Revision Total Hip Arthroplasty With Dual Mobility Cup for Neglected Non- Traumatic Dislocation Following Conversion Long Stem THA After Failed Intertrochanteric Fracture Fixation: A Case Report

Abstract Background Conversion total hip arthroplasty (THA) following failed internal fixation of proximal femoral fractures is technically challenging and is associated with an increased risk of complications, including postoperative instability.¹˒² Dual mobility constructs have been increasingly used in revision THA to improve stability and reduce the risk of recurrent dislocation.⁴˒⁵ Case presentation We report the case of a 62-year-old South Asian female who presented with chronic pain and inability to walk following neglected non-traumatic dislocation of a previously operated left long-stem total hip replacement. She had initially sustained a left intertrochanteric femur fracture following a slip and fall at home, which was treated with open reduction and internal fixation using an angle blade plate. Following implant failure, she underwent conversion to an uncemented long-stem THA. Within two weeks, she developed spontaneous anterior dislocation of the prosthetic hip without trauma. Closed reduction under anaesthesia was attempted but failed, and she subsequently had persistent pain, functional limitation, and inability to bear weight. Imaging demonstrated a dislocated prosthesis with extensive fibrosis and pseudo-acetabulum formation. Revision THA was performed using an extended trochanteric osteotomy for removal of the existing femoral stem, an uncemented long diaphyseal-fitting revision femoral stem, and a cemented dual mobility acetabular cup. Cerclage wiring was used to provide additional support. The hip was stable intraoperatively, and postoperative rehabilitation was initiated. The patient achieved full weight-bearing mobilisation with a walker from postoperative day 2, with satisfactory postoperative radiographs and significant relief of pain. Conclusion Neglected prosthetic hip dislocation following conversion THA after failed fracture fixation presents a complex reconstructive challenge because of altered anatomy, fibrosis, pseudo-acetabulum formation, and compromised soft tissues.¹˒² Revision THA using an uncemented long revision stem combined with a cemented dual mobility acetabular component can provide a stable reconstruction in such high-risk cases.⁴˒⁶ Dual mobility articulation should be considered in revision THA when there are significant risk factors for instability.⁴˒⁵˒⁷