➤ The etiology of clinically relevant trunnion corrosion remains to be fully understood, but appears to be multifactorial with synergy among implant-based, surgeon-based, and patient-based factors.➤ Trunnion corrosion causing an adverse local tissue reaction (ALTR) typically manifests as delayed onset of groin, buttock, or thigh pain after primary total hip arthroplasty.➤ Trunnionosis is probably underreported since it often causes osteolysis and loosening, and the awareness of the problem, although increasing, is not universal.➤ Measurement of serum cobalt and chromium ions and advanced cross-sectional imaging, including metal artifact reduction sequence magnetic resonance imaging, can aid in diagnosis.➤ Revision for trunnion corrosion-induced ALTR can often be accomplished with a head and liner exchange, with retention of the acetabular and femoral components.➤ The surgeon should be aware of implant recalls and be cognizant of ongoing litigation against implant manufacturers.➤ The surgeon should strive to preoperatively identify the angle and type of taper in the well-fixed stem and request that the proper implants are available for the revision total hip arthroplasty.