A fusion device for fusing a joint of a human or animal patient is provided, wherein the joint is a synovial joint comprising two articular surfaces and a gap therebetween, and wherein the device comprises: at least one anchorage portion (1) and at least one stabilization portion (2), wherein the anchorage portion(s) and the stabilization portion(s) constitute separate parts wherein the fusion device has an overall depth (D) parallel to an implantation direction (I), the overall depth extending from a proximal face (4) to a distal end of the fusion device, an overall width (W) and a thickness profile (T1 and T2) perpendicular to the implantation direction (I), wherein the at least one anchorage portion (1) comprises a thermoplastic liquefiable material being arranged on a surface of the anchorage portion (1) or inside a perforated sheath (52) constituting a part of the anchorage portion (1), and wherein the anchorage portions are configured to be positioned and anchored between the articular surfaces in the joint first, and the stabilization portion is capable of being mounted on the proximal ends of the anchorage portions or wherein the stabilization portion is configured to be positioned between the articular surfaces first, and the anchorage portions are capable of being pushed through or past the stabilization portion and anchored in the bone tissue beside and/or beyond the stabilization portion.
