Short-term primary and revision modular dual-mobility cup total hip arthroplasty outcomes in high-risk dislocation patients: a retrospective study.

PURPOSE

Modular dual-mobility cups (MDMCs) have a lower risk for dislocation after total hip arthroplasty (THA). The primary aims of our study were to analyze implant survivorship and to determine complications, especially dislocation, and revision rates of primary THAs used for hip fracture patients and for revision THAs. Secondary aims were to evaluate mortality after MDMC surgery and to find out if introduction of MDMC at our institution (Kuopio University Hospital, Finland) have decreased dislocation rate.

METHODS

This retrospective cohort study consisted of 101 MDMC patients who were consecutively operated at our institution between April 1, 2018 and June 30, 2020. The implant survival rate, complications and mortality were evaluated with minimum of 2-year follow-up. Finnish Hospital Discharge Register was used to find out yearly dislocation rates following THA at our institution.

RESULTS

The cumulative estimate implant survival after MDMC in the primary THA group was 97% at 2 years, and in the revision THA group, it was 90% at 2 years. Dislocation was a rare complication in the primary THA group (1.4%), while it was common in revision THA group (12.9%). The cumulative estimate for mortality after MDMC in the primary THA group was 13% at 2 years, and in the revision group, it was also 13% at 2 years. The yearly number of patients who had re-hospitalization period due to THA dislocation decreased 46% after implementation of MDMC.

CONCLUSION

Short-term survival and complication rates after MDMC were excellent after primary THA and moderate after revision THA. Implementation of MDMC THA for hip fracture patients seems to have effectively decrease dislocation rate during a short follow-up.