Transverse spinal rod connector clip

Abstract: A device for connecting two elongated spinal rods to one another in a spinal fixation system comprising a clip body including a first portion and a second portion, the first portion of the clip body configured to receive and engage a first elongated spinal rod, the second portion of the clip body having a transverse bore therein for receiving a second elongated spinal rod extending transverse to the first elongated spinal rod; and a locking member dimensioned and configured for mounting in the transverse bore in the second portion of the clip body so as to fix the position of the second elongated spinal rod with respect to the first elongated spinal rod.

Description: 1. Field of the Invention The present invention relates to implantable spinal fixation systems for the surgical treatment of spinal disorders. More particularly, this invention relates to a transverse rod connector clip for connecting elongated spinal rods to each other. 2. Background of the Invention For years doctors attempted to restore stability to the spine by fusion (arthrodesis) of the problem area. This treatment yielded marginal results due to the inherently flexible spinal column. Over the past ten years spinal implant systems have been developed to add stability to the spine to enhance the arthrodeds rates. Such systems often include spinal instrumentation having connective structures such as a pair of plates and/or rods which are placed on opposite sides of the portion of the spinal column which is intended to be fused. These spinal systems consist of screws and hooks for segmental attachment to the spine and longitudinal rods connected to screws or hooks. These components provide the necessary stability both in tension and compression yet yield minimal torsional control. It has been found that when a pair of spinal rods are fastened in parallel on either side of the spinous process, the assembly can be significantly strengthened by using at least one additional rod to horizontally bridge the pair of spinal rods. A cross brace assembly is disclosed in US. Pat. No. 5,084,049. Devices such as these commonly consist of a threaded rod for providing the desired lateral support. The threaded rod is fastened to each of the spinal rods by clamps located on each end of the threaded rod. However, this configuration is bulky and can cause irritation of the patient's back muscles and other tissue which might rub against the device. A cross brace assembly that fits closer to the spine, preferably in the same general plane as the vertical spinal rods, would reduce the complications associated with bulkier devices. Most existing transverse connectors consist of rods, plates, and bars linked to the longitudinal rods by coupling mechanisms with set screws, nuts, or a combination of each. These connectors require several components and instruments to build the constructs. Each additional Ornponent or instrument required to assemble the connectors adds to the "fiddle factor" of the surgical technique. Examples of these transverse connectors include Tranverse Link Device (DLT) and Crosslink manufactured by Sofamor Danek, Trans-Connector manufactured by Synthes, and Modular Cross Connector and Transverse Rod Connector (TRC) manufactured by AcroMed. Telescopic rod to rod couplers for use in a spinal implant systems have also been described. Prior to the locking member being engaged, the telescoping sections may be easily slid past their extremes and out of engagement with one another. While this is a convenient method of connecting and disconnecting the coupler sections, it can be inconvenient during surgery if the sections accidentally disengage. U.S. Patent No. 5,275,600 describes a telescopic rod to rod coupler in which the telescopic rod sections are assembled together using a 180 degree twisting motion. This is designed to minimize the risk of the rod sections accidentally disconnecting during the implant procedure. Presently available spinal fixation systems frequently require careful alignment of the hardware used to connect the components of the spinal instrumentation with each other. A need has thus arisen for improved rod connectors to transversely connect spinal rods without requiring additional manipulation of the spinal instrumentation and to minimize the use of pedicle screws while at the same time reducing requirements to assemble small pieces of hardware during the surgical procedure. Further, there are different rod connectors in the state of the art, like the holding and fixing mechanism disclosed in US 5,507,746 or the perpendicular rod connector disclosed in EP 0 565 149 A2. In addition, US 5,380,326 discloses a clamping device for a vertebral locking rod according to the preambular of claim 1. SUMMARY OF THE INVENTION The present invention is directed to transverse connector clips for connecting elongated spinal rods in spinal fixation systems and provides a connector for connecting two elongated spinal rods to one another according to claim 1. Preferred embodiments of the invention are defined in the dependent claims. The transverse connectors of the present invention can be used to transversely connect spinal rods without requiring additional manipulation of the spinal instrumentation. Because the connectors of the present invention do not require any additional locking mechanism, they reduce the assembly of small pieces of hardware during the surgical procedure. