Nonconcentric and Irregular Dislocations of Total Hip Arthroplasties: Radiographic Analysis and Review of the Literature.

Abstract Background Total hip arthroplasty (THA) is one of the most successful operations in all of medicine in improving patient pain and restoring function. However, complications do arise after primary and revision THA. Dislocation of a THA, also known as instability, occurs in 1–2% of primary THAs and up to 30% of revision THAs. Most dislocations in the United States are initially managed with closed reduction under procedural sedation in emergency departments (EDs) by on-call orthopedists or emergency medicine specialists. Objective In this review the characteristics of the articulations that may require closed reduction in the ED are described, as well as their radiographic findings prior to reduction. Finally, we present subtle radiographic findings associated with failed closed reductions. Discussion Due to the different types of implants that have been introduced, closed reduction can be challenging in certain cases. Iatrogenic intraprosthetic dislocations are becoming more common with the increased use of dual-mobility liners. There are also dislocations after staged revision THA cases with the use of spacers. In spacers with semi-constrained articulation, there is the possibility of partial reduction of the spacer. Conclusions Dislocation is one of the most common mechanical complications after primary and revision THA. In the majority of the cases, acute closed reduction can be achieved successfully in the ED setting. However, there are specific dislocation types that present unique challenges to acute reduction.