The Avanta CMC implant is a “ball and socket” design used to treat basal joint arthritis of the thumb. The prosthesis is offered in various sizes to accommodate anthropomorphic variations in trapezio-metacarpal sizes. The metacarpal component is titanium and is designed to fit the medullary canal of the thumb metacarpal. The implant is fixed in the metacarpal using a mantle of bone cement. The stem has a conical shape to resist impaction stresses and a highly polished ball for engagement with the trapezial component. The trapezial component is made from ultra-high molecular weight polyethylene (UHMWPe) and has a proximal stem for insertion into the prepared trapezium. A mantle of bone cement is used to facilitate fixation to the trapezium bone. The trapezial component has a congruous cup corresponding to the polished ball on the metacarpal component. The components are coupled together using a snap fit. The “ball and socket” design allows for 90° of conical articulation that permits radial circumduction of the CMC joint. The implant is provided with instrumentation to aid in bone preparation and proper size determination.