Surgery – Instruments – Orthopedic instrumentation
Reexamination Certificate
2000-02-25
2001-10-02
Smith, Jeffrey A. (Department: 3732)
Surgery
Instruments
Orthopedic instrumentation
Reexamination Certificate
active
06296644
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a spinal osteosynthesis instrumentation adapted to stabilize at least a part of the spine.
BACKGROUND
As is known, spinal osteosynthesis devices usually comprise vertebral rods which are rigid and bent so as to adapt them to the anatomy of the considered spinal segment, bone anchorage means formed by screws or pedicle hooks, and connecting elements between these anchorage means and the rods. Sometimes the rods are interconnected by transverse connecting devices.
The bending of the rods in two planes (sagittal plane and frontal plane) is a complex operation difficult to properly carry out outside the patient. When this bending operation is carried out on the patient during the surgical intervention, it is also a difficult undertaking and not free from risk for the patient. Moreover, such devices require a large number of parts which considerably increases the time required for the surgical intervention and renders them costly. Naturally, it is desirable to decrease the length of such surgical procedures to reduce the risk posed to the patient and to accordingly reduce associated costs.
In order to overcome these drawbacks, a system has been proposed in Spanish patent application No. 940 10/5 to Barbera Alacreu, filed May 13, 1994, which comprises a plurality of pins fitted one inside the other in pairs so as to form a kind of articulated chain. These pins are provided with anchorage hooks and are traversed longitudinally by a cable for maintaining the assembly under tension in the desired position. When the cable is put under tension, the pins are locked together by friction.
However, such a device has various notable drawbacks. For example, it requires a very high tension to obtain a good adherence or grip between the surfaces in contact. Further, the cable must be fixed at its end by a setting or forming-over operation which requires a high degree of skill to effectively carry out in the operating theatre. Lastly, in the event of breakage of the cable, the assembly of the pins is no longer maintained and the device collapses, which is a particularly serious risk for the patient.
Thus, there is a need for a spinal stabilization system that may be more readily shaped to conform to desired contours in the sagittal and frontal planes. Preferably, such multidimensional shaping may be easily performed and still provide a rigid stabilization construct once the desired shape is attained. The present invention meets these needs and has other significant advantages and benefits.
DISCLOSURE OF THE INVENTION
In one form of the present invention, a spinal osteosynthesis apparatus includes a first module having a ball and a second module having a socket receiving the ball therein. Also included is a clamping member element disposed on the second module that is made of a shape memory material. The clamping member permits relative motion of the ball in the socket when at a first temperature to correspondingly position the first module relative to the second module. Further, the clamping member clamps the ball within the socket to provide a generally rigid assembly of the first module and the second module when at a second temperature greater than the first temperature. This form permits contouring the modules to a desired shape while the clamping member is at the first temperature and raising temperature to the second temperature to retain the shape. Preferably, the first temperature is less than about 20 degrees Celsius and the second temperature is greater than about 20 degrees Celsius. More preferably, the second temperature is about the nominal body temperature of a human patient.
In an additional form of the present invention, a spinal osteosynthesis apparatus includes a first module having a ball at one end and a second module defining a socket receiving the ball therein. The second module is elastically deformable to receive the ball in the socket by a clipping action and retain the ball in the socket. The second module is configured to permit positioning of the first module relative to the second module while the ball is retained in the socket and to selectively fix the ball in the socket to provide a generally rigid assembly. At least one of the first and second modules carries a bone anchorage element configured to engage a patient's spine.
In a further form of the present invention, a spinal osteosynthesis apparatus includes a first chain of a first number of articulated modules connected together by a corresponding first number of ball-and-socket joints. A first one of the first modules includes a first hook configured to engage a patient's spine, and a second one of the first modules defines a first opening configured to receive a first threaded fastener for engaging the patient's spine. The apparatus also includes a second chain of a second number of articulated modules connected together by a corresponding second number of ball-and-socket joints. A first one of the second modules includes a second hook configured to engage the patient's spine and a second one of the second modules defines a second opening configured to receive a second threaded fastener for engaging the patient's spine. A third one of the first modules is transversely connected to a third one of the second modules by a ball-and-socket joint laterally disposed between the first and second chains.
In a further form, the spinal osteosynthesis instrumentation comprises two independent modules, means for ensuring a retaining connection between the modules enabling them to be oriented in all directions, means for connecting the modules to a bone, and means for immobilizing the modules relative to each other, the instrumentation permitting effecting a correction and then a final immobilization.
In another form of the present invention, the instrumentation comprises at least two modules provided with bone anchorage elements articulated together by a male-female spherical connection permitting a relative orientation of the modules in all directions, and means for rigidifying the assembly of the modules in the desired orientation so as to adapt the assembly to the anatomy of the considered spinal segment. The instrumentation according to the invention thus constitutes an assembly of a plurality of modules articulated together in pairs, which permits arranging them to conform in a multidirectional manner to the spine of the patient in the manner of an articulated chain, with no force exerted on the spine and with the assembly exactly conforming to the anatomy of the latter. Once this chain has been put into shape in the desired position, it can be maintained rigidly in this configuration by suitable means.
In still another form, some sections of the articulated chain may be rendered rigid while others remain freely articulated to permit corrections in situ, which is not generally available when bent rigid rods are employed. In this way, corrections can be effected and then the assembly can be finally immobilized. The bone anchorage may be ensured by any adapted means such as: threads, cables, ligaments, cages, rods, curved or flat plates, screws.
In yet another form of the invention, each module comprises a body in which is formed a spherical socket opening onto one end of the body for receiving a spherical head of an adjacent module, this head being maintained in its socket by a clipping action, thereby forming a ball joint. One or more of the modules of the instrumentation may comprise a body and a spherical articulation head in one piece with the body, the latter having for example a substantially cylindrical outer surface which imparts to the module the appearance of a pawn or a kind of skittle. One or more modules may be equipped laterally with a bone anchorage hooking strip, or a plate receiving a bone screw.
According to another advantageous feature of the invention, rigidifying means for the connections between the modules comprise rings composed of a shape memory alloy. The rings are adapted to surround the corresponding bodies in the reg
Barbera Alacreu Jose Vicente
Saurat Jean
Robert Eduardo C.
Smith Jeffrey A.
Woodard Emhardt Naughton Moriarty & McNett
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