Delayed Adverse Reactions to Metal Debris Secondary to Polyethylene Liner Wear in Total Hip Arthroplasty Presenting as a Hemorrhagic Trochanteric Pseudotumor: A Case Report

gradual decline in mobility over 4 months, limiting her walking distance to <500 m in the past month due to pain.She had undergone right uncemented THA 7 years ago with a Stryker Meridian modular femoral stem (size 3, 155 mm), Trident-2 Tritanium clusterhole acetabular shell (46 mm), polyethylene liner (36 mm), and cobalt-chromium femoral head (32 49 mm).There was no recent trauma, fever, weight loss, or increased activity prior to symptom onset.On examination, the patient had an antalgic gait and tenderness over the anterior hip joint line.FABER and FADIR tests were positive, and IntroductIonTotal hip arthroplasty (THA) remains one of the most effective orthopedic procedures, providing sustained pain relief and improved mobility in patients with end-stage hip disorders.Despite its overall success, long-term complications such as polyethylene wear and aseptic loosening continue to pose challenges, particularly in patients with systemic comorbidities or higher activity levels.Polyethylene liner degradation can result in eccentric loading and eventual metal-on-metal (MoM) contact, generating particulate debris that incites adverse local tissue reactions (ALTR), including pseudotumor formation and metallosis.We present a rare case of adverse reaction to metal debris (ARMD) in a patient with a MoP THA, where significant liner wear led to acetabular osteolysis, metallosis, and intraoperative discovery of a hemorrhagic trochanteric bursal cyst.This case underscores the importance of recognizing atypical soft tissue responses to wear debris, even in seemingly stable MoP constructs, and highlights the need for ongoing surveillance and timely surgical intervention to prevent progressive implant failure. case descrIptIonA 67-year-old female with a history of rheumatoid arthritis, hypertension, and hypothyroidism for 15 years presented with gradually progressive right hip pain and difficulty walking for 1 month.Previously an active ambulator walking 3 km daily, she reported a 1-