Surgery: splint – brace – or bandage – Orthopedic bandage – Splint or brace
Reexamination Certificate
1998-08-12
2001-10-30
Lewis, Kim M. (Department: 3761)
Surgery: splint, brace, or bandage
Orthopedic bandage
Splint or brace
C602S005000, C602S016000
Reexamination Certificate
active
06309368
ABSTRACT:
The invention relates to a knee-joint orthesis which has two different orthesis hinges so that a displacement of the pivot axis of the knee-joint orthesis is possible upon movement and extension.
From work carried out on the biomechanics of the knee joint, it has been scientifically demonstrated that the human knee joint is subject to a multi-dimensional movement. Flexion and extension of the joint take place about a pivot axis which is not fixed in location and which thus changes its position. This results from the relative position of the anterior and posterior cruciate ligaments. Scientific investigations have shown that the pivot point is displaced by about 14 mm in the dorsal direction and by about 3 mm in the caudal direction on the outer side of the joint during flexion. The change in position of the pivot axis on the inner side of the joint is negligibly small. The result of this is an outward pivoting of the lower leg during flexion.
In order to protect the damaged and, where appropriate, surgically reconstructed knee joint, so-called functional orthesis are used nowadays. The basic principle of their construction is a solid frame consisting of a thigh part and of a lower leg part. The two parts of this orthesis are connected to one another by a hinge on the medial side and on the lateral side.
In the case of the products already known in the prior art, the hinges are of identical construction on both sides, whether single-axle or polycentric. This results without exception in a mechanism which is subject to one pivot axis. Some constructions displace the pivot axis symmetrically towards the rear, i.e. the pivot point migrates rearwards to the same extent on the outer side and inner side. The lower leg rotation, which is necessary from biomechanical considerations, is not permitted.
The object of the invention is to make available a knee-joint orthesis which, like the human knee joint, is able to permit the displacement of the pivot axis upon movement and extension of the joint.
This object is achieved by the knee-joint orthesis having a lower leg part and a thigh part, and having lateral orthesis hinge and a medial orthesis hinge which connect the lower leg part and the thigh part to each other, characterized in that the lateral orthesis hinge is formed by a hinge which consists of two intermeshing toothed wheels whose axles are each securely connected on both sides to a hinge plate, each of the two toothed wheels having in each case a strut which is used for securely connecting the lateral orthesis hinge to the lower leg part and to the thigh part, the medial orthesis hinge being formed by a single-axle hinge which consists of a U-shaped upper part which encloses a lower part, the upper part and lower part being connected to each other in an articulated manner by means of a pin.
The knee-joint orthesis according to the invention consists of a lower leg part and of a thigh part which are fixed to the respective leg section. The connection of the lower leg part and of the thigh part is effected by a lateral orthesis hinge and a medial orthesis hinge.
The lateral orthesis hinge is formed by a hinge which consists of two intermeshing toothed wheels whose axles are each securely connected on both sides to a hinge plate. Each of the two toothed wheels has a strut which ensures the connection of the lateral orthesis hinge to the lower leg part and to the thigh part.
The medial orthesis hinge is formed by a single-axle hinge which is composed of a U-shaped upper part and of a lower part enclosed by the upper part, where the upper part and lower part are connected to one another in an articulated manner by a pin. Advantageously, the pin has a slight spherical shape in the hinge-forming section.
The connection of the lower leg part and of the thigh part to the lateral orthesis hinge and the medial orthesis hinge is preferably effected using an adjustment device.
To form the adjustment device, the upper strut and the lower strut of the lateral orthesis hinge, the upper part and the lower part of the medial orthesis hinge and the distal section of the thigh part in the lateral side and in the medial side, and the proximal section of the lower leg part in the lateral side and in the medial side, in each case have an oblong slot. The oblong slots in the thigh part and in the lower leg part are in each case offset in particular by 90° in relation to the oblong slots in the struts of the lateral orthesis hinge and in the upper part and in the lower part of the medial orthesis hinge. The two corresponding oblong slots are in each case connected centrally via a slide bracket, movement of the respective parts being prevented with the aid of a central locking screw.
The upper of the two toothed wheels in the lateral orthesis hinge preferably has a smaller radius than the lower one, the upper one preferably having a radius of 15 mm and the lower one preferably having a radius of 27 mm.
This permits the advantageous displacement of the pivot point of the lateral orthesis hinge during the movement of the knee-joint orthesis from 0° extension to 90° flexion, by about 14 mm in the dorsal direction and 3 mm in the caudal direction.
Stop means are advantageously provided on the lateral orthesis hinge and on the medial orthesis hinge in order to limit the extension and flexion of the knee-joint orthesis.
In the lateral orthesis hinge, the device for limiting the extension and flexion preferably consists of an oblong slot in the form of a portion of a circle in the lower toothed wheel, of oblong slots, likewise in the form of a portion of a circle, on the medial hinge plate and on the lateral hinge plate, the three oblong slots being congruent when the knee-joint orthesis is extended. The oblong slots on the hinge plates preferably have a slightly narrower width than the oblong slot in the lower toothed wheel.
In addition, use is made of two sleeves which extend from the medial hinge plate into the oblong slot of the lateral hinge plate. Screws are guided in the inside of the sleeves, which screws are secured by means of nuts which are guided in the oblong slot of the medial hinge plate and are thus secured against rotation. And fix the sleeves in their position in the oblong slot on the lateral hinge plate.
The thigh part and the lower leg part of the knee-joint orthesis preferably consist of a frame structure which is applied in particular to the anterior aspect of the leg. This frame structure is made up, preferably in composite design, from a combination of an individually shapeable light metal frame with corresponding inner pads and of an outer frame covering.
The knee-joint orthesis according to the invention affords a number of advantages, which demand that this orthesis be used when it is necessary to immobilize the knee or in the event of post-operative rehabilitation of the knee.
Thus, by using two differently designed orthesis hinges, of which the lateral orthesis hinge is a toothed wheel joint, it is possible to displace the pivot axis of the knee-joint orthesis, as is necessary according to the most recent scientific knowledge, so as not to adversely effect the natural pattern of movement of the knee joint.
Furthermore, because of the special design of the lateral orthesis hinge, the necessary limitation of the extension and flexion of the knee-joint orthesis is particularly easy to set.
The advantageous design of the medial orthesis hinge as a type of ball joint permits the three-dimensional movement of the medial orthesis hinge, thus ruling out the possibility of the latter becoming jammed as the pivot axis migrates during the course of a movement. This orthesis hinge also makes it possible in a particularly simple manner to limit the extension and flexion of the knee-joint orthesis.
The special adjustment device which serves to connect the two orthesis hinges to the thigh part and to the lower leg part makes it possible to bring the knee-joint orthesis individually to the anatomically optimum position and at the same time to reduce to a minimum any micro-movements in relation t
Albrod Andreas
Herzberg Thorsten
Beiersdorf AG
Lewis Kim M.
Norris & McLaughlin & Marcus
LandOfFree
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