Patent Application
20120203278
The present invention relates to a prosthetic device and a manner of using the same, and more particularly, but not exclusively, relates to the interconnection of components to assemble an orthopedic construct for treatment of a spinal deformity.
The use of prosthetic implants to address orthopedic injuries and ailments has become commonplace in spinal surgery. In this arena, it is often desired to decrease the invasiveness of the procedures, improve implant integrity, reduce the potential for revision surgery, and provide more positive patient outcomes. Some of these implants depend on interconnection between various system components. Unfortunately, current interconnection devices can be limiting in certain applications. For example, crosslink devices employed to medially-laterally interconnect a pair of spinal rods restrict medial-lateral growth of the spinal column segment to which the rods and crosslink device is attached. Without revision, the crosslink device may constrain growth. Subsequent surgical procedures may be required to replace or adjust the length of the crosslink. Thus, there is a need for additional contributions in this area of technology
According to one aspect, a unique prosthesis is provided to interconnect elongate connecting elements that extend along the spinal column while accommodating medial-lateral growth of the spinal column segment to which the prosthesis is connected. Other aspects include unique methods, systems, devices, instrumentation, and apparatus involving an orthopedic stabilization system that reduces or eliminates constraint of medial-lateral growth of the instrumented spinal column segment.
The system includes a pair of elongate connecting elements positionable along two or more vertebrae of a spinal column segment. Also included is a crosslink device which is structured to form a mechanical connection between the two connecting elements and is capable of spanning a range of distances separating the two connecting elements to accommodate medial-lateral separation of the connecting elements as the spinal column segment grows over time.
The crosslink device includes first and second linking members, each including an end member at a first end thereof that is engaged to respective ones of the elongate connecting elements. Each of the first and second linking members also includes an elongate arm extending from the end member toward the other of the first and second linking members. In one embodiment, the elongate arms are engaged in a sliding telescoping arrangement relative to one another. In yet another embodiment, the elongate arms are received in a sliding interfitted arrangement relative to one another. In a further embodiment, each of the arms includes a bracket extending outwardly therefrom adjacent to the end member thereof. Each of the arms is slidingly received in the bracket of the other arm. In one specific embodiment, at least one of the brackets includes a locking mechanism to lock the first and second members in engagement with one another to prevent medial-lateral sliding movement of the first and second arms when it is desired to constrain medial-lateral growth of the spinal column segment, or when the growth of the spinal column segment has reached maturity.
Related features, aspects, embodiments, objects and advantages of the present invention will be apparent from the following description.
For the purposes of promoting an understanding of the principles of the invention, 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 invention is thereby intended. Any such alterations and further modifications in the illustrated devices, and such further applications of the principles of the invention as illustrated herein are contemplated as would normally occur to one skilled in the art to which the invention relates.
In certain procedures, spinal stabilization system 20 is secured to a spinal column segment SC of a patient to provide stability to a deformed spine while allowing patient growth and without fusion of adjacent vertebrae V. Spinal stabilization system 20 may involve thoracic stabilization in a pediatric orthopedic procedure, although spinal stabilization system 20 is not limited to such procedures. In certain procedures, the patient's spinal column segment SC grows over time in the cephalad-caudal directions and also grows in the medial-lateral directions transversely to the sagittal plane of spinal column segment SC. Crosslink device 30 extends between and is engaged to connecting elements 23 positioned on the opposite sides of the sagittal plane to provide stability to stabilization system 20. Crosslink device 30 lengthens over time in the medial-lateral direction to accommodate growth of spinal column segment SC in the medial-lateral direction while remaining fixed relative to connecting elements 23 in the cephalad-caudal directions to increase the stability of spinal stabilization system 20.
In one specific embodiment, bone attachment devices 22 are bone anchors that are engaged to bony structure of vertebrae V. Bone attachment devices 22 may be, but are not limited to, multi-axial, poly-axial, uni-axial, uni-planar bone screws with a distal bone engaging portion for engaging the bony structure and a proximal receiving portion that is engaged to one of the connecting elements 23. The distal bone engaging portion may be in the form of a bone screw, hook, staple, clamp, tack, wire, adhesive or other suitable bone engaging structure or arrangement. The distal bone engaging portion may be engaged to any suitable bony structure such as a pedicle, lamina, spinous process, transverse process, facet, or anterior portion of a vertebral body. The proximal receiving portion may be a saddle, yoke, post, clamp, eyelet, or other suitable structure that can be engaged to connecting element 23 with or without a separate fastener. In one particular embodiment, the bone engaging portion and receiving portion are movable relative to one another at least initially until engaged to the connecting element 23. In one specific embodiment, the distal bone engaging portion and receiving portion are engaged together with a “ball and joint” or swivel type of coupling that permits relative movement therebetween during at least some stages of assembly.
In addition, connecting element 23 can be in the form of an elongated spinal rod. The spinal rod may be solid or hollow along some or all of its length and/or may be of homogenous or heterogeneous composition. The spinal rod may also be of uniform cross-section along its entire length, or have a variable cross-section along its length. The spinal rod may include one or more interconnected spinal rod portions that lengthen or adjust in length to accommodate growth of spinal column segment SC over time in the cephalad-caudal directions. The spinal rod can be rigid, flexible, or include one or more flexible portions to permit at least limited spinal motion. Other embodiments of connecting element 23 contemplate any suitable spinal stabilization element positionable along the spinal column, including plates, bars, tethers, wires, cables, cords, inflatable devices, expandable devices, and formed in place devices, for example.
