Patent Application
20090182428
1. Technical Field
The embodiments herein generally relate to medical devices, and more particularly, to a flanged interbody device used during orthopedic surgeries.
2. Description of the Related Art
Anterior lumbar interbody fusion (ALIF), posterior lumbar interbody fusion (PLIF), and transforaminal lumbar interbody fusion (TLIF) are common spinal fusion procedures for fusing and stabilizing vertebrae. In these procedures, interbody spacers are placed within the intervertebral disc space. They are responsible for transmitting load across the disc space from one vertebra to the other. The spacer serves as a temporary column or structural support until fusion occurs. The loads across the interbody spacer include the weight of the person and any load being carried by the person.
Peripheral walls of the vertebrae are the strongest bones on vertebral endplates whereas subchondral bone (e.g., bone beneath cartilage) is the soft and weaker bone. Anterior column support may fail if the interbody spacer subsides through the vertebral endplates. Also, if the interbody spacer subsides the entire load is transferred to soft subchondral bone. Consequently, this may lead to increased pain and potentially neurologic complications. It may also lead to malunion, which is a successful fusion but with the vertebrae in nonanatomic alignment or suboptimal alignment. Furthermore, it may also lead to pseudarthrosis or failure of fusion.
Interbody spacers are typically available as threaded cylinders, screws, etc. Surface area is important to controlling postoperative pain and achieving successful fusion. Conventional implants tend to provide a limited amount of surface area. Conventional implants also generally do not include any supporting structure which can prevent decoupling of the implant from the vertebrae, which gives rise to subsidence of the implants. Some implants also suffer from the disadvantage of involving piercing and tapping of vertebral endplates for insertion. Additionally, restoration of natural curvature of the spine is also very difficult. Most implants are available in different sizes (e.g., longer and wider implants). The longer implants may be clinically specified but the wider implants are not desirable as the increased width involves more of facet scissoring which leads to a decrease in stability. Accordingly, there remains a need for a new interbody device to prevent subsidence while increasing torsional stability.
In view of the foregoing, an embodiment herein provides a flanged interbody device to prevent subsidence while increasing torsional stability. The flanged interbody device includes an implant to be inserted in a vertebral body. The implant includes a first lateral portion, a second lateral portion, a top wall, a bottom wall and teeth positioned on the top wall and the bottom wall. The second lateral portion is positioned opposite to the first lateral portion. The top wall and the bottom wall are attached to the first lateral portion and the second lateral portion. The bottom wall is positioned opposite to the top wall. The first lateral portion further includes at least one flange surface and the second lateral portion further includes an opening. The top wall further includes a plurality of holes. The implant may include a plurality of cuts positioned between the first lateral portion and the second lateral portion.
The teeth may be adapted to provide a mechanical interlock between the implant and vertebral endplates of the vertebral body. The plurality of holes and the plurality of cuts may be dimensioned and configured to receive bone graft material. The plurality of holes may be dimensioned and configured to receive pre-insertion bone graft material and the plurality of cuts may be dimensioned and configured to receive post-insertion bone graft material. The opening on the second lateral portion may be dimensioned and configured to accommodate an insertion tool to place the implant in the vertebral body. The at least one flange surface may be configured to couple to a peripheral wall of the vertebral body and may be adapted to provide at least one of a torsional property, an axial property, and a shear property to the implant.
Another aspect provides an apparatus to stabilize a vertebral body. The vertebral body includes a peripheral wall and a subchondral bone. The apparatus includes a first interbody implant which includes a first lateral portion having a flattened configuration, a second lateral portion positioned opposite to the first lateral portion, a top wall, a bottom wall positioned opposite to the top wall, and at least one cut positioned between the first lateral portion and the second lateral portion. The second lateral portion includes a tapered configuration with a width smaller than the width of the first lateral portion. The top wall and the bottom wall are attached to the first lateral portion and the second lateral portion.
The first lateral portion further includes a top flange surface and a bottom flange surface. The top wall further includes top teeth and at least one hole, and the bottom wall further includes bottom teeth. The top flange surface and the bottom flange surface are coupled to the peripheral wall of the vertebral body and adapted to divert vertebral forces to the peripheral wall of the vertebral body and from the subchondral bone. The vertebral forces may be at least one of a torsional force, an axial force, or a shear force.
The apparatus may include a second interbody implant placed in the vertebral body from a direction opposite to that of the first interbody implant. The top teeth and the bottom teeth may be adapted to provide mechanical interlock between the first interbody implant and the vertebral body. The at least one hole and the at least one cut may be dimensioned and configured to receive bone graft material. The apparatus may include an opening positioned on the second lateral portion. The opening may be adapted to accommodate an insertion tool to place the first interbody implant in the vertebral body.
Another embodiment provides a method of performing a surgical procedure that includes inserting a first interbody implant in a vertebral body, engaging teeth of the first interbody implant to endplates of the vertebral body, inserting a second interbody implant into the vertebral body from a direction opposite to that of the first interbody implant, positioning an inserter tool through an opening of the first interbody implant for placement of the first interbody implant in the vertebral body, compressing the vertebral body against the first interbody implant and inserting bone grafting material in the first interbody implant.
The vertebral body includes a peripheral wall and the endplates. The first interbody implant includes a flanged end opposite to a tapered end. A flange surface of the flanged end may be adapted to provide at least one of a torsional property, an axial property, or a shear property to the first interbody implant. Additionally, the first interbody includes outwardly protruding teeth positioned along a top wall and a bottom wall of the first interbody implant. The teeth may be adapted to provide mechanical interlock between the first interbody implant and the endplates of the vertebral body. The first interbody implant is dimensioned and configured based on a physical property of a vertebral segment of the vertebral body supported by the first interbody implant. The physical property may be at least one of a length, a surface area, or a lordosis. The direction may be at least one of an anterior direction, a posterior direction, or a lateral direction with respect to the vertebral body.
