Spinal implant with opposing taper coaxial drive system
An opposing taper coaxial spinal implant. The system consists of a centrally located drive screw with opposing lead threads and actuators. The actuators contain pins positioned through angular slots located on sidewalls attached to end plates. The angular slots are opposing to create a wedge effect when the actuator pins translate through them. A carriage contains a drive screw and centrally located pin. The centrally located pin provides axis to contain each end plate, allowing them to pivot and translate relative to the carriage. An adjustment nut is axially retained by the carriage, but allowed to rotate. To expand/contract the end plates, the drive screw and adjustment nut are rotated together, with no relative motion between them. To change the angle of the end plates, the adjustment nut is rotated while keeping the drive screw rotation fixed.
1. An opposing taper coaxial spinal implant system comprising:
a substantially rectangular bottom endplate having a first inner vertical sidewall extending from a front edge to a rear edge of said bottom endplate and a second inner vertical sidewall spaced apart from said first inner vertical sidewall, each said inner vertical sidewall including a front angled slot, a rear angled slot, and a centrally disposed vertical slot;
a substantially rectangular top endplate having a first outer vertical sidewall extending from a front edge to a rear edge of said top endplate and a second outer vertical sidewall spaced apart from said first outer vertical sidewall, each said outer vertical sidewall including a front angled slot, a rear angled slot, and a centrally disposed vertical slot;
a carriage having a threaded aperture, said carriage positionable between said inner and outer vertical sidewalls with a centrally disposed pin positioned in each of said vertical slot of said inner sidewalls and said outer sidewalls;
a drive screw rotatably insertable into said carriage aperture, said drive screw having clockwise threads along a first portion and counterclockwise threads along a second portion;
a first actuator threadably attached to said first portion of said drive screw, said first actuator having a front lower pin extending across a lower surface of said carriage, said front lower pin operatively associated with said front angled slot in said inner sidewalls of said bottom endplate, said first actuator having a front upper pin extending across an upper surface of said carriage with said front upper pin operatively associated with said front angled slot in said outer sidewalls of said top endplate;
a second actuator threadably attached to said second portion of said drive screw, said second actuator having a rear lower pin extending across the lower surface of said carriage, said rear lower pin operatively associated with said rear angled slot in said inner sidewalls of said bottom endplate and a rear upper pin operatively associated with said rear angled slot in said outer sidewalls of said top endplate; and
an adjustment nut rotatably secured to said carriage, said adjustment nut threadingly attached to the drive screw;
whereby simultaneous rotation of said drive screw and said adjustment nut moves said actuators in unison wherein said pins engage said slots to cause equal separation of said bottom and top endplates;
whereby rotation of said adjustment nut without said drive screw rotation repositions said screw drive in respect to said carriage wherein said pins engage said slots to cause an angular positioning of said bottom and top endplates.
2. The opposing taper coaxial spinal implant system according to claim 1 wherein rotation of said adjustment nut in a clockwise position expands the distance between frontal edges of said bottom endplate and said top endplate.
3. The opposing taper coaxial spinal implant system according to claim 1 wherein rotation of said adjustment nut in a counter clockwise position expands the distance between rearward edges of said bottom endplate and said top endplate.
4. The opposing taper coaxial spinal implant system according to claim 1 wherein said rear edge of said bottom endplate and said top endplate includes a sloped outer surface.
5. The opposing taper coaxial spinal implant system according to claim 1 wherein an outer surface of each said endplate has a plurality of grooves constructed and arranged to engage bone.
6. The opposing taper coaxial spinal implant system according to claim 5 wherein each said outer surface of each said endplate includes an aperture for receipt of bone or bone graft material.
7. The opposing taper coaxial spinal implant system according to claim 5 wherein said angled slots in said inner sidewalls are about 45 degrees relative to the outer surface of said bottom endplate.
8. The opposing taper coaxial spinal implant system according to claim 5 wherein said angled slots in said outer sidewalls are about 45 degrees relative to the outer surface of said top endplate.
9. The opposing taper coaxial spinal implant system according to claim 1 wherein said angled slots are sloped toward said centrally disposed pin.
10. The opposing taper coaxial spinal implant system according to claim 1 wherein said drive screw has a star driver receptacle.
11. The opposing taper coaxial spinal implant system according to claim 1 wherein in said drive screw and adjustment nut can be rotated simultaneously or independently by an instrument driver comprising:
a handle having formed from a base to allow gripping by an individual on one end and a driver head for rotating of said drive screw on an opposite end;
an extendable sleeve having a proximal end slidably securable to said base using a slide collar, said slide collar engaging said handle to allow simultaneous rotation of said adjustment nut and said drive screw when said slide collar is attached to said base, said base to allow only rotation of said adjustment nut when said collar is detached from said base.