Patent Application
20070270817
The present disclosure broadly concerns spinal fixation systems and generally relates to a connector apparatus used to connect spinal rods. The apparatus can be useful for correction of spinal injuries or deformities.
Several techniques and systems have been developed for use in correcting and stabilizing spinal curvatures, and for facilitating spinal fusion in the case of spinal disorders or degenerative conditions. In some systems, a pair of bendable rods may be longitudinally disposed adjacent the vertebral column and are fixed to various vertebrae along the length of the spine by way of a number of fixation elements, such as hooks and screws. In certain situations, it is desirable to supplement an existing spinal rod connected to the vertebral column with a new spinal rod, to add strength and stability to the fixation system.
Numerous spinal rod systems have been developed which provide transverse connectors for linking the adjacent spinal rods across the spinal midline to provide a rigid and stable construct. Such systems can present one or more difficulties for spinal surgeons. Many of the devices are high profile which increases soft tissue trauma and surgical complications. Moreover, it certain situations it is desirable to provide a transverse connection between adjacent spinal rods on the same side of the spinal midline.
Rigid transverse connections between spinal rods are beneficial because they restrict rod migration and increase construct stiffness. In many cases involving multi-level fusion of the spine, these features are essential while solid bone fusion is accomplished. In the post-operative period before fusion occurs, a significant amount of motion can occur between rods or other elongated members and other structure such as wires and hooks. That motion can, for example, allow a scoliotic correction to decrease or the pelvis to de-rotate towards a previous, deformed position. By providing a rigid transverse connection between two spinal rods, the loss of correction can be reduced and a stiffer construct can be created which may enhance the promotion of a solid fusion. A need remains for low profile devices which link adjacent spinal rods in a top-loading, top-tightening fashion with a minimum of components and steps, providing increased stability to the fixation system.
For the purpose of promoting an understanding of the principles of the disclosure, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the claims is thereby intended, such alterations and further modifications in the illustrated device, and such further applications of the principles of the disclosure as illustrated therein, being contemplated as would normally occur to one skilled in the art to which the disclosure relates.
In certain embodiments of the present application, a connector apparatus for linking elongate members comprises a connector body defining a first channel configured to receive a first elongate member and a second channel configured to receive a second elongate member. The channels are each defined by an inner contact surface configured to engage the corresponding elongate member. The first channel is U-shaped and opens at a top surface of the body. Additionally, the first channel includes an inner threaded portion configured to receive a first threaded retaining member to secure the first elongate member in the first channel. The second channel opens at a side surface of the body. The channels may open in substantially perpendicular directions. Additionally, the connector body defines a threaded through-hole, in communication with the second channel, configured to receive a second threaded retaining member to secure the second elongate member in the second channel. The connector apparatus creates a low profile, side opening, top tightening fixation system, providing a stable, rigid system that sufficiently restricts movement and bending of the spinal rods and increases overall rigidity.
Referring generally to
The illustrated embodiment of screws 42 and 44 include threaded portions 43 and 45, respectively, which engage with threaded surfaces of through-hole 38 and threaded portions 40. Screw 42 includes a bearing surface 46 configured to contact and push a spinal rod into engagement with inner contact surface 30. Bearing surface 46 is shaped to conform to an outer surface of a rod positioned in channel 26. In some embodiments, bearing surface 46 is curved in a similar manner as the curved outer surface of a spinal rod. Additionally, screws 42 and 44 include internal, recessed hexagonal tops 47 and 49 to receive conventional driving tools. In other embodiments, other internal prints or external configurations could be used for accommodating gripping or driving tools. In the illustrated embodiment, through-hole 38 and screw 42 are at least partially offset from the positioning of a spinal rod in channel 26.
Referring generally to
In certain embodiments, as illustrated, both spinal rods 34 and 36 are positioned on the same side of the spinal midline, or the spinous processes, of vertebrae 62. In other words, spinal rods 34 and 36 can both be positioned between one transverse process and the adjacent spinous process of each relevant vertebra 62. Positioning rods 34 and 36 in this fashion can be done in 5 several ways. Rods 34 and 36 can be placed simultaneously, providing a dual-rod construct along a portion of the spine (e.g.