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a perspective view of an embodiment of the present invention illustrating the method of assembly; and Figure 2 is a perspective view of the assembled embodiment of the invention of Fig. 1. DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT The present invention is directed to a transverse connector clip 10E and assemblies used in spinal fixation systems. Spinal fixation systems typically include spinal instrumentation having connective structures such as a pair of plates and/or rods which are placed on opposite sides of the spinal column near vertebrae that are intended to be fused. These spinal systems consist of screws and hooks for segmental attachment to the spine and longitudinal rods connected to screws or hooks. These components provide the necessary stability both in tension and compression yet yield minimal torsional control. In addition, it has been found that when a pair of spinal rods are fastened in parallel on either side of the spinous process, the assembly can be significantly strengthened by using at least one additional rod to horizontally bridge the pair of spinal rods. The transverse connector clips 10E of the present invention consist of a component with a means to dip the device on a spinal or cylindrical rod 11 and a component with a means to link two rod connectors together laterally. Transverse connector clip 10E concept consists of a clip body 12 with a first portion and a second portion (Figure 1). On first portion are two, mirror image hemi-cylindrical shells 18 and 20. These two, mirror image hemi-cylindrical shells 18 and 20 have an inner surface that defines a rod bore through which the cylindrical rod 11 can extend. Rod bore has an inner diameter that is designed to be slightly smaller than the outer diameter of the cylindrical rod 11 it will receive. Top surface of the hemi-cylindrical shells 18 and 20 defines an outer diameter. It should be noted that the two, mirror image hemi-cylindrical shells 18 and 20 can be connected to the first portion of clip body 12 as shown in clip 10E of Figure 1 or in mirror image relationship. Clip body 12 is placed on the cylindrical rod 11 at 90 degrees and turned so that the hemi-cylindrical shells 18 and 20 spread around the rod 11. The deflection of the hemi-cylindrical shells 18 and 20 and the inner diameter of the shells 22 allow the clip 10 to securely clamp on the rod 11. The second side of the clip body 12 includes an outwardly extending U-shaped receptacle designed to receive a semi-cylindrical or cylindrical rod and a locking cap device (Clip 10E, Figures 1-2). In an embodiment of the inventive transverse connector (clip) 10E, the first portion of the clip body 12 is as previously described, while the second portion of the clip body 12 comprises an outwardly extending rod holding portion 120 and a locking mechanism 130. The rod holding portion has a longitudinal axis positioned perpendicular to the longitudinal axis LA1-LA1 of the first portion of the clip body 12. The locking mechanism 130 is configured to engage with the rod holding portion 120 in order to locking the longitudinal rod into the rod holding portion 120. The rod holding portion is in the shape of a solid holding portion having a through bore for receiving a hemi-cylindrical or cylindrical rod and the locking mechanism can be of any locking mechanism known to one skilled in the art, such as tapered locking caps, set screws or locking nuts. In one embodiment, the holding portion is a U-shaped holding portion 120 having a longitudinal axis LA3-LA3 positioned perpendicular to the longitudinal axis LA1-LA1 of the first portion of connector clip 10E (Figures 1-2). The U-shaped holding portion 120 has an upper portion 122 and a lower portion 124. The lower portion 124 is configured to receive a flat side 126 of a hemi-cylindrical and 128. A locking mechanism for the U-shaped portion 120 can include a locking cap 130 with an upper 132 and lower side 134 configured to slide into and mate with the upper portion 122 of U -shaped portion 120. Upper side 132 of locking cap 130 has a tapered portion 136 