Patent Application
20120109203
The present application is directed to devices and methods for stabilizing vertebral members, and more particularly, to interspinous implants to engage onto the spinous processes.
Vertebral members comprise a body, pedicles, laminae, and processes. The body includes sections on inferior and superior ends and has an hourglass shape with a thinner middle section and wider ends. Intervertebral discs are positioned between the bodies of adjacent vertebral members to permit flexion, extension, lateral bending, and rotation. The pedicles are two short rounded members that extend posteriorly from the body, and the laminae are two flattened members that extend medially from the pedicles. The processes are projections that serve as connection points for the ligaments and tendons. The processes include the articular processes, transverse processes, and the spinous process. Each vertebral member has four articular processes including two superior and two inferior processes. The superior processes of a first vertebral member join with the inferior processes of a second vertebral member to form facet joints. The facet joints work with the intervertebral discs to allow motion of the spine. The spinous process is a single member that extends posteriorly from the junction of the two lamina. The spinous process may act as a lever to effect motion of the vertebral member.
Various conditions may lead to damage of the intervertebral discs and/or the vertebral members. The damage may result from a variety of causes including a specific event such as trauma, a degenerative condition, a tumor, or infection. Damage to the intervertebral discs and vertebral members can lead to pain, neurological deficit, and/or loss of motion.
One manner of correcting the damage is insertion of an implant onto the spinous processes. The implant may reduce or eliminate the pain and neurological deficit.
The present application is directed to implants for attaching to spinous processes. The implants may include a first plate sized to extend along a first lateral side of the spinous processes and a second plate sized to extend along a second lateral side of the spinous processes. The second plate may include a bore that extends through the second plate. An elongated post may extend through the bore with a first end attached to the first plate and a second end positioned outward beyond the outer surface of the second plate away from the first plate. A joint may be positioned along the post that attaches a first section of the post to a second section of the post. The joint may be constructed to align the first and second sections in a collinear orientation and to remove the second section from the first section. Additional joints may also be positioned along the post. The bore may be sized relative to the post for the second plate to be movable along a length of the post.
The present application is also directed to methods of attaching an implant to spinous processes. The methods may include positioning a first plate on a first lateral side of the spinous processes and positioning a post that extends outward from the first plate through an interspinous space formed between the spinous processes. The method may include positioning a second plate on a second lateral side of the spinous processes with the post extending through a bore in the second plate. The second plate may be slid along the post towards the spinous processes from a distal section of the post, over a joint, and onto a proximal section of the post. The first plate may be positioned against the first lateral side of the spinous processes and the second plate against the second lateral side of the spinous processes. The second plate may be secured on the proximal section of the post with the first and second plates contacting against the lateral sides of the spinous processes. The distal section may be detached from the proximal section of the post at the joint.
The various aspects of the various embodiments may be used alone or in any combination, as is desired.
The present application is directed to a spinous process implant with two plates that are connected together with a post. The implant is configured for each plate to be positioned on outer lateral sides of spinous processes with the post extending through the interspinous space. One or both plates may be movable along the length of the post to accommodate different anatomies such as for relatively wide or thin spinous processes. The post includes an adequate length for the plates to remain on the post and prevent disengagement. The post also includes a joint to remove a distal section. The distal section is usually removed after the implant is adjusted and secured to the spinous processes. The post may also include additional joints to remove different lengths of the post.
The first plate 20 includes a receptacle 24 to receive a head 43 of the post 40.
A locking member 60 may be attached to the plate 20 to secure the head 43 within the receptacle 24. In one embodiment, the locking member 60 is positioned within a groove 26 in the plate 20. Other embodiments include the locking member 60 secured to the plate 20 by mechanical fasteners or adhesives. The locking member 60 includes an opening for the post 40 to extend outward from the receptacle 24. In one embodiment, the locking member 60 is a C-ring that fits within the groove 26.
The receptacle 24 may also extend completely through the first plate 20 as illustrated in
The second plate 30 includes a bore 34 to receive the post 40. The bore 34 is sized relative to the post 40 for the plate 30 to be movable along the length of the post 40 for adjusting a distance from the first plate 20. The bore 34 may include various cross-sectional shapes and sizes depending upon the post 40.
As illustrated in
The post 40 includes a head 43 and a shaft 44 as illustrated in
The post 40 and the bore 34 may include various sectional shapes to control the rotational orientation of the second plate 30 relative to the post 40.
The first and second sections 45, 46 may include the same or different sectional shapes. In one embodiment, the shapes are the same.