The use of connector device 20 will be described in certain embodiments as follows, with particular reference to a spinal orthopedic procedure. It will be appreciated that other uses of connector 20 in other surgical procedures could be made.
Once an appropriate access to a surgical site is obtained, connector 20 can be inserted to the surgical site, and may be placed in a desired position at or adjacent certain vertebra(e) 62. In certain embodiments, a surgical procedure may be needed to revise a prior surgery. In such cases, spinal rod 36 may be an existing spinal rod that was previously connected to vertebrae 62 via pedicle screws 64, and spinal rod 34 is to be introduced to the surgical site and connected to vertebrae 62. Connector device 20 may be loaded onto spinal rod 36 from an underneath direction, with rod 36 being positioned in channel 28 at a desired position along rod 36. Thus, connector device 20 can be loaded onto spinal rod 36 from a position between rod 36 and a given vertebra 62 and/or other tissue material. Additionally, spinal rod 36 is loaded through an opening of channel 28 in top surface 25. Screw 44 is inserted into channel 28, so that threaded portion 45 engages with threaded portions 40. Screw 44 is advanced through channel 28 so as to bear against and push spinal rod 36 against inner contact surface 32. Screw 44 is sufficiently tightened to engage and lock connector device 20 to spinal rod 36.
Rod 34 can be pre-loaded into or otherwise connected to connector device 20 before engagement of connector device 20 to spinal rod 36, or rod 34 can be loaded into or otherwise connected to connector device 20 after engagement of connector device 20 to spinal rod 36. Spinal rod 34 is loaded into connector device 20 from a side direction, at a desired position along rod 34. Screw 42 is inserted into and advanced through through-hole 38 so as to bear against and push spinal rod 34 against inner contact surface 30. In the illustrated embodiment, bearing surface 46 of screw 42 contacts rod 34 to urge rod 34 against contact surface 30. Screw 42 is sufficiently tightened to engage connector device 20 to spinal rod 34. Final engagement is accomplished by tightening screws 42 and 44 against spinal rods 34 and 36, thereby locking the spinal rods laterally relative to each other. Spinal rod 34 can be connected to vertebrae 62 via pedicle screws 64. A vertebral fixation system involving connector device 20, spinal rods 34 and 36, and screws 42 and 44 is now in place, providing a rigid transverse connection between the adjacent spinal rods.
It will be appreciated that an existing rod (e.g. rod 36) can be received in channel 26 and a new rod (e.g. rod 34) can be received in channel 28. Thus, connector 20 can be maneuvered toward rod 36 from the side so that a portion of rod 36 enters channel 26 and is adjacent contact surface 30 of connector 20. Screw 42 can be threaded into connector 20 so as to loosely or tightly hold rod 36 in channel 26. If further adjustments of connector 20 with respect to rod 36 are expected or possible, then a loose holding of rod 36 can easily allow such adjustments, and tightening of screw 42 can occur after any final adjustments. Rod 34 can be placed in channel 28 either before or after connection of connector 20 to rod 36, and connector 20 (if loosely connected to rod 36) could be rotated or further maneuvered so that channel 28 is adjacent rod 34. Such rotation or maneuvering may be necessary if rod 34 has been fixed or otherwise connected to another implant or vertebra 62, and thus has less freedom of movement.
The above-described methods are useful both with the parallel dual-rod construct embodiment shown in
The parts of connector device 20 are composed of biocompatible materials that are also compatible with particular elongated members or other implants with which connector device 20 will be used. Thus, connector device 20 may be made of titanium, nickel, alloys of titanium and nickel, stainless steel, certain sturdy plastic materials, or other sturdy materials. The materials chosen for connector device 20 should be the same as those of the rods with which connector device 20 is used, or at least of a material that will not cause discomfort or an adverse reaction when used with the rods. It will be appreciated that materials other than those described above could also be used.
While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character. It should be understood that only the preferred embodiments have been shown and described and that all changes and modifications that come within the spirit of the invention are desired to be protected.
