Femoral Head-Trunnion Dissociation in Metal-on-Polyethylene Total Hip Arthroplasty – A Unique Case Report

Background : Gross trunnion failure (GTF) after total hip arthroplasty is a rare complication and has only been reported in a few case series. Some of the associated risk factors have been described in the literature and include larger femoral heads, greater offset, and increased BMI. Despite this, the mechanism behind GTF is poorly understood and early diagnosis and treatment continues to be challenging. Case Presentation : We present the case of complete femoral head and trunnion dissociation in a 63 year-old female nine years after total hip arthroplasty. Unique to this case is the lack of classic patient and implant risk factors for GTF along with the acute onset nearly nine years after implantation.  Discussion : This case presentation highlights the fact that the contributing factors and mechanism behind GTF continue to be poorly understood. There is a need for future research to help better understand this phenomenon and to help potentially identify those at risk for GTF.