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.

Are Routine Follow-up Radiographs Necessary for Extra-articular Scapula Body Fractures Managed Conservatively?

INTRODUCTION: Extra-articular scapula body fractures have been shown to have good outcomes with nonsurgical management. What is not known is whether routine postinjury imaging of these fractures is necessary for monitoring healing and alignment. As the shift toward providing cost-effective healthcare continues, we sought to evaluate if routine postinjury imaging of these fractures resulted in any change in management while secondarily evaluating the imaging for fracture patterns at risk of displacement. METHODS: A retrospective review of all extra-articular scapula body fractures managed nonsurgically at our institution was performed from January 2013 to December 2017. We measured the glenopolar angle, lateral border offset, sagittal angulation, and translation on both injury CT scans and follow-up radiographs to evaluate if any displacement occurred. In fractures that displaced more than 10 mm or 10° in any measurement, we evaluated the fracture pattern to see if any particular pattern posed a risk for displacement. In addition, we evaluated the cost of imaging for all radiographs obtained in the follow-up period. RESULTS: A total of 139 patients with 147 extra-articular scapula body fractures were included in our analysis. No patient experienced a change in management based on postinjury radiographs. A total of 120 patients underwent postinjury imaging with a total of 204 radiographic series ordered, equating to $172,769.50 in radiograph expenses. Final radiographs were obtained at an average of 48.4 days postinjury, and overall, no significant difference was observed (P < 0.05) in any radiographic measurement when compared with the initial injury imaging; however, when looking at fractures that displaced, transverse fracture patterns of the scapula body represented a risk factor for displacement (relative risk = 6.5). DISCUSSION: Satisfactory outcomes have previously been demonstrated with nonsurgical management of scapula body fractures and for most of these injuries postinjury imaging may not be necessary or cost effective. LEVEL OF EVIDENCE: Level IV.

Mycobacterium senegalense Osteomyelitis of the Distal Tibia: A Case Report.

Mycobacterium senegalense infection is rare. We present the third documented case of M. senegalense infection and the first to involve the musculoskeletal system. A 55-year old immunocompetent male developed chronic osteomyelitis of the ankle and required antibiotic spacers, an Ilizarov external fixator and multiple antibiotic regimens to eradicate the infection.