Total Hip Arthroplasty Failure Leading to a Delayed Life-Threatening Hematoma: A Case Report and Analysis of the Pathological Mechanism

Background: Chronic expanding hematoma (CEH) represents a rare complication subsequent to total hip arthroplasty (THA), characterized by a delayed-onset, progressively enlarging soft-tissue mass capable of inducing severe osteolysis. Its imaging characteristics frequently overlap with granulomatous lesions induced by wear particles, thereby necessitating a systematic diagnostic approach to exclude pseudotumor, malignant soft-tissue neoplasm, and deep periprosthetic joint infection. Reported cases in the literature predominantly involve cementless prosthetic fixation. However, its occurrence in association with a cemented acetabular component featuring a ceramic-on-polyethylene bearing surface, particularly in the absence of significant prosthetic wear, is exceedingly rare and, to our knowledge, undocumented. Case Presentation: We present the case of a 66-year-old male with a remote history of acetabular fracture who underwent left THA in 2015 for secondary osteoarthritis, receiving a cementless femoral stem and a cemented all-polyethylene acetabular component. Eight years postoperatively, he presented with progressively worsening hip pain. Imaging studies revealed catastrophic failure of the acetabular construct, manifesting as massive osteolytic defects involving the ischial and pubic rami, alongside a complex soft-tissue mass exhibiting heterogeneous signals indicative of an organized hematoma. Intraoperative exploration confirmed the evacuation of approximately 800 mL of mixed acute and chronic hematoma and identified a persistently bleeding venous plexus at the site of a medial acetabular wall defect. Histopathological examination confirmed old hemorrhage with hemosiderin deposition, ruling out infection and neoplasia. A staged revision strategy was consequently employed. The initial stage focused on hematoma evacuation and securing hemostasis. The definitive reconstruction in the second stage was achieved using a patient-specific, 3D-printed titanium acetabular component designed from preoperative CT data. At the two-year postoperative follow-up, the prosthesis remained radiographically stable, accompanied by significant clinical and functional improvement. Discussion and Conclusion: In conclusion, this case illustrates that mechanical abrasion from a loosened cemented acetabular component can erode adjacent vascular structures, culminating in an expanding hematoma. Furthermore, it highlights that for such complex presentations involving concurrent hematoma and massive acetabular bone loss, reconstruction utilizing three-dimensionally printed, patient-customized implants is pivotal for achieving successful and stable revision outcomes.