal 9 thigh band . the medial vertical strut 11 is integral with the distal horizontal band 9 and the proximal thigh band 8 . the horizontal bands 8 , 9 are rigid at the lateral sides , providing a rigid connection to the lateral strut 10 , while the medial sides are thinner and more flexible for size adjustability and for comfort . the thigh cuff 1 is closed with adjustable dorsal bindings 12 . the shin cuff 2 , constructed out of composite , is designed to achieve a grip on the tibia and the fibula bone by surrounding the soft tissue . the proximal end reaches until the condyles for stabilizing the knee joint . the shin cuff 2 has rigid areas to achieve proper function ; a lateral strut 15 and a proximal 13 and distal 14 shin band . the medial vertical strut 16 is integral with the proximal horizontal band 13 and the distal shin band 14 . the horizontal bands 13 , 14 are rigid at the lateral sides , providing a rigid connection to the lateral strut 15 , while the medial sides are thinner and more flexible for size adjustability and for comfort . the shin cuff 2 is closed with adjustable dorsal bindings 17 . both the thigh cuff and the shin cuff are replaceable and produced in three different sizes ( small , medium , large ) in order to fit legs of various sizes . it is possible to combine e . g . a small shin cuff with a medium thigh cuff and all other combinations . the hinge elements are shown in fig3 without the cuffs . the hinge is preferably located at the lateral side . the hinge portion consists of uprights 20 for attachment to the thigh and shin cuffs and hinge plates 21 . the uprights have holes 7 for attachment to the respective cuff as will be explained more in detail below . the hinge plate 21 is provided with two of the four axes 18 to achieve the desired articulated connection between the uprights . the other two axes 18 are connected by an element ( not shown ) located inside the hinge plates 21 . in fig4 the hinge elements are shown together with parts of the thigh cuff 1 and the shin cuff 2 in cross - section . it will be seen that the uprights 20 are connected to the hinge plates 21 forming the four axes joint . the uprights 20 are attached to the thigh cuff 1 and shin cuff 2 by means of adjustment fixtures . for best possible adjustment , it is suitable that there are two adjustment fixtures , one each for the thigh and shin cuff , respectively . the adjustment fixtures comprise tilting mechanisms 4 and two pairs of screws 6 fitted in the holes 7 . the holes 7 are oval to provide a clearance between the holes 7 ( fig3 ) and the screws 6 such that an angle adjustment is possible . the tilting mechanism is formed by opposed v - shaped faces 4 on the cuffs 1 , 2 and the uprights 20 , respectively , such that the cuffs 1 , 2 are in line contact at 5 with the respective upright 20 along a sagittal axis ( an axis parallel with the sagittal plane ) thus , the angle between the cuffs and upright elements may be adjusted by tilting around the sagittal axis at the contact line 5 . one screw 6 is located at each side of the contact line 5 . the tilting angle is set by adjusting the respective pair of screws 6 , that is one screw is tightened while the other screw is loosened or vice versa . in this way , a positive adjustment fixture is obtained . thus , when the knee brace is attached to the leg of a patient , the angle between the cuffs 1 , 2 and the uprights 20 of the hinge results in a biasing force which acts as a correction force to provide the desired valgus or varus position . thus , it will be appreciated that the knee brace of the present invention provides a sagittal correction force , which is caused by the hinge portion without any use of a cross - strap or inflatable pad . the force or angle adjustment is easily achieved by setting the pairs of screws . this can be done even when the patient is wearing the knee brace . also , the thigh cuff and shin cuff are designed as partly rigid cages which hold the knee brace firmly on the patient &# 39 ; s leg . the thigh and shin cuffs are interchangeable with various sizes , so that the knee brace is easily adapted for different sizes of the patient &# 39 ; s thigh and shin . the scope of the invention is only limited by the claims below .
the invention relates to a knee brace with sagittal adjustment , that is a brace or an orthotic device capable of correcting the knee joint into varus or valgus for osteoarthritis treatment . the knee brace comprises a thigh cuff and a shin cuff interconnected by a hinge portion on the lateral side of the knee brace only . according to the invention , the hinge portion is capable of providing a sagittal correction force to correct the position of a knee joint into varus or valgus . preferably , the hinge portion comprises a structure which may be locked in a curved or angled position to provide the sagittal correction force .