Metal-on-metal (MoM) hip arthroplasty was re-popularized in the 1990s to resolve osteolysis and wear associated with metal-on-polyethylene products. Despite early success, registries began reporting high failure rates due to adverse reactions to metal debris (ARMD), manifesting as pseudotumors, hip effusions and osteolysis. Evaluation includes clinical exam, advanced imaging, and blood metal ions and infectious markers. This review provides physicians with an evidence-based update on the 1) clinical workup and management of patients with existing MoM implants, 2) risk and prognostic factors associated with suboptimal results and 3) the precipitating events and lessons learned applicable to future orthopedic prosthesis.