Expandable interbody implant

Abstract

An intervertebral implant that can be surgically introduced between adjacent vertebrae and expanded in situ to occupy an optimal space between the vertebrae. The implant is inserted into the evacuated disc space obliquely and then oriented so as to extend laterally across the anterior adjacent vertebrae with its outer ends of the implant supported by the cortical rims on the opposite sides of the vertebrae. The implant has two body members with a space therebetween so the implant may be then distracted and a spacer of predetermined thickness that may be inserted within the space between the body members so as to maintain a desired amount of distraction. The upper and lower surfaces of the implant may have a desired lordotic angle. A method of using an implant is disclosed which permits endoscopic visualization of the disc space.

1 . An expandable spinal implant for insertion in a disc space between two adjacent vertebrae bodies to be fused together by bone graft material placed in said disc space, said vertebrae bodies each having a cortical rim and an end plate within said cortical rim, said disc space being substantially defined by an annulus attached to said adjacent vertebrae bodies and by the endplates of said adjacent vertebrae bodies, said implant comprising an elongate body having a height and a width such that said implant may be inserted into the disc space through an incision in a posterior portion of the annulus, said implant having a length such that with said implant positioned within said disc space the implant may be oriented to extend across the disc space so that said implant is at least in part supported on said cortical rim of at least one of said vertebrae bodies, said implant having a lower body member and an upper body member each of which is adapted to be cooperable with a distractor for distraction of said body members while said implant is within said disc space so as to effect distraction of said disc space, said implant further comprising a spacer insertable into said disc space through said incision in said annulus and to be positioned between said upper and lower body members while the upper and lower body members are distracted within said disc space such that said implant with said spacer installed between said upper and lower body members is configured to maintain distraction of said disc space a desired amount. 
     
     
         2 . An implant as set forth in  claim 1  wherein said implant has a first end and a second end, and wherein said implant is of such a length that with its first end at least partially received in a first opening in an anterior portion of said annulus generally opposite said incision, and with said implant oriented to extend across said vertebrae bodies and with the second end of said implant at least partially received in a second opening in an anterior portion of said annulus generally opposite said first opening, said implant is at least in part supported on at least one of said cortical rims. 
     
     
         3 . An implant as set forth in  claim 1  wherein one of said body members has an inner surface and a pair of stabilizing posts extending from said inner surface and the other of said body members has a pair of bores for receiving said stabilizing posts, said posts and said bores being configured to maintain said body members in desired relation to one another and yet permitting distraction and retraction of the body members relative to one another. 
     
     
         4 . An implant as set forth in  claim 3  wherein each said bore has a sliding axial fit relative to its respective said post so as to aid in stabilizing said body members relative to one another and so as to permit distraction and retraction of said body members relative to one another. 
     
     
         5 . An implant as set forth in  claim 1  wherein said implant is configured to be supported on said one cortical rim at two or more locations spaced from one another. 
     
     
         6 . A spinal implant for insertion in a disc space between two adjacent vertebrae bodies, said disc space being defined by an annulus attached to said adjacent vertebrae bodies, each of said vertebrae bodies having a cortical rim and an endplate within its cortical rim, said implant comprising an elongate body configured to be inserted within the disc space through an incision in a posterolateral portion of said annulus, said implant having a length, a first end, and a second end such that with said first end of the implant being at least partially received in a first opening formed in an anterior portion of the annulus, said implant may be oriented within said disc space so that with said first end received in said first opening said first end is supported on one of said cortical rims proximate said first opening and so that with said implant extending generally laterally of said vertebrae bodies with its second end being at least partially received within a second opening in said annulus generally opposite said first opening said implant being least in part supported on the one cortical rim, said implant having a lower body member and an upper body member, each of said body members being configured to be cooperable with a distractor so that upon operation of said distractor said body members are forced apart so as to in turn distract the disc space, said implant further comprising a spacer of a predetermined thickness adapted to be inserted through said incision into said disc space and positioned between said upper and lower body members while said body members are distracted so as to substantially maintain a desired amount of distraction of said disc space.