Spinal implant adjustment

Abstract

An adjustable spinal implant 10 is provided for use in connecting elongate members 12 as well as in vertebral spacers such as corpectomy devices, intervertebral fusion devices, and other prostheses. The implant 10 may have fittings 80 on either end comprising fixed 100 or articulating jaws 200 , endplates, or other engagement structures. The implant 10 comprises a housing 40 with an internal rotor 60 ; an extending shaft 20 ; and a locking collar 70 . The extending shaft 20 has an external helical groove 23 that meshes with an internal helical groove 63 on the rotor 20 . Length adjustment occurs by transforming axial movement of the extending shaft 20 into a rotary movement of the rotor 60 via helical engagement. The locking collar 70 comprises protrusion 73 engaging grooves 63 of rotor 60 , thus providing a simple, positive locking mechanism without requiring the surgeon to apply excessive force to lock the length.

1 . An adjustable corpectomy implant comprising: 
 a shaft having a proximal end and a distal end and having at least one helical profile on an external surface thereof;    a housing having a proximal end with a first axial opening therein and a distal end and an inner surface and an outer surface, wherein said first axial opening receives therewithin said proximal end of said shaft;    a first endplate attached to said distal end of said shaft for engaging a first vertebral body;    a second endplate attached to said distal end of said housing for engaging a second vertebral body;    a rotor disposed within said first axial opening having an inner surface and an outer surface, wherein said inner surface has a profile that matingly engages said at least one helical profile on said external surface of said shaft, wherein said rotor spins about a cylindrical axis in response to axial movement imparted to said shaft within said housing; and    a locking collar engageable with said rotor, wherein said locking collar is moveable from a first, unlocked position wherein said rotor is free to rotate about said cylindrical axis to a second, locked position wherein said rotor is prevented from rotating about said cylindrical axis.    
     
     
         2 . The adjustable corpectomy implant of  claim 1  wherein said rotor further comprises grooves on said outer surface.  
     
     
         3 . The adjustable corpectomy implant of  claim 2  wherein said locking collar further comprises at least one protrusion directed radially inwardly for engagement with said grooves of said outer surface of said rotor.  
     
     
         4 . The adjustable corpectomy implant of  claim 3  wherein said first endplate is fixedly attached to said distal end of said shaft.  
     
     
         5 . The adjustable corpectomy implant of  claim 4  wherein said second endplate is fixedly attached to said distal end of said housing.  
     
     
         6 . The adjustable corpectomy implant of  claim 4  wherein said second endplate is articulatably attached to said distal end of said housing.  
     
     
         7 . The adjustable corpectomy implant of  claim 3  wherein said first endplate is articulatably attached to said distal end of said shaft.  
     
     
         8 . The adjustable corpectomy implant of  claim 7  wherein said second endplate is fixedly attached to said distal end of said housing.  
     
     
         9 . The adjustable corpectomy implant of  claim 7  wherein said second endplate is articulatably attached to said distal end of said housing.  
     
     
         10 . A bi-directional adjustable corpectomy implant comprising: 
 a shaft having a first end and a second end and having at least one helical profile disposed on an outer surface thereof,    a housing having a first end for receiving said first end of said shaft in an axial relationship and also having a second end;    a first endplate attached to said second end of said shaft for engaging a first vertebral body;    a second endplate attached to said second end of said housing for engaging a second vertebral body;    an annular rotor disposed within said housing having a cylindrical axis and an outer surface and an inner surface, wherein said inner surface has a profile that intimately engages said at least one helical profile of said shaft;    a locking collar coupled to said housing and moveable from a first position wherein said rotor is free to spin about its cylindrical axis, to a second position wherein said rotor is prevented from spinning about its cylindrical axis;    wherein when said locking collar is in said first position said at least one helical profile on said shaft and said profile of said rotor provide bi-directional adjustability for said implant, said shaft being freely extendable within said housing in response to an applied tension force on said first and second endplates, and said shaft being freely retractable within said housing in response to an applied compression force on said first and second endplates.    
     
     
         11 . The bi-directional adjustable corpectomy implant of  claim 10  wherein said outer surface of said annular rotor further comprises grooves.  
     
     
         12 . The bi-directional adjustable corpectomy implant of  claim 11  wherein said locking collar further comprises at least one protrusion directed radially inwardly for engagement with said outer surface of said rotor.  
     
     
         13 . The bi-directional adjustable corpectomy implant of  claim 12  wherein said first endplate is fixedly attached to said distal end of said shaft.  
     
     
         14 . The bi-directional adjustable corpectomy implant of  claim 13  wherein said second endplate is fixedly attached to said distal end of said housing.  
     
     
         15 . The bi-directional adjustable corpectomy implant of  claim 13  wherein said second endplate is articulatably attached to said distal end of said housing.  
     
     
         16 . The bi-directional adjustable corpectomy implant of  claim 12  wherein said first endplate is articulatably attached to said distal end of said shaft.  
     
     
         17 . The bi-directional adjustable corpectomy implant of  claim 16  wherein said second endplate is fixedly attached to said distal end of said housing.  
     
     
         18 . The bi-directional adjustable corpectomy implant of  claim 16  wherein said second endplate is articulatably attached to said distal end of said housing.  
     
     
         19 . An adjustable length corpectomy implant comprising: 
 a corpectomy cage having a first end and a second end;    a first endplate attached to said first end of said cage;    a second endplate attached to said second end of said cage;    a means for providing bidirectional length adjustment responsive to tension or compression on said first and second endplates, respectively; and    a means for selectively fixing a length of said implant.    
     
     
         20 . The adjustable length corpectomy implant of  claim 19  wherein said means for providing bi-directional length adjustment responsive to tension or compression on said first and second endplates further comprises a shaft having at least one helical profile disposed on an outer surface thereof coupled with complementary surface profile on an inner surface of said corpectomy cage.  
     
     
         21 . The adjustable length corpectomy implant of  claim 20  wherein said means for selectively fixing a length of said implant further comprises a rotor within said corpectomy cage having an internal surface that mates with said at least one helical profile, and an external surface having grooves for receiving a projection from a locking collar coupled to said corpectomy cage.  
     
     
         22 . A bi-directionally length adjustable corpectomy implant comprising: 
 a corpectomy cage having a first end and a second end;    a first endplate attached to said first end of said cage;    a second endplate attached to said second end of said cage;    a means for adjusting a length of said implant responsive to tension or compression on said first and second endplates, respectively; and    a means for selectively preventing length adjustability.    
     
     
         23 . The bi-directionally length adjustable corpectomy implant of  claim 22  wherein said means for adjusting a length of said implant responsive to tension or compression on said first and second endplates further comprises a shaft having a helical external profile and a rotor within said corpectomy cage having a mating internal helical profile.  
     
     
         24 . The bi-directionally length adjustable corpectomy implant of  claim 23  wherein said means for selectively preventing length adjustability further comprises external surface contours on said annular rotor for receiving a protrusion from a locking collar coupled to said corpectomy cage.