Surgery: splint – brace – or bandage – Orthopedic bandage – Splint or brace
Reexamination Certificate
2001-07-27
2003-02-11
Robert, Eduardo C. (Department: 3732)
Surgery: splint, brace, or bandage
Orthopedic bandage
Splint or brace
Reexamination Certificate
active
06517504
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention pertains to a knee support or replacement appliance, comprising
at least one joint each consisting of at least one proximal section and at least one reciprocally articulated distal section,
fixtures for attaching at least one proximal section of the said joint to a femoral part of a lower limb and at least one distal section of the said joint to a tibial part of the said lower limb, and
guiding devices for the reciprocally articulated elements, allowing relative movement with flexion-extension, antero-posterior rolling in conjugation with slippage, rotation and/or varus between the said femoral and tibial parts, and thus allowing, looking laterally at the knee from an antero-posterior vertical plane, close-to-life reproduction of the physiological movement of the knee as achieved in the joint by the cruciate ligaments.
In terms of the invention, the term knee support appliance should be interpreted as a knee orthesis and the term replacement appliance as a knee prosthesis or endoprosthesis.
In the following document, the femoral and tibial parts of a lower limb refer not only to the parts of an existing limb but also the superior and/or inferior rigid sections replacing this limb.
The proximal section may therefore be adapted to a superior rigid section attached to the femur, or it may be extended for the length of the femur and be attached thereto, and the distal section may be adapted to an inferior rigid section attached to the tibia, or it may be extended for the length of the tibia and be attached thereto.
In the following document, flexion and extension refer to a relative movement between the femoral and tibial parts of a limb about a roughly horizontal axis traversing the knee schematically from left to right. Rotation refers to a relative movement between these parts about a vertical axis. Varus movement refers to a relative movement between these parts around an antero-posterior horizontal axis. Finally, rolling and antero-posterior slippage refer to a relative movement between the extremities of the tibial and femoral parts in an antero-posterior plane.
Ortheses are orthopaedic appliances which maintain movement and joint function of a deficient limb in a disabled person. Such appliances are made of two rigid parts, interlinked by a joint at the knee level, and fitted to one side or to both sides of the leg. The entire appliance may be attached with belts or moulds which run the length of the thigh and leg. Ortheses used for the lower limbs are customarily two symmetrical joints fitted at the knee, which allow them to move solely in flexion-extension with at best simultaneous antero-posterior displacement of the proximal part on the distal part (see EP-A-0297766, U.S. Pat. No. 3,779,654). Physiological movement of the knee is, however, three-dimensional, and these ortheses inevitably inevitably stress the ligaments, which defeats the purpose of any medical or surgical treatment.
We know from other sources that there are multiaxial ortheses fitted with grooved planar plates which operate in tandem, thus allowing the tibia to slide posteriorly in relation to the femur at the beginning of flexion followed by flexion without slippage (WO-A-92/15264).
There is also a polyaxial knee brace which is three-dimensional (see Orthotics Inc. Generation II polyaxial knee brace, Vancouver, Canada) and which comprises a joint which can be adjusted on one side of the deficient knee. In this joint, two spherical segments operate in tandem: they have two circularly arcuate grooves lying in an offset manner about an axis. In the initial degrees of flexion, the proximal section shifts, and once it reaches the limit of its grooved track, flexion continues over the groove on the second spherical segment, thus providing a three-dimensional if non-physiological movement. In fact, physiological movement of the knee, by means of the ligament rod system, comprises an antero-posterior rolling and slippage movement conjugated with rotation and varus movement. According to most medical studies, rotation and varus movement take place principally at the beginning of flexion, which this known applicance is not able to reproduce.
Another orthesis is known in which the guiding device is composed of grooved spherical shells which operate one inside the other (U.S. Pat. No. 5,107,824). In view of the fact that the center of the shells of the external joint of this appliance is situated at another position from the center of the shells of the internal joint the appliance is inevitably bound to block since the external and internal shells are also integrally interlinked by means of rigid belts around the thigh and leg. Moreover, the spherical shape of the shells and the fact that one is very snugly apposed to the other prevents a complex trajectory movement being obtained which mimics physiological movement of the knee.
Protheses are orthopaedic appliances which allow persons who have partially or totally lost their leg to remain ambulant. Fitted with a socket at the top and a joint at the level of the axis of the knee enabling flexion of the prosthesis, these appliances allow the disabled person to put weight on his stump. For femoral protheses for long amputation or amputation through the knee joint, it is impossible to position the prosthetic joint at its physiological site. The prosthetic joint is placed lower than the physiological axis of the knee, which makes walking uncomfortable and makes sitting look unaesthetic, since the thigh section is abnormally longer than the tibial section.
Finally, knee support or replacement appliances as described at the beginning of this document (see WO 94/09729) are known. These appliances, by means of a special configuration of the weight-bearing surfaces of the guiding devices of each joint, enable mutual movement of the articulated elements in the same way as is produced by a crossed rod system. Applied to curved, complex surfaces, it allows flexion to incorporate movements of rotation and varus simultaneously which vary in amplitude in proportion to the degree of flexion-extension.
During experiments with previously known appliances it emerged that, even in the best of the previously proposed solutions, joints were subject either to blocking of the guiding devices or to uncontrolled slippage between the articulated elements. This gives rise to excessively high wear of the guiding surfaces and to forcing of the ligaments in order to overcome the blocking of the mechanisms.
It is important to note that, in the present invention, a distinction is made between two types of “slippage” : “antero-posterior slippage” which has already been defined above and which involves a relative movement between tibia and femur, and “uncontrolled slippage of articulated elements” which relates solely to parts of the appliance.
SUMMARY OF THE INVENTION
The object of the present invention is to develop a knee support or replacement appliance such as would overcome the previously mentioned drawbacks and in particular aid the guiding of articulated elements in order to make it impossible for articulated elements to block or for reciprocal uncontrolled slippage to occur, while allowing physiological and relative movement between the femoral and tibial parts, in particular their antero-posterior slippage.
To solve these problems we have provided, according to the invention, a knee support or replacement appliance as described at the outset of the document, this appliance comprising in addition
on at least one proximal section of at least one joint, a first engagement surface which extends over the length of a trajectory corresponding to a displacement from an instantaneous centre of movement formed by a projection of a crossover of the said ligaments in the said at least one proximal section during the said relative movement, and
on at least one distal section of the said at least one joint, a second engagement surface which extends over the length of a trajectory corresponding to the displacement from the said instantaneous centre of mo
Magalie Postelmans
Robert Eduardo C.
Sughrue & Mion, PLLC
LandOfFree
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