This paper proposes the conceptual design of a mechanical stimulator that uses a tissue engineering strategy to develop a diarthrosislike structure in vivo. The adopted design approach is based on a function analysis. The approach has resulted in the design of a stimulator consisting of four components: cages, a compliant four-bar mechanism, a transmission mechanism, and a fixation component. The implanted stimulator is driven by internal body power, particularly by the longitudinal deformation of a skeletal muscle. The compliant mechanism is designed to impose controlled shear and compressive strain to the growing joint construct in order to initiate cartilage formation. The paper emphasizes the conceptual design and its rationale. Evaluation using finite element analysis was performed, which showed that the design meets the technical demands. Titanium prototypes were fabricated for stiffness and endurance testing.