Metal-on-Metal Total Hip Arthroplasty Associated with Adverse Local Tissue Reaction and Pseudoaneurysm of the Superior Gluteal Artery: A Case Report and Literature Review.

Adverse local tissue reaction (ALTR) and pseudoaneurysm formation are rare but known complications following metal-on-metal hip total hip arthroplasty (THA). We report the first known case in the English literature of a concurrent unilateral ALTR and pseudoaneurysm of the superior gluteal artery in the same patient. Following minimal rise in serum metal ions, an ultrasound of the right hip demonstrated an avascular solid/cystic lesion anterolaterally in keeping with an ALTR. More posterolaterally, a second discrete thick-walled cystic lesion was identified. Doppler interrogation demonstrated a "yin yang" pattern suggestive of a pseudoaneurysm. Magnetic resonance imaging confirmed the presence of an anterolateral periarticular lesion with a second discrete lesion within the gluteus medius. Subsequent computed tomography angiography confirmed the presence of arterial contrast blush within the posterior gluteal lesion adjacent to the superior gluteal artery. The patient remains asymptomatic and is being managed conservatively. We review the imaging characteristics of ALTR and pseudoaneurysm occurring post-THA. When a complex solid/cystic lesion is encountered in a patient with a THA, radiologists must ensure that the lesion is interrogated with color Doppler to confidently distinguish a pseudotumor from a pseudoaneurysm. This information is vital to the surgeon to avoid unexpected hemorrhage if revision joint replacement surgery is being contemplated.