Recurrent and radiographically unrecognized iatrogenic intra-prosthesis hip dislocations

Intraprosthetic Dislocation of a Modular Dual-Mobility Total Hip Arthroplasty With Posterior Migration of the Polyethylene Liner

Dual-mobility (DM) implants have been used in total hip arthroplasty since 1974. Modular DM implants have seen an increase in use in primary and revision total hip arthroplasties given the theoretical decreased dislocation rate. DM constructs have 2 articulation sites, one between the acetabular shell and a polyethylene liner, as well as one between the liner and the femoral head component. However, dislocations with modular DM implant dislocations can still occur. These dislocations occur via an extraprosthetic or intraprosthetic mechanism. Intraprosthetic dislocation is a phenomenon in which the smaller femoral head dissociates from the polyethylene liner. We present a case of intraprosthetic dislocation in an 81-year-old female with migration of the polyethylene liner into her gluteal muscles after 2 attempted closed reductions.

Dual mobility hip arthroplasty: iatrogenic intraprosthetic dislocation of a 22 mm head

We describe the first intraprosthetic dislocations of a 22 mm head in a dual mobility hip replacement in the literature. This case emphasises the importance of information gathering and planning when dealing with arthroplasty complications. Furthermore, it highlights the necessity of adequate muscle relaxation and analgesia when dealing with hip dislocations. A 78-year-old patient presented to the emergency department (ED) with a spontaneous dislocation of her left dual-mobility total hip replacement 3 months after first-stage revision surgery for infection. Reduction via manipulation under analgesia was then attempted in the ED but was ultimately unsuccessful; an iatrogenic intraprosthetic dislocation of the polyethylene liner was sustained. Several factors may have contributed to liner dislocation: a failure to appreciate the implant type, multiple manipulations in ED were attempted under analgesia, but no sedation or muscle relaxation was administered to the patient. The patient subsequently underwent revision surgery.