Femoral head dislodgement complicating use of a dual mobility prosthesis for recurrent instability.

The dual mobility cup is an unconstrained tripolar configuration newly introduced to the United States in February 2011. The dual mobility construct allows for a larger femoral head to improve motion and minimize the risk of dislocation. We present a case of a patient who received the dual mobility cup for the treatment of recurrent dislocation following total hip arthroplasty. Early in the patient's postoperative course, the implant failed at the articulation between the larger outer polyethylene head and inner smaller metal femoral head following an attempt at closed reduction. This implant specific complication has not been reported in the North American literature.