Abstract
Introduction
Revision procedures for unstable total hip arthroplasty have been reported with high failure rates. Many options have been proposed in such challenging cases, including dual mobility. The purpose of this retrospective study was to assess the clinical and radiologic features associated with the dual mobility cup in case of revisions for instability.
Materials and Methods
Sixty four total hip arthroplasties (62 patients) were revised for THA instability using a dual mobility cup at our institution between March 2000 and April 2008.
Mean age at reoperation was 67.3 year old (range, 35 to 98). The outcome of the revision procedure was assessed using the Harris Hip Score, and complications were determined by detailed review of the patient's records. Anteroposterior and lateral radiographs of the involved joint were reviewed to assess the position of the prosthesis and to look for osteolysis and signs of loosening of the implant.
Results
Mean follow-up was 7.5 years (range, 3.5 to 11.1). At last review 11 patients had died and one was lost to follow up. Postoperatively there was a significant improvement of the Harris Hip Score. Sixty-three patients (98.4%) had no further episodes of dislocation. There were 3 revisions for deep infection, and 4 for mechanical failures including 2 dissociation of the bipolar component, one head-trunion dissociation, and one aseptic loosening of the acetabular construct. For the remaining patients, no radiolucent lines around the components and no osteolysis were observed at latest follow up.
Conclusion
The dual mobility cup is a highly effective option to manage unstable total hip arthroplasty. Unlike constrained devices, such implants provide encouraging radiologic results regarding the potential for loosening and osteolysis at mid- to long-term.
