Aseptic hip pneumarthrosis following modular total hip arthroplasty: a potential mimic of hip infection

Pneumarthrosis following total hip arthroplasty accompanied by acute hip symptoms is a potentially ominous finding suggesting infection with gas-forming bacteria, a medical emergency. We describe a case of a 61-year-old male presenting to the Emergency Department 43 months following a titanium/titanium (Ti/Ti) modular neck-stem total hip arthroplasty (MTHA) (Wright Medical Systems, Arlington, Tennessee) with acute presentation of hip symptoms and joint gas on radiographs proven to be aseptic hip pneumarthrosis. We review the imaging features of aseptic hip pneumarthrosis following MTHA which have not been elaborated on previously and suggest a less aggressive workup in select cases. We believe emergency radiologists should be aware of this unusual complication as it may mimic a septic hip which may entail an unnecessarily aggressive workup.