Variable angle depth limited fastener driver and variable angle fixation system for use in orthopedic plates

Abstract

The present invention relates to an orthopedic fastener driver which can be used with a variable angle fixation system, and in particular in which the driver has a variable angle drive tip that is capable of screwing a fastener in an orthopedic plate assembly at a variable angle relative to the drive axis of the driver, and further wherein the driver has a drive mechanism including an interference clutch mechanism that disengages so as to limit the relative depth of the fastener in the plate assembly as to avoid driving the fastener or fastener assembly through the plate.

What is claimed is: 
     
         1 . A fastener driver for use in driving a fastener having a fastener axis in bone in a fastener aperture in an orthopedic plate, the fastener aperture having an aperture axis, the fastener axis being at an angle other than 0° to the aperture axis, the fastener driver comprising:
 a drive shaft, a drive tip and a drive couple operatively aligned along a drive axis, the drive couple being resiliently axially biased by a first force toward the drive tip so as to operatively couple the drive shaft and the drive tip, and a sleeve which has a recess that receives the drive tip, the sleeve terminating in an annular surface about the recess whereby a force applied to the annular surface in an axial direction opposite the direction of the first force will cause the drive tip to disengage from the drive shaft. 
 
     
     
         2 . A fastener driver as set forth in  claim 1  wherein the drive tip comprises a replaceable drive tip unit. 
     
     
         3 . A fastener driver as set forth in  claim 2  further including a recess that receives the drive tip unit and a detent which retains the drive tip unit in the recess. 
     
     
         4 . A fastener driver as set forth in  claim 1  wherein the drive tip unit includes a drive tip that is positionable at various angles relative to the drive axis of the fastener driver. 
     
     
         5 . A fastener driver as set forth in  claim 4  wherein the drive tip resides in a recess in a drive tip unit and the drive tip includes rounded surfaces joined at drive ridges. 
     
     
         6 . A fastener driver as set forth in  claim 5  wherein the drive tip has a forward drive section, and a rearward hexball. 
     
     
         7 . A fastener driver as set forth in  claim 1  wherein the fastener driver further includes a spring, a drive couple and a drive feature having a torque driving recess that receives a torque driving section of the drive tip, and the drive feature is rotatably held in a recess within the drive shaft which has a portion that forms one surface of a spring housing, the drive shaft further including a second torque driving surface that is received within a torque driving recess within the drive couple, the drive couple including a recess that forms a second, axially aligned surface of a spring housing, and the spring residing in the spring housing and applying a first force to bias the first and the second spring housing surfaces apart to a maximum spaced relation, and the drive feature also including a torque driving surface that is received in the torque driving recess within the drive couple when the first and second spring housing surfaces are in the maximum spaced relation. 
     
     
         8 . A fastener driver as set forth in  claim 7  further including a sleeve that has a recess ending in a terminal surface and the recess housing the drive tip and which is operably joined to the drive couple such that a sufficient axial force applied to the terminal surface opposes the first force and causes the drive feature to disengage from the drive shaft. 
     
     
         9 . A fastener driver as set forth in  claim 8  wherein the torque driving recess of the drive couple has a configuration in cross-section transverse to the drive axis that is rectilinear and has from 3 to 8 sides, and the torques driving surfaces of the drive shaft and of the drive feature have a corresponding shape and size configuration. 
     
     
         10 . A fastener driver for use in driving a fastener having a fastener axis in bone in a fastener aperture in an orthopedic plate, the fastener aperture having an aperture axis, the fastener axis being at an angle other than 0° to the aperture axis, the fastener driver comprising:
 a drive shaft defining a drive axis and being operatively coupled to a drive tip having a drive portion that can be positioned at a variable angle with respect to the drive axis so as to allow the fastener driver to be used to drive the fastener with the drive axis at an angle to the aperture axis. 
 
     
     
         11 . A fastener driver as set forth in  claim 10  further including a drive tip unit wherein the drive tip unit includes a drive tip unit drive shaft that includes a recess that houses the drive tip, and the drive tip has a first rounded portion which resides in the recess and a second torque driving recess that projects from the recess. 
     
     
         12 . A fastener driver as set forth in  claim 11  wherein the rounded portion includes partially spherical portions that are joined by drive ridges. 
     
     
         13 . A fastener driver as set forth in  claim 12  wherein the rounded portion forms a hexagon in cross-section. 
     
     
         14 . A fastener driver as set forth in  claim 10  further comprising a drive tip unit that snaps into position in the drive shaft. 
     
     
         15 . A fastener driver as set forth in  claim 14  including a plurality of drive tips units each having a different configuration drive tip. 
     
     
         16 . A fastener driver as set forth in  claim 10  further including a clutch and a sleeve having a recess through which the drive tip projects, and a terminal surface surrounding the recess, wherein the clutch is engaged by a force to the terminal surface of the sleeve so as to disengage the drive tip from the drive shaft. 
     
     
         17 . A system for providing for implanting a fastener in variable angle fixation in an orthopedic implant comprising:
 an orthopedic implant having a fastener aperture, the fastener aperture defining an aperture axis,   a fastener defining an axis, the fastener being implantable in the aperture at a selected angle to the fastener aperture axis; and   a fastener driver which can be used to implant the fastener in the orthopedic plate and having a drive mechanism including a housing which receives a drive tip and the drive tip being positionable at the selected angle within said housing whereby the fastener driver can be used to drive the fastener at the selected angle.   
     
     
         18 . A system for providing for implanting a fastener in variable angle fixation in an orthopedic implant as set forth in  claim 17  wherein the fastener driver further includes a drive mechanism that is disengages when the fastener is driven to a desired depth. 
     
     
         19 . A system for providing for implanting a fastener in variable angle fixation in an orthopedic implant as set forth in  claim 17  wherein said drive mechanism includes a clutch. 
     
     
         20 . A system for providing for implanting a fastener in variable angle fixation in an orthopedic implant as set forth in  claim 17  wherein the drive shaft includes a recess and the drive tip is held in the recess by a spring detent and the system further includes a plurality of drive tips.