Intraprosthetic dislocation of dual-mobility total hip arthroplasty implant.

Dual-mobility total hip arthroplasties were developed to decrease the risk of dislocation and instability seen with traditional fixed-bearing total hip arthroplasties. However, dual-mobility constructs, notably the first-generation design, come with a risk of intraprosthetic dislocation (IPD). These dislocations occur when the polyethylene femoral head component is dislodged, causing direct articulation between the inner ceramic femoral head and the metal acetabular shell. This is different than a polyethylene liner dislocation in a standard total hip arthroplasty. Causes of IPD include polyethylene wear and iatrogenic dislocation from closed reduction attempts. Timely identification is essential to reduce the risk of soft tissue metallosis, raised cobalt and chromium levels, and the need for major revisions. This complication can be seen on imaging, but radiologists must be aware of the various components and mechanisms of failure to recognize this unique complication. We present a case of a dual-mobility construct with IPD between the femoral head components, illustrated on radiographs and CT and subsequently confirmed at the time of surgery.

Blastomycosis of the Central Nervous System.

The reported incidence of blastomycosis is increasing in certain regions of the United States. The diagnosis is primarily made via urine antigen testing, culture, or cytology smear. The differential diagnosis for blastomycosis includes pneumonia, tuberculosis, and non-infectious pulmonary disease. Clinical context and epidemiologic exposure play a crucial role in diagnosis. However, the differential can expand significantly if there is disseminated central nervous system involvement, especially if pulmonary manifestations are not seen. Imaging begins to play a vital role when differentiating disseminated blastomycosis from other etiologies such as malignancy. Herein we present a case of a 58-year-old male who presented with seizures and right sided gaze preference found to have disseminated central nervous system blastomycosis. In this article, we will discuss symptoms and imaging findings of disseminated blastomycosis to help guide diagnosis and management.