A procedure and device that resolves CMC arthritis by mimicking a thumb CMC joint fusion, while avoiding common shortcomings of the fusion surgery as well as existing alternative surgeries for thumb CMC arthritis which can also replace the trapezium bone in the carpometacarpal joint with a stemmed trapezial implant. In addition, the trapezial implant device replicates skeletal anatomy and is configured to directly contact native bone and cartilage in order to more evenly distribute stresses.

An apparatus can include a metacarpal implant, a trapezium implant, and a spacer. The metacarpal implant can include a stem to be inserted into a first cavity of a metacarpal bone and having a first end and a second end, a radial lip, the radial lip extending from the second end, and an opening, the opening extending from the radial lip to the first end. The trapezium implant can include an implant head portion having a shape to match a shape of a trapezium bone and a first cavity insert, to be inserted into a second cavity of the trapezium bone extending from the bottom surface. The spacer can include a spacer head portion congruent to the implant head portion and an opening insert to be inserted in the opening and extending from the bottom surface.

The invention relates to a device for producing spacers, which comprises a lower part and an upper part, wherein the lower part can be connected to the upper part, and wherein the lower part comprises a first mold cavity, and the upper part comprises a second mold cavity, wherein the first mold cavity is configured to jointly form a hollow space together with the second mold cavity, wherein the first mold cavity comprises a spacer body mold for forming a spacer body, and the second mold cavity comprises a shaft mold for forming a shaft.