Abstract
Introduction
Total hip arthroplasty (THA) instability is well documented to be more common in specific demographic groups. We report a retrospective analysis of the use of a dual mobility implant for primary hip replacements in selected patients at risk for dislocation. The aim of this study was to assess the long-term clinical and radiologic features associated with the dual mobility cup in case of primary THA.
Materials and Methods
At our institution 119 primary THA were performed in 114 patients (74 females and 40 males) at high risk of instability between January 2000 and December 2002. 84% of the patients had at least two risk factors for dislocation. The mean age was 71 years old (range, 21.4 to 93.2 years) at the time of the arthroplasty. A dual mobility cup was used in all cases. Clinical result was assessed using Harris Hip Score, and complications were determined by detailed review of the patient's records. 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
During the study period, 56 patients (47%) died of unrelated causes. 17 patients (15%) were lost to follow-up. For the remaining 41 patients (46 hips, 38%), the minimal follow-up was 10 years (119 to 154 months, mean 133 months). Harris hip score improved from 39.6 to 82.4 (p<0.05). Only one late dislocation was observed, 7 years after the surgery, in a 35-year old female with Mannosidosis.
Two hips were revised at latest follow-up, for deep infections. No aseptic loosening of the cup or osteolysis was observed at latest follow-up.
Conclusion
The dual mobility system was extremely successful in achieving stability in this continuous series of patients with increased risk for dislocation. In addition, no mechanical failure, and no osteolysis or aseptic loosening of the cup has been reported. The use of dual mobility cup to prevent instability in selected patients is a reliable option at long term follow-up.
