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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.

Trunnion fracture is an incredibly rare complication of total hip arthroplasty. Of the few reported cases, all involve implants with faulty designs, a small neck taper, or an extended neck length or offset. Most also report corrosion and an adverse soft-tissue reaction. We present a review of the literature and report on the first case, to our knowledge, of trunnion fracture in a well-fixed, cemented cobalt-chromium femoral component with a standard neck length and offset with no evidence of corrosion. This failure was likely related to scratching of the metal during previous procedures which led to crack propagation and catastrophic failure. The patient was treated with revision hip arthroplasty to an uncemented, distal-fit femoral component and insertion of new bearing surfaces.

In the setting of chronic instability following total hip arthroplasty, implantation of a constrained acetabular liner may be warranted. We report on a patient who sustained a posterior prosthetic hip dislocation out of the constrained acetabular liner component (Stryker Trident [Kalamazoo, MI]), which had been previously replaced 2 months prior, and underwent a successful closed reduction in the emergency department. At 2-year follow-up, the patient’s prosthetic hip has remained stable with no reported issues. To our knowledge, this is the first reported closed reduction of a revised constrained total hip arthroplasty with this implant system, size, and length of follow-up.

Obesity and lower-extremity arthritis are challenging problems to address as they are often mutually exacerbating. Due to the known perioperative risk of morbid obesity, the modality and timing of weight loss prior to arthroplasty is debated. We present a case of a 55-year-old nonambulatory female patient with an initial body mass index of 80.3 kg/m2. This individual underwent a staged bariatric and joint replacement surgical pathway employing personnel of differing treatment disciplines. Our patient successfully lost a substantial amount of weight and has been able to ambulate, exercise, and engage in new, strenuous physical activities. In the care of the nonambulatory bariatric patient, employing a multidisciplinary treatment plan can produce successful results.