Modular femoral stem-head systems are used increasingly due to their ease of application and offset adjustment. However, this modularity has brought complications of trunnion wear and breakage. Although very rarely encountered, trunnion fracture is a catastrophic complication that requires challenging revision surgery. This report presents a trunnion fracture of a cobalt-chrome alloy, fully porous-coated femoral stem. Following single-stage revision surgery, full weight-bearing was achieved in six weeks, and the patient was painlessly mobile with a single cane and had a Hip Score of 81 in the last follow-up. Despite all the advantages of the femoral stem and head modularity, one should remember that a catastrophic complication such as trunnion wear and fracture that require revision surgery is possible.