Abstract: Reference numeral 10.1 generally depicts a prosthesis which includes an implant 12.1 which is configured to imitate or replicate the anatomic characteristics and functions of a trapezium bone 14 and a mounting means 16 for mounting the implant 12.1 on a FCR tendon 18 of a patient to inhibit dislocation of the implant 12.1 in use. The implant 12.1 is formed from any synthetic plastics or metallic material suitable for insertion in a CMC joint capsule 20. The implant 12.1 is contoured and/or dimensioned to facilitate engagement with and/or articulation of the trapezoid 22, scaphoid 24, index metacarpal 26, and thumb 28 metacarpal bones as shown in FIG. 1.