Spontaneous Early Intraprosthetic Dislocation of 22 mm Skirt
A 76-year-old lady presented to the clinic with painful hip hemiarthroplasty after a fractured neck of the femur. CT scans suggested acetabular erosion. She was an American Society of Anesthesiologists with 3 patients with concerns of balance issues and a high BMI of 42. She underwent complex primary THR using the standard posterior approach to the hip. The stem was a well-fixed cemented JRI stem, to reduce the morbidity, the stem was retained a dual mobility uncemented acetabular ACE cup was used with a size 40 poly head. The inside metal head used was 22 mm (+3) plus head to achieve optimum leg length and offset. A good range of movement and stability were achieved. The patient had an eventful recovery with satisfactory postoperative radiographs.

The patient had immediate relief from groin pain. The wound pain settled in 2 weeks. At 5 weeks, she was mobilizing with one stick and no pain. She woke up one morning with spontaneous onset pain in the groin region and difficulty in weight-bearing. She presented to the emergency department. Radiographs showed the eccentric position of the femoral neck in the socket. A diagnosis of IPD was established and revision surgery was planned. She underwent exploration of her hip. The metal head had dislocated from the polyethylene head and both components were resting in the acetabular socket. No macroscopic erosion of the acetabulum was noticed. The components used were a 52 mm shell (ACE; JRI acetabular system) and dual mobility cup 40 mm outer and 22 mm inner small femoral component. The polyethylene component and femoral head were retrieved. The acetabular component and femoral stem were found stable and well-fixed intraoperatively, so a decision to revise only the liner and femoral head was taken. With previous failed dual mobility decision was made to achieve stability with a larger head size and lipped liner posteriorly. The components placed at revision surgery were a hooded liner with a 10° hood (ACE; JRI) and ceramic femoral head Biolox 36 mm (CeramTec, Germany). Post-operative radiographs confirmed that the femoral head was concentrically reduced in the acetabulum after the revision total hip replacement. At 3 months follow-up, the patient is doing well clinically and radiographically.