Method and apparatus for spondylolisthesis reduction

• US 5,697,977 A
• Filed: 06/07/1995
• Issued: 12/16/1997
• Est. Priority Date: 03/18/1994
• Status: Expired due to Fees

• Current Assignee: Madhavan Pisharodi
• Original Assignee: Madhavan Pisharodi
• Inventors: Pisharodi, Madhavan
• Primary Examiner(s): Prebilic, Paul B.
• Application Number:
  US08/482,974
• Time in Patent Office: 923 Days
• Field of Search: 623/16, 623/17, 606/61, 606/62, 606/63, 606/65, 606/66, 606/70, 606/76
• US Class Current: 606/279
• CPC Class Codes: A61B 17/025 Joint distractors
• CPC Class Codes: A61B 2017/0256 for the spine
• CPC Class Codes: A61F 2/30965 Reinforcing the prosthesis by embedding particles or fibres during moulding or dipping
• CPC Class Codes: A61F 2/442 Intervertebral or spinal discs, e.g. resilient non-disc-shaped intervertebral inflatable pockets A61F2/441; non-disc-shaped intervertebral fusion implants A61F2/4455
• CPC Class Codes: A61F 2/446 having a circular or elliptical cross-section substantially parallel to the axis of the spine, e.g. cylinders or frustocones
• CPC Class Codes: A61F 2/4603 for insertion or extraction of endoprosthetic joints or of accessories thereof
• CPC Class Codes: A61F 2/4611 of spinal prostheses
• CPC Class Codes: A61F 2002/2835 Bone graft implants for filling a bony defect or an endoprosthesis cavity, e.g. by synthetic material or biological material
• CPC Class Codes: A61F 2002/30169 Pi-shaped
• CPC Class Codes: A61F 2002/30214 having tapered sections of different conicities
• CPC Class Codes: A61F 2002/30224 cylindrical
• CPC Class Codes: A61F 2002/30253 ellipsoidal or ovoid
• CPC Class Codes: A61F 2002/30286 barrel-shaped
• CPC Class Codes: A61F 2002/3037 Translation along the common longitudinal axis, e.g. piston
• CPC Class Codes: A61F 2002/30398 Sliding
• CPC Class Codes: A61F 2002/30405 made by screwing complementary threads machined on the parts themselves
• CPC Class Codes: A61F 2002/30426 Bayonet coupling
• CPC Class Codes: A61F 2002/30433 using additional screws, bolts, dowels, rivets or washers e.g. connecting screws
• CPC Class Codes: A61F 2002/30553 for adjusting a position by translation along an axis
• CPC Class Codes: A61F 2002/30579 with mechanically expandable devices, e.g. fixation devices
• CPC Class Codes: A61F 2002/30593 : hollow
• CPC Class Codes: A61F 2002/30594 : slotted, e.g. radial or meridian slot ending in a polar aperture, non-polar slots, horizontal or arcuate slots
• CPC Class Codes: A61F 2002/30777 : Oblong apertures
• CPC Class Codes: A61F 2002/30797 : internally-threaded
• CPC Class Codes: A61F 2002/3085 : with a threaded, e.g. self-tapping, bone-engaging surface, e.g. external surface
• CPC Class Codes: A61F 2002/30873 : Threadings machined on non-cylindrical external surfaces
• CPC Class Codes: A61F 2002/30879 : Ribs
• CPC Class Codes: A61F 2002/4627 : with linear motion along or rotating motion about the instrument axis or the implantation direction, e.g. telescopic, along a guiding rod, screwing inside the instrument
• CPC Class Codes: A61F 2002/4629 : connected to the endoprosthesis or implant via a threaded connection
• CPC Class Codes: A61F 2220/0025 : Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements
• CPC Class Codes: A61F 2220/0033 : made by longitudinally pushing a protrusion into a complementary-shaped recess, e.g. held by friction fit
• CPC Class Codes: A61F 2220/0041 : using additional screws, bolts, dowels or rivets, e.g. connecting screws
• CPC Class Codes: A61F 2230/0047 : Pi-shaped
• CPC Class Codes: A61F 2230/0063 : Three-dimensional shapes
• CPC Class Codes: A61F 2230/0067 : conical
• CPC Class Codes: A61F 2230/0069 : cylindrical
• CPC Class Codes: A61F 2230/0076 : ellipsoidal or ovoid
• CPC Class Codes: A61F 2250/0008 : for adjusting a position by translation along an axis or two perpendicular axes
• CPC Class Codes: A61F 2310/00023 : Titanium or titanium-based alloys, e.g. Ti-Ni alloys

