Dual Mobility Acetabular Cups in Revision TJA

Inclusion Criteria: * Any patient older than 18 years of age scheduled for a revision THA, including revision of both components, conversion of a hip resurfacing to THA, conversion of a hemiarthroplasty to THA, and revision of single components which allow implantation of dual-mobility bearings. In addition, patients undergoing reimplantation of a total hip arthroplasty following a two-stage revision for periprosthetic infection will also be included. Only patients with an acetabular shell diameter capable of accommodating at least a 36mm femoral head will be included. Exclusion Criteria: * Less than 18 years of age, primary THA, * conversion of non-arthroplasty femoral neck fracture fixation to THA, * patients unwilling to participate. * patients where the surgeon makes the intraoperative decision to use a constrained liner will be excluded.