A spacer for implantation into a subject is provided that includes a sterilized piece of cartilaginous allograft tissue. The piece forms a Y-shape with a base adapted to insert within a first carpo-metacarpal joint or carpo-metatarsal joint of the subject, and has a first arm adapted to secure to a trapezium bone adjoining the joint, and a second arm adapted to secure to a proximal metacarpal or metatarsal bone adjoining the joint. A procedure for implanting the spacer includes exposing a target joint and abrading a bone surface interior to the joint to induce surface bleeding. The spacer base is then inserted into the joint. The spacer first arm is adhered to the first bone of the joint and the spacer second arm is adhered to the second bone of the joint. A kit is also provided for surgical implantation of the spacer.