that engages and mates with a tapered portion 138 of the upper portion 122 of the U-shaped portion 120. Further, the top portion 132 of the locking member 130 includes a pair of opposed supplemental retention members spaced from the opposed tapered retention members 136. The lower side 134 of the locking cap 130 is configured to accommodate at an arcuate side 140 of the hemi-cylindrical rod 128. The advantage of the inventive clip 10E, when used in combination with the locking cap 130, the hemi-cylinder support bar 128, and cylindrical rod 11 (Figure 1-2) is that connecting clip 10E is a single piece that connects two rods together, thus reducing the requirement of the prior art connectors to assemble small pieces of hardware during the surgical procedure. It should be understood that in keeping with spinal surgery techniques, a plurality of cylindrical rods 11 can be used, each with a plurality of attachment devices affixed thereto, with the present attachment devices transversely connecting either two rods 11 together or connecting portions of rods together in other alignments. The foregoing disclosure and description of the invention are illustrative and explanatory thereof, and various changes in the details of the illustrated apparatus and construction and method of operation may be made without departing from the scope of the invention, as defined in the claims

Claims: A connector (10 E) for connecting two elongated spinal rods (11, 128) to one another in a spinal fixation system comprising: a clip body (12) including a first portion and a second portion, the first portion of the clip body configured to receive and engage a first elongated spinal rod (11), the second portion of the clip body having a transverse bore (120) therein for receiving a second elongated spinal rod (128) extending transverse to the first elongated spinal rod; and a locking member (130) dimensioned and configured for mounting in the transverse bore in the second portion of the clip body so as to fix the position of the second elongated spinal rod with respect to the first elongated spinal rod, wherein the locking member (130) comprises a top portion (132) having a tapered portion (136) that engages and mates under a tapered portion (138) in an upper portion (122) of the u-shaped portion (120), characterized in that the U-shaped transverse bore has a pair of spaced apart side walls and a substantially planar lower portion extending between the side walls. A connector as recited in Claim 1, wherein the first portion of the clip body includes a pair of opposed spaced apart arcuate rod engaging hooks (18, 20) for receiving and engaging the first elongated spinal rod (11). A connector as recited in any of the preceding claims, wherein each arcuate rod engaging hook (18, 20) defines a curve having a common central axis. A connector as recited in any of the preceding claims, wherein the second elongated spinal rod (128) has a generally semi-circular transverse cross-section for reception by the lower portion (124) of the U-shaped opening. A spinal fixation system comprising: a first elongated spinal rod (11) having a first transverse cross-section; a second elongated spinal rod having a second transverse cross-section different than the transverse cross-section of the first elongated spinal rod; and a connector according to claim 2. A spinal fixation system as recited in 5, wherein the first elongated spinal rod (11) has a circular transverse cross-section and wherein the second elongated spinal rod (128) has a generally semi-circular transverse cross-section. A spinal fixation system as recited in any of the preceding claims, wherein the second elongated spinal rod (128) includes a planar surface for contacting the substantially planar lower portion (124) of the second portion (120) of the connector (10 E). A spinal fixation system as recited in any of the preceding claims, wherein each side wall has a tapered engagement slot (138) formed therein, and the locking member (130) includes a top portion (132) and a bottom portion (134), the top portion having a pair of opposed tapered retention members (136) each for engaging a respective one of the tapered engagement slots in the side walls, and a hemi-cylindrical groove in a bottom surface (134) thereof for accommodating a portion of the second elongated spinal rod. A spinal fixation system as recited in any of the preceding claims, wherein the top portion (132) of the locking member (130) includes a pair of opposed supplemental retention members spaced from the opposed tapered retention members (136) on the top portion.

Inventors: LIN CHIH-I, NICHOLS DAVID, LIN, CHIH-I, NICHOLS, DAVID
Applicants: HOWMEDICA OSTEONICS CORP, HOWMEDICA OSTEONICS CORP.
Application year: 1998
Main classification: A61B17
IPC codes: A61B17