An in-vitro musculoskeletal loading simulator was developed to replicate the internal forces of mastication, and then employed in a comparison of clinically relevant facial fracture repairs. Muscle forces are simulated by pneumatic pistons via 3D printed mounts that are reverse-engineered from CT scan to match muscle attachment sites, which are adhered to bone in order to simulate native stress distributions. Bite force and bone strain pattern of the craniofacial structure under load were measured using a force sensor and strain gauges respectively. In a series of five fresh-frozen cadaveric heads, it was found that strain patterns of the craniofacial structure were different between internal and external loading. In a zygomatic complex fracture with an intact zygomatic arch, an infraorbital rim plate made no difference in strain pattern. However, with a fractured arch, a repair done without an infraorbital rim plate better restored the strain pattern of an intact craniofacial structure.