Anterior implant for the spine

Abstract

Implant for the cervical spine comprising an anterior plate ( 1 ) for maintaining a bone graft, bone anchorage screws ( 6, 7, 8 ) for the plate and means ( 22 ) for blocking the screws and preventing any migration of the screws, characterized in that the blocking means comprises at least one slide ( 22 ) slidably mounted on the plate so as to be applicable on at least one anchorage screw head ( 15, 16 ). The slide cooperates with means ( 33, 34 ) for retaining the slide on the head of the screw. The slide may be formed by a thin platelet ( 22 a ) which is provided with lateral flanges ( 25 ) and is slidable in a complementary cavity ( 18 ) provided in the plate ( 1 ) while being flush with the surface of the plate ( 1 ). The plate ( 1 ) includes ramps ( 26 ) for retaining the slide ( 22 ) on which the flanges ( 25 ) are slidable, the slide ( 22 ) being slidable to a position in which it at least partly overlaps the heads of the associated screws ( 6 or 7 ) and is locked in position by suitable means.

What is claimed is:  
     
         1 . An implant for the spine comprising: an anterior plate for stabilizing the spine and maintaining a bone graft, the plate having a number of openings, a number of bone anchorage screws for correspondingly engaging the openings of the plate, and means for blocking the screws and preventing any migration of the screws, characterized in that the blocking means comprise at least one slide slidably mounted on the plate so as to be capable of partially covering at least on anchorage screw head, and the slide cooperates with means for retaining the slide on the head of the screw.  
     
     
         2 . An implant for the spine characterized in that it comprises: 
 a plate for stabilizing the spine, the plate having a number of openings;    a number of bone anchorage screws each operable to engage a corresponding one of the openings of the plate; and    means for blocking the screws and preventing screw migration, the blocking means including at least one slide slidably mounted on the plate to selectively cover at least a part of at least one of the screws and means for retaining the slide on the at least one of the screws, the slide cooperating with the retaining means.    
     
     
         3 . An implant for the spine characterized in that it comprises: 
 a plate for stabilizing the spine, the plate including a number of openings and defining a cavity adjacent at least one of the openings;    a number of bone anchorage screws each operable to pass through a corresponding one of the openings of the plate to engage the spine; and    a slide slidably mounted in the cavity of the plate, the slide being operable to selectively cover at least a portion of at least one of the screws mounted in the at least one of the openings.    
     
     
         4 . The implant according to  claim 1  or  2 , characterized in that the retaining means comprises a boss on the slide which is clicked into a corresponding recess defined by a bridge of the plate when the slide is in a position for blocking the screws.  
     
     
         5 . The implant according to  claim 1  or  2 , wherein the plate defines a cavity and the slide is mounted within the cavity.  
     
     
         6 . The implant according to  claim 3 , wherein the plate includes a bridge adjacent the slide, and one of the bridge and the slide includes a boss and another of the bridge and the slide includes a recess to correspondingly receive the boss to retain the slide in a screw retaining position.  
     
     
         7 . The implant according to  claim 5  or  6 , characterized in that the slide is formed by a platelet including at least one flange, the cavity includes at least one ramp to engage the at least one flange and retain the platelet on the plate.  
     
     
         8 . The implant according to  claim 7 , characterized in that the platelet is provided with two lateral flanges each adapted to slide along a corresponding one of two ramps, the ramps retaining the platelet in the cavity and being formed on opposite sides of the cavity, the platelet being cambered to allow the platelet to be resiliently inserted in the cavity, and the platelet is dimensioned for at least partially overlapping a pair of screw heads each belonging to a corresponding one of the bone anchorage screws.  
     
     
         9 . The implant according to  claim 7  or  8 , characterized in that the cavity and the platelet are so dimensioned that the surface of the platelet is generally flush with a surface of the plate when the platelet is placed in the cavity.  
     
     
         10 . The implant according to any of claims  7 - 9 , characterized in that plate defines another cavity arranged to receive another slide slidably mounted to the plate.  
     
     
         11 . The implant according to any of claims  7 - 10 , characterized in that the cavity communicates with a pair of the openings of the plate.  
     
     
         12 . The implant according to any of claims  10 - 11 , wherein a central part of the plate defines a central opening and further comprising a selected bone anchorage screw to pass through the central opening, the selected bone anchorage screw including a first thread and a screw head, the first thread being separated from the screw head by a generally smooth part the first thread having a diameter larger than the width of the screw passage opening for preventing the return of the selected bone anchorage screw after the bone anchorage screw is inserted in through the central opening.