Freely separable surgical drill guide and plate

Abstract

Instrumentation for osteofixation including a locking bone plate and a surgical drill guide. The plate has a plurality of fastener holes with inner walls of a preselected hole diameter. The drill guide has a guide member, for guiding a drill bit, and a hollow collet disposed substantially coaxially with the guide member. A radially expandable forward end of the collet comprises a radially expandable neck and an outwardly projecting rim disposed forward of the neck. This rim defines a contracted outer rim diameter that is smaller than the hole diameter in a contracted collet position, and an expanded outer rim diameter that is larger than the hole diameter in an expanded position. Thus, the rim is freely extractable through the plate hole in the contracted position, but is unreceivable through the plate hole in the expanded position. The collet neck is configured and dimensioned to press outwardly against an inner wall of the plate hole when the neck is expanded.

1. Instrumentation for osteofixation comprising:
 a bone plate with a plate hole for receiving a bone fastener and having an inner wall; and  
 a surgical drill guide comprising a guide member, for guiding a drill bit, and a hollow collet disposed substantially coaxially with the guide member and having a radially expandable forward end with a radially expandable neck and an outwardly projecting rim disposed forward of the neck, the rim being configured and dimensioned such that it is freely extractable through the plate hole in a contracted collet position and impassable through the plate hole in an expanded collet position, the neck being configured and dimensioned for pressing outwardly against an inner wall of the plate hole in the expanded collet position for releasibly releasably securing the drill guide to the plate.  
 
     
     
       2. The instrumentation of  claim 1 , wherein the plate hole has a preselected hole diameter, and the rim defines an outer rim diameter that is smaller than the hole diameter in the contracted collet position and larger than the hole diameter in the expanded collet position. 
     
     
       3. The instrumentation of  claim 2 , wherein the collet forward end comprises a plurality of longitudinally extending fingers that define the neck and rim and that are biased radially outwardly when the guide sleeve is moved into a forward position. 
     
     
       4. The instrumentation of  claim 2 , wherein the neck and rim have an axis and the rim has a rounded cross section in a plane extending through the axis for preventing the rim from catching on the plate during extraction of the rim from the plate hole. 
     
     
       5. The instrumentation of  claim 4 , wherein the rounded cross-section of the rim has a radius of about 0.15 mm. 
     
     
       6. The instrumentation of  claim 2 , wherein the rim has a surface substantially adjacent the neck and configured at a first angle thereto of less than about 55°. 
     
     
       7. The instrumentation of  claim 6 , wherein the first angle is about 45°. 
     
     
       8. The instrumentation of  claim 1 , wherein the guide member comprises a guide sleeve disposed movably axially and telescopically within the collet and defining a guide bore for axially receiving and guiding a drill bit, the guide sleeve having a first position within the collet in which the sleeve biases the collet towards the expanded collet position. 
     
     
       9. The instrumentation of  claim 8 , wherein the sleeve has a surface tapered inwardly at a second angle of between 3° and 5° for cooperatively biasing the collet towards the expanded collet position when the collet sleeve is moved forward therein. 
     
     
       10. The instrumentation of  claim 9 , wherein the second angle is about 4°. 
     
     
       11. Instrumentation for osteofixation comprising:
 a bone plate with a plate hole for receiving a bone fastener and having an inner wall of a preselected hole diameter; and  
 a surgical drill guide comprising a guide member, for guiding a drill bit, and a hollow collet disposed substantially coaxially with the guide member and having a radially expandable forward end with a radially expandable neck and an outwardly projecting rim disposed forward of the neck, the rim defining a contracted outer rim diameter that is smaller than the hole diameter in an a contracted collet position and an expanded outer rim diameter that is larger than the hole diameter in an expanded collet position such that the rim is freely extractable through the plate hole in the contracted collet position and impassable through the plate hole in the expanded collet position, the neck being configured and dimensioned for pressing outwardly against an inner wall of the plate hole in the expanded collet position for releasibly releasably securing the drill guide to the plate.  
 
     
     
       12. The instrumentation of  claim 11 , wherein the contracted rim diameter is at least about 0.1 mm smaller than the hole diameter. 
     
     
       13. The instrumentation of  claim 12 , wherein the contracted rim diameter is no more than about 0.3 mm smaller than the hole diameter. 
     
     
       14. The instrumentation of  claim 13 , wherein the contracted rim diameter is about 0.2 mm smaller than the hole diameter. 
     
     
       15. The instrumentation of  claim 11 , wherein the contracted rim diameter is about 95% of the hole diameter. 
     
     
       16. The instrumentation of  claim 11 , wherein the rim protrudes radially from the neck by less than about 0.1 mm. 
     
     
       17. The instrumentation of  claim 16 , wherein the neck has a contracted neck diameter in the contracted collet position, the contracted rim diameter being equal to the contracted neck diameter. 
     
     
       18. The instrumentation of  claim 11 , wherein the neck has a diameter when the neck is in the contracted collet position that is at least about 95% as large as the contracted rim diameter. 
     
     
       19. The instrumentation of  claim 11 , wherein the collet is configured for naturally and resiliently biasing the rim to the contracted collet position. 
     
     
       20. The instrumentation of  claim 11 , wherein the collet comprises a shoulder having a diameter larger than the hole diameter, the shoulder, neck, and rim being a single piece of unitary construction. 
     
     
       21. Instrumentation for osteofixation comprising:
 a locking bone plate with a plurality of plate holes for receiving a an anchor screw therethrough and having an inner wall of a preselected hole diameter; and  
 a surgical drill guide comprising a guide member, for guiding a drill bit, and a hollow collet disposed substantially coaxially with the guide member and having a radially expandable forward end with a radially expandable neck and an outwardly projecting rim disposed forward of the neck, the rim defining a contracted outer rim diameter that is smaller than the hole diameter in an a contracted collet position and an expanded outer rim diameter that is larger than the hole diameter in an expanded collet position such that the rim is freely extractable through the plate hole in the contracted collet position and unreceivable through the plate hole in the expanded collet position, the neck being configured and dimensioned for pressing outwardly against an inner wall of the plate hole in the expanded collet position for releasibly releasably securing the drill guide to the plate hole in precise alignment therewith.  
 
     
     
       22. Instrumentation for osteofixation comprising:
   a bone plate with a plate hole for receiving a bone fastener and having an inner wall; and        a surgical drill guide comprising a guide member for guiding a drill bit, and a hollow collet disposed substantially coaxially with the guide member and having a forward end that includes a radially expandable neck which is configured and dimensioned such that the neck is freely extractable through the plate hole in a contracted collet position, the neck being configured and dimensioned for pressing outwardly against an inner wall of the plate hole in an expanded collet position for releasably securing the drill guide to the plate.     
     
     
       23. The instrumentation of  claim 22 , wherein the plate hole has a preselected hole diameter, and the neck has a neck diameter that is smaller than the hole diameter in the contracted collet position, and the neck diameter is expanded in the expanded collet position. 
     
     
       24. The instrumentation of  claim 22 , wherein the guide member comprises a guide sleeve disposed movably axially and telescopically within the collet and defining a guide bore for axially receiving and guiding a drill bit, the guide sleeve having a first position within the collet in which the sleeve biases the collet towards the expanded collet position. 
     
     
       25. The instrumentation of  claim 24 , wherein the sleeve has a surface tapered inwardly at an angle of between  3 ° and  5 ° for cooperatively biasing the collet towards the expanded collet position when the sleeve is moved forward therein.