The long-term outcomes of orthopaedic joint implants are only beginning to be understood, making it imperative to monitor the contact loads across the entire implant interface. This capability will elucidate the force transmission and distribution mechanisms exhibited by these implants in-service over time. This study explores the design and implementation of 3D-printed smart-polymer force sensor arrays, consisting of piezoresistive polyaniline (PANI) structures embedded within a polymeric parent phase. This unique multi-material additive manufacturing process was then employed to realize transducers embedded in the humeral component of a replacement prosthetic device conventionally used to restore the functionality of the shoulder joint. Ultimately, implant designers that better understand the interface loads can combat the wear and loosening of these prosthetics early on, reducing the number of design revisions required and increasing the longevity of the implants.