Inflammatory pseudotumor of the hip: a complication of arthroplasty to be recognized by the radiologist

Abstract

Soft tissue complications following hip arthroplasty may occur either in cases of total hip arthroplasty or in hip resurfacing, a technique that has become popular in cases involving young patients. Both orthopedic and radiological literatures are now calling attention to these symptomatic periprosthetic soft tissue masses called inflammatory pseudotumors or aseptic lymphocytic vasculites-associated lesions. Pseudotumors are associated with pain, instability, neuropathy, and premature loosening of prosthetic components, frequently requiring early and difficult reoperation. Magnetic resonance imaging plays a relevant role in the evaluation of soft tissue changes in the painful hip after arthroplasty, ranging from early periprosthetic fluid collections to necrosis and more extensive tissue damage.

Reactive Peri-Arthroplasty Pseudotumors: A Rare Cause of Hip Pain and Iatrogenic Sciatica

“…Post-MoM pseudotumor refers to the formation of a cystic lesion at the site of the original THA and is theorized to be an acute inflammatory response to metallic debris, causing lymphocyte recruitment with subsequent soft tissue fibrosis and necrosis [11]. Despite often being asymptomatic, large cysts may cause a nonspecific prodrome, including palpable hip mass, periprosthetic tenderness, and a mass effect [12]. Additionally, some patients may experience a rise in serum chromium and cobalt levels in their blood, urine, and/or synovial fluid due to prosthetic leakage, although it is not always seen.…”