Prosthetic implant for intervertebral spinal fusion

• US 5,425,772 A
• Filed: 09/20/1993
• Issued: 06/20/1995
• Est. Priority Date: 09/20/1993
• Status: Expired due to Term

• Current Assignee: Depuy Acromed Incorporated (Johnson & Johnson)
• Original Assignee: John W. Brantigan
• Inventors: Brantigan, John W.
• Primary Examiner(s): Willse, David H.
• Application Number:
  US08/123,191
• Time in Patent Office: 638 Days
• Field of Search: 623/17, 606/61
• US Class Current: 623/17.11
• 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 2/447 substantially parallelepipedal, e.g. having a rectangular or trapezoidal cross-section
• 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 2002/2839 Bone plugs or bone graft dowels
• CPC Class Codes: A61F 2002/30153 rectangular
• CPC Class Codes: A61F 2002/30158 trapezoidal
• CPC Class Codes: A61F 2002/30261 parallelepipedal
• CPC Class Codes: A61F 2002/30405 made by screwing complementary threads machined on the parts themselves
• CPC Class Codes: A61F 2002/30593 hollow
• CPC Class Codes: A61F 2002/30774 internally-threaded
• CPC Class Codes: A61F 2002/30777 Oblong apertures
• CPC Class Codes: A61F 2002/30845 with cutting edges
• CPC Class Codes: A61F 2002/30904 serrated profile, i.e. saw-toothed
• CPC Class Codes: A61F 2002/448 comprising multiple adjacent spinal implants within the same intervertebral space or within the same vertebra, e.g. comprising two adjacent spinal implants
• CPC Class Codes: A61F 2002/449 comprising multiple spinal implants located in different intervertebral spaces or in different vertebrae
• CPC Class Codes: A61F 2220/0025 Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements
• CPC Class Codes: A61F 2230/0019 rectangular
• CPC Class Codes: A61F 2230/0026 trapezoidal
• CPC Class Codes: A61F 2230/0082 parallelepipedal
• CPC Class Codes: Y10S 606/912 : Radiolucent material

Abstract

Block or plug implants provide weight-bearing support for adjacent vertebrae in a vertebral column while allowing sufficient area between and beside the plugs for packing of autologous bone graft to allow bony healing and fusion. The plugs have a laterally directed slot to allow ingrowth of blood supply from the side and to allow locking the permanent device in place with living bone. The plugs have a patterned surface to grip the vertebrae. Plugs used for fusion in the L4-5 and L5-S1 levels are wedged-shaped to reproduce the normal shape of these discs, which are higher anteriorly than posteriorly. The height of the plugs is greater than the width. The implants are made of a biocompatible carbon fiber reinforced polymer or alternately made of traditional orthopaedic implant materials such as chrome cobalt, stainless steel or titanium. In the surgical procedure, undamaged annulus fibrous disc tissue connecting the adjacent vertebrae is preserved and a pair of side-by-side implant plugs are forced into side-by-side transverse channels in the adjoining vertebrae to stretch the remaining annulus and support body weight applied through the vertebrae. The plugs are bottomed in the channels on cortex bone and bone ingrowth and fusion is facilitated by packing a patient'"'"'s own graft into the center of the plug and beside and between the two adjacent plugs.

Claims

1. A surgical prosthetic device adapted to maintain normal disc space between adjoining vertebrae in a spinal column having transverse posterior to anterior open ended flat sided channels with bottoms of uniform depth along their lengths cut in the end faces of the adjoining vertebrae adapted to provide an unimpeded supply of bone graft material facilitating fusing the vertebrae together which comprises, a rigid rectangular wedge shape block defined by top, bottom, side and end walls, said block being higher than wide and longer than high, said top and bottom walls being imperforate and oriented to converge from the anterior to the posterior ends of the channels and permit the vertebrae receiving the block in the channels to be pulled together to restore normal disc contour and sagittal plane alignment, said side walls of the block being smooth to prevent irritation of the sides of the channels, said side walls having a slot providing a chamber to receive bone growth material packed around the block, one of said end walls of the block having a tool receiving recess facilitating insertion of the block into the channels, and said top and bottom walls of the block having teeth for biting into the bottoms of the channels.

2. The device of claim 1 wherein the wedge shaped block has an anterior end about 2 mm higher than the posterior end.

3. The device of claim 1 wherein the block has a posterior height of about 8.5 to 12.5 mm and an anterior height of about 11 to 15 mm.

4. A surgical prosthetic device adapted for fusing together spaced adjoining vertebrae on opposite sides of the disc in a spinal column prepared with a pair of laterally spaced posterior to anterior rectangular channels of uniform depth along their lengths providing side and bottom walls which comprises, an inert narrow rigid wedge shaped plug higher than wide and longer than high, said plug defined by top, bottom, side, and end walls, said top and bottom walls of the plug being imperforate and having means for locking with the bottom walls of adjoining vertebrae, said top and bottom walls of the plug also being inclined for converging toward the posterior ends of the channels, said side walls of the plug having a slot therethrough for receiving bone growth material facilitating fusion of the plug to the adjoining vertebrae, and said plug having a tool receiving portion facilitating insertion of the plug between the adjoining vertebrae with the top and bottom walls of the plug bottomed on the bottom walls of the channels of said adjoining vertebrae and with the incline of said top and bottom walls of the plug permitting the vertebrae to be pulled together to restore normal disc contour and to maintain sagittal alignment of the vertebrae.

5. The device of claim 4 wherein the means for locking are teeth adapted to bite into the adjoining vertebrae.

6. The device of claim 4 wherein the slot extends longitudinally of the plug.

7. The device of claim 4 wherein the side walls of the plug are smooth.

8. The device of claim 4 wherein the tool receiving portion is a recess in an end wall of the plug.

9. A pair of wedge shaped prosthetic devices adapted for fusing together spaced adjoining vertebrae in a spinal column prepared with a pair of laterally spaced posterior to anterior rectangular channels in their adjoining faces with each said pair of devices having an imperforate support function separate from a fusion function which comprises, a pair of wedge shaped inert rigid plugs defined by top, bottom, side and end walls, each of said plugs being substantially narrower than high and longer than high, said top and bottom walls having surfaces for engaging the bottoms of the channels and being oriented to converge along their length toward the posterior end of the channels receiving the plug, said side walls having smooth flat faces with bone growth receiving windows configured to face the sides of the channels, and one of said end walls of each plug having a tool receiving recess facilitating insertion of the plug in its channels.

10. The device of claim 9 wherein the window of each plug is a slot through the plug.

11. The device of claim 9 wherein the windows are provided by a horizontal slot through the plug.