Component dissociation secondary to trunnionosis is rare, and its causes are multifactorial. It is a major complication of total hip replacement, in most cases requiring revision arthroplasty. In this paper, we present a case of taper/head modular interface dissociation in a metal-on-metal total hip replacement. We review the literature of both trunnionosis, as well as a systematic review of modular dissociation of the femoral component in total hip arthroplasty, identifying commonalities with our own case.