End members 34, 64 are shown to be mirror images of one another, although end members 34-64 having different configurations from one another are not precluded. In any event, end member 34 will be described further with it being understood that the description of end member 34 also applies to the illustrated embodiment of end member 64. End member 34 includes a C-shaped body 38 that defines a passage 40 for receiving connecting element 23 in a transverse relation to linking member 32. Connecting element 23 extends cephaladly and caudally from upper and lower ends, respectively, of body 38. Passage 40 also opens along a distal side of body 38 so that connecting element 23 can be bottom-loaded into passage 40 when crosslink device 30 is positioned into the patient and onto connecting elements 23. Body 38 also includes a receptacle 42 opening at a proximal side thereof that intersects passage 40. An engaging member 44 is engageable in receptacle 42 to contact connecting element 23 and secure it against the lateral side of body 38 in passage 40 to fix connecting element 23 in position relative to end member 34.
In the illustrated embodiment, engaging member 44 includes a threaded portion 46 that threadingly engages internal threads along receptacle 42, and is threaded into receptacle 42 to contact connecting element 23 and seat it securely against body 38 of end member 34. Engaging member 44 also includes a tool engaging portion 48 mounted to the proximal end of threaded portion 46 to facilitate installation of engaging member 44. In one specific embodiment, tool engaging portion 48 is removable upon application of a threshold torque to provide a lower profile for crosslink device 30. Other embodiments contemplate other means for securing connecting element 23 in passage 40, including set screws without break-off portions, clamps, and bands, for example. In other embodiments, body 23 provides a snap fit or interference fit with connecting element 23 in passage 40. It is further contemplated that end member 34 can be configured other than with the distally opening passage 40 shown in
First linking member 32 includes first elongate arm 36 extending from a medial side of body 38 toward second linking member 62. In addition, second linking member 62 includes second elongate arm 66 extending toward and telescopingly receiving first elongate arm 36. As further shown in
First and second arms 36, 66 separate end members 34, 64 by a length L1 that varies as end members 34, 64 move away from one another as a result of medial-lateral growth of spinal column segment SC. In addition, bore 68 provides an overlap length L2 between arms 36, 66 that is sufficient to accommodate the anticipated amount of medial-lateral growth of the spinal column segment SC without causing linking members 32, 62 to become disengaged from one another. Furthermore, overlap length L2 provides stability in the cephalad-caudal directions by preventing or resisting pivoting movement of linking members 32, 62 relative to one another in a plane that includes or is along the plane that is defined by connecting elements 23. The telescoping and overlapping arrangement also prevents pivoting in the anterior-posterior directions toward and away from spinal column segment SC. In one specific embodiment, arms 36, 66 are configured so that overlap length L2 is at least 50% of length L1 when crosslink device is initially implanted. In a further embodiment, overlap length L2 is at least 50% of length L1 at the greatest anticipated L1 that will result due to medial-lateral growth of spinal column segment SC.
First elongate arm 236 includes a first bracket 238 extending cephaladly from an outer end of first elongate arm 236. Second elongate arm 266 includes a second bracket 268 extending caudally from an outer end of second elongate arm 266. Second elongate arm 266 is slidingly received through a bore of first bracket 238 so that first bracket 238 is located at an outer end of second elongate arm 266 that is adjacent to second end member 264. First elongate arm 236 is slidingly received through a bore of second bracket 268 so that second bracket 268 is located at an outer end of first elongate arm 236 that is adjacent to first end member 234. The spinal column segment SC grows in a medial-lateral direction, elongate arms 236, 266 slide in respective ones of the brackets 268, 238 to allow end members 234, 264 to separate as the connecting elements 23 engaged to end members 234, 264 laterally separate. The cephalad-caudally extending brackets 238, 268 prevent cephalad-caudal pivoting of linking members 232, 234 relative to one another and anterior-posterior pivoting of linking members 232, 234 relative to one another. Brackets 238, 268 can be formed monolithically with the respective elongate arm 236, 266, or formed as separate components that is fastened to the respective elongate arm 236, 266 via fasteners, welded connections, rivets, adhesives, or other suitable fastener or joining technique.
In
Materials for the implants disclosed herein can be chosen from any suitable biocompatible material, such as titanium, titanium alloys, cobalt-chromium, cobalt-chromium alloys, stainless steel, PEEK, polymers, or other suitable metal or non-metal material and combinations and composites thereof. Of course, it is understood that the relative size of the components can be modified for the particular vertebra(e) to be instrumented and for the particular location or structure of the vertebrae to which the anchor assembly will be engaged.
Although various embodiments have been described as having particular features and/or combinations of components, other embodiments are possible having a combination of any features and/or components from any of embodiments as discussed above. As used in this specification, the singular forms “a,” “an” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, the term “a member” is intended to mean a single member or a combination of members, “a material” is intended to mean one or more materials, or a combination thereof. Furthermore, the terms “proximal” and “distal” refer to the direction closer to and away from, respectively, an operator (e.g., surgeon, physician, nurse, technician, etc.) who would insert the medical implant and/or instruments into the patient. For example, the portion of a medical instrument first inserted inside the patient's body would be the distal portion, while the opposite portion of the medical device (e.g., the portion of the medical device closest to the operator) would be the proximal portion.
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 being understood that all changes and modifications that come within the spirit of the invention are desired to be protected.