Abstract

Method and apparatus for reduction of spondylolisthesis involving the insertion of an elongate implant which is split longitudinally into two side-by-side members, one of which is movable relative to the other, into the disk space between two misaligned vertebrae. Each of the members is provided with teeth for engaging the adjacent vertebrae and positioned on the members so as to be located on opposite sides of the implant. The implant formed by the two side-by-side members is generally rectangularly-shaped in cross section, the height of the rectangularly-shaped cross section being less than the width so that the implant can be inserted between the adjacent vertebrae with the lesser, height dimension oriented in the same direction as the axis of the spinal column and the larger width dimension at approximately a right angle to that axis. One of the two members is then moved relative to the other from the first position in which the members are in the abovedescribed, side-by-side relationship along the longitudinal axis of the implant to a second position in which the members are aligned with the respective, adjacent, misaligned vertebrae and the implant is then rotated by approximately 90° to cause the teeth to contact the bodies of the adjacent vertebrae. The two members are then brought back into the first side-by-side relationship to draw the misaligned vertebrae into alignment and the implant is rotated approximately 90° to disengage the teeth from the vertebrae for removal of the implant from the disk space.

Claims

1. A method of aligning adjacent vertebrae after removing a portion of the intervertebral disk from therebetween to form a disk space comprising the steps of:

inserting an elongate body having means formed on opposite sides thereof for selectively engaging the vertebrae adjacent the disk space into the disk space, the body being comprised of first and second side-by-side members, with the vertebrae engaging means extending into the disk space without engaging the adjacent vertebrae;

moving the second member relative to the first member until the first and second members are approximately aligned with each of the adjacent vertebrae;

rotating the body approximately 90°

to cause the vertebrae engaging means thereon to engage the vertebrae; and

moving the second member relative to the first member to align the vertebrae to which each member is engaged.

2. The method of claim 1 wherein the first and second members are moved by moving a mandrel to which the second member is mounted.

3. The method of claim 1 wherein the body is elongate and wider in the middle portion than at the ends thereof and the first and second members are aligned with the adjacent vertebrae by positioning at the point relative to the adjacent vertebrae at which the respective wider middle portions maximally engage the respective adjacent vertebrae.

4. The method of claim 1 wherein the body is substantially rectangularly-shaped in cross section, the sides of the body defining a height of smaller dimension than the dimension of the sides defining the width of the body, the vertebrae engaging means being formed on the sides of the body defining the height thereof.

5. The method of claim 1 wherein the body is inserted into the disk space on one side of the center of the adjacent vertebrae.

6. The method of claim 1 additionally comprising replacing the first body with a monolithic implant after aligning the adjacent vertebrae.

7. The method of claim 6 additionally comprising replacing the second body with a second monolithic implant.

8. A method of aligning adjacent vertebrae after removing portions of the intervertebral disk from therebetween to form first and second disk spaces on the sides of the center thereof comprising the steps of:

inserting a first elongate body having means formed thereon for selectively engaging the vertebrae adjacent the disk space into the first disk space, the first body being comprised of first and second side-by-side members;

moving the second member of the first body relative to the first member of the first body to a position in which the first and second members of the first body are approximately aligned with the adjacent vertebrae;

rotating the first body approximately 90°

to cause the vertebrae engaging means formed thereon to engage the adjacent vertebrae;

moving the second member of the first body relative to the first member of the first body to align the adjacent vertebrae;

inserting a second elongate body having means formed thereon for selectively engaging the adjacent vertebrae into the second disk space, the second implant being comprised of first and second side-by-side members;

moving the second member of the second body relative to the first member of the second body to a position in which the first and second members of the second body are approximately aligned with the adjacent vertebrae;

rotating the second body approximately 90°

to cause the vertebrae engaging means formed thereon to engage the adjacent vertebrae; and

moving the second member of the second body relative to the first member of the second body to align the adjacent vertebrae.

9. The method of claim 8 wherein the first and second members of the first and second bodies are moved by moving a mandrel to which the respective second members are mounted.

10. The method of claim 8 wherein the first and second elongate bodies are wider in the respective middle portions than at the ends thereof.

11. The method of claim 8 wherein the first and second elongate bodies are substantially rectangularly-shaped in cross section, the sides of the respective bodies defining the height being of smaller dimension than the dimension of the sides defining the width of the respective bodies, and the vertebrae engaging means are formed on the sides of the respective bodies defining the height thereof.