The present invention discloses an improved shoulder joint implant assembly including a plastic ball secured to a first joint defining bone end face and a plastic receiver secured to a second joint defining bone end face. Each of the ball and receiver implants are constructed of a composite hardened plastic with a softened cartilage wear surface plastic. A fastener is secured to the first joint defining bone end face and over which is mounted the plastic ball. Anchoring of the receiver is established by a pair of integrally formed and inwardly extending mounting tabs, these further extending into further recess machined cavities in the first bone.