A joint prosthesis spacer (2, B') comprises a first side (2b, B2) to be disposed away from a bone of a patient and a second side (2c, B1') opposite the first side, the second side comprising a patient specific bone facing portion to face the bone of the patient. The joint prosthesis spacer further comprises a body extending between the first side and the second side, the body configured to adjust the spacing of a prosthesis component (10, 10') coupled with the first side from a surface of the bone to which the patient specific bone facing potion is coupled. At least the second side of the joint prosthesis spacer has been compressed from a first state to a second state that is more compressed that the first state.
