A patient-specific tissue graft and a method of forming the graft is disclosed. A 3D image of a patient's targeted implant site and surrounding anatomy is obtained to note the boundary of the implant site. A 3D model of the graft is formed by utilizing the boundary of the implant site, a surface curvature, extrapolated from the patient's target implant site surrounding anatomy, and a depth, defined by a plane parallel to a plane normal to a point of curvature at the surface. Donor tissue is chosen that has a location with a close approximation to the 3D model of the graft. The donor tissue is visualized to determine a cutting path to shape or modify the architecture of the tissue. A cutting path is determined with imaging technology and computational methods. The graft is cut out of the donor tissue utilizing a fluid cutting process.

An expandable implant is disclosed having an adjustable height for insertion between two adjacent bony structures or joint surfaces, for example between two adjacent spinal vertebrae. The implant includes at least one gear associated with at least one threaded shaft. Rotation of the gear engages the threaded shaft to expand the implant. The implant can be inserted in a collapsed configuration and expanded in situ. The invention also provides methods for using the implant to facilitate arthrodesis or fusion of adjacent joint surfaces or spinal vertebrae.