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 mentioned, there remains a need for a new interbody device to prevent subsidence while increasing torsional stability. The embodiments herein achieve this by providing an interbody device that uses a flange to allow the lateral vertebral body to participate in load bearing and shear and torsional resistance. The device can be used in the anterior column (front of the vertebrae) or middle column (which may be the middle or anterior column). Referring now to the drawings and more particularly to
The first lateral portion 102 further includes a top flange surface 110 and a bottom flange surface 112. The second lateral portion 104 includes a concave opening 114. The top wall 106 and the bottom wall 108 include outwardly protruding teeth 116, 118, respectively. Additionally, the interbody device 100 includes a plurality of cuts 120, 122, 124, 126 positioned between the lateral portions 102, 104, out of which cuts 122,124 are of same length and width and cuts 120, 126 are of same length and width. The top wall 106 includes two holes 128, 130 which are of uniform length and width. The top flange surface 110 and the bottom flange surface 112 of the implant 100 extend beyond the width of the implant 100.
The cuts 120, 122, 124, 126 and the holes 128, 130 are dimensioned and configured for insertion of bone graft material. The holes 128, 130 may be dimensioned and configured for pre-insertion bone graft material packing. Bone graft material may be inserted through the holes 128, 130 of the interbody device 100 before the interbody device 100 is inserted into the vertebral body 202. The cuts 120, 122, 124, 126 may be adapted for post-insertion bone graft material packing. Bone graft material may be inserted through the cuts 120, 122, 124, 126 of the implant 100 after the interbody device 100 is inserted into the vertebral body 202. The opening 114 may serve as a position to accommodate insertion tools (e.g., not shown) to be placed for repositioning of the interbody device 100 in the column area 200 in the vertebral body 202. The interbody device 100 may be used as a stand-alone implant or may be used as an adjunct to the second interbody implant 208 to reduce the risk of subsidence or provide improved torsional resistance to the other interbody supports.
The interbody device 100 may be used to augment conventional interbody devices. As depicted in
Preferably, the interbody device 100 is placed by a surgeon at the periphery of the vertebral endplates 206. The interbody device 100 may compress the vertebral body 202 against the interbody device 100 providing increase in stiffness/strength of construct. The ALIF approach (e.g., as illustrated in
The interbody device 100 also decreases the risk of subsidence by allowing the peripheral walls 204 of the vertebrae 202 to carry a partial load (e.g., through the flange surfaces 110, 112). As the interbody device 100 is placed on the peripheral walls 204, the flange surfaces 110, 112 allow the lateral vertebral wall 204 to participate in preventing subsidence of the interbody device 100. The lateral vertebral wall 204 also carries part of the axial load rather than soft subchondral endplate bone 206 carrying the entire load. This significantly decreases the risk of subsidence and should directly translate into less postoperative pain and less risk of pseudarthrosis. The resistance provided by the teeth 116, 118 will no longer be the only resistance to shear or torsional forces. The flange surfaces 110, 112 also participate in resisting torsional, axial and shear forces.
The second interbody implant 208 may be placed in a direction opposite to that of the interbody device 100 in the vertebral body 202. The direction may include at least one of an anterior direction, a posterior direction, and a lateral direction with respect to the vertebral body 202. The interbody device 100 with the flange surfaces 110, 112 also allows the surgeon to use the second interbody implant 208. Thus, the load bearing capacity of the interbody device 100 is significantly improved by diverting vertebral forces (e.g., at least one of a torsional force, an axial force, and a shear force) from traveling entirely through the top and bottom flange surfaces 110, 112, respectively of the interbody device 100 into the endplate 206 and the soft subchondral bone.
In step 302, the first interbody implant 100 is inserted into the vertebral body 202. The flange surfaces 110, 112 are coupled to the peripheral walls 204 of the vertebral body 202. In step 304, the teeth 116, 118 of the first interbody implant 100 are engaged to the endplates 206 of the vertebral body 202 (e.g., as illustrated in
The interbody device 100 allows the peripheral walls 204 of the vertebral body 202 or the most peripheral portion of the vertebral body 202 to take a significant force from the implant 100. Moreover, the interbody device 100 permits a lateral portion of the vertebral body 202 to share in the forces through the interbody device 100. Additionally, the interbody device 100 may be used or inserted from any direction that the interbody implant 206 may be placed. The interbody device 100 further increases an axial, a shear, and a torsional stability, which, in turn, provides significant clinical benefit to postoperative patients. The interbody device 100 resists subsidence and provides improved torsional resistance thus resulting in less risk of subsidence and ultimately a safer and more comfortable recovery from interbody fusion surgery.
Generally, the interbody device 100 comprises a first lateral portion 102, a second lateral portion 104, a top wall 106, and a bottom wall 108. The second lateral portion 104 is positioned opposite to the first lateral portion 102. The top wall 106 and the bottom wall 108 are attached to the first lateral portion 102 as well as the second lateral portion 104. The bottom wall 108 is positioned opposite to the top wall 106. The first lateral portion 102 further includes at least one flange surface 110 and the second lateral portion 104 further includes an opening 114. The top wall 106 further comprises at least one hole 128, 130. Both the top wall 106 and the bottom wall 108 include teeth 116, 118, respectively.
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.
