US 5,026,373 A · Surgical method and apparatus for fusing adjacent bone structures

Abstract

A fusion cage 10 having an external thread 12 can be surgically inserted into a threaded bore extending laterally between the adjacent bony structures such as two vertebrae 94, 95 with the thread 12 penetrating into cancellous bone of each of the vertebrae 94, 95. The fusion cage 10 is easily screwed into place by hand without damage to the bony structures 94, 95. Cage 10 is then packed with a bone-growth-inducing substance such as cancellous bone. When a pair of such cages 10 are implanted between adjacent vertebrae 94, 95, patients have been able to sit without pain by the second or third day, much earlier than has been possible in prior spinal fusions except those involving steel plates and screws. Eventually, the ingrowth of bone through perforations 13 in the valley 14 of the thread 12 of the fusion cage 10 forms a permanent interconnection between the two bony structures 94, 95.

Claims12

Dependent claims

Surgical method of fusing adjacent vertebral bony structures, said method comprising the steps of

(a) spreading apart the adjacent vertebral bony structures, and forming between said vertebral bony structures a lateral bore, which extends into the disc space between adjacent vertebral bony structures, with a female threat that penetrates into cancellous regions of the bony structures,
(b) selecting an appropriately sized hollow cylindrical fusion cage which has an external, substantially continuous helical threat which defines a plurality of turns with a valley between adjacent turns and that is perforated in the valley between adjacent turns and that can mate with said female thread,
(c) screwing the cage into said threaded bore, and
(d) packing the cage with bone-inducing substance.

1 more element

Method for surgically preparing two adjacent vertebrae for implanting a hollow cylindrical fusion cage that has an external, substantially continuous helical thread which defines a plurality of turns with a valley between adjacent turns and that is perforated in the valley between adjacent turns of the thread, said method comprising the steps of:

(a) cutting away ligaments to expose the site,
(b) spreading the vertebrae apart,
(c) nibbling away as much of the lamina as is necessary to access the site,
(d) drilling a pilot hole laterally between said vertebrae of sufficiently small diameter to be self-seeking of the center of the disc space,
(e) inserting a pilot rod into the pilot hole,
(f) sliding over the pilot rod a hollow lamina drill to cut the spinous process and to score the lamina,
(g) drilling to remove the lamina within the score then removing the hollow lamina drill and the pilot rod,
(h) fitting into the resulting acruate opening in the lamina a C-retractor which has a split cylindrical sleeve of about the same diameter as the lamina drill and a handle extending from one end toward the upper end of the spine,
(i) reinserting the pilot rod to rest on the bottom of the pilot hole,
(j) sliding a hollow vertebral drill over the pilot rod and inside the sleeve of the C-retractor,
(k) forming with the hollow drill a bore that penetrates into at least the cortical bone of each of said vertebrae,
(l) removing the hollow drill, the pilot rod, and the cut bone, and
(m) using the C-retractor as a guide, tapping a female thread, the crown of which extends into the cancellous bone of each of the vertebrae.

10 more elements

Dependencies are inferred from the claim text.

Surgical method and apparatus for fusing adjacent bone structures

Life of this patent

Surgical method and apparatus for fusing adjacent bone structures

Life of this patent

Abstract

Claims12