The joint 41 is positioned at an intermediate point along the shaft 44 between the first and second ends. As illustrated in
The joint 41 may be weaker than the first and second sections 45, 46 and fracture upon the application of an external force on the second section 46. The external force may be substantially perpendicular to a longitudinal axis of the post 40 as illustrated by arrow F in
One construction for a weakened joint 41 includes a notch 48 that extends around a portion or the entirety of the periphery of the shaft 44.
The weakened joint 41 may also be formed by the post 40 having an abutment face between different materials.
The different aspects that form the weakened joint 41 may be used separately or in combination. For example, the joint 41 may include a notch 48 and a void 49, and a joint 41 with a notch 48 positioned at a connection between first and second sections 45, 46 that are constructed of different materials.
The joint 41 may also include a mechanical connection that secures together the first and second sections 45, 46.
Another mechanical connection is illustrated in
In use, the implant 10 is positioned in the patient with the first plate 20 on a first lateral side of the spinous processes 100 and the second plate 30 positioned on an opposing second lateral side of the spinous processes 100. The post 40 extends outward from the first plate 20 and through the interspinous space 101 and through the bore 34 in the second plate 30. In one embodiment, the second plate 30 is positioned on the post 40 prior to insertion into the patient (i.e., the complete implant 10 of the plates 20, 30 and post 40 are inserted as a single unit into the patient). In another embodiment, the implant 10 may be inserted into the patient as separate elements and attached together within the patient.
The extended length of the post 40 that includes the first and second sections 45, 46 allows the plates 20, 30 to be separated apart by a large amount to facilitate the positioning relative to the spinous processes 100. The distance between the plates 20, 30 can be increased well beyond what is necessary to position each of the plates 20, 30 on the opposing lateral sides of the spinous processes 100 and maintain the plates 20, 30 on the post 40. The enlarged distance between the plates 20, 30 positions the second plate 30 on the second section 46 of the post 40.
Once positioned, the plates 20, 30 are moved together and into contact with the lateral sides of the spinous processes 100. This includes the second plate 30 moving along the length of the post 40 from the second section 46, over the joint 41, and onto the first section 45. The plates 20, 30 may be moved together to apply a compressive force to the spinous processes 100. Once positioned the proper distance apart, the locking element 50 is engaged with the post 40 to maintain the spacing of the plates 20, 30.
With the plate 30 secured to the first section 45 of the post 40, the second section 46 is no longer necessary. The second section 46 is removed by fracturing the joint. Once separated, the second section 46 can be removed from the patient.
The second section 46 may include a longitudinal section with a different cross-sectional shape to form one or more gripping surfaces for applying the force. In one embodiment, a majority of the second section 46 includes a circular cross-sectional shape with the gripping section including opposing flattened sides. The flattened sides facilitate contact with the second section 46 and application of the force.
The post 40 may include more than one joint 41 located along the longitudinal length L. The different joints 41 provide for separating different lengths of the post 40 from the remainder depending upon the patient anatomy and the needs of the particular surgical procedure.
The multiple joints 41 may be evenly spaced apart along the length of the post 40. Alternatively, the joints 41 may be spaced at different, non-equal intervals. Further, the number of joints 41 may vary.
The various joints 41 along the length L of the post 40 may have the same or different constructions.
A spacer may also be positioned around the post 40 between the first and second plates 20, 30. The spacer includes a central bore that receives the post 40. The spacer includes a first contact surface to contact against the first spinous process, and a second contact surface to contact against the second spinous process.
U.S. patent application Ser. No. 12/916,761 entitled Spinous Process Implant with a Post and an Enlarged Boss, filed on the same day as the present application, discloses an interspinous device with a pair of plates and a post, and is herein incorporated by reference in its entirety.
The implants 10 may be implanted within a living patient for the treatment of various spinal disorders. The implant 10 may also be implanted in a non-living situation, such as within a cadaver, model, and the like. The non-living situation may be for one or more of testing, training, and demonstration purposes.
Spatially relative terms such as “under”, “below”, “lower”, “over”, “upper”, and the like, are used for ease of description to explain the positioning of one element relative to a second element. These terms are intended to encompass different orientations of the device in addition to different orientations than those depicted in the figures. Further, terms such as “first”, “second”, and the like, are also used to describe various elements, regions, sections, etc and are also not intended to be limiting. Like terms refer to like elements throughout the description.
As used herein, the terms “having”, “containing”, “including”, “comprising” and the like are open ended terms that indicate the presence of stated elements or features, but do not preclude additional elements or features. The articles “a”, “an” and “the” are intended to include the plural as well as the singular, unless the context clearly indicates otherwise.
The present invention may be carried out in other specific ways than those herein set forth without departing from the scope and essential characteristics of the invention. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.
