Patent Application
20100174322
1. Technical Field
The embodiments herein generally relate to devices used in spinal surgeries, and, more particularly, to a biased bumper mechanism to achieve a desired poly-axial dynamism regardless of the insertion angle of the implant assembly in a dynamic screw system.
2. Description of the Related Art
Dynamic stabilization is a surgical procedure performed to change the biomechanics of the affected lumbar segment by reducing the load on the disc without loss of motion. A dynamic system works by limiting motion and altering stress patterns across the degenerated segment, preventing excessive motion or postures that result in pain. In dynamic spine stabilization, the vertebrae are stabilized while leaving the spine itself intact, and capable of bending, straightening, or twisting within new limits. There are conventional devices that use the biased angle concept. These devices are rigid and fixed for fusion applications. Further, they do not provide for the surgeon to adjust the device to a desired location for a given insertion angle.
In view of the foregoing, an embodiment herein provides a dynamic screw assembly. The dynamic screw assembly includes a screw head having a pair of diametrically opposed arms, a slot between the arms, an inwardly curved bottom portion, an outwardly protruding and expandable bulbous end extending from the inwardly curved bottom portion and an opening positioned through the bulbous end, a bumper mechanism adjacent to the screw head that adjusts an angle of the screw head to a desired location in the dynamic screw assembly, a fixation component coupled to the bumper mechanism, a saddle connection positioned in the opening and engaging the screw head and the fixation component, a longitudinal member positioned in the slot and a blocker coupled to the screw head and the longitudinal member.
The bumper mechanism may include any of a one-piece bumper and a stacked bumper. The one-piece bumper may generate a resultant angle, the resultant angle is any of a zero degree angle or a sum of an angle by the one-piece bumper and the fixation component. The stacked bumper may generate a resultant angle and the resultant angle is an accumulated angle between the stacked bumper and the fixation component. The bumper mechanism may limit an angulation of the screw head based on an orientation of the bumper mechanism with respect to the fixation component.
The fixation component includes an open concave head and a threaded end. The open concave head of the fixation component may contact the bumper mechanism. The open concave head of the fixation component includes an inner portion that receives the bulbous end of the screw head, a hole and an outer portion comprising grooves. The bulbous end may be positioned opposite to the pair of diametrically opposed arms. The hole of the fixation component preferably engages the saddle connection.
Another embodiment provides an apparatus for dynamic spinal stabilization. The apparatus includes at least one bumper having a flexible material and composed of two intersecting planes, the bumper adjusts an insertion angle of the apparatus to a desired location based on an orientation of the bumper, a bone anchor having an open concave head and a threaded end, the open concave end engages the bumper, a coupling member having a first portion including a pair of arms that are diametrically opposed, a U-shaped slot positioned between the pair of arms, an inwardly curved bottom portion, a second portion having a an outwardly protruding and expandable bulbous end extending from the inwardly curved bottom portion configured to engage the open concave head of the bone anchor and an opening positioned between the first portion and the second portion, a saddle connection that engages the opening of the coupling member, the saddle connection being coupled to the bone anchor, a rod coupled to the U-shaped slot and a threaded blocker that engages the pair of arms of the coupling member and secures the rod in the coupling member.
The open concave head of the bone anchor further includes an inner portion that receives the bulbous end of the coupling member, a hole that engages the saddle connection and an outer portion comprising grooves. The pair of arms includes an outer wall and an inner wall, the outer wall having an indent feature and the inner wall having threads. The bumper preferably includes any of at least a one-piece bumper and a stacked bumper. The stacked bumper includes a slot and generate a resultant angle. The resultant angle is an accumulated angle between the stacked bumper and the bone anchor. The one-piece bumper may generate a resultant angle. The resultant angle is any of a zero degree angle or a sum of an angle by the one-piece bumper and the bone anchor.
Yet another embodiment provides a method of inserting a dynamic screw assembly in a vertebral body. The method includes engaging the dynamic screw assembly with the vertebral body, the dynamic screw assembly includes a screw head having a pair of diametrically opposed arms, a slot between the arms, an inwardly curved bottom portion, an outwardly protruding and expandable bulbous end extending from the inwardly curved bottom portion and an opening positioned through the bulbous end, a bumper mechanism adjacent to the screw head that adjusts an angle of the screw head to a desired location in the dynamic screw assembly, a fixation component coupled to the bumper mechanism, a saddle connection positioned in the opening and engaging the screw head and the fixation component, a longitudinal member positioned in the slot and a blocker coupled to the screw head and the longitudinal member, positioning the fixation component to form a first angle, adjusting a top portion of the bumper mechanism to form a second angle and obtaining a resultant angle between the fixation component and the bumper mechanism.
