Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Implantable prosthesis – Bone
Reexamination Certificate
2002-01-09
2004-12-28
Snow, Bruce (Department: 3738)
Prosthesis (i.e., artificial body members), parts thereof, or ai
Implantable prosthesis
Bone
C623S022140, C623S023170
Reexamination Certificate
active
06835207
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a skeletal implant, and more particularly to an implant of this type to be used for connecting at least two elements of the skeleton, which implant is embodied in at least two parts, each of which is capable of being connected to one of these elements.
According to a first aspect of the invention, it relates to a consolidating and/or connecting implant, and more particularly to an implant of this type to be used to consolidate a connection between two bone elements, of the type comprising a first part designed to be attached to one of the elements and a second part designed to be attached to the other element.
2. Background and Material Information
There are known implants of this type that are capable of being used, for example, in the case of a performance of a bone graft or during the formation of a callus following a fracture. The two ends of the implant, which are rigidly connected to one another, for example because they are embodied in one piece, are each attached, for example screwed, to a bone element located on either side of the graft. When the graft has consolidated, the implant can be removed.
However, there are numerous cases where the implant is left in place. This is particularly the case when the implant is used to replace a bone structure which is impossible to restore or to construct.
In such cases, the rigidity of the implant, which is often indispensable at the beginning of the implantation, during the formation of the callus, later constitutes a drawback. In effect, the bone structures no longer sustain sufficient mechanical stress. Therefore, they do not reconstitute themselves in an optimal way, this reconstitution being tied to a satisfactory stressing of the bone, the disturbance of which has consequences which can result in post-surgical pain that is very difficult to treat.
Moreover, when the implant is to be used to connect two bone elements which are normally capable of moving relative to one another, as in the case of a rachidian implant, this rigidity results in a functional handicap in the patient in whom it is implanted, and excessive stress on the neighboring joints.
SUMMARY OF THE INVENTION
The object of the invention is, among other things, to eliminate these drawbacks.
According to a second aspect of the invention, it relates to an articulated implant, and more particularly to an implant of this type intended either to be intercalated between two bone elements in relative motion, such as an artificial intervertebral disk, or to replace a joint or an element of a joint, such as an artificial head of the femur.
As regards the intercalated implant, it can be beneficial to assist the adjacent bone structures and the ligaments during rapid, or even violent movements. On the other hand, it may be preferable to allow these structures and ligaments to work during slow movements or simple static loads in order to prevent atrophy or weakening.
As regards the articulated implant itself, a completely rigid structure fully transmits the shocks and vibrations to the other element of the joint, resulting in a risk of dystrophy or rupture of this other element.
Also, once a surgical skeleton implant is implanted no modification can be made to adapt the implant to the changing needs of the patients.
Another object of the present invention is to eliminate these drawbacks.
To this end, the subject of the invention is a skeletal implant of the type to be used for connecting at least two elements of the skeleton, which implant is embodied in at least two parts, each of which is capable of being connected to one of these elements, there parts being movable with respect to each other, characterized in that it comprises between these two parts at least one adjustable device responsive to non invasive control means, said control means being preferably located on said implant, to exert an adjustable force, for example a distraction or compression force, between said parts, and/or to authorise an adjustable displacement between said parts between a starting position and a displaced position in which said parts should, at least temporarily, be maintained, and/or to secure a damping effect with an adjustable coefficient of resistance.
It is noted, first of all, that the adjustment can be discrete as well as continuous, and for example, can include only two positions of adjustment.
It is known that a shock-absorbing device is a device generally comprising two chambers of variable volume filled with a hydraulic fluid and connected by a calibrated opening. A device of this type is intended to <<cushion>> the movements between two elements, one of which is connected to a structure of one of the chambers, the other being connected to an element in which the calibrated opening is formed.
When the two elements move relative to one another, the volumes of the two chambers vary in inverse proportion to one another, the hydraulic fluid being laminated at the level of the calibrated opening. The result is a force which opposes the relative movement between the two elements which, as will be shown, is proportional to the speed of this movement.
Used within the scope of the invention, a device of this type applied to an implant of the consolidating and/or connecting type has the advantage of allowing the bone structures to function, and thus to develop, in a practically normal way at moderate relative speeds between the bone elements connected by the implant, particularly in the case of static stresses. On the other hand, the greater the relative speeds, particularly in the case of voluntary rapid movement or shock, that is, dynamic stresses, the greater the portion of the stress absorbed by the implant.
The result is that the osteo-ligamentous structure, weakened by the situation which justified the insertion of the implant, can nevertheless function and thus reconstitute normally as long as the stresses remain moderate. But the greater these stresses, the more the natural structure is assisted by the implant.
Moreover, the coefficient of resistance being adjustable, it is possible to reduce it progressively as the bone structure reconstitutes. The latter can also sustain more and more dynamic stresses until, eventually, it returns to normal functioning.
It is noted that it has already been suggested in the prior art to endow prostheses with viscous and/or elastic means intended to absorb shocks. Likewise, it is well known to provide, in certain prostheses, regulating or adjusting means. However, no prosthesis with a functional characteristic of viscous resistance has yet been proposed wherein the coefficient of resistance would be adjustable. This combination is essential in the primary function of the invention, which is to allow a progressive reconstitution of the bone structure and an optimal continuous adaptation to the state of this structure.
When applied to an articulated implant, the invention also makes it possible to give the articulation greater flexibility, which, as in the prior art, allows it to absorb shocks, but in this case also allows the neighboring bone structures and ligaments to work.
Finally, the consequence of this shock-absorbing characteristic is to protect the implant itself, as well as joints located above and below the implant, from shocks.
In one particular embodiment, the implant comprises removable means for locking the shock-absorbing device at a predetermined length.
The implant according to the invention, in this embodiment, can function during a first period in the traditional way, like a rigid implant. This phase of functioning is for example that of the formation of the callus in the case of a graft. During a second period, the locking means are removed and the implant functions according to the invention, exerting between the elements to which it is connected a force which is proportional to their relative speed and is therefore a function of the stresses exerted in the graft.
In another particular embodiment, the implant comprises means for
Caballero Efren Vigil
Canal Jose Angel Alvarez
Zacouto Fred
Greenblum & Bernstein P.L.C.
Snow Bruce
Zacouto Fred
LandOfFree
Skeletal implant does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Skeletal implant, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Skeletal implant will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3327760