Abstract: Disclosed is an atlantoaxial joint replacement device and method that allows up to full normal axial rotation while stabilizing C1-C2 vertebrae. The device includes a rail member curved in a circular path with a path of curvature oriented in an axial plane. The rail member includes a track body having a non-circular cross-sectional shape. A rider member is slidingly coupled to the rail member and includes a body defining a through slot that receives there through the rail member. The through slot has a non-circular cross-sectional shape compatible to the non-circular cross-sectional shape of the track body of the rail member.

Abstract: A cannulated and possibly fenestrated device for injection of material into bone can be dangerous because large, uncontrolled pressures are introduced during injection into a somewhat closed system, and material may extrude undesirably or emboli may be introduced. Methods and devices are described for providing venting of pressure upon injection of material through cannulated and possibly fenestrated screws. The first method involves a bone screw and/or anchor device that includes multiple channels to allow material to flow in through one channel and out through another channel. The second method involves a plunger that can force material into bone if advanced or lessen pressure if withdrawn. The third method involves usage of two separate screws. Material is alternately injected or withdrawn from each screw to cause material to flow from one screw to the other in a controlled way that creates a uniform or asymmetrical distribution of material as desired.

Abstract: An implantable device assembly including a bone fusion cage assembly having first and second housing members and a biasing member. The first housing member defines a first contact surface. The second housing member defines a second contact surface that faces generally opposite the first contact surface. The biasing member is operable to bias the first and second housing members away from each other into an expanded position. Each of the first and second housing members may include at least one pivot portion that defines the contact surfaces. The implantable device assembly may also include a plate assembly that is mounted to the bone fusion cage assembly.

Abstract: A cannulated and possibly fenestrated device for injection of material into bone can be dangerous because large, uncontrolled pressures are introduced during injection into a somewhat closed system, and material may extrude undesirably or emboli may be introduced. Methods and devices are described for providing venting of pressure upon injection of material through cannulated and possibly fenestrated screws. The first method involves a bone screw and/or anchor device that includes multiple channels to allow material to flow in through one channel and out through another channel. The second method involves a plunger that can force material into bone if advanced or lessen pressure if withdrawn. The third method involves usage of two separate screws. Material is alternately injected or withdrawn from each screw to cause material to flow from one screw to the other in a controlled way that creates a uniform or asymmetrical distribution of material as desired.