The resultant angle is any of a zero degree angle or a summation of the first angle and the second angle. The resultant angle may be obtained based on an orientation of the bumper mechanism being stacked. The resultant angle is an accumulation of the first angle of the bumper mechanism and the second angle of the fixation component. The stacked bumper mechanism may generate a resultant angle. The resultant angle may be an accumulated angle between the stacked bumper mechanism and the fixation component.
The bumper mechanism may limit an angulation of the screw head based on an orientation of the bumper mechanism with respect to the fixation component. The fixation component includes an open concave head and a threaded end. The open concave head of the fixation component preferably contacts the bumper mechanism. The open concave head of the fixation component includes an inner portion that receives the bulbous end of the screw head, a hole and an outer portion including grooves. The bulbous end is positioned opposite to the pair of diametrically opposed arms. The hole of the fixation component preferably engages the saddle connection.
These and other aspects of the embodiments herein will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following descriptions, while indicating preferred embodiments and numerous specific details thereof, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the embodiments herein without departing from the spirit thereof, and the embodiments herein include all such modifications.
The embodiments herein will be better understood from the following detailed description with reference to the drawings, in which:
The embodiments herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
As indicated above, there remains a need for a dynamic screw assembly which can be fixed to a desired position later during the surgery. The embodiments herein achieve this by providing a biased bumper mechanism which assists the surgeon to adjust the angulation of the coupling member to a desired location in a dynamic screw implant. With the help of the bumper mechanism, the bone anchor can be inserted in any direction at the time of implanting the assembly and later be adjusted to a final desired position.
Thus, the biased bumper mechanism helps the surgeon to achieve a desired polyaxial dynamism regardless of the insertion angle of the implant assembly. Referring now to the drawings, and more particularly to
The biased bumper(s) 106 may be located between the bone anchor 102 and the coupling member 104. The biased bumper(s) 106 may provide a mechanism for adjusting the angulation of the coupling member 104 to a desired angle in the dynamic screw assembly 100 and allows for the fixation of the bone anchor 102 to a desired location after implanting the dynamic screw assembly 100 in the spine (not shown). The rod 108 may be embodied as a longitudinal member positioned along a horizontal axis in the coupling member 104 to connect a saddle connection 202 (shown in
The coupling member 104 includes a pair of arms 402, an inwardly curved bottom portion 404, a bulbous end 406, and a U-shaped slot 408. The arms 402 further include an outer wall 410 and an inner wall 412. The inner wall 412 includes threads 414 to engage the blocker 204 (of
The bulbous end 406 includes channels 420. The U-shaped slot 408 is positioned between the arms 406 to receive the rod 108 (of
The biased bumper(s) 106 are located between the bone anchor 102 and the coupling member 104. The biased bumper(s) 106 includes two intersecting planes, one at the top and one at the bottom. The bumper(s) 106 are designed with one or more pieces of flexible materials. In one embodiment, for a one-piece bumper, the angle of the top portion of the bumper 106 and the other angle created by the bone anchor 102 generate the resultant angle. The resultant angle, created by these two components (e.g., the top portion of the bumper 106 and the bone anchor 102) may be at least one of a zero degree angle or an angle that is the sum of both angles. In an alternative embodiment, for stacked bumpers, the accumulated angles between the bumpers 106 and the bone anchor 102 determines the resultant angle based on the orientation of the bumpers 106 with respect to one another. At least one of the stacked bumpers 106 may include a slot.
The embodiments herein provide a dynamic screw assembly 100 with a biased bumper mechanism 106 that supports for dynamic stabilization. The biased bumper mechanism 106 of the dynamic screw assembly 100 assists a surgeon to adjust the angulation of the coupling member 104 to a desired location in the dynamic screw system 100 making it flexible for non-fusion applications. The bumper mechanism also allows the bone anchor 102 to be inserted in any direction and later to be adjusted to a final position, thus helping to achieve a desired polyaxial dynamism regardless of the insertion angle of the implant assembly 100. The dynamic screw assembly 100 provides both translating in different directions and rotating movements to increase the moment arm.
The screw head further includes a pair of diametrically opposed arms (e.g., the pair of arms 402 of
The bumper mechanism (e.g., the biased bumper(s) 106 of
In step 1204, the fixation component is positioned to form a first angle. In step 1206, a top portion of the bumper mechanism is adjusted to form a second angle. In step 1208, a resultant angle between the fixation component and the bumper mechanism is obtained. The resultant angle may be at least one of a zero degree angle or a summation of the first angle and the second angle. The resultant angle may be obtained based on an orientation of the bumper mechanism being stacked. The resultant angle may be an accumulation of the first angle of the bumper mechanism and the second angle of the fixation component.
The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the appended claims.
