Expandable interbody fusion cage and method for insertion

An expandable fusion cage adapted to be inserted between a pair of vertebral bodies, comprising:

• a body having an outer bone engaging surface and an inner surface defining an internal chamber and a retaining mechanism, said body defining at least a first branch, said branch having a fixed portion connected to said body and an expandable portion movable with respect to said body, said body defining at least a second branch connected to said body;
• and
• an expansion mechanism sized to be at least partially received within said internal chamber and to engage said expandable portion, said expansion mechanism having an outer surface adapted to engage said retaining mechanism, whereby movement of said expansion mechanism within said internal chamber urges said first branch expandable portion to move with respect to said body thereby expanding said body, said expansion mechanism moving said first branch expandable portion at a greater rate than said second branch, said expansion mechanism retained in position by engagement with said retaining mechanism of the body.

An expandable cage adapted to be inserted between a pair of vertebral bodies, comprising:

• a tubular body having an outer bone engaging surface and an inner surface defining an interior chamber and a retaining mechanism, said body includes a fixed end and an expandable end and further including four longitudinal channels extending between said outer surface and said inner surface and from said expandable end toward said fixed end, said channels defining an opposing first and second branches separated by opposing third and fourth branches;
• and
• an expansion mechanism having an outer surface configured to engage said inner surface and said retaining portion, whereby said expansion mechanism is moved against said inner surface to move said expandable end to expand said body, said expansion mechanism expanding said opposing first and second branches at a substantially greater rate than said opposing third and fourth branches, and said expansion mechanism retained in position by engagement with said retaining mechanism.

The expandable cage of claim 13, wherein said retaining mechanism includes at least one flange defined adjacent said inner surface and said expansion member includes a shoulder cooperable with said flange to maintain the position of said expansion member.

An expandable fusion cage adapted to be inserted between a pair of vertebral bodies, comprising:

• a body having an outer bone engaging surface and an inner surface defining an internal chamber, said body defining at least two branches, each of said at least two branches having a fixed portion and at least one of the branches having a movable portion;
• and
• an expansion mechanism at least partially disposed within said internal chamber whereby movement of said expansion mechanism along said internal chamber causes said body to expand with said at least one branch expanding at a greater rate than another of said at least two branches.