Dislocation rate and survivorship of dual mobility cup in primary total hip arthroplasty in high risk population: a prospective study

Background: Instability after Total Hip Arthroplasty (THA) remains an important complication, with reported dislocation rates ranging vary between 0.2% and 10%. The present study aims at reporting the rate of dislocation and survivorship in dual mobility cup THR, the possible cause and assess the clinical results.

Materials and methods: We evaluated 111 patients using dual mobility cup THR between October 2014 to July 2017. Clinical and radiographic evaluations were performed at immediate post operation, 3 months and 6 months and 1 year after surgery. Patients were clinically examined for pain, walking and range of motion using the Harris Hip Scores (HHSs) system. Postoperatively complications including aseptic loosening, osteolysis, infection, periprosthetic fracture, dislocation and implant fracture were recorded.

Results: According to Kaplan-Meier method, survival probability was 97.3% (95.0% confidence interval 92.01% to 99.42%) at 1 year of follow up with dislocation rate 2.7% (3 patients). The three patients which dislocated were treated with open reduction and did not re-dislocate at 1 year follow up.

Conclusions: The prevalence of dislocation is low in our high-risk population and we consider it preferred concept for patients undergoing complex total hip replacement.