Expandable interfusion cage
An expandable interfusion cage comprising a cage body and a spacer. The cage body includes a seat part which is pierced by an orifice and a branch part which defines therein an inside space and has a plurality of elongate branches integrally formed at their proximal ends with the seat part. An opening is defined between two adjoining branches to communicate with the inside space. The spacer is movably assembled in the inside space of the cage body to expand the cage body radially outward. Inward projections are formed at distal ends, respectively, of the branches to project radially inward toward an axis of the cage body. The inside space of the cage body has substantially a circular or polygonal sectional shape. The spacer is engaged with the inward projections of the branches while expanding the cage body.
1. An expandable interfusion cage, comprising a cage body including a seat part provided with an orifice and a branch part defining an inside space and having a plurality of elongate branches formed at their proximal ends integrally with said seat part, with each two of said adjoining branches defining therebetween an opening which communicates with said inside space, said branch part having a guiding slit communicating with said opening and defined between each two of said adjoining branches when viewed on distal end surfaces of said branches, so that four said guiding slits are formed and cooperate to create a cross-shaped space; and a spacer movably arranged in said inside space of said cage body and having a substantially cylindrical spacer body with a head portion which is formed as a cross-shaped protrusion biasing said branches radially outwardly, and a base portion formed as a disc with a diameter larger than a diameter of said head portion and having a pair of guide pieces oppositely formed at both sides of said disc and engaging in said guiding slits.
2. An expandable interfusion cage as defined in claim 1 , wherein said cage body has a shape selected from the group consisting of a quadrangular shape.